SCIENCE BRINGS NATIONS TOGETHER LXXIV International conference Nucleus-2024: Fundamental problems and applications

1 Jul 2024, 09:00 → 5 Jul 2024, 21:00 Europe/Moscow

Bogoliubov Laboratory of Theoretical Physics (Dubna, Russia)

Nucleus-2024 is a part of a series of annual conferences held since 1950 by major nuclear research centers of the Russian Federation and CIS states. We will use this occasion to celebrate the 75th anniversary of Hans Jensen's and Maria Goeppert Mayer's seminal 1949 work.

Conference topics include:

• Nuclear structure: theory and experiment
• Experimental and theoretical studies of nuclear reactions
• Heavy ion collisions at Intermediate and high energies
• Neutrino physics and nuclear astrophysics
• Applications of nuclear methods in science, technology, medicine and radioecology
• Design of new experimental facilities

The participants will be able to present their talks only in person

It is recommended to submit no more than one abstrct from each participant 

Participants from Russian institute must attach a scanned copy of the publication permission from their native institute to abstracts

Conference fee: 12 000 rub

The conference fee may be waived for students and PhD students at the request of their supervisor

Important dates:
Abstract submission deadline: 15 April 22 April
Program committee decision communicated to authors of abstracts:  24 May
Conference fee payment deadline: 31 May

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NUCLEUS-2024 will open on July 1, 2024 at 10:00 AM in the conference hall of the Bogoliubov Laboratory of Theoretical Physics of the Joint Istitute of Nuclear Research (for directions see link to Google Maps below).

Registration of participants starts at 9:00 AM.

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Local organizing committee

Chairman: N. V. Antonenko, A. V. Karpov

Scientific secretaries: E. V. Mardyban, I. S. Rogov

Members: N. N. Arsenyev, A. P. Severyukhin, M. A. Mardyban, N. M. Dokalenko, R. V. Jolos,  E. A. Kolganova, F. R. Studenikin, A. P. Chernyaev, T. M. Shneidman, T. Yu. Tretyakova, U. A. Bliznyuk, P. Yu. Borshchegovskaya, E. N. Lykova

The working language of the conference is English and Russian.

IJMPE flyer.pdf

IJMPE highlight.pptx

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Poster-nucleus2024_final.pdf

Monday 1 July

09:30 Opening

Plenary

1 Status and development plan of accelerator complex FLNR

The presentation give information about current state of the FLNR accelerator complex, general information and last results work of facilities DC-280 and U-400, first results of U-400M facility modernization, information about New facilities for applied research DC 140 and creation process and Information about project U-400R.

Speaker: Dr Semin Vasily (Joint Institute for Nuclear Research)

2 Synthesis and study of the decay properties of isotopes of superheavy elements Ds and Lv

Bla-bla

Speaker: Dr Nikita Kovrizhnykh (Joint Institute for Nuclear Research)

3 Studies of light exotic nuclei at FLNR JINR

Bla-bla

Speaker: Prof. Leonid Grigorenko (Joint Institute for Nuclear Research)

11:30 Coffee break

Plenary

4 Quantum shells in nuclei and beyond

The present review covers historical aspects and present status of quantum shells (QS) in nuclei and some other quantum systems. The relation of QS with various nuclear features (deformation, pairing, giant resonances etc) is outlined. QS in nuclei and atomic clusters are compared. Supershells in atomic clusters are briefly described. Further, the recent studies related with QS in nuclei are reviewed, first of all, for superheavy (SH) nuclei. The last experimental and theoretical results for K-isomers are briefly discussed. Predictions for magic numbers in SH nuclei, obtained in modern density-functional theory (DFT) (with relativistic, Skyrme and Gogny forces), are outlined. Finally, we present some last Skyrme DFT results of our group for shell effects in low-energy spectra of nobelium isotopes.

Speaker: Valentin Nesterenko (BLTP, Joint Institute for Nuclear Research)

5 Heavy ion linac for nuclear physics.

Heavy ion linac for nuclear physics.
T.Kulevoy
NRC “Kurchatov institute” – Kurchatov Complex of theoretical and experimental physics

The high intensity heavy ion linac is an attractive instrument for the nuclear investigation. The high energy linac can be effectively used for the rare isotope production (for example – FRIB facility in MSU, USA and SPIRAL2 in GANIL, EU). The low energy linac (~ 7 MeV/nucleon) can be used for multi-nucleon transfer reactions investigation. In particular, the reactions study is important for understanding the so-called 3rd peak of the distributions of the astrophysical p-process. The project of the room temperature heavy ion cw-linac is based on the technology which is under development in framework of compact accelerator driven neutron source DARIA setup, it could be useful also for the other constructions [1,2]. The talk presents the linac structure and results of the cw RFQ and DTL development.

1. “Дорожная карта” в области ядерной физики, Ред. Л.В. Григоренко, М.: РАН, 2021. ISBN 978-5-907366-33-6.
2. Развитие физики и технологии ускорителей заряженных частиц, Ред.-сост. Б.Ю. Шарков, И.Н. Мешков, М: РАН, 2021. ISBN 978-5-907366-27-5.

Speaker: TIMUR KULEVOY (ITEP-NRC KI)

6 Ab initio расчеты структуры легких ядер и ядерно-физический эксперимент

Обсуждаются возможности использования современных ab initio подходов для описания различных характеристик легких ядер и ядерных реакций, индуцированных их столкновениями, границы этих возможностей и перспективы расширения этих границ.
Анализируется качество описания: спектров уровней энергии ядер; их размеров; электромагнитных моментов, вероятностей электромагнитных переходов между уровнями как одинаковой, так и разной четности; вероятностей испускания резонансными состояниями нуклонов и кластеров, в частности амплитуд приведенных ширин распада этих состояний; асимптотических нормировочных коэффициентов связанных состояний.
Демонстрируется, что результаты ab initio вычислений перечисленных выше характеристик могут во многих случаях оказаться полезными для описания сечений резонансных и прямых ядерных реакций, предсказания их сечений и анализа результатов их измерений.

Speaker: Yury Tchuvil’sky (Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia)

7 Российские высокоскоростные (125-1000 МВыб/с) многоканальные диджитайзеры

Доклад будет посвящен результатам
разработки российских скоростных
диджитайзеров 65, 14 бит - 125, 14 бит - 500 МГц,
14 бит, а также алгоритмическим
подходам, используемым при обработке
сигналов. Будет показано как решение в
железном виде, так и
продемонстрированы некоторые
результаты его совместного
использования с различными группами.

Speaker: А.В. Пашков (ООО "Диджитайзер")

14:00 Lunch

Experimental and theoretical studies of nuclear reactions: Reactions with light nuclei

8 Dimensions of $^{6}$Li in low-lying states

$^{6}$He is one of the simplest nuclei with a halo in the ground state 0$^{+}$; its study has received considerable theoretical attention [1]. In [2], an assumption was made about a halo-like structure in the isobar-analogue state of the 3.56 MeV state, 0$^{+}$ $^{6}$Li. This structure is a spatially extended halo-like structure with an alpha particle core and a proton and neutron surrounding it. In [3], it was shown that the radius of the 3.56 MeV, 0+ state is 2.5 $\pm$ 0.2 fm and, within errors, coincides with the radius of $^{6}$He, which allows for the possibility of the presence of a halo (proton-neutron, and in some works called tango-halo) [4]. Let us recall that the spatial structure of the $^{6}$He nucleus was predicted to be quite complex, in which correlations of two types appeared: “cigar” and “dineutron”.
The question arises: does the structure of the state change so much when going from $^{6}$He to the isobar analogue in $^{6}$Li that it requires the introduction of a special type of “tango-halo” [4]. To answer this question, new experimental data were required. Not long ago, the $^{7}$Li(d,t)$^{6}$Li experiment was performed on the deuteron beam of the U-150M cyclotron at the Institute of Nuclear Physics (Almaty, Republic of Kazakhstan) at an energy of 14.5 MeV. The angular distributions of the studied nuclear reactions cover the angle range from 18$^\circ$ to 128$^\circ$ (lab.). The angular distributions for the ground and first four states were obtained: 2.19, 3.56, 4.31 and 5.36 MeV. The experimental data were analysed within the framework of the DWBA method and the coupled channel method. The analysis is currently ongoing to estimate the radii of low-lying excited states. There is some indication of an increased radius of the 3.56 MeV state, confirming its halo nature.
[1] Y. Suzuki, Nucl. Phys. A 528, 395 (1991).
[2] K. Arai et al., Phys. Rev. C 51, 2488 (1995).
[3] A.S. Demyanova et al., KnE Energy & Physics, 1, DOI 10.18502/ken.v3i1.1715 (2018).
[4] I.N. Izosimov, Phys. At. Nucl. 80, 867 (2017).

Speaker: Alla Demyanova (NRC "Kurchatov Institute")

9 Search for halo structures in $^{8}$Li

One of the main directions of modern nuclear physics is the study of exotic nuclei far from the stability line, i.e. nuclei with an excess of neutrons or protons. One of the most famous representatives of exotic nuclei is halo.
In the A=8 multiplet, a halo was firstly discovered in $^{8}$B in [1] based on increased quadrupole moment. It was shown that the halo structure is $^{7}$Be core and a valence proton. It should be noted that the halo is detected despite the presence of both the Coulomb and centrifugal barriers. In [2], the presence of a proton halo in $^{8}$B was confirmed using the total cross section, as well as the root-mean-square radius R$_{rms}$ = 2.58 fm and the halo radius R$_{h}$ = 4.24 fm. The question arises about the possibility of the halo in $^{8}$Li. In [1], using the value of quadrupole moment for $^{8}$Li, it is said that there is a thin neutron skin around the $^{7}$Li core. In [2], using total cross section, it is stated that there is no halo in $^{8}$Li. To analyze the possibility of the halo in $^{8}$Li, we propose to use (d,p) reaction. Deuteron stripping is usually used as a sample of the single-neutron structure of nuclear states for last decades. The $^{7}$Li(d,p)$^{8}$Li experiment was performed using the deuteron beam of the U-150M cyclotron at the Institute of Nuclear Physics (Almaty, Republic of Kazakhstan) at an energy of 14.5 MeV. The $^{7}$Li isotope (enrichment ≈ 90%) was used as a target. The angular distributions were measured in the angle range from 18$^\circ$ to 80$^\circ$ (lab). Angular distributions were obtained for the ground and first two excited states 0.98 and 2.26 MeV.
[1] T. Minamisono et al., Phys. Rev. Lett. 69, 2058 (1992).
[2] G.A. Korolev et a., Phys. Lett. B 780, 200 (2018).

Speaker: Andrey Danilov (NRC Kurchatov Institute)

10 Population of tetraneutron continuum in reactions of 8He on deuterium

The search for the the multineutron systems is old, but still unsettled problem of the low-energy nuclear
physics. Numerous attempts of search for the existence of the tetraneutron as a bound or resonant state
have been realized using multiple approaches (e.g. uranium fission reactions, pion-induced double-chargeexchange and transfer reactions). However, no certain evidence of tetraneutron existence have bee obtained.
The situation has changed with the recent studies of 4n population in reactions with 8He, where four neutrons can be found in a spatially-separated neutron-halo configuration. The result of the recent 1H(8He,p α)
experiment [1] showed the observation of the “resonance-like structure” at E(4n) = 2.37 MeV with Γ = 1.75 MeV.
The high intensity 8He secondary beam with energy 26 AMeV, produced at the recently commissioned ACCULINNA2 fragment separator [2], was used for the population of the tetraneutron in the 8He+d interaction. The
detection the low-energy recoils 6Li and 3He made with high energy and angular resolution allowed us to
reconstruct the tetraneutron missing-mass spectra in the two reactions: 2H(8He,6Li)4n and 2H(8He,3He)7H-

3H+4n. Both of these approaches showed the evidence for a hump in the 4n continuum at about 3.5 MeV.
The applied experimental techniques, the results of the data analysis and simulations are be presented in the
report.
In this work we demonstrate that an evidence for the low-energy structures analogous to the observation
of [1] can be found in the other reactions with the 8He beam. Such results shed light on the search and
spectroscopy of the multineutron system.
[1] M. Duer et al., Nature 606 (2022) 678–682.
[2] A.S. Fomichev, L.V. Grigorenko, S.A. Krupko, S.V. Stepantsov, G. M. Ter-Akopian, The EPJ A 54 (2018) 97.

Speaker: Ivan Muzalevskii (JINR)

11 Investigation of spectral structure of $^{11}$Be in breakup reactions within quantum-quasiclassical approach

Abstract. We investigate the breakup of the $^{11}$Be halo nuclei on a light ($^{12}$C ) target within quantum-quasiclassical approach in a wide range of beam energy (5–67 MeV/nucleon) including the low-lying resonances of $^{11}$Be. The obtained results are in good agreement with existing experimental data at 67 MeV/nucleon. The developed computational scheme can potentially be used for interpretation of low-energy breakup experiments on different targets in studying spectral properties of nuclei. In particular, the region around 20-10 MeV/nucleon is of great interest, since this is the energy range of HIE-ISOLD at CERN and the future ReA12 at MSU, it has hardly been investigated theoretically so far.

Speaker: Dinara Valiolda (BLTP/KAZNU)

12 Measurement of angular distributions of differential cross sections of products of the 7Li+10B reaction

Measurements were carried out of the angular distributions of the differential cross sections of the reaction products 7Li+10B ELAB = 58 MeV. One of the objectives of the measurements was to compare the root-mean-square radii of the ground and excited states of nuclei obtained in the reaction. In the experiment, the angular distributions of 7Lig.s, 6Lig.s, 6Li(3.56 MeV), as well as 11B(8.56 MeV) were of interest. The 6Li nucleus is in the Jπ=0+; T=1; E=3.56 MeV is the isobaric analogue state of 6Heg.s. The 11B nucleus is in the Jπ=3/2- state; E=8.56 MeV, according to [1], is a cluster state, similar to the previously discovered Hoyle state 12C*, Jπ =0+; T=0; E=7.65 MeV, predicted in [2] and first discovered in [3] by measuring the angular distributions of differential cross sections. The measurements were carried out on the 7Li beam (ELAB = 58 MeV) of the U-400 accelerator of the FLNR JINR using 8 dE-E semiconductor telescopes. A typical two-dimensional dE-E spectrum is shown in Fig. 1.
This research was funded by the Russian Science Foundation, project No. 24-22-00117.
[1] Y. Kanada-En’yo, Phys. Rev. C 75, 024302 (2007);
[2] F. Hoyle, Astrophys. J. Suppl. Ser. 1 (1954) 12.
[3] D.N.F. Dunbar, R.E. Pixley, W.A. Wenzel, W. Whaling, Phys. Rev. 92 (1953) 649.

Speaker: Sergei Stukalov (FLNR JINR)

13 MICROSCOPIC ANALYSIS OF ELASTIC SCATTERING AND TRANSFER REACTION IN THE 7Li+10B COLLISION AT ENERGY 58 MEV

Analysis of cross sections of the $^7$Li+$^{10}$B elastic scattering and the transfer reaction $^7\rm{Li}+^{10}$B$\rightarrow^6$Li+$^{11}$B at the beam energy E$_{LAB}$ = 58 MeV is carried out by using the microscopic optical potential (OP) [1]. Such OP is calculated by a corresponding double folding procedure taking into account antisymmetrization effects and depends on the nucleon density distribution of interacting nuclei. The only free parameters are the depths of the real and imaginary parts of the OPs determined by fitting the experimental angular distributions for the elastic scattering channel and the transfer channel obtained in 2023 at the U-400 cyclotron of the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Russia [2]. A reasonable agreement of the theoretical results with the experimental data is achieved which confirms a peripheral character of the scattering. This research was funded by the Russian Science Foundation, project № 24-22-00117.

References:
[1] V. K. Lukyanov, E. V. Zemlyanaya, and K. V. Lukyanov, Phys. At. Nucl. 69, 240 (2006)
[2] S.S. Stukalov, Sobolev Yu.G., Penionzhkevich Yu.E et al., Measurement of angular distributions of differential cross sections of charged products of the $^7\rm{Li}+^{10}$B reaction, in this book.

Speaker: Elena Zemlyanaya (MLIT JINR)

Yadro2024_Zemlyanaya_prezent.pdf

Nuclear structure: theory and experiment

14 DYNAMICS OF YRAST BANDS UP TO MAXIMUM KNOWN SPINS I N EVEN THORIUM NUCLEI

There are only a few works using the boson approach to describe the intersection of the collective band and the band built on a two-quasiparticle mode. The first of these was the work of Gelberg and Zemel [1] based on IBM1. In it, the Hamiltonian term responsible for the interaction of the collective and non-collective bands was replaced by a constant and did not depend on either the spin $J$ of a pair of quasiparticles or the total spin $I$. The limit val-ue $J^\pi=10^+$ is accepted for the case of Xe, Ba, Ce, etc. due to configuration $(h_{11/2}^2$. In [2], collective states were considered in the IBM2 approximation, and the interaction of collective and quasiparticle excitation modes was considered sequentially through a long chain of matrix elements. Thus, to couple a collective mode with a mode con-taining a pair of quasiparticles $J^\pi=10^+$, fourth order in perturbation theory is required. As a result, in such a model a very weak interaction of intersecting bands of states is realized. These works did not receive further development. In [3], using IBM1, the space was also ex-panded to include bosons up to $J^\pi=10^+$, but the parameters of the interaction terms of collective states and states including quasiparticle pairs were calculated microscopically. How-ever, even in this case, automatic strong mixing of bands with different modes as the leading level could not be fully achieved.
This problem was solved in a series of works, the idea of which was outlined in more detail in [4]. It turned out that it is necessary to take into account the connection between high-spin quasiparticle modes and states that also contain quasiparticles, but which are used when renormalizing the microscopically calculated parameters of the traditional Hamiltonian IBM1. This allowed us to significantly expand the channels of interaction. As a result, strong mixing of states was obtained for several states at once in the band intersection region, which led to large values of $B(E2)$ at the band intersection point, regardless of the position of the energy of the quasiparticle pair. Moving on to heavy and superheavy nuclei, the need arose to expand the two-quasiparticle basis of phonons and, accordingly, bosons to pairs with due to the pair of quasiparticles $(j_{15/2})^2$.
This was done in [5], on the basis of which all even isotopes of Th for which excitation energies were known were analyzed. These are nuclei in the $^{220-236}$Th range. The first of them has an almost ideal vibration spectrum and a first excitation energy of 373 keV. The latter, respectively, has an energy of 48 keV. A preliminary analysis of excitation energies us-ing IBM1 phenomenology showed that it is possible to reproduce energies well up to the max-imum known spins, and this is, for example, up to $30^+$ in $^{232}$Th. In this regard, the question arises about the role of high-spin quasiparticle modes and their influence on the spec-trum of observed states. It turned out that in nuclei with A = 220, 222 the crossing of the bands occurs, but very smoothly, so it doesn't significantly affect the smooth dependence of the moment of inertia on the square of the frequency, at least for $^{222}$Th. For heavier thorium isotopes, where the band energies are already significantly reduced, the main compo-nent remains collective. The reasons for this are being discussed.

1. A. Gelberg, A Zemel. Phys. Rev. C, 22, 937 (1980).
2. N. Yoshida, A. Arima, T. Otsuka, Phys. Let. B, 114, 86 (1982).
3. A. D Efimov., V. M. Mikhajlov, Phys. Rev. C, 59, 3153 (1999).
4. A. D. Efimov, Phys. At. Nucl. 83, 651 (2020).
5. A. D. Efimov, I. N. Izosimov, Phys At. Nucl, 86, 333 (2023).

Speaker: Aleksandr Efimov (Admiral Makarov State University of Maritime and Inland Shipping, St.-Petersburg, Russia; Ioffe Institute, St.-Petersburg, Russia)

15 АНАЛИЗ МЕЖПОЛОСНЫХ И ВНУТРИПОЛОСНЫХ ПЕРЕХОДОВ СОСТОЯНИЙ ПОЛОЖИТЕЛЬНОЙ ЧЕТНОСТИ ИЗОТОПОВ $^{182,184}\rm{W}$

$\qquad$ Изотопы $^{182,184}\rm{W}$ многократно изучались в распаде $^{182,184}\rm{Ta}$ и многочисленных ядерных реакциях [1-5]. Наиболее полные результаты по этим ядрам представлены в работе [1,2]. Энергии коллективних уровней низколежащих полос близки к рассчитанным по сверхтекучей модели [6].

$\qquad$ Экспериментальные данные энергии, вероятностей внутриполосных и межполосных электрических переходов, также отношения вероятностей переходов для $^{182,184}\rm{W}$ указывают на наличие отклонения от правила Алаги [1-5].

$\qquad$ В настоящей работе исследованы структура, энергетические и электрические свойства состояний положительной четности ядер $^{182,184}\rm{W}$ в рамках феноменологической модели [7-9], учитывающей кориолисово смешивание состояний низколежащих ротационных полос. Вычислены спектр энергии, структура состояний ротационных полос, вероятности внутриполосных и междуполосных $E2$-переходов и отношения вероятностей $E2$-переходов из уровней $\gamma$ - вибрационной полосы, также статические матричные элементы основной и $\gamma$ - полос. Вычисленные значения энергии, вероятностей $E2$-переходов и их отношений сравниваются с существующими экспериментальными данными, которые дают хорошие согласия с экспериментом.

1. S. Balraj // Nuclear Data Sheets. 2015. V.130. Р. 21.
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3. R.D. Herzberg, A. Zilges, P. von Brentano et al. // Nucl. Phys. 1993. V.563, P. 445.
4. R. Kulessa, R. Bengtsson, H. Bohn and et al. // Phys.Lett. B218.1989. P.421.
5. C.Y. Wu, D. Cline, E.G. Vogt and et al. // Nucl. Phys. 1991. V.A533.P.359.
6. Е.П. Григорьев, В.Г. Соловьев // Структура четных деформированных ядер // М: Наука, 1974.
7. P.N. Usmanov, I.N. Mikhailov // Phys. Part. Nucl. 1997. V.28. P.348.
8. P.N. Usmanov, A.I. Vdovin, E.K. Yusupov, U.S. Salikhbaev // Phys. Part. Nucl. Lett. 2019. V.19. P.706.
9. P.N. Usmanov, A.A. Okhunov, U.S. Salikhbaev, A.I. Vdovin // Phys. Part. Nucl. Lett. 2010. V.7(3). P.185.

Speaker: Prof. Pazlitdin Usmanov (Namangan Institute of Engineering and Technology)

16 Excitation spectra and electromagnetic transitions between low-lying nonrotationalstates

Calculations of the structure of the low-lying states of nuclei with $Z = 97–109$ play an important role in understanding the properties of nuclei belonging to the new region of the nuclide chart, which is available
now for experimental study. We calculated quasiparticle-phonon structure and the reduced $\gamma$-transition probabilities for the excitedstates with excitation energies below 1 MeV for odd-proton nuclei in this region.

Speaker: Mrs Anna Bezbakh (JINR)

17 Three-particle binding energy and wave function of 14A nuclei based on the HH method

-

Speaker: B. F. Irgaziev

18 Исследование структуры нижайших квадрупольных возбуждений в изотопах Ge

В настоящее время накоплен большой объем экспериментальной информации по структуре низколежащих возбужденных состояний в изотопах Ge [1-3]. Интерес к этим ядрам связан с тем, что с ростом числа нейтронов происходит переход между сферической и деформированными формами ядра, определяющих их структуру [4,5]. С другой стороны, микроскопические расчеты демонстрируют, что изотопы Ge оказываются мягкими по отношению к триаксиальной деформации. В данном докладе мы анализируем свойства низколежащих 2+ возбуждений в изотопах 70-88Ge. Вычисления проводились путем построения и диагонализации коллективного квадрупольного гамильтониана [6,7]. Поверхности потенциальной энергии и массовые параметры, рассчитывались в рамках релятивистской модели среднего поля с двумя параметризациями функционала плотности энергии: PC-PK1 и NL3 [8]. Результаты расчетов сравниваются с имеющимися экспериментальными данными и результатами, полученными в рамках других подходов.

[1] M. Lettmann at al., Phys. Rev. C 96, 011301 (R) (2017).
[2] A.M. Forney at al. Phys. Rev. Lett. 120, 212501 (2018).
[3] A.D. Ayangeakaa at al. Phys. Rev. C 107, 044314 (2023).
[4] K. Heyde, and J.L. Wood, Rev. Mod. Phys. 83, 1467 (2011).
[5] P.E. Garrett, M. Zielińska, and E. Clément, Prog. Part. Nucl. Phys. 124, 103931 (2022).
[6] A. Bohr, B.R. Mottelson, Nuclear Structure, Vols. I & II, World Scientific, Singapore, 1998.
[7] E.V. Mardyban, E.A. Kolganova, T.M. Shneidman, and R.V. Jolos, Phys. Rev. C 105, 024321 (2022).
[8] B.-N. Lu, J. Zhao, E.-G. Zhao, and S.-G. Zhou, Phys. Rev C 89, 014323 (2014).

Speaker: Evgenii Mardyban (JINR BLTP)

16:35 Photo

Poster session

18:30 Welcome party

Tuesday 2 July

Applications of nuclear methods in science, technology, medicine and radioecology: Radiation therapy

19 Increasing The Accuracy Of Dose Delivery To CTV During PBS Proton Therapy

Currently, the proton therapy (PT) method, which uses a thin scanning beam, is one of the most ef-fective and modern methods for creating a conformal (shape-matching with the tumor) distribution of the absorbed dose in the tumor. A highly conformal dose distribution is achieved by optimizing thou-sands of thin proton beams. In order to prevent the occurrence of clinically significant errors, increased requirements are placed on the accuracy of delivery of each individual thin beam.
The advantages provided by the Bragg peak allow for more accurate dose distribution, but also re-quire greater precision in patient positioning. Incorrect patient positioning during PT can lead to serious errors, including underexposure of tumors and overexposure to healthy tissue. To neutralize this effect, the concept used is to irradiate an area that exceeds the size of the subclinical spread of the tumor. The clinical volume of a tumor, including the microscopic spread of cancer cells around it, is called CTV. Planned target volume (PTV) is CTV plus some margin. It is assumed that some of the normal tissue surrounding the CTV within the irradiated area may be included in the irradiation to ensure adequate coverage of the target with a uniform dose, taking into account possible geometric uncertainties.
In radiotherapy, the presence of various inhomogeneities in the path of the proton beam (e.g., bone, lung, air cavities) can lead to a significant deterioration in the predictability of the final dose distribu-tion in the event of errors in beam delivery. Before each PT session, it is necessary to check the pa-tient's position using two orthogonal images and then evaluate the position correction. In the Russian Federation, standards for PTV margins for PT have not yet been established. Therefore, generally ac-cepted margins applied for photon therapy are used. Typically, the CTV-PTV margin ranges from 3 mm to 20 mm.
When comparing PT to conventional photon therapy, a different approach must be taken to deter-mine the margin between the CTV and PTV. Especially in the case of PT using PBS for fixed targets surrounded by bone structures, it is possible to determine a minimum margin that takes into account the accuracy of dose delivery of a particular PT system. There is no mention in the literature of meth-ods for assessing the accuracy of PT systems and the impact of the results of such assessment on the accuracy of radiation dose delivery to tumors of various locations.
The Proton Center of the Federal Scientific Clinical Center for Medical Radiology and Oncology of FMBA of Russia (FSCCRO of FMBA of Russia) uses the IBA Proteus Plus PT system, based on the IBA C235-V3 cyclotron. In 2011-2012, the cyclotron was assembled and tested at the Joint Institute for Nuclear Research in Dubna, then delivered to Dimitrovgrad. Given the characteristics of the system and the organization of clinical processes, the accuracy of dose delivery to the CTV can be influenced by various factors, such as radiation output, accuracy of narrow beam delivery, energy choice and col-linearity of X-ray and PT systems. To speed up the process of morning measurements (quality assur-ance QAs), a combination of the IBA LynxPT scintillation detector and the IBA Sphinx phantom was chosen, which made it possible to significantly reduce the time of daily morning QA checks from 2-2.5 hours to 20-30 minutes. This optimization increased efficiency in the use of clinical time and allowed additional patients to be treated, increasing PT center throughput capacity by 18%.
The dimensions of the CTV-PTV margins established by the FSCCRO of FMBA of Russia are based on clinical recommendations developed for the use of photon devices in radiation therapy, and are 3 mm for the case of intracranial tumors. However, to take into account errors in dose delivery to the CTV, it is necessary to calculate the minimum required CTV-PTV margin. This calculation requires analyzing the stability of the dosimetric parameters of the PT system, such as the constancy of the size and position of the narrow beam, the collinearity of the central axes of the proton and X-ray systems, as well as the stability of the energy selection system.
PT system parameters measurements were recorded in the IBA MyQA software database, including date and measured values. This data was exported into a spreadsheet format for further analysis. Daily morning checks of the PT system parameters were carried out over a period of 11 months. Measure-ments were taken at different gantry angles (0°, 90° or 270°) on weekdays. As a result, over three working weeks, 5 measurements were made at each gantry angle.
The position of the narrow beam was set to ±10% of the reference value to ensure a constant beam penumbra within 1 mm. The position of the narrow beam remained within ±1 mm throughout all meas-urements in both PT rooms. The average deviation of the narrow beam position from the reference val-ue did not exceed 0.4 mm. Analysis of the images obtained on the LynxPT screen as part of the morn-ing checks also showed that the fluctuations in the position of the narrow beam were insignificant. The range of deviations of all studied parameters of the PT system from the reference values remained within the limits recommended in TG-224.
There is no mention in the literature of methods for assessing the accuracy of PT systems and the impact of the results of such assessment on the accuracy of radiation dose delivery to tumors of various locations. Therefore, it was decided to adapt the well-known approach to calculating the margin to take into account geometric uncertainties to the results of an 11-month monitoring of the stability of the parameters of the PT system.
Errors in the lateral direction come from errors in narrow beam position and collinearity, and in the axial direction from errors in energy parameters. Based on the standard orientation of the patient on the treatment table, lateral errors in the X direction are used to calculate the margin in the head-foot direc-tion, and in the Y direction for left-right and abdomen-back. Axial errors are used to calculate the mar-gin along the beam axis. In the lateral directions relative to the beam axis, the calculated margin was 0.8 mm, along the beam axis – 0.4 mm.
The calculated values represent the minimum indentations in the corresponding directions for plan-ning PT in the FSCCRO of FMBA of Russia. Their use, taking into account the accuracy of dose de-livery by the PT system, ensures CTV coverage of 95% of the prescribed dose. This is especially im-portant for stationary targets surrounded by inert structures, for example, for brain tumors, where in-trafractional movement of the target can be neglected.
After studying the methods for conducting morning QAs of the parameters of the PT system, the optimal set of parameters was determined that should be measured as part of the daily quality assur-ance program for the PT system IBA Proteus Plus, used in the Proton Center of the FSCCRO of FMBA of Russia.
The methodology for morning checks of the PT system parameters was optimized using the LynxPT+Sphinx complex, which led to a reduction in the time of inspections by 7.5 times and an in-crease in the throughput of the PT center by 18%. These tests include all recommended tests from TG-224 for PBS systems.
The constancy of the relative dosimetric parameters of the PT system affecting the calculation of the CTV-PTV margin was analyzed. Over nine months, no significant deviations from reference values exceeding acceptable limits were detected. The total mechanical error exceeded 1 mm in 1.3% of cases, the maximum value was 1.3 mm.
Using the approach known from the literature for calculating the CTV-PTV margin taking into ac-count the patient positioning error, the CTV-PTV margin was calculated taking into account the dose delivery error of the PT system. The obtained minimum margin values, taking into account the accuracy of dose delivery, can be applied both for single-field (0.8 mm in the lateral directions relative to the beam axis, 0.4 mm in the direction along the beam axis) and for multi-field (0.8 mm in all directions) irradiation. It is proposed to use this margin calculation method, which takes into account the accuracy of dose delivery by the PT system, in new PT centers.

Speaker: Vasilii Kiselev (FSCCRO of FMBA of Russia)

20 RESEARCH OF THE FLASH EFFECT AT THE PROTON ACCELERATOR OF INR RAS

The flash effect, which consists in better sparing of normal cells at mean dose rates Ḋm > 100 Gy/s, has been experimentally established quite confidently. However, its practical application requires further study of the regularities and biological nature of this effect. To this end, we studied the change in various manifestations of the flash effect with an extreme increase in the mean proton dose rate Ḋm > 104 Gy/s. This possibility is provided by the INR high-current linear proton accelerator, which in single-pulse flash (splash) mode allows increasing Ḋm up to 106 Gy/s when biological targets are irradiated with a single pulse up to 100 µs long with an instantaneous proton current up to 10 mA. We studied [1] the dependence of the response of cells and living organisms on Ḋm in the widest range: in the conventional mode with Ḋm < 1 Gy/s, in the flash mode with Ḋm ~ 102 Gy/s and in the splash mode with Ḋm > 104 Gy/s. Dosimetry in high dose-rate modes was provided with EBT-XD films [2,3] and with an original detector using Cherenkov radiation [4]. In continuation of previous work [1], we irradiated tumor cells HT29 and HCT116 and normal cells - fibroblasts (ADSC) in all three irradiation modes both at the SOBP and on the plateau. As living organisms for study, we used live fertilized quail eggs. Cell response was studied using the following methods: flow cytometry, fluorescence microscopy, PCR analysis of gene expression, clonogenic analysis of cell survival etc. To study the response of live embryos to irradiation in different modes, their development and properties were studied before and after hatching from eggs. The analysis of new data is still ongoing, but the following results can be stated with sufficient statistical significance (p<0.01). In the single-pulse mode with extreme dose rates (splash), compared to the usual flash mode, the following effects are observed at the same values of the absorbed dose: further reduced apoptosis of normal cells compared to tumor cells; increased expression of some important genes; reduced embryonic mortality. These results allow us to make a cautious conclusion that the flash effect does not yet reach saturation upon irradiation by protons with Ḋm in the region of 102 Gy/s. Confirmation and biological substantiation of these results may initiate a further development of new accelerator techniques for application in oncology.
The work was supported by the Russian Science Foundation, grant No. 24-15-00040.
[1] S. V. Akulinichev, Yu. K. Gavrilov, S. I. Glukhov, A. V. Ivanov, D. A.Kokontsev, T. M. Kulinich, E. A. Kuznetsova, V. V. Martynova, and I. A. Yakovlev. «Analysis of Cell Response to Ultrahigh Dose-Rate Proton Irradiation». Bull. Russ. Acad. Sci. Phys.Vol. 87, No. 8, pp. 1224–1228 (2023) doi:10.3103/S1062873823702830.
[2] S.V. Akulinichev, Yu.K. Gavrilov, R.M. Djilkibaev, D.A. Kokontsev, V.V. Martynova, G.V. Merzlikin, I.A. Yakovlev, «The Dosimetry of Proton Beams in Flash-Therapy», Bull. Russ. Acad. Sci. Phys. 87 (8),1233 (2023), doi: 10.3103/S1062873823702878.
[3] G. V. Merzlikin, S. V. Akulinichev, I.A. Yakovlev. «Simulation of a proton beam facility in the TOPAS MC software package». Moscow Univ. Phys. Bull. 11 (2023), doi.org/ 10.55959/MSU0579-9392.78.2310201.
[4] S.V.Akulinichev, Yu.K.Gavrilov, R.M.Djilkibaev, «Calibration of the Proton Beam Cherenkov Monitor», Instrum. Exp. Tech. 66 (4), 365 (2023), doi: 10.1134/S0020441223020124.
V.V. Martynova, G.V. Merzlikin, I.A. Yakovlev, «The Dosimetry of Proton Beams in Flash-Therapy», Bull. Russ. Acad. Sci. Phys. 87 (8),1233 (2023), doi: 10.3103/S1062873823702878.
[3] G. V. Merzlikin, S. V. Akulinichev, I.A. Yakovlev. «Simulation of a proton beam facility in the TOPAS MC software package». Moscow Univ. Phys. Bull. 11 (2023), doi.org/ 10.55959/MSU0579-9392.78.2310201.
[4] S.V.Akulinichev, Yu.K.Gavrilov, R.M.Djilkibaev, «Calibration of the Proton Beam Cherenkov Monitor», Instrum. Exp. Tech. 66 (4), 365 (2023), doi: 10.1134/S0020441223020124.

Speaker: Sergey Akulinichev (INR RAS)

21 ASSESSMENT OF SOME UNACCOUNTED CONTRIBUTIONS TO THE ABSORBED DOSE DURING RADIATION THERAPY

Radiation therapy is widely used in the treatment of various types of cancer today. However, a number of factors are not taken into account at the planning stage of radiation treatment. This may be the reason for the additional dose load on the patient.

When medical electron accelerators operate at energies above 8 MeV, fluxes of secondary neutrons can be generated. The contribution to the dose from secondary neutrons is not estimated and is not taken into account in modern planning systems. To evaluate this contribution, a computer model of the medical linear accelerator head, verified based on the depth dose distribution in water, is used. As a result of Monte Carlo simulation, spectra of secondary neutrons were obtained and their contribution to the absorbed and equivalent doses was assessed.

Secondary neutrons can also be produced on structural elements of proton accelerators and even in the patient's body during proton and hadron therapy. A simulation was carried out and an estimate of the additional dose load from neutrons produced on the modulator wheel of a proton accelerator was obtained. In addition, to assess the risks for personnel and accompanying personnel, the parameters of neutron radiation generated in the water phantom during irradiation with proton beams were calculated.

Another factor not taken into account is distortion of MR images. It can lead to radiation treatment not meeting the plan. As a result of various experiments on MRI machines with a magnetic field induction of 0.5 T and 1.5 T, the distortion of images of homemade phantoms was assessed. Based on the images obtained, a radiation treatment plan was constructed and compared with a similar plan based on CT images, and the unaccounted dose was assessed.

Speaker: Alexey Shcherbakov (Lomonosov MSU)

22 Эксперименты по облучению биологических моделей в протонном пучке

Протонная терапия с высокой мощностью дозы или флэш - терапия является одним из актуальных и перспективных направлений развития методов лечения онкологических образований. Современные исследования показали, что превышение мощности дозы облучения свыше 40 Гр/с снижает негативные последствия воздействия на нормальные клетки, сохраняя эффективность лечения новообразований. Работа посвящена подготовке и проведению экспериментов по облучению биологических моделей на примере оплодотворенных яиц японского перепела (Coturnix japonica) в широком диапазоне мощности дозы.
Подготовка к экспериментам состоит из оценки действующей модели симуляции установки комплекса протонной терапии ИЯИ РАН [1], написанной с использованием библиотек Geant4 и Topas MC и проведения последующих симуляций геометрий включающих сборки перепелиных яиц, а также их крепления, устанавливаемых на глубине модифицированного пика Брэгга. Рассмотрены возможные варианты положения сборок с мишенями в пучке, а также влияние линейной передачи энергии и других характеристик, влияющих на биологическую эффективность радиационного воздействия.
Данная работа выполнена при поддержке гранта РНФ № 24-15-00040 «Разработка ядерно-физических и радиобиологических методов протонной флэш-терапии».

[1] G. V. Merzlikin, S. V. Akulinichev, I.A. Yakovlev. «Simulation of a proton beam facility in the TOPAS MC software package». Moscow Univ. Phys. Bull. 11 (2023), doi.org/10.55959/MSU0579-9392.78.2310201

Speaker: Ivan Yakovlev

Эксперименты по облучению биологических моделей в протонном пучке.pptx

23 Technological state and prospects of production of modern X-ray diagnostic systems

The report is devoted to the general review of technologies and prospects of development of modern X-ray diagnostic devices. In the course of progressive qualitative movement of scientific and technological progress there is a development of technologies and improvement of medical equipment, which certainly has a positive impact on the development of world medicine in general and domestic medicine in particular. Research and innovations in the field of medical equipment contribute to the development of X-ray diagnostic systems. Among the main areas of development are: achieving more accurate diagnostics, increasing resolution, improving image quality while minimising X-ray dose, automation and introduction of artificial intelligence and machine learning technologies, improving ergonomics and functionality of X-ray diagnostic systems.

Structurally, a typical X-ray diagnostic system is a single independent product developed on the basis of X-ray diagnostic apparatus with a teleoperated table-tripod for standard and special X-ray diagnostic examinations in the modes of radiography and fluoroscopy.

The basic principle of operation of a typical X-ray diagnostic system is as follows: the X-ray power supply unit (PSU) supplies power to the X-ray emitter unit with the X-ray tube, as a result of which the X-ray tube generates braking ionising X-ray radiation in the direction of the patient located on the tripod table. Thanks to the collimator, the X-ray radiation is geometrically corrected for the size of the field and is directed towards the patient's anatomical region to be examined. After the X-rays pass through the patient's body, the X-rays reach the detector inside the tripod table and are converted into electrical signals, which are then processed by a digital computer station to form a clinical image. The tripod table is rotatable, which allows the patient to be examined in various inclined positions, and is remotely controlled (i.e. teleoperated), allowing medical staff to stay in the control room to avoid exposure to ionising radiation. Clinical images are visualised on monitors. Thanks to the laboratory technician's automated workstation (AWS), the images can be edited, archived and transmitted over the network in DICOM format to the PACS system or to the hospital intranet.

Currently, there is a tendency to develop the technological side of X-ray diagnostic devices, for example, the creation of a new generation of X-ray tubes for projection radiography. Clinical practice of the past years has shown that for successful implementation of the projection radiography method the size of the focal spot of the used X-ray tubes should not exceed 0.1 mm or 100 µm. According to GOST 22091.9-86 such X-ray tubes belong to the class of microfocus tubes. Long-term studies have shown that in case of using microfocus X-ray tubes a number of peculiarities (effects) appear during X-ray image formation. The main ones are: the effects of increasing the depth of field and contrast, the effects of pseudo-volume image and phase contrast, the effect of reducing the exposure dose. However, due to the limited power supplied to the target of a microfocus X-ray tube by an electron beam of small cross-section, the intensity of the radiation generated by it is small in comparison with a "conventional" X-ray tube. This significantly limits the scope of application of microfocus radiography in such socially important areas of medical diagnostics as angiography, mammography, fluorography, tomography, etc. The intensity of radiation can be increased both by increasing the tube current and the tube voltage, so both directions were used in the development of a new generation of microfocus X-ray tubes [1].

The problem of performing X-ray diagnostic studies in non-specialised settings, such as at the patient's home, should be highlighted separately. Obviously, it is impossible to use traditional stationary X-ray devices in the home. Accordingly, the issue of ensuring radiation safety for the personnel conducting the study and for others who may also be involved in the study, for example, when laying the patient, becomes important. However, it is practically impossible to use special means of protection from unused X-ray radiation - screens, booths, etc., as well as to remove the surrounding people to a safe distance at home. Therefore, it is necessary to apply such techniques of X-ray imaging that will significantly reduce the exposure dose of radiation in comparison with imaging with stationary devices. In this case, it is extremely important to obtain image quality of the examined organ, necessary and sufficient to make a decision on the presence or absence of pathology.

The diagnostic efficiency of portable chest radiography (defined as the number of chest radiographs showing new findings or changes in known findings divided by the total number of chest radiographs) for patients admitted to the ICU is 84.5%. These conclusions were reached by Palazzetti V. et. al, (2013) in a study of the effectiveness of mobile radiography in the ICU [2]. Portable technical means in radiography are now also proposed for use in dental practice [3,4].

When using 'hand-held' X-ray machines, there is a small increase in the dose level for X-ray laboratory technicians. However, the dose remains well below the recommended levels. The position of the machine relative to the X-ray technician has a significant effect on the total absorbed dose. The availability of individual dosimeters to monitor exposure levels is recommended. In addition, guidance, training and protocols for exposure levels should be available on site and strictly adhered to; regular checks are necessary to ensure that all regulations are being followed [5].

From the prospects of development of X-ray diagnostic devices, we can separately emphasise the direction of tomography and dual energy. In general purpose radiography traditional linear tomography allows to obtain layer-by-layer images of the object, but during one pass of the radiator only one slice is imaged. As a result, in case of necessity to obtain a layer-by-layer image of all lungs the procedure is performed not less than 10 times, which leads to significant increase of radiation load on the patient and duration of the procedure. Computed tomography method allows to obtain information about the whole volume of the thorax, but significantly increases the dose load on the patient [6]. Tomosynthesis technology is at the junction of linear and computed tomography (CT), combining high informativeness (compared to linear tomography) and low dose load (compared to CT). The use of modern tomosynthesis and dual-energy technologies makes it possible to significantly increase the informativeness of the examination and improve the diagnosis of pathology at early stages. The main advantage of these technologies is that they can be used on teleoperated tripod tables with a digital flat panel dynamic detector without significant modifications of the hardware, as well as on modern devices for two workplaces [7,8].

It is expected that the introduction of dual-energy and tomosynthesis technologies into medical practice will, in a number of cases, make it possible to eliminate the need for follow-up examinations in CT rooms. This will help to relieve CT rooms of routine examinations and provide access to them for more patients.

Based on the above, it can be concluded that the development of X-ray technology at the present stage should be assessed not as the final milestone of evolution, but as the transition of X-ray technology to a qualitatively new digital level, the potential capabilities of which are enormous.

References
1. Мазуров А. И., Элинсон М. Б. Современное состояние медицинской рентгенотехники // НИПК «Электрон».
2. Palazzetti V, Gasparri E, Gambini C, Sollazzo S, Saric S, Salvolini L, et al. Chest radiography in intensive care: an irreplaceable survey, Radiol Med (Torino). 2013 Aug;118(5):744-51.
3. Клестова И. А., Васильев А. Ю., Потрахов Н.Н. Значение панорамной микрофокусной рентгенографии в оценке стоматологического статуса и идентификации личности у военнослужащих по призыву // Изд-во Радиология – Практика №4(58), 2016. – 19 с.
4. Потрахов Е. Н. Радиационная нагрузка при применении портативных рентгеновских аппаратов семейства «ПАРДУС» в стоматологии // Медицинская техника. 2012, №5. – С.37-40.
5. Makdissi J, Pawar RR, Johnson B, Chong BS. The effects of device position on the operator's radiation dose when using a handheld portable X-raydevice.Dentomaxillofac Radiol. 2016;45(3):20150245.
6. J. M. Sabol, B. Heckel «Techniques for Very Low Dose Thoracic Digital Tomosynthesis» / Proceedings of conference of European Society of Thoracic Imaging (ESTI), 2012.
7. Tsutomu Gomi « X-ray digital linear tomosynthesis imaging» / Journal of Biomedical Science and Engineering, Issue 4, 2011. — 444 с.
8. S. Richard «Optimization of imaging performance and conspicuity in dual-energy x-ray radiography » / Department of Medical Biophysics, University of Toronto, 2008. – 160 с.

Speakers: Mr Andrey Popov (Lomonosov MSU), Mr Dmitry Sosnov (Lomonosov MSU)

24 Анализ клеточной гибели и пролиферативной активности клеточных культур при облучении протонами в режиме флэш

Главным достоинством протонной флэш-терапии является повышенная выживаемость нормальных тканей по сравнению с опухолевыми. Протоны имеют дополнительное преимущество по сравнению с электронами и фотонами из-за большей конформности распределения дозы облучения тяжелыми частицами и дополнительных эффектов, связанных с высокой линейной передачей энергии (ЛПЭ) в области модифицированного пика Брэгга (SOBP). Именно поэтому изучение протонной флэш-терапии актуально для дальнейшего развития лучевой терапии.
В данной работе представлены результаты серии экспериментов по облучению клеточных культур на сильноточном линейном ускорителе протонов средних энергий ИЯИ РАН. В этих экспериментах в водном фантоме облучались опухолевые клетки - рака толстой кишки (HCT116) и аденокарциномы толстой кишки человека (HT-29). В качестве нормальных клеток были взяты мезенхимальные стволовые клетки (ADSC) жировой ткани человека – фибробласты. Доза подводилась в трех разных режимах: конвенциональный режим (мощность дозы Ḋ < 3 Гр/с), флэш - режим (Ḋ ~ 100 Гр/с) и одноимпульсный флэш - режим (Ḋ > 104 Гр/с) в области модифицированного пика Брэгга и на плато до пика. За время инкубации для клеточной гибели были взяты 24 и 48 часов после облучения. Пролиферативный потенциал оценивался в течении 10 дней после облучения. Для анализа клеточной гибели производилась окраска йодистым пропиедием и аннекисном. Для пролиферативного потенциала воспроизводился EdU-тест. Анализ проводился с помощью флуоресцентной микроскопии.
Среди полученных результатов анализа можно выделить повышенный уровень позднего апоптоза у опухолевых клеток в одноимпульсном режиме облучения по сравнению с флэш и конвенциональным режимами спустя 24 часа. Также наблюдается высокий уровень некроза опухолевых клеток во всех режимах. Замечены явные различия в репликации ДНК у опухолевых и нормальных клеток в зависимости от режима облучения и величины поглощенной дозы.

Данная работа выполнена при поддержке гранта РНФ № 24-15-00040 «Разработка ядерно-физических и радиобиологических методов протонной флэш-терапии».

Speaker: Mrs Valeriia Martynova (INR RAS)

Мартынова В.В. ядро 2024.pptx

25 CONTRIBITION OF PHOTOELECTRIC EFFECT TO THE DOSE ENHANCEMENT FACTOR IN PHOTON ACTIVATION THERAPY

Radiation therapy is fundamental method for treating cancer, however depositing precise dose to the target and preventing damage of vitally important healthy tissue surrounded by cancer cells remains challenging. Potential solution for this might be to inject high-Z containing elements into a tumor just before radiation therapy. In our research, we quantitatively evaluated the potential of biocompatible elements with different atomic numbers (Z) to act as radiation dose enhancers. Among these, Ag utilized in the form of nanoparticles to robust antimicrobial properties. Ag nanoparticles exert their antimicrobial effects through multiple mechanisms: they disrupt microbial cell membranes, induce apoptosis, and exhibit synergistic effects when combined with other antimicrobial agents. Sm in the form of a pharmacological drug (Sm-153 preparations) have been used for a long time in the radiation therapy of metastases. Gd contrast agents, as Magnevist®; Au nanoparticles are useful for contrast imaging, drug delivery, or radiation therapy enhancement. Bi metallic nanoparticles having preclinical proofs for theranostic applications [1-3].
Evaluating the contribution of the photoelectric effect to the dose enhancement factor (DEF) is calculated via the analytical approach developed in [4]. The photoelectric effect depends on the accumulation of radiosensitizer nanoparticles with a certain concentration and nanoparticle dimensions on the surface of the cells. The X-ray spectrum is generated by SpecPy, a tool for modeling X-ray tube spectra in [5]. The calculation is derived by taking into account the interaction of Ag, Au, Bi, Gd, and Sm nanoparticles with incident photons produced by the X-ray tube (1 mA current, 100 kV voltage, 3 mm thick aluminum filter, rhodium anode (W) with a 12° angle, and a 1 m distance from the tube focus).

Speaker: Dildora Rasulova (Institute of Nuclear Physics of Academy of Sciences of the Republic of Uzbekistan)

26 DOSES OF INTERNAL HUMAN RADIATION FROM RADON DURING HEATING OF RESIDENTIAL BUILDINGS WITH NATURAL GAS IN THE CONDITIONS OF THE NORTH

Some sources contain information [1,2] that natural gas may contain radon, but there are no detailed studies of the emission of radon from network natural gas, and this problem of radon emanation from natural gas is of important practical importance in connection with the implementation of the gasification program for populated areas points of Yakutia [3]. Radon is one of the main causes of cancer, including most often lung cancer. Studies conducted in different countries have shown that even low concentrations of radon detected in residential areas create health risks and contribute to the development of lung cancer. It is known, that prolonged exposure to radon with an average concentration increased by 100 Bq/m3 increases the likelihood of developing lung cancer by 16% [4]. This paper presents the results of experimental studies of equivalent equilibrium volumetric activities (EEVA) of radon 222Rn and maximum annual dose loads for the heating season (from September to May) in residential premises of the city of Yakutsk, the central regions of the Republic of Sakha (Yakutia). The measurements were carried out using radon radiometers RRA-01M-03 and Alpha Guard PQ2000. Calculation of the individual annual effective dose of internal irradiation of residents of a populated area due to short-lived daughter products of radon isotopes in the air is carried out according to the data of measurements of EEVA of radon isotopes 222Rn in indoor and outdoor air using the following formula [5]:
E_(internal.Rn)=9.5·〖10〗^(-6)∙t∙(0.2∙〖EEVA〗_outdoor+0.8∙〖EEVA〗_indoor ),mSv/N,
where 9.5∙10-6 is the dose coefficient (in units (mSv∙m3)/(hour∙Bq)); t – number of hours in one month; 0.2 and 0.8 – the proportion of time spent indoors and outdoors, respectively; if there are no EEVAout values for the outside air on the territory of a populated area, then for calculations of radiation doses it is necessary to take EEVAout = 6.5 Bq/m3 in accordance with data on the world average EEVAout values of radon isotopes in the ground layer of atmospheric air, N is the number of months of the heating season ( N=9 months).
The EEVA of radon for a nonequilibrium mixture of short-lived daughter decay products in the air is calculated using the following formula [6]:
EEVA_Rn=VA_Rn·F
where VARn is the volumetric activity of radon, F is the equilibrium coefficient between radon and its decay products, which can take values from 0 to 1. In the absence of experimental data on the average value of this coefficient, F=0.5 is taken.
The table provides examples of the results of calculated dose load readings depending on the season.
Table. Dose loads
Locality Gas boiler type VARn, Bq/m3
(max, value) EEVARn , Bq/m3
(max, value) Einternal, mSv/N

Yakutsk, three-story residential building Rinnai (made in Japan) 205±50 102,5±25,0 5,2
Oy village, Khangalassky ulus Wolf (made in Germany) 126±36 63,0±18,0 3,2
Oy village, Khangalassky ulus AOGV (made in Russia) 229±53 114,5±26,5 5,7
Oy village, Khangalassky ulus KSG-10 (made in Russia) 73±24 36,5±12,0 1,9
Oy village, Khangalassky ulus KSG-7 (made in Russia) 103±32 51,5±16,0 2,6

To assess the possibility of an increase in radon concentration due to emanation from the soil, the release of radon from soils selected from the subfloor of houses was measured using semiconductor gamma spectrometry and using a test chamber. Measurements have shown that radon emanation from the underground (24 Bq/m3) makes an insignificant contribution to the concentration of radon in residential premises.
The results of the studies show that the dose load from radon does not exceed the permissible value (10 mSv/year). Basically, the obtained values of VARn > 200 Bq/m3 and EEVARn > 100 Bq/m3 exceed the standard values that are recommended for residential premises under construction. As can be seen from the examples of results shown in the dose load table, there is a dependence of VARn and EEVARn on the types of boilers: dose load readings correspond to standard values only in the case of using Russian-made KSG-10. In accordance with the data obtained, EEVA values may depend on several factors, such as ventilation systems, thermal insulation, on which the volume of gas used depends, on types of boilers, etc. Thus, there is a need to control EEVA in residential premises to prevent dose loads from radon and take measures to reduce them at different stages: 1) ventilation systems during construction; 2) commissioning of a gas heating system. To achieve this, uniform standards must be adopted based on research such as this work. In addition, the high dose rates presented in this work may be the reason for the increase in the level of malignant neoplasms in the localities in which these studies were conducted since the time of their gasification.
Literature
1. Abel X. Gonzalez and Jeanne Andere. Comparative analysis of radiation sources in the living environment // IAEA BULLETIN, 2/1989. 23-35 s.
2. Anikin V.M. Radiophysical model of the process of accumulation of radon and its decay products in the body // Heteromagnetic microelectronics - Saratov: Publishing House OJSC Scientific Research Institute "Tantal", 2013. 73-96 p.
3. Order of the Government of the Republic of Sakha (Yakutia) dated December 22, 2021 N 1322-r “On approval of the regional gasification program for settlements of the Republic of Sakha (Yakutia) for 2021 - 2030”
4. «Radon and its effects on human health» https://www.who.int/ru/news-room/fact-sheets/detail/radon-and-health
5. Assessment of individual effective doses of irradiation of the population due to natural sources of ionizing radiation / Methodological instructions MUK 2.6.1.1088-02 // Ministry of Health of Russia, Moscow, 2002. – 22 p.
6. Yakovleva V.S. Methods for measuring the flux density of radon and thoron from the surface of porous materials: monograph. Tomsk: Tomsk Polytechnic University Publishing House, 2011. – 174 p.

Speaker: Kristina Petrova (M. K. Ammosov North-Eastern Federal University)

Experimental and theoretical studies of nuclear reactions

27 EMISSION OF HIGH-ENERGY 4He AND 6,7Li NUCLEI IN NUCLEAR REACTION OF 56Fe IONS ON 238U TARGET

The energy spectra of alpha particles and 6,7Li nuclei emitted at an angle of 0° in the reaction induced by a 56Fe beam (400 MeV) incident on a 238U target were measured by means of the high-resolution magnetic analyzer (MAVR setup) [1]. The resulting spectra (Fig. 1) were found to contain fast alpha particles and 6,7Li nuclei with the energy corresponding to the two-body and three-body exit channels [2]; the energy of alpha particles was close to the two-body kinematical limit. In the region of lower and higher energies, the ratios of the cross sections for the emission of alpha particles to the cross sections for the emission of lithium nuclei are very different, which indicates different mechanisms for the formation of these nuclei. The obtained data were analyzed based on the model of moving sources. The emission of nonequilibrium alpha particles and 6,7Li nuclei in the forward direction is also considered within the quantum time-dependent approach [2, 3].

Fig. 1. Energy spectra of alpha particles (circles), 6Li (squares), and 7Li (triangles) measured at an angle of 0° in the reaction 56Fe (400 MeV) + 238U.

1. V.A. Maslov, V.I. Kazacha, I.V. KoIesov, S.M. Lukyanov, V.N. Melnikov,
   N.F. Osipov, Yu.E. Penionzhkevich, N.K. Skobelev, Yu.G. Sobolev, E.I. Voskoboinik.
   // J. Phys. Conf. Ser. 2016. V. 724. P. 012033.
2. Yu.E. Penionzhkevich, V.V. Samarin, S.M. Lukyanov, V.A. Maslov, M.A. Naumenko.
   // Chin. Phys. C. 2022. V. 46. P. 114002.
3. V.V. Samarin. // Phys. At. Nucl. 2018. V. 81. P. 486.

Speaker: Vladimir Maslov (JINR)

28 Resonance amplification of nuclear reaction X(a,b)Y near the a+X channel threshold

Deviation of the cross section for the nuclear reaction X(a, b)Y from the Gamow formula due to an interaction additional to the Coulomb one in the entrance channel has been analyzed. It is shown that the reaction cross section has an oscillating structure at low energies. If the maximum of the first oscillation is close to the threshold of the channel a+X, it has a resonance behavior. To analyze the effect, simple relations between the period and the amplitude of the oscillations with parameters of the interaction have been derived. Specifically, they predict the cross-section oscillations of fusion reactions of the type X(a,b)Y for slow collisions between nuclei (a) and atomic target (X), as, for example, the reaction D(d,p)T between deuterons (d) and deuterium atoms (D) [1].
This simple formalism is used for analysing the resent data on process $e^++e^-\rightarrow \Lambda^+_c+{\bar \Lambda}^-_c$ obtained recently by the BESIII Collaboration [2].

[1] V.S. Melezhik, Nucl. Phys. A550, 223 (1992)
[2] M. Ablikim et. al.Phys. Rev. Lett. 131, 191901 (2023)

Speaker: Vladimir Melezhik (BLTP JINR Dubna)

29 Neutron transfer in reactions 7Li ,48Ca + 197Au at above-barrier energies

Studies of neutron transfers with the formation of neutron-excess Au isotopes in the reaction are presented for reactions 7Li ,48Ca + 197Au. Using the activation method, the formation cross sections for target-like products were measured. An assembly of several gold targets was irradiated with an ion beam 48Са at energies 228, 257, 286 MeV. Total flux of particles passing through the collector was measured by elastic scattering on the target Au (2 µm) located after the activation stack [1].
Experimental cross sections for isotopes 191-203Au (in reaction 48Ca+197Au) were obtained, which were produced in the stripping and pick-up neutrons, up-to ±6 neutrons respectively. The time-dependent Schrödinger equation for the outer neutrons was used to calculate the probability of neutron transfer. The isotopic distributions obtained from measurements were compared with calculations from the TDSE approach and the Grazing code. [3][4] (fig.1).

Fig.1. Mass distribution of 197±xAu isotopes nuclear in stripping and pickup neutrons in the reaction 48Ca + 197Au at energies of Elab = 228 (a). Experimental data is represented by circles; calculations using the Grazing code are shown as red curves (with evaporation) and black curves (without evaporation); calculations within the TDSE approach are indicated by asterisks

These results offer valuable insights into the feasibility of generating neutron-rich nuclei through neu- tron transfer reactions and extend the prospects for producing exotic neutron-rich nuclei by selecting appropriate combinations of projectiles and targets.
Similar study was carried out for the 7Li (70 MeV)+Au reaction. Neutron transfer reaction for 1n and 2n channels were observed as well as neutron evaporation channels for fusion reaction, leading to the formation of compound nucleus. Data analyze for this reaction is still in progress now.

1. A. K. Azhibekov et al., Eur. Phys. J. A (2023) 59:278.
2. C. S. Palshetkar et al., Phys. Rev. C 89, 024607 (2014)
3. [nrv.jinr.ru].
4. Resource is based on the Program Grazing ver.9 (2005) code of Aage Winther

Speaker: Aleksei Shakhov (JINR)

30 SYMMETRY BREAKING EFFECTS IN THE INTERACTION OF SLOW NEUTRONS WITH LEAD NUCLEUS

Spatial parity breaking effects in the interaction of slow and resonant neutrons with Lead nucleus will be investigated. For scattering and capture processes, spin rotation, asymmetry of emitted neutrons and asymmetry of emitted gamma quanta were evaluated and compared with existing experimental data. Parity breaking effects were evaluated in the frame of the formalism of the mixing states of compound nucleus with the same spin and opposite parities [1]. Applying the approach described in [2], from theoretical evaluations and related scattering and capture experimental data, weak matrix element was extracted. Matrix element of weak non leptonic interaction is usually of order of meV and for slow neutrons, parity violation effects are of order of 10-6-10-4 and lower. Similar values were obtained in the analysis of parity violation effects on other processes and nuclei [2]. From obtained results, the existence of a new negative resonance of compound nucleus near the neutron threshold it is confirmed [3].
Symmetry breaking effects in the scattering and capture process on Lead nucleus are planned to be measured at basic facilities from FLNP JINR Dubna and from other neutrons research centers from Russia.

REFERENCES

1. V. V. Flambaum, G. F. Gribakin, Prog. Part. Nucl. Phys. 1995 V. 35, P. 423
2. A.I. Oprea, C. Oprea, Yu.M. Gledenov, P.V. Sedyshev, C. Pirvutoiu, D. Vladoiu, Romanian Reports in Physics, ISSN 1221-1451, 2011, V. 63, № 2, P. 357-375
3. G. A. Lobov, Yadernaya Fizika, 2000, V. 63, № 8, P. 1465 (in Russian)

Speaker: Dr Иоан Опреа (Joint Institute for Nuclear Research (JINR) Frank Laboratory for Neutron Physics (FLNP))

PrezPb204_Nucleus2024.ppt

31 Quenching factor of spectroscopic factors extracted from single-nucleon transfer reactions

The spectroscopic factors are generally quenched relative to the occupancy numbers predicted by the independent particle model(IPM), which is quantified by the reduction/quenching factor Rs[1,2] and is associated with nucleon-nucleon correlations [3,4]. Rs extracted from knock-out reactions were found to be strongly dependent on the isospin asymmetry (ΔS = Sn- Sp / Sp- Sn for neutron/proton removing reaction) [5,6]. Rs deduced from the transfer reactions induced by stable nuclei were found to be independent on ΔS[7], while it’s controversial from the unstable nuclei with large ΔS. For example, Rs from (d,3He) of neutron-rich Li isotopes decreases significantly as the number of neutrons increases [8], while that from Ar and O isotopes was found weak dependencies[9,10].
In order to more clearly study the dependence between Rs and ΔS of unstable nuclei, a combined experiment with radioactive beams of 15C and 16N was performed at Radioactive Beam Line in Lanzhou (RIBLL) in 2022[12,13]. The differential cross sections in the mass center system for the single-nucleon transfer reactions of 15C(p, d)14C, 15C(d, 3He)14B and 16N(p, d) 15N were obtained . By comparing the experimental angular distributions to the DWBA theoretical calculations, the spectroscopic factors and the corresponding Rs with ΔS = -19.12, 8.99 and 19.86 MeV were extracted. Weak dependencies were found from these single-nucleon transfer reactions induced by weakly bound nuclei, which were performed in one experiment using the same target in order to reduce the systematic errors as much as possible.
[1] T. Aumann, C. Barbieri, D. Bazin, et al., Prog. in Part. and Nucl. Phys., 2021(1):103847.
[2] Y.P. Xu, D.Y. Pang, X.Y. Yun, et al.,Phys. Lett. B, 2019, 790: 309.
[3] T. Nakamura, A. M. Vinodkumar, T. Sugimoto, et al., Phys. Rev. Lett. 2006, 96: 252502.
[4] M. Duer, O. Hen, E. Piasetzky, et al., Nature, 2018, 560: 7720.
[5] J. A. Tostevin, A. Gade, Phys. Rev. C, 2021, 103, 054610.
[6] C. Louchart, A. Obertelli, A. Boudard, et al., Phys. Rev. C, 2011, 83, 011601.
[7] B. P. Kay, J. P. Schiffer, S. J. Freeman, et al., Phys. Rev. Lett. 2013, 111: 042502.
[8] A. Matta, D. Beaumel, H. Otsu, et al., Phys. Rev. C, 2015, 92, 041302(R).
[9] Jenny Lee, M. B. Tsang, D. Bazin, et al., Phys. Rev. Lett. 2010, 104: 112701.
[10] F. Flavigny, A. Gillibert, L. Nalpas, et al., Phys. Rev. Lett. 2013, 110: 122503.
[11] Z. Sun, W.L. Zhan, Z.Y. Guo, et al., Nucl. Instr. Meth. A, 2003, 503: 496.
[12] Hong-Yu Zhu, Jian-Ling Lou, Yan-Lin Ye, et al., Nucl. Sci. Tech., 34 (2023) 159

Speaker: Hongyu Zhu (Peking University)

32 ASYMPTOTIC NORMALIZATION COEFFICIENTS FOR $^{16}$O+n→$^{17}$O FROM THE $^{16}$O(d,p)$^{17}$O REACTION

emphasized textThe differential cross sections (DCs) of theneutron transfer $^{16}$O(d,p)$^{17}$O reaction leading to the ground and first excited states of the $^{17}$O nucleus were measured at deuteron energies of 36 MeV and they used to extract the spectroscopic factors for the $^{16}$O+n→$^{17}$O vertex[1]. In the present work, the analysis of the experimental DCs of the above mentioned reaction has been performed within the modified distorted wave Born approximation (MDWBA) [2] to obtain the “indirectly determined” values of the asymptotic normalization coefficients for the $^{16}$O+n→$^{17}O_{g.s.}$ and $^{16}$O+n→$^{17}$O (0.87 MeV) vertexes. To determine the absolute values of the ANCs in $^{17}$O nucleus, the ANC forthe d→p+n vertex was taken from the value of the nuclear vertex constant, $G^2$=0.43±0.01 fm, which extracted in Ref. [3]. All calculations were performed using the DWUCK5 code [4].
It was shown that the neutron transfer $^{16}$O(d,p)$^{17}$O reaction at the projectile energyof 36MeV was peripheral and the weighted mean value of the extracted ANCs were found to be $C^2_{{16}_{O n}}$=0.855±0.068 $fm^{-1}$ for the $^{16}$O+n→$^{17}O_{g.s.}$ vertex and $C^2_{{16}_{O n}}$=10.765±0.345 $fm^{-1}$ for the $^{16}$O+n→$^{17}$O(0.87 MeV) vertex. The different parameters of the optical potential also were used in the calculation for estimation of the values of ANCs for the $^{16}$O+n→$^{17}O_{g.s.}$ vertex and the $^{16}$O+n→$^{17}$O (0.87 MeV) vertex and their uncertainties.
The weighted mean values of the extracted asymptotic normalization coefficients are used for the calculation of the astrophysical S-factors of the $^{16}$O(n,γ)$^{17}$O reaction at low energies. The work is in progress now.
References
1. M.D. Cooper, W.F. Hornyak and P.G. Roos., Nucl. Phys. A218 (1974) 249-273.
2. A.M.Mukhamedzhanov et al., Phys. Rev. C 56 (1997) p. 3.
3. L.D.Blokhintsevet al., Fiz. Elem.Chast. Atom. Yad. 8 (1977) p. 6.
4. P.D.Kunz, Computer code DWUCK5.http://spot.colorado.edu/kunz/DWBA.html .

Speaker: Erkinjon Ikromkhonov (Institute of Nuclear Physics, Academy of Sciences of Uzbekistan)

Experimental and theoretical studies of nuclear reactions: Fission

33 Оценка коэффициентов корреляции спинов фрагментов двойного деления ядер

Представленная работа посвящена развитию квантово-механического описания различных характеристик атомных ядер, возникающих в процессе двойного деления. Основной акцент в рамках данного исследования делается на оценку коэффициентов корреляции спинов фрагментов деления (ФД).
Методика построения коэффициентов корреляции спинов строится на основе концепции «холодного» делящегося ядра [1], т. е. когда предфрагменты деления не претерпевают нагрева на всем пути их спуска с внешнего барьера деления и вплоть до точки разрыва. В рамках этой концепции энергия возбуждения ФД уходит на их неравновесную деформацию, поэтому за формирование спинов ФД отвечают делительные моды нулевых колебаний, а именно продольных wriggling- и bending-колебаний [2], учет которых позволяет непротиворечиво описать исследуемое явление и связанные с ним величины, в том числе коэффициенты корреляции спинов ФД спонтанного и низкоэнергетического вынужденного двойного деления ядер-актинидов.
Предложенная методика расчета коэффициентов корреляции интересна тем, что позволяет избежать температурного подхода, поскольку в рамках развиваемой методики ФД находятся в «холодных», но неравновесных по своей деформации состояниях. Полученные оценки не согласуются с результатами, представленными в экспериментальной [3] и теоретической [4] работах, которые предполагают отсутствие корреляции между спинами ФД, хотя в рамках рассмотренной концепции впервые получены результаты разумно согласующиеся с законом сохранения полного спина.

1. Кадменский С.Г., Любашевский Д.Е., Титова Л.В. Изв. РАН, Сер. физ. 79. 975. (2015).
2. Nix J.R. and Swiatecki W.J. Nucl. Phys. 71. 1. (1965).
3. Wilson J. et. al. Nature 590. 566. (2021).
4. Randrup J. and Vogt R. Phys. Rev. Lett. 127. 062502. (2021).

The presented article is devoted to the development of quantum mechanical description of various characteristics of atomic nuclei arising in the process of binary fission. The main accent in the framework of this study is placed on the estimation of the correlation coefficients of the fragments fission spins (FFs).
The methodology for building the spin correlation coefficients is based on the concept of a "cold" fissile nucleus [1], i.e., when the fission pre-fragments do not undergo heating along the entire path of their descent from the outer fission barrier and up to the scission point. In the framework of this concept, the excitation energy of FF is spent on their nonequilibrium deformation; therefore, the splitting modes of zero-point oscillations, namely, longitudinal wriggling and bending oscillations [2], are responsible for the formation of FFs spins; taking these modes into account makes it possible to describe the phenomenon under study and related quantities, including the correlation coefficients of the FFs spins of spontaneous and low-energy induced fission of actinide nuclei, in a consistent manner.
The proposed method of calculating the correlation coefficients is interesting because it avoids the temperature approach, since, in the framework of the developed methodology, the FFs are in "cold" but nonequilibrium states in terms of their deformation. The obtained values do not agree with the results presented in the experimental [3] and theoretical [4] articles, which assume the absence of correlation between the spins of the FFs, although in the framework of the considered concept the results reasonably consistent with the total spin conservation law were obtained for the first time.

1. Kadmensky S.G., Lyubashevsky D.E., Titova L.V. Bull. Russ, Acad. Sci.: Phys. 79. 975. (2015).
2. Nix J.R. and Swiatecki W.J. Nucl. Phys. 71. 1. (1965).
3. Wilson J. et. al. Nature 590. 566. (2021).
4. Randrup J. and Vogt R. Phys. Rev. Lett. 127. 062502. (2021).

Speaker: Andrey Pisklyukov (Voronezh State University)

34 Influence of angular momentum on Mass-Total Kinetic Energy distribution of fragments formed in the $^{24}$Mg + $^{232}$Th and $^{48}$Ca + $^{208}$Pb reactions

Investigation of the influence of angular momentum and the excitation energy of the compound nucleus on the Mass-Total Kinetic Energy (M-TKE) distribution of fission fragments give important insight into the fission process. The aim of the present work is to study the influence of compound nucleus angular momentum on the M-TKE distributions of fission fragments formed in the $^{24}$Mg + $^{232}$Th and $^{48}$Ca + $^{208}$Pb reactions, both the reactions leading to the formation of $^{256}$No$^*$ compound nuclei.

The experiments were carried out using the U400 cyclotron at the Flerov Laboratory of Nuclear Reactions, Dubna, Russia. Thin targets of $^{232}$Th and $^{208}$Pb bombarded with 125 - 181 MeV $^{24}$Mg and 208 - 281 MeV $^{48}$Ca beams, respectively, to populate the $^{256}$No$^*$ compound nuclei at different excitation energies. The mass-energy distributions of binary reaction products were measured by the double-arm time-of-flight (ToF-ToF) spectrometer CORSET [1]. In order to understand the influence of angular momentum of the compound nucleus on the M-TKE distribution, a detailed analysis has been carried out for the obtained M-TKE distributions.
References
[1] E. M. Kozulin et al., Instrum. Exp. Tech. 51, 44 (2008).

Speaker: Dr Sanila S (FLNR, JINR)

35 Deviations from A.Bohr’s formula for fission fragments angular distributions with taking into account zero wriggling-vibrations of the fissile nucleus

The description of the fission fragments (FFs) angular distributions requires the use of quantum concepts about the dynamics of the fission process. It was demonstrated [1] that during spontaneous and low-energy induced binary fission FFs near the scission point should be in cold nonequilibrium states. For the construction of FFs angular distributions, it is necessary to take into account only zero transverse wriggling-vibrations of the fissile nucleus [2] near its scission point. The directions of FFs emission from the fissile nucleus, according to A. Bohr's hypothesis [1], are close to the symmetry axis of the fissile nucleus, which makes it possible to represent the amplitude of the FFs an-gular distribution in the form of a smeared delta function determined by the coherent superposition of large relative orbital momenta $L$ of these fragments. The appearance of this superposition can be associated with the occurrence of zero collective transverse vibrations of pre-fragments in the vicinity of the scission point of the fissile nucleus, which leads to large values of the relative orbital momenta $L$ of the FFs. Using the distribution of orbital momentum [3] $P(L)=1/(\pi C_w)\exp (L^2/C_w)$, where $C_w$ is the coefficients of wriggling -vibrations [2], the possibilities of detecting deviations of the FFs angular distributions in low-energy binary fission of aligned acti-nide nuclei by resonant neutrons and for the sub-barrier photofission of even-even actinides from the angular distributions described by the A. Bohr’s formula are investigated. From the comparison of the relative measurement errors of the anisotropy coefficients in the FFs angular distributions with deviations of the theoretical values of the anisotropy coefficients calculated by taking into account the wriggling-vibrations of the fissile nucleus from their values calculated using the A.Bohr for-mula, an estimate of the wriggling vibration parameter , were carried out.

1. A.Bohr, B.Mottelson Nuclear Structure (Benjamin, New York, 1975), Vol. 2
2. J. R. Nix and W. J. Swiateсki, Nucl. Phys. A 71, 1 (1965).
3. S.G. Kadmensky, L.V. Titova, D.E. Lyubashevsky, Phys. Atom. Nucl. 83, 581 (2020)

Speaker: Larisa Titova (Voronezh State University)

36 New indications and evidences of multibody partitions of 252Cf(sf)

In our previous publications [1-4] we presented experimental evidences of rare ternary decay mode of low excited heavy nuclei called collinear cluster tri-partition (CCT). Essential feature of this process is that some of the fission fragments (FFs) born during binary fission undergo a break-up, while they pass a solid-state foil. This break-up is delayed and occurs after the binary fission of the mother system. It is reasonable to think of such specific FFs as formed in the shape-isomer states [5]. The break-up is due to the FF inelastic scattering in the foil medium. In the recent series of experiments at the double-armed time-of-flight COMETA spectrometer, we have obtained both indications of the FFs spontaneous fission from the shape-isomer states, and evidences of new modes of the break-up of such fragments in different foils.

References
1. Yu.V. Pyatkov et al., Eur. Phys. J. A 45, 29 (2010).
2. Yu.V. Pyatkov et al., Eur. Phys. J. A 48, 94 (2012).
3. Yu.V. Pyatkov et al., Phys. Rev. C 96 (2017) 064606.
4. Yu.V. Pyatkov et al., Eurasian Journal of Physics and Functional Materials
v.4 №1 (2020) 13-18
5. D.V.Kamanin, Yu.V.Pyatkov, A.N.Solodov et al., Journal of Physics: Conference Series 2586, 2023, art. 012043.

Speaker: Yury Pyatkov (National Nuclear Research University “MEPHI” &amp; Joint Institute for Nuclear Research)

37 Развитие квантовой теории спонтанного двойного деления

Проблема описания спинов фрагментов деления (ФД), а также их относительного орбитального момента обсуждаются более шести десятилетий, причем она является частью фундаментальной задачи по развитию квантовой теории деления. В настоящей работе показано, что для случая спонтанного деления появление коллективного деформационного движения делящегося ядра определяется структурой наборов переходных делительных состояний введенных О. Бором [1], отвечающих выходам различных пар фрагментов деления. Причем указанные ФД вплоть до точки разрыва должны находиться только в холодных и сильно неравновесных по своим деформациям состояниях. В рамках подхода [2] были получены энергии возбуждения для ядра ${}^{252}\text{Cf}$, которые в случае легкого и тяжелого ФД лежат в диапазонах от 7.5 МэВ до 32.5 МэВ и от 5 МэВ до 20 МэВ соответственно. Используя оболочечные поправки к жидкокапельной модели ядра, полученные [3], были восстановлены неравновесные деформации ФД, которые не удается наблюдать экспериментально, но возможно оценить теоретически. Далее в рамках сверхтекучей модели атомного ядра, развиваемой в работе [4] были получены моменты инерции ФД в подходах с использованием осцилляторного и прямоугольного потенциала, а также гидродинамической модели. Используя нулевые поперечные bending- и wriggling-колебания делящегося ядра [5], были построены спиновые распределения, причем наилучшего согласия удалось достичь с экспериментальными данными [6] и лучшего по сравнению с другими теоретическими группами [7, 8] в рамках сверхтекучей модели атомного ядра с прямоугольным потенциалом. Далее используя неравновесные деформации ФД, предлагается провести расчет потенциалов деформации для каждой пары ФД и оценить относительные выходы ФД, поскольку этот механизм позволит качественно восстановить кривую массового выхода ФД. Указанный подход кардинальным образом отличается от широко развиваемого подхода западных научных групп, в основе которого лежит нагрев ядра до температур порядка 1 МэВ.

1. Bohr A., Mottelson B., Nuclear Structure, (Benjamin, N-Y, 1974) V.2.
2. Грудзевич О.Т. Вопросы атомной науки и техники. Cер. Ядерные константы, 2000, вып. 1.
3. Strutinsky V. M. Nucl. Phys. A 95. 420. 1967.
4. Мигдал А.Б., ЖЭТФ, 37, 249 (1959).
5. Nix J. R. and Swiatecki W. J., Nucl. Phys. 71, 1 (1965).
6. Wilson J. N. et al., Nature (London) 590, 566 (2021).
7. Randrup J. and Vong R., Phys. Rev. Lett. 127. 062502(2021).
8. Bulgac A. et al., Phys. Rev. Lett. 127, 022501 (2022).

The problem of describing the spins of fission fragments (FFs) and their relative orbital momenta has been discussed for more than six decades, and it is part of the fundamental task of developing the quantum theory of fission. In the present article it is shown that for the case of spontaneous fission the appearance of the collective deformation motion of the fissile nucleus is determined by the structure of sets of transient fission states introduced by O. Bohr [1], corresponding to the yields of different pairs of fission fragments. Moreover, the indicated FFs up to the scission point should be only in cold and strongly nonequilibrium states in terms of their deformations. In the framework of the approach [2], the excitation energies for the ${}^{252}\text{Cf}$ nucleus were obtained, which in the case of light and heavy FFs lie in the ranges from 7.5 MeV to 32.5 MeV and from 5 MeV to 20 MeV, respectively. Using shell corrections to the liquid-drop model of the nucleus obtained [3], nonequilibrium deformations of FF, which cannot be observed experimentally but are possible to estimate theoretically, have been recovered. In the framework of the superfluid model of the atomic nucleus developed in the article [4], the moments of inertia of the FF were obtained in the oscillatory and rectangular potential approaches as well as the hydrodynamic model. Using zero-dimensional transverse bending- and wriggling-oscillations of the fissile nucleus [5], spin distributions were constructed, with the best agreement with experimental data [6] and other theoretical groups [7, 8] in the framework of the superfluid model of the atomic nucleus with a rectangular potential. Using nonequilibrium strains of FFs, it is proposed to calculate the strain potentials for each pair of FFs and to estimate the relative yields of FFs, since this mechanism will allow a qualitative reconstruction of the mass yield curve of FFs. The indicated approach is fundamentally different from the widely developed approach of western scientific groups, which is based on heating the nucleus to temperatures of the order of 1 MeV.

1. Bohr A., Mottelson B., Nuclear Structure, (Benjamin, N-Y, 1974) V.2.
2. Grudzevich O.T. Voprosy atomnoy nauki i tekhnika. Ser. Nuclear Constants, 2000, V. 1.
3. Strutinsky V. M. Nucl. Phys. A 95. 420. 1967.
4. Migdal A.B., JETF, 37, 249 (1959).
5. Nix J. R. and Swiatecki W. J., Nucl. Phys. 71, 1 (1965).
6. Wilson J. N. et al., Nature (London) 590, 566 (2021).
7. Randrup J. and Vong R., Phys. Rev. Lett. 127. 062502(2021).
8. Bulgac A. et al., Phys. Rev. Lett. 127, 022501 (2022).

Speaker: Dmitrii Lyubashevsky (Voronezh State University)

38 EXPERIMENTAL STUDY OF MODAL FISSION OF EXITED HEAVY NUCLEI

Recent observation of mass-asymmetric fission in neutron-deficient Hg and Pt nuclei has reignite interest in studying the fission properties of heavy nuclei both theoretically and experimentally.
To study the multimodal fission of excited preactinide (Pt, Hg, Pb) and heavy actinide (Fm, Cf, No) nuclei formed in reactions with O, Ar and Ca ions at various excitation energies a series of experiments was conducted.
The measurements were carried out at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions (JINR, Dubna, Russia) using the double-arm time-of-flight spectrometer CORSET [1].
The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus. The stabilization role of proton numbers at Z ≈ 36, 38, Z ≈ 45, 46, and Z = 28/50 in asymmetric fission of excited preactinide nuclei was observed [2, 3]. It was also shown that in the fission of heavy actinides, the increased yield of fragments in the mass region ~100 u is associated with the influence of the deformed proton shell Z ≈ 38.

References:
[1] E. M. Kozulin et al., Instrum. Exp. Tech. 51, 44 (2008).
[2] A. A. Bogachev et аl., Phys. Rev. C 104, 024623 (2021).
[3] E. M. Kozulin et аl., Phys. Rev. C 105, 014607 (2022).

Speaker: Yulia Itkis (FLNR JINR)

Heavy ion collisions at Intermediate and high energies

39 DOUBLE POLARIZED DEUTERON-DEUTERON SCATTERING AND TEST OF T-INVARIANCE

The total cross section of the interaction of deuterons polarized transversely with respect to the beam direction with the polarization Py and a tensor-polarized deuteron target with the polarization Pxz is a null-test signal of the effect of violation of invariance with respect to time reversal (T) while conserving spatial (P) parity. This effect is very similar to that expected in double polarized pd and 3He-d scattering with vector polarized protons and 3He nuclei and tensor polarized deuterons studied in Refs. [1,2]. Here this effect is studied on the basis of the Glauber theory with account of full spin-dependence of nucleon-nucleon scattering amplitudes. Previously such an extension of the Glauber model was done for pd elastic scattering in Ref. [3]. For dd elastic scattering, the corresponding formalism is developed for the first time in the present work. For simplicity we restrict ourselves by single- and double-scattering mechanisms of dd scattering and keep only the S-component of the deuteron wave function. All types of NN interactions nonvanishing on the mass shell [4] are taken into account. Numerical results for the energy dependence of the expected effect of T-violation under P-parity conservation are obtained at the deuteron beam energies of 150-1000 MeV/nucleon.

The research was carried out at the expense of the grant of the Russian Science Foundation No. 23-22-00123, https://rscf.ru/project/23-22-00123/.

List of references

1. Yu.N. Uzikov, J. Haidenbauer, Phys. Rev. C 94, 035501 (2016).
2. Yu.N. Uzikov, M.N. Platonova, JETP Lett. 118, 785 (2023).
3. M.N. Platonova, V.I. Kukulin, Phys. Rev. C 81, 014004 (2010).
4. M. Simonius, Phys. Rev. Lett. 78, 4161 (1997).

Speaker: Yury Uzikov (Joint Institute for Nuclear Researches)

Nucelus-2024-uzikov-5.pdf

40 Splitting effect of light nuclei momentum distributions at fragmentation of iron ions with energy of 230 MeV/nucleon.

The results of iron fragmentation on different targets at energy 230 MeV/nucleon are presented. Experimental data were obtained with the FRAGM experiment and TWA heavy ion facility, which has a unique opportunity to measure the momentum distribution of fragments with high resolution at small angles [1,2]. In contrast to the typical fragmentation, where the momentum spectra have Gaussian-like shapes, the emission of light fragments has a double-humped structure. This splitting effect is most clearly manifested in proton spectra. An attempt to describe the effect by asymmetric fission and multifragmentation is discussed. Experimental data are compared with the results of the FRS-GSI measurements [3] and with the predictions of various models of nucleus-nuclear collisions.

[1] B.M. Abramov et al., Phys.Atom.Nucl. 85, 1541 (2022).
[2] A.A. Kulikovskaya et al., Phys.Atom.Nucl. 85, 466 (2022).
[3] P. Napolitani et al., Phys.Rev. C 70, 054607 (2004).

Speaker: M. A. Martemianov (NRC “Kurchatov institute”, 123182 Moscow, Russia)

Conference-Martemianov2024.pdf

41 Study of correlations of charged particles in Xe+W interactions at an energy of 3.0 GeV/nucleon.

Experimental results on spatial correlations of charged particles in Xe+W interactions at the energy of 3 GeV/nucleon obtained at the Nuclotron internal target station are presented. The simulation of the detectors of the experimental setup has been performed using the Geant4 software package and the PHQMD (Parton-Hadron-Quantum-Molecular Dynamics) event generator.

Speaker: Ksenia Legostaeva

Legostaeva.pdf

42 Дибарионы: поиск и теоретические оценки

В работе анализируются нуклон-нуклонные взаимодействия $pn \to d\pi^0\pi^0$, $pn \to d\pi^+\pi^-$ и $pp \to d\pi^+\pi^0$ , в которых в конечном состоянии образуется дейтрон и пара пи-мезонов. Им противопоставляются конечные состояния с парой свободных нуклонов.
Получено экспериментальное подтверждение формулы, вляющейся следствием сохяранения изоспинов
$\sigma(d\pi^+\pi^-)$= 2$\sigma(d\pi^0\pi^0)$ + 1/2$\sigma(d\pi^+\pi^0)$. Масса 2380 МэВ и ширина 80 МэВ резонансной особенности в сечении подтверждают оценки теории мультиплетов.
Если резонансная структура видна в s-канале для системы протон-нейтрон, то она так же прояляется в поведении некоторых наблюдаемых величин для упругого рассеяния np, например, для анализирующей способности $A_y$.

Speaker: Eugene Doroshkevich (Institute for Nuclear Research RAS)

43 Fragmentation features of Be, B, C nuclei in nuclear track emulsions

The report will give a brief overview of the experimental results of the relativistic fragmentation of $^{7,9}$Be, $^{10}$B, $^{10,12}$C in the Becquerel project in JINR. The fragmentation of a large variety of light nuclei was investigated using the emulsions exposed to few A GeV nuclear beams at JINR Nuclotron-NICA complex . A nuclear track emulsion is used to explore the fragmentation of the relativistic nuclei. The presented observations serve as an illustration of prospects of the modern accelerators and nuclear track emulsions for nuclear physics researches. Due to a record space resolution the emulsion technique provides unique entirety in studying of light nuclei, especially, neutron-deficient ones. Providing the 3D observation of narrow dissociation vertices this classical technique gives novel possibilities of moving toward more and more complicated nuclear systems. It was studied fragmentation of Be, B, C nuclei with energy 1.2 A GeV in a nuclear track emulsion, derived at the Nuclotron-NICA, JINR. The results of an exclusive study of the interactions of relativistic $^{7,9}$Be, B and C nuclei lead to the conclusion that the known features of their structure are clearly manifested in very peripheral dissociations
References
[1] P. I. Zarubin Lecture Notes in Physics, Vol. 875, Clusters in Nuclei, Volume 3. Springer Int. Publ., 51 (2013) [arXiv:1309.4881].
[2] P.I. Zarubin et al. Prospects of Searches for Unstable States in Relativistic Fragmentation of Nuclei. Phys. Atom. Nuclei 85, 528–539 (2022). https://doi.org/10.1134/S1063778822060035

Speaker: Denis Artemenkov (JINR)

44 Production of protons, deuterons, tritons in argon-nucleus interactions at 3.2 AGeV

Abstract

First physics results of the BM@N experiment at the Nuclotron/NICA complex are presented on studies of proton , deuteron and triton production in interactions of an argon beam with fixed targets of C, Al, Cu, Sn and Pb at 3.2 AGeV. Transverse mass distributions, rapidity spectra and multiplicities of protons, deuterons, tritons are measured. The results are treated within a coalescence approach and compared with predictions of theoretical models and with other measurements.

Speaker: Mr Lalyo Kovachev (JINR)

Production_of_p_d_t_in_Аr_A_interactions_LK.pdf

Nuclear structure: theory and experiment: Few-body systems

45 Lattice system of two fermions with first and second nearest-neighboring-site interactions

A system of two identical spinless fermions on the two-dimensional lattice is studied [1] under the assumption that the first and second nearest-neighboring-site interactions between the fermions are only nontrivial and that these interactions are of magnitudes $\lambda$ and $\mu$, respectively. A partition of the $(\lambda,\mu)$ plane is established such that, in each its connected component, the two-fermion Schroedinger operator corresponding to the zero quasi-momentum of the center of mass has definite (fixed) numbers of eigenvalues that are located below the bottom of the essential spectrum and above its top. Furthermore, for each connected component, a sharp lower bound is established on the number of isolated eigenvalues for the two-fermion Schroedinger operator corresponding to any admissible nonzero value of the center-of-mass quasimomentum. The results obtained help one to clarify the mechanism of emergence of eigenvalues of a two-fermion lattice Schroedinger operator from the essential spectrum as $\lambda$ and $\mu$ vary as well as to understand the inverse process, the absorption of eigenvalues by the essential spectrum.

This research was supported in part by the Ministry of Innovative Development of the Republic of Uzbekistan (Grant No. FZ-20200929224).

1. S.N. Lakaev, A.K. Motovilov, and S.Kh.Abdukhakimov, "Two-fermion lattice Hamiltonian with first and second nearest-neighboring-site interactions", J. Phys. A: Math. Theor. 56 (2023), 315202 [23 pages].

Speaker: Alexander K. Motovilov (BLTP, Joint Institute for Nuclear Research)

46 Self-consistent evolution: new neural network approach to bound state calculations

An application of neural networks for solving quantum mechanical problems has been suggested in [1,2]. Many improvements, including an adaptation of deep neural network techniques [3], have been proposed since. Development of a new computational technology which could lift the curse of dimensionality, however, has not yet been completed, although some steps in this direction have already been made [4,5].

We propose a new approach to training neural networks for approximation of quantum Hamiltonian invariant subspaces corresponding to bound states. The approach is based on training an artificial neural network to solve the Schrödinger equation in imaginary time with initial conditions that put the solution into an invariant subspace.

The advantage of the proposed approach is a simpler objective function which leads to better performance.

Theoretical results are illustrated with numerical examples.

[1] I.E. Lagaris, A. Likas, and D.I. Fotiadis, Artificial Neural Networks for Solving Ordinary and Partial Differential Equations // IEEE TRANSACTIONS ON NEURAL NETWORKS 1998, V. 9, N. 5, P.987
[2] I.E. Lagaris, A. Likas, and D.I. Fotiadis, Artificial neural networks in quantum mechanics // Comp. Phys. Comm. 1997, V.104, P.1-14
[3] Sirignano, J., Spiliopoulos, K., DGM: A deep learning algorithm for solving partial differential equations// arXiv preprint arXiv:1708.07469
[4] Hong Li, Qilong Zhai, Jeff Z. Y. Chen, Neural-network-based multistate solver for a static Schrödinger equation // Phys.Rev. A 2021,V. 103, P. 032405
[5] V.A. Roudnev, M.M. Stepanova, Deep learning approach to high dimensional problems of quantum mechanics // Proceedings of Science 2022, V.429, P. 13

Speaker: Vladimir Roudnev (St-Petersburg State University)

47 Виртуальные и резонансные состояния в трёхчастичных системах d-\mu^--t, d-\mu^--d

В работе находятся корни однородных уравнений Фаддеева на физическом и нефизическом листах трёхчастичной энергии систем d-μ^--t, d-μ^--d с использованием процедуры прямого численного интегрирования [1] по комплексной плоскости энергий. Осуществлено аналитическое продолжение связанных по каналам упругого рассеяния и термоядерным реакциям двухчастичных уравнений Липпмана-Швингера на нефизический лист энергии [2], решения для которого генерируются зависящими от углов двухчастичными потенциалами MT-типа. Параметры этих потенциалов подобраны из наилучшего описания оценённых экспериментальных данных по термоядерным dt и dd реакциям. Кулоновское взаимодействие в двухчастичных секторах учитывается в рамках двухпотенциальной модели [3] с введением экранированного кулоновского потенциала. Проведённые численные расчёты показывают наличие нескольких связанных состояний в системах d-t-μ^-,d-t-e^-, которые исчезают при выключении короткодействующего dt взаимодействия. На нефизическом листе энергий в области энергий [0;20] кэВ с шагом по энергии 500 эВ расчёты показывают наличие нескольких виртуальных и резонансных состояний в системах d-μ^--t, d-μ^--d. Обсуждается также более реалистичное шестичастичное обобщение данных систем dμ^- t-nμ^-4He и dμ^- d-nμ^-3He(pμ^-3H), которые возникают уже на трёхчастичных порогах.

[1] H.Liu, Ch.Elster, W.Glöckle, Three-body scattering at intermediate energies // Phys.Rev.C72(2005)054003.
[2] Ю.В. Орлов, Об аналитическом продолжении интегральных уравнений теории рассеяния на нефизический лист энергии // Письма в ЖЭТФ, Т.33, вып.7. 1981 г, стр.380-384.
[3] Sh. Oryu, Two- and three-charged-particle scattering in momentum space: A two-potential theory and a boundary condition model // Phys. Rev. C73(2006)054001.

Speaker: Mr Mikhail Egorov (Tomsk State University)

Nucleus-2024.pdf

48 Induced dipole interaction in scattering of positrons and electrons off light atomic target

Induced dipole interaction in scattering of positrons and electrons off light atomic target
V.A. Gradusov1, S.L. Yakovlev1
1St Petersburg State University, St Petersburg, Russia;
E-mail: v.gradusov@spbu.ru, s.yakovlev@spbu.ru

Scattering of a charged particle with a two-particle target system which is bound by the attractive Coulomb interaction is considered. Although, the leading contribution to the asymptotic form of the wave function and its components comes from the asymptotic Coulomb interaction between the two-particle target and the spectator particle, the next long-range terms of the multipole expansion of this interaction plays important role in energy regions where the excited state channels are open [1,2]. In this contribution we discuss the role of the explicit asymptotic representations for the wave function components which take into account as the Coulomb as well as the induced dipole interactions between the two-body target and the spectator particle. The general method from [3] is used for constructing asymptotic solutions. The derived asymptotics is then intended for the use in electron and positron scattering off the hydrogen (anti hydrogen) atom calculations in the energy region above the thresholds of exited states of the target where the induced dipole interaction produces specific effects in scattering data [4-6]. The Faddeev-Merkuriev set of equations is used for describing the scattering process [7].
This research is supported by RSF grant № 23-22-00109

References
1. M. Gailitis, J. Phys. B: Atom. Mol. Phys. 9, 843 (1976).
2. V.А. Gradusov, S.L. Yakovlev, Theor. Math. Phys., 217 (2): 1777-1787 (2023)
3. S.L. Yakovlev, Theor. Math. Phys. 203 (2), 664 (2020).
4. V.A. Gradusov et al., J. Phys. B: At. Mol. Opt. Phys. 52, 055202 (2019).
5. V.A. Gradusov et al., JETP Letters 114, No. 1, 11 (2021).
6. V.A. Gradusov, S.L. Yakovlev, JETP Letters, 119, No. 3, 151-157 (2024)
7. L.D. Faddeev and S.P. Merkuriev, Quantum Scattering Theory for Several Particle Systems, Kluwer, Dordrecht (1993).

Speaker: Sergey Yakovlev (Saint Petersburg State Univesrsity)

49 Single ionization of helium atom by protons in the parabolic quasi-Sturmian approach

Singly ionizing ion-atom collisions are investigated theoretically. A parabolic quasi-Sturmian approach is applied to the single ionization of helium atom by intermediate- and high-energy protons. The fully differential cross sections (FDCSs) are calculated for 1 MeV and 75 keV protons.

Speaker: Yuri Popov (Nuclear Physics Inst., Moscow State Univ., BLTP JINR)

50 Quantum control of molecular alignment and orientation by two-color trapezoidal laser pulses

The alignment and orientation of the linear molecule by the two-color trapezoidal laser pulses were theoretically investigated. The use of the trapezoidal shape of a laser pulse enhances the maximum alignment degree for the same intensity and duration comparing to the Gaussian laser pulse. Influence of pulse duration on the maximum degrees of molecule alignment and orientation was investigated. The influence of temperature effects is shown. It is shown that the use of additional preimpulse increases the maximum degree of orientation, and the application of two-color rather than monochromatic preimpulse leads to a higher maximum degree of orientation. The influence of change of relative phase between fundamental and second harmonics on orientation of molecules in the case of one and two impulses was also studied.

Speaker: Eugene Koval (BLTP, JINR)

51 Diffractionless solutions for the bound states of the model 1D three-body problem

The model of the one-dimensional impenetrable particles with interactions via the boundary conditions is considered. This model, besides its relation to the three-body problem [1-3],
describes also the wave diffraction problem for
the impedance wedge [4]. Previously, an exact solution was obtained by means of the Maluzhinetz-Sommerfeld transformation [4,2,3]. In the present report it was found that the bound-state solution turns out to be in the diffractionless (Bethe ansatz) form. A simple analytical expression for the eigenvalues is given. The relation to this model problem to the zero-range interaction problem [5] is discussed.

References

[1] E. Lieb and H. Koppe, Phys. Rev. 116, 367 (1959).
[2] J.B. McGuire and C.A. Hurst, J. Math. Phys. 13,
1595-1607 (1972).
[3] K. Lipszyc, J. Math. Phys. 21, 1092–1102 (1980).
[4] G. D. Maluzhinetz, Dokl. Akad. Nauk SSSR 121, 436-439 (1958).
[5] O.I. Kartavtsev, A.V.Malykh, S.A. Sofianos, ZhETF 135,
419 (2009).

Speaker: Anastasiya Malykh (BLTP JINR)

11:30 Coffee break

Applications of nuclear methods in science, technology, medicine and radioecology: Detectors/Therapy

52 SILICON PIXEL SENSORS FOR DETERMINATION OF CHARACTERISTICS OF PROTON BEAMS IN THE ENERGY RANGE 100 – 1000 MeV FOR THEIR USE IN TRACKING DETECTORS

Silicon pixels detectors may be used in proton computed tomography for tumor treatment planning in hadron therapy. In the context of this task it seems important to obtain the characteristics of the proton beam used for diagnostics and for therapy with high precision. It is also important to study the properties and influence on the beam of various materials that make up tomography detector systems. In this work the characteristics of proton beams of different energies using experimental setup of silicon pixels detectors system have been studied. The study of properties of carbon composite supporting structures used for digital track calorimeter will also be presented.
The reported study was supported by the Russian Science Foundation, project no. № 23-12-00042, https://rscf.ru/project/23-12-00042/

Speaker: Vitalii Petrov (St Petersburg State University (RU))

53 Оценка точности дозиметрии протонов с плёночными детекторами

На сильноточном линейном ускорителе протонов ИЯИ РАН имеется
возможность использовать максимально широкий диапазон средней мощности
дозы Ḋ, от конвенционального режима с Ḋ<3 Гр/с до одноимпульсного режима
FLASH (SPLASH) с Ḋ >10 4 Гр/с. В данной работе мы продолжили анализ
согласованности и корректности расчетов и измерений дозовых распределений
вблизи пика Брэгга, где характерен быстрый рост ЛПЭ. Исследования
показали, что отклик плёночных детекторов ухудшается в области высокого
градиента ЛПЭ, что не характерно для ионизационных камер. В то же время
показана нелинейность отклика ионизационных камер в областях мощностей
доз характерных для FLASH-режима. В силу невозможности использования
ионизационных камер для абсолютной дозиметрии при максимально высоких
значениях мощности дозы нами было проведено исследования влияния
мощности дозы и ЛПЭ на отклик плёночных детекторов в референтных
условиях при фиксированной дозе протонного излучения.
В продолжение предыдущих работ [1], были исследованы теоретические и
экспериментальные характеристики глубинных дозовых распределений
протонов в области пика Брэгга. Использованы расчеты по Монте-Карло с
пакетом TOPAS MC и экспериментальные данные, полученные с помощью
пленочных детекторов, ионизационных камер и оригинального черенковского
монитора пучка [2]. Рассмотрены взаимосвязь полученных значений
поглощенной дозы и корректность применения детекторов для ее измерения. В
частности, получено хорошее совпадение рассчитанных и измеренных с
помощью ионизационных камер дозовых распределений для начального и
модифицированного пика Брэгга в конвенциональном режиме облучения и
показана возможная взаимосвязь значения линейной передачи энергии и
точности измерения дозы с пленочными детекторами.
[1] G. V. Merzlikin, S. V. Akulinichev, I.A. Yakovlev. «Simulation of a proton beam facility
in the TOPAS MC software package». Moscow Univ. Phys. Bull. 11 (2023), doi.org/
10.55959/MSU0579-9392.78.2310201.
[2] Djilkibaev R.M., «A Cherenkov Proton-Beam Monitor», Instruments and Experimental
Techniques, 2021, v. 64, No. 4, pp. 508– 515. doi: 10.1134/S002044122104014X.
S.V. Akulinichev, Yu.K. Gavrilov, R.M. Djilkibaev, D.A. Kokontsev, V.V. Martynova, G.V.
Merzlikin, I.A. Yakovlev, «The Dosimetry of Proton Beams in Flash-Therapy», Bull. Russ.
Acad. Sci. Phys. 87 (8),1233 (2023), doi: 10.3103/S1062873823702878.

Speaker: Grigorii Merzlikin (INR RAS)

Мерзликин_Ядро2024.pptx

54 Позиционно-чувствительный черенковский монитор мощных пучков протонов

Цель данной работы – разработка позиционно-чувствительного монитора, работающего в широком диапазоне интенсивностей и длительностей импульса протонного пучка, в условиях сильного низко-энергичного электромагнитного фона. Монитор, предложенный в работе [1] позволяет измерять в on-line режиме временную структуру, число протонов и положение центра пучка в каждом отдельном импульсе протонного пучка. Этот монитор протонного пучка предназначен для работы на медицинском канале центра коллективного пользования ИЯИ РАН в широком диапазоне интенсивностей протонного пучка. В настоящее время монитор используется для исследования флэш-эффекта при облучении биологических объектов пучками протонов высокой мощности дозы, достигающей значений более 10 кГр/с [2,3]. Конструкция черенковского монитора протонного пучка позволяет преобразовать монитор в позиционно-чувствительный детектор заменой фотоумножителя (XP2020) на позиционно-чувствительный многоканальный кремниевый фотоумножитель (SiPM). Для пучков протонов с энергией 160 МэВ и импульсным средним током 1 мА получено хорошее согласие измерений монитора с данными пленочного детектора Gafchromic и индукционного датчика тока. При этом, в отличие от индукционного датчика тока, данный монитор находился в обычной атмосфере, а не в вакууме. Проведены стендовые измерения координаты положения светового потока, имитирующего световой образ протонного пучка в радиаторе 2х координатного монитора. Представлен анализ алгоритмов восстановления координаты положения светового пучка с результатами моделирования монитора.

Работа выполнена при поддержке Российского научного фонда, грант No. 24-15-00040 «Разработка ядерно-физических и радиобиологических методов протонной флэш-терапии».

[1] Djilkibaev R.M., «A Cherenkov Proton-Beam Monitor», Instruments and Experimental Techniques, 2021, v. 64, No. 4, pp. 508– 515. doi: 10.1134/S002044122104014X.
[2] S.V.Akulinichev, Yu.,K.Gavrilov, R.M.Djilkibaev, « Calibration of the Proton Beam Cherenkov Monitor»,Instruments and Experimental Techniques, 2023, Vol. 66, No. 4, pp. 365– 368. doi: 10.1134/S0020441223020124.
[3] S.V. Akulinichev, Yu.K. Gavrilov, R.M. Djilkibaev, D.A. Kokontsev, V.V. Martynova, G.V. Merzlikin, I.A. Yakovlev, «The Dosimetry of Proton Beams in Flash-Therapy», Bull. Russ. Acad. Sci. Phys. 2023, Vol. 87, No. 8, pp. 1233–1238. doi: 10.3103/S1062873823702878.

Speaker: Yuri Gavrilov (INR RAS)

55 Study of the yield of positron emitters after irradiation with 100 and 200 MeV protons of natural calcium targets

The most powerful means of achieving high conformality dose distributions is currently proton therapy. It allows a significant reduction in radiation exposure to normal tissues compared to traditional photon beam radiotherapy methods. This can be achieved even when the target is close to critical body structures. The energy of the beams used in proton therapy is in the range of 50–300 MeV. This range of proton energies corresponds to a Bragg peak depth of ~3–30 cm and is determined by the possible depth of the tumour in the patient's body. Traditionally, analytical calculations of the dose rate neglect the contribution of nuclear reactions on the accelerated protons. However, the interaction of protons of such energies with light nuclei in biological tissue produces a large number of radionuclides that decay by emitting positrons. According to some estimates, they can increase a patient's dose by more than 20% [1].
We have investigated the activity yields of $^{34m}$Cl (T$_{1/2}$=32 min) and $^{38}$K (T$_{1/2}$=7.6 min) when irradiating natural calcium targets with accelerated protons of energies of 100 and 200 MeV. The irradiation was performed at the Prometheus proton therapy complex of the Physical-Technical Center, Lebedev Physical Institute of the Russian Academy of Science. The irradiated targets were measured using Ortec$^®$ and Canberra$^®$ semiconductor spectrometers with ultrapure germanium detectors having an energy resolution of 1.8–2.0 keV for 1333 keV $^{60}$Co gamma radiation. The detection efficiency of the spectrometers was determined using standard calibration sources $^{152}$Eu, $^{226}$Ra, $^{137}$Cs.
The gamma transitions accompanying the decay of $^{34m}$Cl and $^{38}$K were reliably determined in the measured gamma spectra. For 100 MeV protons, the cross sections of these processes were found to be σ($^{nat}$Ca(p, XpYn)$^{34m}$Cl)=6.5±0.6 mbn, σ($^{nat}$Ca(p, 2p1n)$^{38}$K)=9.3±1.0 mbn. For protons with energies of 200 MeV, the activity ratios of $^{34m}$Cl and $^{38}$K were found to be similar within the measurement error.
The activity yields of $^{34m}$Cl were (3.1±0.2)10$^{–8}$ Bq/proton for 100 MeV and (3.2±0.2)10$^{–8}$ Bq/proton for 200 MeV. The results are discussed.

Speaker: Mr Stepan Adonyev (Lomonosov Moscow State University)

56 Measurement of the Photo-peak Efficiency and Covariance Analysis of -Ray Detectors of TANGRA Project using 22Na, 60Co, 133Ba, 137Cs, 152Eu, 228Th and Comparison with the Geant4 and MCNP Simulation.

Conducting thorough research on the inelastic scattering of 14.1 MeV neutrons on atomic nuclei using the tagged neutron technique is the main objective of the TANGRA project at the Frank Laboratory of Neutron Physics (FLNP) of the Joint Institute for Nuclear Research (JINR) in Dubna, Russia [1,2,3]. We tested the respective photo-peak efficiency of the HPGe and LaBr3(Ce) gamma-ray detectors in a recently built experimental facility as part of this ongoing programme of study. We have conducted our experiment with some common gamma-ray radioactive point sources such as 22Na, 60Co,133Ba, 137Cs, 152Eu, and 228Th. Furthermore, we used the GEANT4 code to do Monte Carlo (MC) simulations in order to determine these efficiencies. The simulations showed that the outcomes of the Monte Carlo computations and the experimental data agreed rather well. Our study results might be helpful for scientists using HPGe and LaBr3(Ce) detectors for gamma-ray spectroscopy, as well as for processing and analysing data collected during TANGRA project tests [4,5]. The agreement between our experimental data and the Geant4 (MC) simulation result is excellent. We have also compared our results with others’ data and MCNP result and found our results are more consistent. The propagation of error or micro-correlations takes into account various sources, including source activity, gamma ray abundance, gamma ray counts, and the half-life of radioactive nuclides. These correlations are thought to be the source of covariance information for the efficiency of the HPGe and LaBr3(Ce) detectors at various γ-ray energies. This study aims to provide a thorough analysis of photo-peak efficiencies together with covariance matrix data. In many different domains, such as nuclear physics, environmental science, medicine, geology, archaeology, and more, gamma-ray spectroscopy is an essential analytical method.

Speaker: Dr Pretam Kumar Das (FLNP, Joint Institute for Nuclear Research)

57 Determination of the Parameters of Prototype of “Gamma” Installation at the IREN Facility

On the flight bases of the 4th (11 meters) channels of the IREN facility, neutron flux density measurements were performed in the neutron energy range from 0.4 eV to 1500 eV. The neutron fluxes (thermal and resonance) were determined using gold foils. The parameters of the resolution function have also been determined and their values, obtained from experimental measurements for several neutron energies, are in good agreement with the calculations.

Speaker: Almat Yergashov (Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Institute of Nuclear Physics, Almaty, Republic of Kazakhstan)

58 Project BECQUEREL at portal of nuclear knowledge BelNET

Since beginning of the XXI century the International Atomic Energy Agency (IAEA) gives big attention to the nuclear knowledge management (NKM), based on research and development as well as industrial applications of nuclear technologies. NKM by the IAEA involves the nuclear science in the educational process through creation and development of different educational networks and portals.
Belarusian Nuclear Education and Training Portal (BelNET https://belnet.by/) was created in 2016 by scientists of the Institute for Nuclear Problems of Belarusian State University (INP BSU) to implement NKM principles. Currently it is the only major portal of nuclear knowledge in Belarus with about 5000 records in the main NK fields including current news, glossaries, monographs, textbooks, preprints, materials of international conferences, analytical reviews, special laboratory works for students etc.
At the end of 2023, mutually beneficial cooperation between the Laboratory of analytical research of INP and the JINR Nuclotron BECQUEREL experiment began.
The purpose of this experiment is to study the clustering in light stable and radioactive nuclei in the relativistic approach with the method of nuclear track emulsion. The investigated events of interaction of relativistic nuclei including complex multiparticle states allow to understand whether it is possible in the laboratory to reproduce the conditions of nuclear matter corresponding to nuclear astrophysics. The BECQUEREL experiment team working at the JINR Laboratory of High Energy Physics named after V.I. Veksler and A.M. Baldin has its own site http://becquerel.jinr.ru/.
The portal BelNET now contains a large number of records devoted to the BECQUEREL experiment. These include review articles and works on the study of nuclear reactions during irradiation of a nuclear emulsion in beams of various relativistic isotopes. Materials can be found in the portal section “Basic science” (https://belnet.by/elib/?i=121) -> “Relativistic nuclear physics” -> “Study of relativistic fragmentation of nuclei using the nuclear photoemulsion method”.
In this report, the scientific results of cooperation between portal BelNET and BECQUEREL experiment are presented and discussed.

Speaker: Dr Svetlana Sytova (Institute for Nuclear Problems of Belarusian State University)

59 Estimation of biological protection at the new cyclotron complex DC-140 using Monte Carlo method

Currently, the Laboratory of nuclear reactions, Joint Institute of Nuclear Research (JINR), is working on the creation of a new cyclotron complex DC-140, designed to solve a wide range of applied tasks. The main objectives of the project include research in solid-state physics, radiation resistance of materials, surface modification, production of track membranes, as well as testing of avionics and electronic component base under heavy charged particles [1].
The declared parameters of the new cyclotron are as follows: ion energy 2,1 and 4,8 MeV/u; ions of elements from O to Bi or U; intensities: 2,1 MeV/u (up to Xe 1012 s-1, Bi :1х1011 s-1, U>109 ), 4,8 MeV/u (up to Xe >1011 s-1, Bi :1х1010 s-1).
An important aspect of designing/engineering and exploitation/operation of accelerators is estimation of the radiation situation in the building. Estimation is performed by calculations that allow us to assess the possible radiation risk to the personnel, as well as to materials and equipment.
One of the methods of calculation is Monte-Carlo method, which is based on statistical modeling processes of interaction of particles with matter. Specialized simulation package FLUKA [2], which is based on this method, emerges as a powerful instrument for modeling the interactions of particles with matter and carrying out calculations of biological protection.
The new accelerator of heavy ions will be installed in the building previously occupied by the outdated cyclotron, hence requiring refinement of the radiation shielding. The simulation package FLUKA was utilized for computation. Performed computations allow us to evaluate the radiation situation of the building and indicate the maximum doses of ionizing radiation at various locations.
In [3], an estimate of the yield and angular distribution of neutrons has already been presented for calculating the biological protection of reconstructed heavy ion accelerators with an energy from 1 to 6 MeV/nucleon.

Speaker: Yeldos Bolatkazyyev

Experimental and theoretical studies of nuclear reactions

60 Роль динамики при описании нейтронных множественностей в спонтанном делении трансфермиевых ядер

Теоретические расчёты нейтронных множественностей в спонтанном делении трансфермиевых ядер проведены в рамках усовершенствованной модели точки разрыва [1]. В модели предполагается, что после прохождения барьера деления ядро может быть описано как суперпозиция двойных систем, характеризующихся массами, зарядами и деформациями фрагментов. Эволюция начального распределения двойных систем анализируется при помощи мастер-уравнения, учитывающего вероятности изменения деформаций фрагментов, передачи нуклонов между фрагментами и развала по координате относительного расстояния. Последний процесс приводит к формированию первичного распределения осколков деления. Получено хорошее согласие с недавними экспериментальными данными по нейтронным множественностям в спонтанном делении $^{246}$Fm [2] и $^{256}$Rf [3].

[1] H. Pasca, A.V. Andreev, G.G. Adamian, N.V. Antonenko, Phys. Rev. C 104, 014604 (2021)
[2] A.V. Isaev et al., Eur. Phys. J. A 58, 108 (2022)
[3] A.V. Isaev et al., Phys. Lett. B 843, 138008 (2023)

Speaker: Alexander Andreev (JINR)

61 Quantum mechanical analysis of angular oscillations at scission point: Implications for fission fragment angular momentum generation

Nuclear fission presents a striking phenomenon where the initial spin-zero spontaneously fissioning nucleus results in primary fission fragments with significant angular momenta (2-8 ¯h) [1]. Various theories have been proposed to explain the mechanism behind this phenomenon, differing in whether they attribute the generation of angular momentum to happen at scission point or at post-scission stages of fission process. In the previous studies, using the dinuclear system concept [2], we explored the role of angular oscillations at scission point in generating the angular momentum of primary fission fragments. The angular momenta of the fragments calculated as a function of the number of evaporated neutrons was found to be in a good agreement with available experimental data for 252Cf spontaneous fission. However, recent experiments [3] have shown no significant correlation between the spins of fragment partners, seemingly contradicting the idea that angular momentum is generated at the scission point. Here, we present a fully quantum-mechanical treatment of angular vibrations at the scission point, explaining the absence of correlation in fission fragments angular momenta and supporting the view that angular momentum is indeed generated at the scission point. We apply this model to recent experimental data for 252Cf spontaneous fission.

[1 ] G. M. Ter-Akopian et al., Phys. Rev. C 55, 1146, (1997).
[2 ] T. M. Shneidman, G. G. Adamian, N. V. Antonenko, S. P. Ivanova,
R. V. Jolos, and W. Scheid, Phys. Rev. C, 65, 064302.
[3 ] J. N. Wilson et al., Nature 590, 566, (2021).

Speaker: Azam Rahmatinejad (JINR)

62 Low-energy incomplete fusion: A systematic study of entrance channel parameters

Research into heavy-ion (HI) fusion, a key area of modern nuclear reaction physics, has flourished in recent decades pursuant to developments in accelerator technology. The primary goal of studying HI reactions is to gain knowledge about the underlying processes and how they are affected by entrance channel parameters, such as beam energy, angular momentum, and mass asymmetry. The fusion mechanism of non-α-cluster projectiles, such 14N and 19F, has been studied in the low-energy zone. It has been challenging to analyze the contributing degrees of freedom in such reactions due to the absence of experimental data. The present study reports the measurement of residual cross sections from the 19F induced reaction on 93Nb within the energy range of 3-7 MeV/A. The stack foil activation technique followed by offline γ spectroscopy was employed to measure the cross sections of residues populated in the reaction. The experimental data were compared with theoretical predictions from statistical model code PACE4 to probe the underlying reaction dynamics. The imitation of xn and pxn channel data grossly by model code suggests the production of residues via the complete fusion (CF) mode, while the enhancement observation in α-channel cross sections hints at the signatures of incomplete fusion in addition to the dominant CF. Thus, the ICF strength fraction (FICF) was calculated. Moreover, the estimated incomplete fusion fraction has been used to study the effect of several entrance channel parameters on incomplete fusion reaction dynamics. The present analysis shows the presence of strong clustering in the 19F projectile as α and 15N.

Speaker: Mr Anuj Kumar Jashwal (Bareilly College MJP Rohilkhand University Bareilly)

Anuj Kumar Jashwal.pptx

63 Validity analysis of gamma-ray strength function models for radiative capture reactions of heavy nuclei

Abstract
Accurate simulation of radiative capture reactions (RCRs), which hold significant importance in various areas of nuclear physics and technology, relies on precise evaluation and modeling of gamma-ray strength functions (GSF). Therefore, several phenomenological and microscopic GSF models have been developed in nuclear reaction codes for practical applications. Since theoretical GSF models behave differently mainly at low energies, GSF models require normalization, typically performed based on experimental data of total radiative width (TRW). In this investigation, it is observed that such normalization fails to adequately reproduce the experimental data of neutron-induced RCRs for 238U and 233Th heavy nuclei. Therefore, re-normalization values are presented for each model and it is demonstrated that such re-normalization brings various GSF models closer together in behavior at low energy regions and a range is obtained for GSF at low energies, where its actual value lies in this range. It is also shown that the widely used standard Lorentzian (SLO) model shows the most reliable fit to the experimental data with the least amount of required normalization.

Speaker: Mehdi Nasri Nasrabadi (Faculty of Physics, University of Isfahan, 81746-73441, Isfahan, Iran; Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia)

64 TOTAL REACTIONS CROSS SECTIONS MEASURING METHODS

Properties of nuclear sizes, such as material and charge root-mean-square radii and density distributions of nuclear matter, provide us with basic information for understanding the structure of the nucleus [1, 2]. One of the experimental approaches to extracting these parameters, particularly for radioactive nuclei, is based on measuring the total reaction cross sections σR and their energy dependencies σR(E) [3-5]. The σR measurement provides us with an objective and model-independent test for various theoretical models.
Currently, the development of methods for measuring σR is especially important due to the low intensities of beams of exotic nuclei located at the boundary of nucleon stability [5].
The paper provides an overview of methods for measuring total reaction cross sections, provides a systematic description of the methods, and outlines the main directions of their development. Particular attention is paid to the analysis of 4π methods for measuring the total cross sections of reactions with radioactive nuclei in the energy range 5 – 50 MeV/nucleon [6,7].
This research was funded by the Russian Science Foundation, project No. 24-22-00117.

References
1. A. Ozawa, Matter radii and Density Distributions, Handbook of Nuclear Physics, editors I. Tanihata, H. Toki, T. Kajino, p. 218-240, World Scientific Publishing Co. Pte. Ltd., Sin-gapore, (2023);
2. Yu. E. Penionzhkevich and R. G. Kalpakchieva, Light exotic nuclei near the boundary of neutron stability, World Scientific Publishing Co. Pte. Ltd., Singapore, (2022);
3. A. Ozawa, T. Suzuki, I. Tanihata, Nuclear size and related topics, Nucl. Phys. A 693, 32–62, (2001);
4. O. A. P. Tavares, E. L. Medeiros, and V. Morcelle, Universal trend for heavy-ion total reac-tion cross-sections at energies above the Coulomb barrier, Phys. Scr. 82, 025201 (2010);
5. Yu. E. Penionzhkevich, Yu. G. Sobolev, V. V. Samarin, M. A. Naumenko, N. A. Lash-manov, V. A. Maslov, I. Siváček, and S. S. Stukalov, Energy dependence of the total cross section for the 11Li + 28Si reaction, Phys. Rev. C 99, 014609 (2019);
6. I. Siváček, Yu. E. Penionzhkevich, Yu. G. Sobolev, and S. S. Stukalov, MULTI-2, a 4𝜋 spectrometer for total reaction cross section measurements, Nucl. Instrum. Methods Phys. Res. Sect. A 976, 164255 (2020);
7. Yu. G. Sobolev, V. V. Samarin, Yu. E. Penionzhkevich, S. S. Stukalov, and M. A. Nau-menko, Total cross sections for the reactions 10,11,12Be + 28Si and 14B + 28Si, submitted to Phys. Rew. C (2024).

Speaker: Yuri Sobolev (FLNR JINR)

65 Influences of the isospin-asymmetry and nuclear skin thickness on the structure and reactions of heavy nuclei

The isospin-asymmetry and its related nuclear matter properties influence most of the nuclear structure, reactions and decays. For instance, the values of the density diffuseness in finite nuclei and its anisotropy and polarization, rely on the asymmetry characteristics of the nucleon-nucleon interaction and nuclear matter at sub-saturation densities. This is related to the allowed maximum isospin asymmetry value for bound asymmetric nuclear matter. Increasing the isospin-asymmetry within the surface and tail regions of the nucleus makes these regions more soft relative to the internal region, and this consequently increases its single-particle and collective dynamicity. This in turn affects its structure and its reactions with other nuclei. Detailed influences of the isospin asymmetry and its related neutron/proton skin thickness, and the symmetry energy coefficients of nuclear matter on the fusion reaction of nuclei and its α and cluster decays will be discussed.

Speaker: Walaa Seif (BLTP-JINR + Cairo University)

Experimental and theoretical studies of nuclear reactions: Fission

66 Formation mechanism of decay fragments in spontaneous ternary fission of heavy nuclei

A model for describing spontaneous ternary fission of heavy nuclei is presented. It follows from the suggested model that heavy nuclei have the same half-lives in spontaneous ternary and binary fission processes. The collinear cluster tripartition process observed in experiments is found to be the dominant reaction channel in spontaneous true ternary fission of heavy nuclei within our model. Competition between binary fission and
the formation of a trinuclear system, which is responsible for the ratio of spontaneous ternary and binary fission yields, is introduced.

Speaker: SHUHRAT Kalandarov (BLTP JINR)

67 Neutron-Induced Fission Cross Section of 237Np up to 500 MeV

The 237Np neutron-induced fission cross section was measured relative to the 235U(n, f) cross section in the energy range from 0.2 MeV to 500 MeV using the GNEIS neutron time-of-flight spectrometer and the pulsed neutron source based on the 1 GeV proton synchrocyclotron of the NRC KI - PNPI (Gatchina). The experimental setup consisted of two position-sensitive MWPC counters, which also allowed simultaneous measurement of the angular distributions of the fission fragments [1]. A brief description of the experimental set-up, data processing and the preliminary results obtained are presented.
1. A. S. Vorobyev et al. Phys. Rev. C 108, 014621 (2023).

Speaker: A.S. Vorobyev (B.P. Konstantinov Petersburg Nuclear Physics Institute of National Research Center ”Kurchatov institute”,)

68 Fission of 243-Am by neutrons of intermediate energy: analysis of cross section and angular anisotropy of fission fragments

The results of measurements of fission cross sections and angular distributions of fission fragments from neutron-induced fission of 243-Am in the energy range 1-500 MeV are presented in [1]. The measurements were performed on the neutron time-of-flight spectrometer based on the GNEIS neutron complex at the 1GeV proton synchrocyclotron of the NRC "Kurchatov Institute" - PNPI (Gatchina). The data obtained can be used to gain insight into the barriers of Am isotope fission, the transition states at these barriers, the magnitude of the collective enhancement in the level density of deformed nuclei, and the role of direct and pre-equilibrium processes in the interaction of intermediate-energy neutrons with nuclei.
In this work, the cross section for the fission of 243-Am nuclei by neutrons with energies from 0.1 to 300 MeV was calculated using the Talys-1.9 program [2]. Our modification of this program [3,4] made it possible to obtain not only the total fission cross section, but also the differential fission cross section. It has been shown that the fission barrier parameters from the RIPL-3 library [5], used as default parameters in Talys-1.9, do not reproduce the energy dependence of the total fission cross section in the entire energy range considered. The parameters of the barriers and the coefficients of the additional collective enhancement of the level density at the barriers have been determined, which make it possible to satisfactorily reproduce the energy behavior of the fission cross section up to an energy of 120 MeV. It is also shown that in the range from 3 to 120 MeV, the angular anisotropy of fission fragments is satisfactorily described within the framework of a statistical approach to the formation of the fission probability distribution over the projection K of the nuclear spin onto the deformation axis.
1. A. M. Gagarski et al. Proc. ISINN-29, JINR, E3-2023-58, Dubna, 2023, p.236
2. A. J. Koning, D. Rochman. Nucl. Data Sheets 113, 2841 (2012).
3. A. L. Barabanov et al.. EPJ Web Conf. 256, 00003 (2021).
4. A. S. Vorobyev et al. Phys. Rev. C 108, 014621 (2023).
5. R. Capote et al. Nucl. Data Sheets 110, 3107 (2009).

Speaker: A. L. Barabanov (NRC "Kurchatov Institute")

69 The effect of the non-axial shape of nuclei on the fission characteristics in the Langevin approach

Description of nuclear fission is still an important problem. This is proved by the existence of various models attempting to describe maximally possible characteristics of the investigated process.

Similar goal is also faced by the model developed [1, 2] in the present study, which describes the dynamics of fission of heavy nuclei in the low- and medium-energy range. It is based on the use of a multidimensional system of Langevin equations responsible for changing the deformation configuration of the fissile system, whose surface is given [3] by Fourier parametrization. The potential of the deformed compound nucleus is described within the macroscopic-mircroscopic approach [4].

In earlier works [1, 2], the model considered the dynamical change of only three parameters corresponding to the nucleus deformation. Their physical meaning corresponds to the elongation of the system, the asymmetry of the pre-fragments, and the thickness of the neck connecting them. This was sufficient to consider the fission process at the final stage - the descent from the last barrier, i.e., we used the pre-deterministic hypothesis of the unavoidable breakup of the system by splitting the nucleus into fragments. This assumption, together with certain initial conditions [2], made it possible to simplify the calculations of such fission characteristics as the mass and charge distributions of the fragments and the total kinetic energies, which were in good agreement with experiment.

In several papers [5 $-$ 8], where similar Langevin models are also used, the fission process was considered starting from the ground state of the system and, obviously, providing the system with sufficient excitation energy to overcome the fission barriers. Nevertheless, only few (e.g. [6, 8]) take into account the non-axiality of the nucleus shape, which has direct influence on fission barrier heights, which is crucial in low-energy fission. However, it is also important for understanding the influence of this parameter on the departure of pre-fission particles, e.g. neutrons.

Therefore, the aim of this work is to generalise the existing model to the four-dimensional case, introducing the nuclear surface non-axiality parameter. Together with taking into account temperature effects acting on the diffusion tensor and shells, the above-mentioned distributions of primary fragments of low-energy fission of actinide nuclei are obtained. The main focus of the work is the comparative analysis of the obtained results with previous ones, due to which the previously used hypotheses are evaluated. In addition new boundary conditions, artefacts and other difficulties encountered in the numerical solution of the four-dimensional system of stochastic Langevin equations are identified. The obtained conclusions allow us to improve the model and prepare it for new modifications.

References
[1] P. V. Kostryukov et al., Chin. Phys. C 45, 124108 (2021).
[2] P. V. Kostryukov and A. Dobrowolski, Phys. Rev. C 108, 024605 (2023).
[3] C. Schmitt et al., Phys. Rev. C 95, 034612 (2017).
[4] K. Pomorski et al., Chin. Phys. C 45, 054109 (2021).
[5] M. R. Pahlavani, and S. M. Mirfathi, Phys. Rev. C 93, 024622 (2016).
[6] A. J. Sierk, Phys. Rev. C 96, 034603 (2017).
[7] L.-L. Liu et al., Phys. Rev. C 103, 044601 (2021).
[8] F. A. Ivanyuk, C. Ishizuka, and S. Chiba, Phys. Rev. C 109, 034602 (2024).

Speaker: Pavel Kostryukov (Voronezh State University of Forestry and Technologies / Voronezh State University)

70 Appearance of the hindrance to complete fusion in heavy-ion collisions

The hindrance to complete fusion is studied as a function of the charge asymmetry of colliding nuclei and orbital angular momentum of the collision. The formation of a dinuclear system (DNS) in the heavy ion collisions is calculated dynamically and its evolution is considered as multinucleon transfer between its fragments. The results prove that a hindrance at formation of a compound nucleus (CN) is related with the quasifission process which is breakup of the DNS into products instead to reach the equilibrated state of the CN. The role of the angular momentum in the charge (mass) distribution evolution for the given mass asymmetry of the colliding nuclei has been demonstrated. The results of this work have been compared with the measured data for the quasifission yields in the $^{12}$C+$^{204}$Pb and $^{48}$Ca+$^{168}$Er reactions to show the dependence of the hindrance on the mass asymmetry of the entrance channel [1]. The new mechanism of the incomplete fusion [2] and the analysis of the mixing of the quasifission yields with the ones of the very asymmetric fusion-fission processes [3] allow us to conclude that complete fusion occurs due to multinucleon transfer through the window (neck) between interacting DNS nuclei. The isotopes $^{272}$Ds and $^{280}$Ds are formed in the cold $^{64}$Ni+$^{208}$Pb and hot $^{48}$Ca+$^{232}$Th fusion reactions, respectively. In spite of the small fusion probability $10^{-5}$ in the former reaction, the ER cross section is large $\sigma_{\rm ER}=15$ pb due to small excitation energy $E^*_{\rm CN}$=12.7 MeV [4] and large fission barrier of $^{272}$Ds. Though the hindrance to complete fusion small for the hot $^{48}$Ca+$^{232}$Th fusion reaction, the maximal value 0.7 pb of the ER cross section was observed for the 4n channel [5] since fission barrier is 3.29 MeV for the CN $^{280}$Ds.

1. A.K. Nasirov, E.D. Khusanov, M.M. Nishonov, arXiv:2403.08489v1 [nucl-th], https://doi.org/10.48550/arXiv.2403.08489 (accepted to Phys. Rev. C) (2024).
2. A.K. Nasirov, B.M. Kayumov, O.K. Ganiev, G.A. Yuldasheva, Phys. Lett. B 842, 137976 (2023).
3. Shruti, B. R. Behera, N. Saneesh, A. K. Nasirov et al., Eur. Phys. Jour. A 59, 238 (2023).
4. G. Giardina et al., Eur. Phys.Jour. A 8, 205 (2000).
5. Yu. Ts. Oganessian et al., Phys. Rev. C 108, 024611 (2023).

Speaker: Avazbek Nasirov (Joint Institute for Nuclear Research)

71 Fission modes and deformed nuclear shells in mass and energy distributions of fission fragments of 237Pu compound nuclei formed in 233U(α,f) reaction at 24 and 29 MeV incident alpha particle energy

Mass and energy distributions of fission fragments of 237Pu compound nuclei formed in 233U(α,f) reaction at 24 and 29 MeV incident alpha particle energy were measured at U-150M cyclotron at Institute of Nuclear Physics, Almaty, Kazakhstan using 2E method. Measured distributions at two different compound nuclei excitation energies were each decomposed into separate yields from fission modes and deformed nuclear shells using a method that takes into account mass yield, average total kinetic energy and variance of average total kinetic energy. This method also assumes that mass yield of each mode and each deformed shell has a shape of gauss distribution. Such assumption reduces the number of parameters required to fit experimental data and as such increases the sensitivity of the method to yields of weaker deformed shells. This allowed to separate yield of Z50 spherical shell from yield of Z52 deformed shell, yield of N88 deformed shell from yield of N84 deformed shell and yield of N50 spherical shell from yield of N46 deformed shell.

Speaker: Andrey Pan (Institute of nuclear physics, Almaty, Kazakhstan)

Heavy ion collisions at Intermediate and high energies

72 The Hyperon Polarization and the Forward-Backward Flow in the Bi+Bi collisions at NICA

The Bi-Bi collisions at $\sqrt{s_{NN}} = 9.0$ GeV are simulated within the PHSD transport model. After spectators separation and fluidization procedure, the velocity and vorticity fields are calculated. Then, the global polarization for different hyperon species is evaluated, and its dependence on the momentum, rapidity, and centrality is analyzed. Finally, the correlations of the polarization and forward-backward flow are shown.

Speaker: Nikita Tsegelnik (BLTP, JINR)

TsegelnikNS-Nucleus2024.pdf

73 Search for unstable nuclear states in the fragmentation of Kr nuclei at 950 MeV/nucleon

Author: A.A. Zaitsev (JINR)
Abstract: Since the discovery of the nuclear component of cosmic rays, the nuclear photoemulsion (NTE) method has made it possible to study the composition of relativistic fragmentation of nuclei at high-energy accelerators. The promising potential of the relativistic approach to the analysis of ensembles of fragments manifested itself in layers of NTE exposed by beams at energy of several GeV per nucleon, accelerated at the Synchrophasotron of JINR and Bevalak (USA) in the 1970s. Since the 2000s, the NTE method has been used in the BECQUEREL experiment at the JINR Nuclotron in relation to the cluster structure of nuclei, including radioactive ones, as well as in the search for unstable nuclear-molecular states. Due to its unique sensitivity and spatial resolution, application of the NTE method makes it possible to study in a unified approach many final states that appear while the dissociation of relativistic nuclei. In this aspect, it seems possible to search in $\alpha$ relativistic approach for an $\alpha$-particle Bose-Einstein condensate ($\alpha$BEC), an unstable state of S-wave $\alpha$ particles. The extremely short-lived $^8\text{Be}$ nucleus is described as 2$\alpha$BEC, and the $^{12}$C(0$^+_2$) excitation or Hoyle state (HS) is described as 3$\alpha$BEC. The feasibility of more complex states is important in nuclear astrophysics.
Using NTE layers longitudinally exposed by beams of relativistic nuclei, it is possible to determine the invariant mass of ensembles of He and H fragments from the emission angles in the approximation of conservation of the initial momentum per nucleon. The decays $^8$Be and HS, as well as the decays $^9$B $\to$ $^8$Bep, are identified during the fragmentation of light nuclei according to the upper limit on the invariant mass [1]. This approach was used to identify $^8$Be and HS and search for more complex $\alpha$BEC states in the fragmentation of medium and heavy nuclei. Recently, the probability of reconstructed $^8$Be was found to increase with increasing number of associated $\alpha$ particles [2]. The exotically large sizes and lifetimes of $^8$Be and HS suggest the possibility of synthesis of $\alpha$BEC by sequential combination of the resulting $\alpha$-particles 2$\alpha$ $\to$ $^8$Be, $^8$Be$\alpha$ $\to$ $^{12}\text{C}(0^+_2)$, $^{12}$C(0$^+_2$)$\alpha$ $\to$ $^{16}$O(0$^+_6$), 2$^8$Be $\to$ $^{16}$O(0$^+_6$) and further with decreasing probability at each step while the emission of $\gamma$-quanta or recoil particles. Ongoing research is aimed at measuring the n$\alpha$ fragmentation channels of $^{84}$Kr at energies up to 950 MeV/nucleon to determine the contributions of the 2$\alpha$ decay of $^{8}$Be, the 3$\alpha$ Hoyle state and the search for the condensate state of 4$\alpha$ particles [3]. In this report discusses new results on the search for unstable nuclear states in the fragmentation of $^{84}$Kr and the prospect of analyzing recent exposure of NTE in beams of Xe nuclei at 3.9 GeV/nucleon at the Nuclotron/NICA accelerator complex.
Keywords: relativistic dissociation, $\alpha$-fragmentation, nuclear emulsion, unstable nuclei

References
[1] D.A. Artemenkov et al., Eur. Phys. J. A 56 (2020) 250; arXiv:2004.10277.
[2] A.A. Zaitsev et al., Phys. Lett. B 820 (2021) 136460; arXiv: 2102.09541.
[3] D.A. Artemenkov et al., Phys. At. Nucl., 85, 528 (2022); arХiv: 2206.09690.

Speaker: Andrei Zaitsev (JINR, LHEP)

Nucleus2024_Zaitsev.pdf

74 Electromagnetic dissociation of nuclei: from LHC to NICA

In ultraperipheral collisions (UPC) of relativistic nuclei without overlap of their nuclear density distributions the collision partners are mutually impacted by Lorentz-contracted Coulomb fields [1]. This leads to a variety of processes induced by equivalent Weizsäcker-Williams photons. In particular, large neutron emission cross sections ($\sim 200$ b) were measured in the ALICE experiment at the LHC for the electromagnetic dissociation (EMD) of $^{208}$Pb nuclei at $\sqrt{s_{\rm NN}}=5.02$ TeV [2], leading to the production of lead isotopes as secondary nuclei. As follows from calculations [3], Tl, Hg, Au, Pt, Ir, Os, Re, W, Ta and Hf are also produced in EMD of $^{208}$Pb at the LHC with the cross sections of 1-30 b exceeding or comparable to the total $^{208}$Pb-$^{208}$Pb hadronic cross section of 7.67 b. The cross sections of neutron and proton emission in the EMD are expected to be smaller for nucleus-nucleus collisions at NICA. However, it is important to calculate these cross sections in order to evaluate a possible contamination of the detected hadronic events by EMD events, which can affect the detector performance.

By means of RELDIS model [1], we have simulated the EMD of $^{209}$Bi and $^{124}$Xe in $^{209}$Bi-$^{209}$Bi and $^{124}$Xe-$^{184}$W collisions in the MPD experiment at NICA in collider and fixed target modes, respectively. The cross sections of the production of given numbers of forward neutrons and protons, their energy and angular distributions have been calculated. Mutual EMD events in $^{209}$Bi-$^{209}$Bi collisions were also modeled, since such events can in principle mimic very peripheral hadronic events. EMD of $^{124}$Xe was also modeled in UPC with CsI target in the BM@N experiment. In such collisions, the emission of a single neutron from electromagnetically excited $^{124}$Xe dominates, providing a unique well-collimated monoenergetic neutron beam that can be used for detector calibration or applied research, e.g. to study unexplored radiobiological effects of high energy neutrons.

References

[1] I.A. Pshenichnov, Electromagnetic excitation and fragmentation of ultrarelativistic nuclei, Phys. Part. Nucl. 42 (2011) 215.
[2] S. Acharya et al. (ALICE Collaboration), Neutron emission in ultraperipheral Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, Phys. Rev. C. 107 (2023) 064902.
[3] U.A. Dmitrieva, I.A. Pshenichnov, Production of various elements in ultraperipheral $^{208}$Pb-$^{208}$Pb collisions at the LHC, Phys. Part. Nucl. Lett. 20 (2023) 1228.

Speaker: Igor Pshenichnov (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow Institute of Physics and Technology)

Pshenichnov_EMD_NICA_Yadro-2024.odp

Pshenichnov_EMD_NICA_Yadro-2024.pdf

75 EMISSION OF CUMULATIVE SECONDARY PARTICLES AND FRAGMENTS IN COLLISIONS OF HEAVY IONS OF INTERMEDIATE ENERGIES BASED ON NON-EQUILIBRIUM HYDRODYNAMIC APPROACH

A.T. D'yachenko$^{1,2}$
$^1$ Emperor Alexander I Petersburg State Transport University, St. Petersburg Russia;
$^{2}$ B.P. Konstantinov Petersburg Nuclear Physics Institute of National Research Center “Kurchatov Institute”, Gatchina, Russia

In development of the nonequilibrium hydrodynamic approach [1,2], we were able to successfully describe [3] the double differential cross sections for the production of cumulative protons, pions, kaons and antiprotons emitted at an angle of 00 for the collision of carbon nuclein the reaction $^{12}$C+$^{12}$C at an energy of 19.6 GeV per nucleon on fixed target, obtained at the U-70 accelerator of the Institute of High Energy Physics (Serpukhov) [4]. For collisions of the same nuclei at the same energy, a description was obtained of the cross sections for the yield of protons and light fragments of deuterons and tritons emitted at an angle of 400 and studied in another experiment in [5]. These double differential cross sections reveal scaling for the yields of different fragments depending on their energy.

In continuation of the analysis of experiments at ITEP (Moscow) based on collisions of carbon nuclei with a beryllium target at the FRAGM installation, it was possible to obtain a description of the yields of 11Be and 10B fragments [6], emitted at an angle of 3.5$^o$ at an energy of carbon nuclei of 300 MeV per nucleon.
For this description, a nonequilibrium hydrodynamic approach and the Goldhaber statistical model were used. Our description of experimental data appears to be superior to cascade models and the quantum molecular dynamics (QMD) model built into the GEANT4 package. Along with the development of the hydrodynamic approach, the possibility of describing experimental data based on solving of the effective Klein-Gordon equation with dissipation was analyzed [7]. Our approach is applicable to collisions of both light and heavy nuclei, as can be seen from comparisons with experimental data and other theoretical approaches. This can be extended to the energy range of the NICA accelerator complex located at JINR (Dubna).

References
1. D’yachenko.A.T., Mitropolsky I.A., Phys. Atom. Nucl. $\bf{86}$, 558 (2020)..
2. D’yachenko A.T., Mitropolsky I.A., Phys. Atom. Nucl. $\bf{85}$, 1053 ( 2022).
3. D’yachenko A.T., Phys. Atom. Nucl. $\bf{87}$, 127 (2024).
4. Afonin A.G. et al., Phys. Atom.Nucl. $\bf{83}$, 228 (2020).
5. Antonov N.N. et al. JETP Lett. $\bf{111}$, 291 (2020).
6. Abramov B.M. et al. Phys. Atom. Nucl. $\bf{85}$, 466 (2022).
7. D’yachenko A.T. Phys. Atom. Nucl. $\bf{86}$, 289 (2023).

Speaker: Alexander D'yachenko (Petersburg State Transport University)

Доклад1_ Дьяченко А.Т._Секция3_2024.pptx

Nuclear structure: theory and experiment: Few-body systems

76 Resonant states of the 3n system in the SS-HORSE–NCSM approach

The SS-HORSE–NCSM method [1] is generalized to the case of democratic decay into an odd number of fragments. This method is applied to the search for resonances in three-neutron system (trineutron) using ab initio No-Core Shell Model [2] calculations with realistic nucleon-nucleon potentials [3-5].
We predict two overlapping trineutron resonances with spin-parities $3/2^−$ and $1/2^−$ which energies $E_r$ and widths $\Gamma$ are nearly the same. For the Daejeon16 interaction [3], we obtain $E_r= 0.5$ MeV and $\Gamma= 1$ MeV; for JISP16 [4] and the chiral interaction of the effective field theory N3LO [5], regularized by the SRG transformation [6] with the parameter $\Lambda=2$ fm$^{-1}$ these values are smaller: $E_r= 0.35$ MeV and $\Gamma= 0.7$ MeV, respectively. On the other hand, these resonances are not supported by $NN$ interactions of chiral effective field theory without SRG modification.
Our results are in line with the conclusions of Ref. [7] predicting the trineutron resonance at lower energy than the tetraneutron resonance [8, 9].

References
[1] A. M. Shirokov et al. // Phys. Rev. C. — 2016. — Vol. 94. — P. 064320.
[2] B. R. Barrett, P. Navrátil, J. P. Vary // Prog. Part. Nucl. Phys. — 2013. — Vol. 69. — P. 131.
[3] A. M. Shirokov et al. // Phys. Lett. B — 2016. — Vol. 761. — P. 87.
[4] A. M. Shirokov et al. // Phys. Lett. B — 2007. — Vol. 644. — P. 33.
[5] D. R. Entem, R. Machleidt // Phys. Rev. C — 2003. — Vol. 68. — 04100(R).
[6] S. D. Glazek, K. G. Wilson // Phys. Rev. D — 1993. — Vol. 48. — P. 5863.
[7] J. G. Li et al. // Phys. Rev. C — 2019. — Vol. 100. — 054313.
[8] A. M. Shirokov et al. // Phys. Rev. Lett. — 2016. — Vol. 117. — 182502.
[9] A. M. Shirokov et al. // AIP Conf. Proc. — 2018. — Vol. 2038. — 020038.

Speaker: Alexander Mazur (Pacific National University)

77 Machine learning in the problem of extrapolation of no-core shell model results

We modify the method of extrapolating the variational calculation results to the case of the
infinite model space using machine learning of neural networks suggested in Ref. [1]. The main
idea of the modified method is to train an ensemble of artificial neural networks using a
preliminary selection of training data, a subsequent selection of the trained neural networks
according to some criteria, and a statistical processing of the selected network predictions. We
propose a new neural network topology with an appropriate set of learning parameters.
The suggested modified method provides stable results, does not require a division of data
into the training and test sets, ensures the convergence of predictions with increasing the learning
data set by including the results from larger model spaces as well as a high statistical confidence
of the final results.
We extrapolate results obtained within the no-core shell model [2] with NN interaction
Daejeon16 [3] for ground state energies and root-mean-square radii of 6 Li, 6 He and 6 Be nuclei.
We obtain the 6 Li ground state with the same accuracy but higher in energy than the predictions
of Ref. [1]. However, our approach has a higher statistical confidence.

References

1. G. A. Negoita et al. // Phys. Rev. C. — 2019. — Vol. 99. — 054308.
2. B. R. Barrett, P. Navrátil, J. P. Vary // Prog. Part. Nucl. Phys. — 2013. — Vol. 69. — P. 131.
3. A. M. Shirokov et al. // Phys. Lett. B — 2016. — Vol. 761. — P. 87.

Speaker: Roman Sharypov

78 FINDING PARAMETERS OF MULTI-CHANNEL RESONANCES FROM DISCRETIZED SPECTRA

Recently we have suggested a new method for calculating resonance parameters in multi-channel and three-body systems, using the formalism of the spectral shift and spectral density functions [1]. The method is based on the possibility of reconstructing the spectral and integrated density of states from discretized spectra of the total and asymptotic Hamiltonians found within the variational method. The key point of the approach is combining many discretized spectra of the same dimension, obtained using bases with slightly changed parameters, into one common dense spectral set (union). Analysis of such a dense spectral set for the total Hamiltonian allows one to determine a position and a width of a multi-channel and three-body resonance.
The efficiency of the proposed approach is demonstrated by several multi-channel and three-body examples using a Gaussian basis. The convergence of results when expanding the basis dimension can be justified within the quasi-continuity concept [2] for the case of a multi-channel problem, while for the three-body case it is shown numerically. The developed approach allows one to avoid difficulties associated with the Coulomb interaction and to study problems with charged particles as well, for example, two-proton radioactivity. In particular, the width of the ground state of the 6Be nucleus was calculated within the framework of the three-cluster α-p-p model [1].

The authors appreciate financial support from the Russian Science Foundation (RSF) grant 23-22-00072.

1. V.N. Pomerantsev, O.A. Rubtsova, V.A. Kulikov, Phys. Rev. C 109, 014002 (2024).
2. O.A. Rubtsova, V.N. Pomerantsev, J. Phys. A 55, 095301 (2022).

Speaker: O. A. Rubtsova (M.V. Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics)

79 Short-range correlations in the lightest nuclei within the dibaryon model of nuclear forces

High momentum components of wave functions and two-nucleon short-range correlations (SRC) for the lightest nuclei with A=2 and 3 are studied within the dibaryon model for 2N and 3N forces [1]. This model accounts for a possibility of an intermediate six-quark (dibaryon) state formation in two-nucleon system at short distances. We evaluate the SRC probability for the deuteron and calculate the universal two-nucleon wave functions for the spin-triplet and spin-singlet channels which define the high-momentum ‘asymptotics’ in two-nucleon momentum distributions for heavier nuclei. Momentum distributions for A=3 nuclei are found from ab initio variational calculations in the three-body Gaussian basis.

The momentum distributions for 3He and 3H nuclei calculated within the dibaryon model are compared with those found with the conventional meson-exchange nuclear forces. The results obtained are interpreted in view of the recent (e,e’) experiments [2] which allowed to extract, in particular, the ratio of pp to np SRC-pairs for the above nuclei.

The authors appreciate financial support from the Russian Science Foundation (RSF) grant 23-22-00072.

1. V.I. Kukulin, V.N. Pomerantsev, O.A. Rubtsova, M.N. Platonova, I.T. Obukhovsky, Chin. Phys. C 46, 114106 (2022).
2. S. Li et al., Nature 609, 41 (2022).

Speaker: Olga Rubtsova (Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University)

80 sd-shell evolution in neutron-rich 13B and 16C via direct reactions

In unstable nucleus, single particle orbitals undergo rearrangement, leading to various shell evolution phenomena. In order to investigate the $sd$-shell structure in $^{13}$B, we need to find all the $s$- and $d$-wave state in $^{13}$B. So for searching the missing positive parity state in $^{13}$B with a configuration of $^{12}$B ${\rm_{g.s.}\bigotimes}$ $d\rm_{5/2}$, a $^{13}$B($d$, $d$') inelastic scattering experiment was carried out using a 23 MeV/nucleon $^{13}$B beam by EN-course (exotic nuclei) beam line at the Research Center for Nuclear Physics (RCNP), Osaka University. Several states at excitation energies of 3.6(1), 4.2(1), 5.4(2), and 6.5(2) MeV in $^{13}$B were observed in its excitation energy spectra, which were derived from the energies and angles of the scattered deuterons from $^{13}$B using the missing mass method. To determine the parity of each populated state, the inelastic scattering differential cross sections (DCSs) were compared to the distorted wave Born approximation (DWBA) calculations.The 5.4- and 6.5-MeV states were inferred to be positive parity states and considered as potential candidates for the missing $d$-wave neutron excitation state. The gap between $s$- and $d$-shell in $^{13}$B and the systematic behaviour of neutron-rich Boron isotopes were also investigated based on the experimental findings.

And in order to investigate whether or not the $sd$-shell inversion in $^{16}$C, We conducted a $\mathrm{^{15}C}(d,p)$ Experiment with a radioactive beam of $^{15}$C at 28.5 MeV/nucleon at the RIBLL1 beamline in the Institute of Modern Physics(IMP), Lanzhou at 2022. As of now, I have completed the normalization and calibration of detectors, particle identification, and reconstructed the excitation energy spectrum of $^{16}$C using the missing mass method. The ground state and the 3.03 MeV excited state of $^{16}$C can be seen in the excitation spectrum, but further analysis is required to determine if this reaction channel generates the 5.45 MeV state or not.

Speaker: Bolong Xia

81 Isospin analogues of the tetraneutron resonance

Searches for bound or resonant state in the system of 4 neutrons (tetraneutron) have been started more than half a century ago. Theory completely excludes the bound tetraneutron. Numerous theoretical studies allowing for the continuum with modern NN interactions exclude also low-lying tetraneutron resonance narrow enough to be detected experimentally. A notable exception is the predictions of the tetraneutron resonance in Refs. [1-3] using softened realistic NN interactions. The first observation of this resonance was reported in Ref. [4] with marginal statistics of 4 events and later confirmed in Ref. [5] in the 1H(8He,pα) experiment with a reasonable statistical significance. However, some authors are skeptical (see, e. g., Refs. [6-8]) about the interpretation that the tetraneutron resonance per se was observed in Refs. [4,5]. For example, the low-energy peaks were observed in reactions 2H(8He,6Li)4n and 2H(8He,3He)7H→3H+4n in Ref. [8] at energies consistent with the tetraneutron resonance observed in Ref. [5] which were, however, interpreted as a manifestation of the 8He structure and the reaction mechanism.

If the tetraneutron resonance do really exists, we should expect an existing of its isospin analogues in excited T=2 resonant states in 4H, 4He, 4Li and in the system of 4 protons (tetraproton). Observation of these resonances can serve as a confirmation of the results and their interpretation of Refs. [4,5]. We will also discuss the possibilities of observations of these T=2 resonances in decays of excited states of heavier nuclei.

1. A. M. Shirokov et al. // Phys. Rev. Lett. — 2016. — Vol. 117. — 182502.
2. A. M. Shirokov et al. // AIP Conf. Proc. — 2018. — Vol. 2038. — 020038.
3. J. G. Li et al. // Phys. Rev. C — 2019. — Vol. 100. — 054313.
4. K. Kisamori et al. // Phys. Rev. Lett. — 2016. — Vol. 116. — 052501.
5. M. Duer et al. // Nature — 2022. — Vol. 606. — P. 678.
6. L. G. Sobotka, M. Piarulli // Nature — 2022. — Vol. 606. — P. 656.
7. R. Lazauskas, E. Hiyama, J. Carbonell, // Phys. Rev. Lett. — 2023. — Vol. 130. — 102501.
8. I. A. Muzalevskii et al. // arXiv — 2023. — 2312.17354.

Speaker: Andrey Shirokov (Moscow State University)

14:00 Lunch

Applications of nuclear methods in science, technology, medicine and radioecology: Radiation technologies/Radioecology

82 Dosimetric planning of radiation treatment of bio-objects and materials

Today more than 70 countries of the world have industrial centres of radiation sterilization of food products and medical devices [1]. Compared to classical approaches, radiation sterilisation has a number of advantages: ionising radiations suppress microorganisms more effectively, the temperature of products does not change during processing, and they can be processed immediately in the package (which excludes the possibility of re-contamination). Today, when planning radiation treatment, all attention is focused on the integral released dose [2, 3], while recent studies [4 - 6] show that the efficiency of radiation treatment also depends on the nature of its distribution over the volume of the object.
The integral absorbed dose is unambiguously determined by the amount of delivered radiation and can be easily measured in practice (e.g., using dosimetric films or alanine dosimetry). The nature of the volume distribution of absorbed dose depends on several factors, including the type of radiation, the shape of the object and the energy spectrum of the beam. In order to take all these factors into account when planning radiation treatment, computer modelling is used [7]. And if the type of radiation and the shape of the treated object are reliably known, the exact energy spectrum of the beam is unknown and difficult to measure in practice. Replacing the exact spectrum by the "effective energy" can lead to an error of up to 20% in the estimation of processing uniformity.
In this paper, we propose a method for recovering the energy spectrum of an electron accelerator beam from the experimentally measured depth distribution of the dose produced by the beam. To implement the algorithm, the depth distributions of absorbed dose in various reference materials under irradiation with monoenergetic beams of accelerated electrons with energies from 100 keV to 20 MeV with a step of 100 keV are pre-calculated using the Geant4 software code [8, 9]. Experimental verification of the algorithm was carried out on the Varian TrueBeam medical electron accelerator in the radiosurgery and radiotherapy department with a day hospital at the Burdenko Neurosurgery Centre, operating in the 6 MeV and 9 MeV modes. The depth dose distributions in aluminium, water and polymer RW3 Slab Phantom were measured. The spectra reconstructed from the measured distributions showed agreement with each other, the discrepancy was not more than 5%.

• References
• Черняев А.П. Радиационные технологии. Наука. Народное хозяйство. Медицина / Черняев А.П. // Москва: Издательство Московского университета, 2019. — 231 с.
• ISO 11137-3-2006 Sterilization of health care products Radiation Part 3: Guidance on dosimetric aspects. Стерилизация медицинской продукции. Облучение. Часть 3. Руководство по вопросам дозиметрии.
• ISO 14470-2011 Food irradiation — Requirements for the development, validation and routine control of the process of irradiation using ionizing radiation for the treatment of food. Радиационная обработка пищевых продуктов. Требования к разработке, валидации и повседневному контролю процесса облучения пищевых продуктов ионизирующим излучением.
• Effect of electron and X-ray irradiation on microbiological and chemical parameters of chilled turkey / U. Bliznyuk, A. Chernyaev, F. Studenikin, V. Ipatova et al. // Scientific reports. — 2022. — Vol. 12, no. 1. — P. 750.
• Применение низкоэнергетических электронов для радиационной обработки охлажденной форели / А. П. Черняев, У. А. Близнюк, П. Ю. Борщеговская и др. // Письма в журнал Физика элементарных частиц и атомного ядра. — 2020. — Т. 17, № 4. — С. 681–687.
• Применение пучков ускоренных электронов для радиационной обработки продуктов питания и биоматериалов / У.А. Близнюк, А.П. Черняев, Ф.Р. Студеникин и др. // Известия Российской академии наук. Серия физическая. — 2017. — Т. 81, № 6. — С. 819–823. DOI: 10.7868/S0367676517060035.
• Computer simulation to determine food irradiation dose levels / F.R. Studenikin, U.A. Bliznyuk, A.P. Chernyeav et al. // IOP Conference Series: Earth and Environmental Science. — 2019. — Vol. 365. — P. 012002. DOI: 10.1088/1755-1315/365/1/012002.
• S. Agostinelli et al., “GEANT4 - a simulation toolkit”, Nucl. Instr. Meth. A, vol. 506, no. 3, pp. 250-303, 2003.
• Recent Developments in Geant4, J. Allison et al., Nucl. Instr. Meth. A 835 186-225 (2016)

Speaker: Sergei Zolotov (Lomonosov Moscow State University)

83 STUDY OF THE RADIOECOLOGICAL SITUATION AT THE SITES OF EMERGENCY UNDERGROUND NUCLEAR EXPLOSIONS IN THE 70S IN YAKUTIA

In the 70s of the XX century, 12 underground nuclear explosions (UNE) were carried out in the Yakut Autonomous Soviet Socialist Republic (ASSR, now the Republic of Sakha (Yakutia) – RS(Ya)). Two UNE became emergency – “Kraton-3” with a capacity of 22 kt produced on August 24, 1978, and “Crystal” with a capacity of 1.7 kt produced on October 2, 1974. The explosion of “Kraton-3” was produced 40 km from the village of Aikhal on the border between Oleneksky and Mirninsky regions on the banks of the Markha River, which flows through the Vilyui region. As a result of the accident, radionuclides were released into the atmosphere and onto the soil surface. The explosion of the “Crystal” was made 2.5 km from the town of Udachny near the border of Mirninsky region. Rehabilitation works were carried out on the burial grounds of both facilities, which were built in 1981 for the first time after the explosions: in 2007, a protective screen was installed at the “Kraton-3” facility and soil 1.5 m thick was poured without fencing the area; In 1992, the “Kristall” explosion site was filled up to twenty meters high with a fence and a protective drainage shaft with a height of 0.9 m was erected to prevent the burial ground from being washed away by spring meltwater and summer rainwater. And 3 control wells were drilled with a diameter of 132 mm and a depth of 3 m below the burial ground [1]. In this paper the study of the migration of radionuclides from the cavity of the explosions “Crystal” and “Kraton-3” into the environment. In July 2023, an expedition was organized to the sites of emergency UNE, during which measurements of the radiation background and collection of environmental samples were carried out: samples of soil and local vegetation: moss, lichen, cypress (Ivan tea). To determine the degree of contamination of the environment with radionuclides and identify the approximate boundaries of the radioactively hazardous zone, an ORTEC semiconductor gamma spectrometer with a detector made of extremely pure germanium GEM-40 and a low-background liquid scintillation alpha-beta spectrometer HIDEX SL-300 were used.
Artificial radionuclide 137Cs and natural radionuclides such as 212Pb, 214Pb, 214Bi, 228Ac, 232Th were found in soil and vegetation samples from both sites of the UNE. The 241Am, traces of 60Co were found in samples from the “Kraton-3” locality. The values of the specific activity of 137Cs in soil samples from the “Craton-3” explosion sites exceed the permissible levels by more than 10 times. The obtained values for the volumetric activity of tritium in water samples from both localities correspond to background values, taking into account the influence of thermonuclear reactions on the Sun, generating tritium rain for northern latitudes. According to 2004 data, the value of the exposure dose rate (EDR) in the area of the “Kraton-3” nuclear power plant reached 1.6 mSv/h [2], and as a result of dosimetric measurements carried out during the 2023 expedition, the maximum value of the EDR turned out to be 1.2 mSv/h. I.e., the EDR exceeds the value of the EDR of a safe gamma background by 2.5 times in the area of the Kraton-3".
Thus, currently there is a high level of radiation pollution in the area of "Kraton-3", unlike "Crystal", which may be explained by insufficient rehabilitation work. In the nearby regions from the area "Kraton-3", the incidence of malignant neoplasms (MN) and mortality from them are higher than the average for RS(Ya). Perhaps the increase in MN is a long–term consequence of emergency UNE - additional dose loads leading to an increase in MN. The results of this study, in conjunction with the level of heat, can be considered as a basis for recognizing the need to develop recommendations and regulations as measures to comply with radiation safety when conducting similar tests in the future and during mining with the release of radionuclides to the surface.

List of literature:
1. Burtsev I.S. Yakutia is radioactive. Yakutsk: "Sahaada" – 2021.
2. Yakovleva V.D., Stepanov V.E. Radioecological problems of peaceful underground nuclear explosions in Yakutia. Moscow: Sputnik. – 2013.

Speaker: Dr Sargylana Mamaeva (North-Eastern Federal University named after M.K. Ammosov)

84 THE EFFECT OF X-RAY RADIATION AND ACCELERATED ELECTRONS ON POTATO YIELD

Chulikova N.S.1, Malyuga A.A.1, Bliznyuk U.A.2,3, Borschegovskaya P.Yu. 2,3, Ipatova V.S.2, Zubritskaya Ya.V.2, Chibisova M.S.2 , Chernyaev A.P.2,3, Yurov D.S.2, Rodin I.A.4

1Siberian Federal Scientific Centre of Agro-BioTechnologies of the Russian Academy of Sciences, Krasnoobsk, Russia
2 Lomonosov Moscow State University, Physics Department, Moscow, Russia
3Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia
4 Lomonosov Moscow State University, Chemistry Department, Moscow, Russia

*E-mail: natalya-chulikova@yandex.ru

Worldwide, there is an increase in demand for the use of radiation technologies for economic purposes. They can be introduced into agriculture to accelerate the development and increase crop yields, improve product quality, and destroy pathogenic microflora[1]. The technology of pre-planting irradiation of seed tubers is based on the ability of ionizing radiation to accelerate plant growth and development, and the possibility of improving crop quality is shown [2].The values of stimulating doses (from 3 Gy to 20 Gy) for most crops, as well as conditions affecting the effectiveness of pre-sowing irradiation, have been determined [3-5].
In this study, Gala potato tubers were irradiated from two opposite sides at the electron accelerator UELR -1-25- T-001 with a maximum energy of 1 MeV and the 1BSV-23 X-ray machine with a RAD 100-10 X-ray tube equipped with a molybdenum anode. The radiation doses ranged from 5 to 30 Gy.
It was found that the treatment of planting material with accelerated electrons and X-ray radiation in doses from 5 Gy to 30 Gy affected the phenology, phytosanitary condition of the agrocenosis and, accordingly, the productivity and quality of potatoes. Irradiation with accelerated electrons at doses of 10 Gy and 15 Gy increased the yield of healthy tubers (with respect to Rhizoctonia solani Kuhn.) by 33.8-43.9%, compared with the control, and doses of 5 Gy and 15 Gy were more effective in weight equivalent, where the yield of healthy tubers was 2.5-2.8 t/ha, but did not exceed the reference value.
X-ray radiation at doses of 15 and 30 Gy increased the yield of healthy tubers (with respect to Rhizoctonia solani Kuhn.) by 27.1-35.2%, compared with the control, and doses of 5 Gy and 25 Gy were more effective in weight equivalent, where the yield of healthy tubers was 2.8-3.0 t/ha, but in the first case it was not exceeded the control value.
This research was funded by the Russian Science Foundation, grant number 22-63-00075.
Bibliography
1. Sanzharova N.I., Kozmin G.V., Bondarenko V.S. Radiatsionnyyetekhnologii v sel'skomkhozyaystve: strategiyanauchno-tekhnicheskogorazvitiya (Radiation technologies in agriculture: strategy for scientific and technical development) // Innovatikaiekspertiza. 2016, Vol. 1(16), p. 197.
2. Chulikova N et al. Electron Beam Irradiation to Control Rhizoctonia solani in Potato // Agriculture. 2023, Vol. 13(6), p. 1221.
3. Khodjaev, T. A. The effect of neutron irradiation on the germination energy and germination of wheat seeds // Young Scientist. 2014, Vol. 3 (62), р. 48–51
4. Impact of Proton Beam Irradiation on the Growth and Biochemical Indexes of Barley (Hordeum vulgare L.) Seedlings Grown under Salt Stress / L. Oprica [et al.] // Plants. – 2020. – Vol. 9, № 9. – P. 1234.
5. Potato Sprout Inhibition and Tuber Quality after Post Harvest Treatment with Gamma Irradiation on Different Dates / M. Rezaee [et al.] // J. Agric. Sci. Tech. – 2001. – Vol. 13. – P. 829-842.

Speaker: Чуликова Chulikova N.S. (СФНЦА РАН)

85 APPLICATION OF COMBINED RADIATION TECHNOLOGIES FOR STERILIZATION OF CULTURAL HERITAGE ARTIFACTS

A set of studies was carried out to establish patterns of changes in the surface characteristics of bone materials as a result of combined sterilizing effects. The results confirmed the possibility of using a combined technique of radiation sterilization of biological tissues for processing tissue samples of fossil biological objects such as mammoths and other ancient animals. Consecutive treatment of bone fragments at the first stage with an ozone-oxygen mixture of low concentration and ionizing radiation with a relatively low absorbed dose at the second stage makes it possible to achieve the required degree of sterility while maintaining the original morpho-mechanical characteristics of the treated objects.
Exposure to ozone at the first stage of the combined sterilization process does not lead to morphological changes in the surface, mechanical properties, or characteristics of bone collagen. The oxygen content increases significantly, which in turn helps to increase the efficiency of radiation exposure at the second stage of sterilization, and, consequently, to further reduce the dose load. Thus, the synergistic effect of exposure occurs due to the effective weakening of the pathogen population and a decrease in their radioresistance under ozone exposure, which enhances the subsequent effect of radiation.
Combined (ozone + radiation) exposure at an absorbed dose of 12 kGy does not lead to significant changes in the collagen content in bone tissue. Noticeable changes in collagen content were recorded at high (20 kGy) values of the absorbed dose during radiation exposure.
The results obtained open up the possibility of using a new promising method for processing biological samples of ancient animals, ensuring the minimum possible changes in their structure, properties and characteristics, and establishing optimal parameters for the sample sterilization process. This technique can be used in the future to work with various samples of fossil biological objects.

Speaker: Nadezhda Nikolaeva (North-Eastern Federal university)

86 Определение тормозной способности ионов углерода в органических соединениях при помощи ядер отдачи

Применение пучков тяжелых ионов для радиотерапии является одним из перспективных направлений при лечении онкологии. Пучок тяжелых ионов позволяет получить хорошую локализацию дозы [1]. Однако, существуют и проблемы, одна из которых неопределенность тормозной способности, в особенности в области низких скоростей ионов. Согласно базе данных МАГАТЭ [2], существуют значительные расхождения в величине тормозной способности ионов С-12 в органических соединениях, при этом имеется только ограниченный набор экспериментальных данных. В данной работе мы предлагаем метод определения тормозной способности ионов С-12 в органических соединениях при помощи резонансной реакции образования протонов отдачи. Измерения тормозной способности были выполнены для полипропилена и полиметилметакрилата.

1. Mohamad, Osama et al. “Carbon Ion Radiotherapy: A Review of Clinical Experiences and Preclinical Research, with an Emphasis on DNA Damage/Repair.” Cancers vol. 9,6 66. 9 Jun. 2017, doi:10.3390/cancers9060066
2. C.C. Montanari et al. The IAEA electronic stopping power database: Modernization, review, and analysis of the existing experimental data,
   Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 551, 2024, 165336

Speaker: Bobrovskiy Timofey (Institute for Physics and Power Engineering (IPPE), Obninsk, Russia)

87 PROSPECTS AND DIRECTIONS FOR IMPROVING RADIATION STERILIZATION TECHNIQUES

Sterilization is an essential process to ensure the integrity and safety of bone materials, regardless of whether they are used in medical procedures, in solving forensic tasks, or in conducting research on fossil fragments. However, the use of "monomethods", such as chemical treatment and even radiation, is not always effective, unlike the use of two-stage combined radiation sterilization methods.
At the first stage of combined radiation sterilization, methods such as chemical treatment, microwave exposure, sterilization with an ozone-oxygen mixture, etc., can be used, depending on factors such as the type and level of initial contamination. After completing the first stage of sterilization, the samples are subjected to a second stage using radiation exposure. Radiation sterilization is effective for eliminating microbial contamination and residual biological load preserved after the first stage [1].
The choice of the type of radiation exposure is crucial to provide the safety and effectiveness of bone implants. Factors to be considered include the type of radiation (e.g. gamma radiation or electron beam treatment), the dose required to achieve the desired level of sterilization, and any potential impact on the physical and mechanical properties of implants.
Choosing the appropriate methods at each stage of combined sterilization is an important step in ensuring the quality of bone implants. Taking into account the specific requirements for each sample and the optimal sterilization options will ensure the manufacture of implants according to the highest standards of safety and efficiency.

1. Rozanov V.V., Matveichuk I.V., Chernyaev A.P., Nikolaeva N.A., Krasnov S.A. Current State and Lines of the Further Development of High-Tech Means of Radiation Sterilization // Bulletin of the Russian Academy of Sciences: Physics. – 2020. – V.84. – № 4. – P. 403-405.

Speaker: Ms Alana Khutsistova (Lomonosov Moscow State University; Hertzen Moscow Research Oncological Institute)

88 New beam dynamics simulation for the updated coil design of MSC230 cyclotron for medical-biological research

JINR is conducting development of the isochronous cyclotron MSC230 for the new JINR’s international biomedical research center, which will be the successor of the medical beam line of currently discontinued Phasotron. The project is entering the production stage. The latest compatibility checkup of the systems showed that the current distance between coils is not sufficient for the insertion of the systems of internal elements' operation. Therefore, the coil distance was increased, that heavily affected magnetic field and required its reshape. This talk concerns the peculiarities of field correction and results of proton beam tracing from ion source to the extraction from cyclotron.

Speaker: Leonid Sedov (JINR)

89 ИЗМЕРЕНИЕ КОНЦЕНТРАЦИИ АЛЬФА-ИЗЛУЧАЮЩИХ НУКЛИДОВ В РАСТВОРАХ С ПОМОЩЬЮ АЛЬФА-СПЕКТРОМЕТРИИ

ИЗМЕРЕНИЕ КОНЦЕНТРАЦИИ АЛЬФА-ИЗЛУЧАЮЩИХ НУКЛИДОВ В РАСТВОРАХ С ПОМОЩЬЮ АЛЬФА-СПЕКТРОМЕТРИИ
Душин В.Н., Ершов К.В., Мишина Н.Е., Хонина И.В.
АО «Радиевый институт им. В.Г. Хлопина»
Данная работа относится к применению методов ядерной спектроскопии для онлайн контроля гидрометаллургических процессов при переработке ОЯТ. Описывается опыт прямого измерения альфа-излучающих радионуклидов в жидкостях с использованием поверхностно барьерного полупроводникового планарного кремниевого диодного детектора и обработки данных методами математического моделирования. Рабочие характеристики и долговечность диодных Si детекторов позволяют напрямую обнаруживать альфа-частицы в образцах жидкости путем размещения диодного детектора непосредственно в объеме образца жидкости, а математическое моделирование позволяет интерпретировать данные, полученные в условиях сильного рассеяния альфа-частиц в жидкости. Было проведено сравнение с результатами, полученными на жидкостном сцинтилляционном спектрометре и спектрометре с PIPS детектором и вакуумной камерой.

Speaker: Konstantin Ershov (V.G. Khlopin Radium Institute)

Experimental and theoretical studies of nuclear reactions

90 ANALYSIS OF THE PROTON AMPLITUDE OF SCATTERING ON THE BOUNDED NUCLEAR NUCLEONS BASING ON THE PROTON-NUCLEUS SCATTERING DATA

The experimental data on the proton elastic and inelastic scattering at energies 200-1000 MeV on the nuclei $^{28}$Si, $^{40}$Ca, $^{58}$Ni and $^{208}$Pb are investigated using the microscopic optical potential model. Such potential is based on the proton-nucleon amplitude of scattering on the bounded nuclear nucleons. The obtained parameters of the amplitude are compared with those known from analysis of the proton scattering on the free unbounded nucleons.

Speaker: Ibrahim Abdulmagead (Joint Institute of Nuclear Research, Dubna, Russia, Cairo university-Giza-Egypt, ASRT-Cairo-Egypt)

I.Abdulmagead_July 2.pdf

91 ANALYTIC CONTINUATION OF DIFFERENTIAL CROSS SECTIONS AS A WAY TO DETERMINE ASYMPTOTIC NORMALIZATION COEFFICIENTS. APPLICATION TO THE 16O(d,p)17O REACTION

L. D. Blokhintsev and D. A. Savin
Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia
Asymptotic normalization coefficients (ANC) are important nuclear characteristics. We discuss a method for determining ANC values from experimental data on differential cross sections of nuclear transfer reactions. The method is based on the use of the analytic continuation of these cross sections to the pole point of the reaction amplitude with respect to the variable cos θ where θ is the center-of-mass scattering angle. The method under consideration is used to determine the ANC for the channel 17O(1/2+; 0.871 MeV) → 16O(0+; 0 MeV) + n from the data on the 16O(0+; 0 MeV)(d,p)17O(1/2+; 0.871 MeV) reaction. When determining the ANC, the corrections caused by the Coulomb interaction in the initial, final and intermediate states of the reaction were taken into account. It is shown that these corrections have a great impact on the extracted ANC. The found ANC value is compared with the results obtained by other methods.

Speaker: Leonid Blokhintsev (Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University)

92 Данные о нейтрон-протонной длине рассеяния, извлеченные в реакции $n+^{2}\text{H}→n+n+p$ при энергии нейтронов 5 МэВ

В работе представлены результаты измерения $^{1}S_{0}$ $np$-длины рассеяния, измеренной в реакции $nd$-развала при энергии нейтронов $5$ МэВ. В кинематически полном эксперименте, проведенном на пучке нейтронов канала РАДЭКС ИЯИ РАН, регистрировались нейтрон отдачи и нейтрон от развала $np$-системы. Энергия первичного нейтрона и протона от развала $np$-системы восстанавливалась по известным углам вылета и энергиям двух нейтронов и факту регистрации развального протона в активной дейтерированной мишени. Значение $np$-длины рассеяния $a_{np} = −30.9 ± 0.8$ Фм получены из сравнения экспериментальной зависимости выхода реакции $nd$-развала от относительной энергии $np$-пары с результатами моделирования. Сделано предположение, что полученное значение длины $np$-рассеяния в совокупности с данными других экспериментов, в которых $np$-длина рассеяния извлекалась из реакций $nd$- и $dd$-развала при различных энергиях, подвержены влиянию $3N$-сил.

Исследование выполнено в рамках научной программы Национального центра физики и математики, направление №6 «Ядерная и радиационная физика».

Speaker: Александр Каспаров (ИЯИ РАН)

93 Вычисление сечения резонансной реакции 6Li(2H, 4He)4He на основе результатов ab initio расчетов спектров высоковозбужденных состояний 8Ве

В настоящее время в теоретических исследованиях свойств легких ядер основное место занимают высокоточные микроскопические подходы, в частности ab initio методы описания атомных ядер. Наиболее популярным среди этих методов расчета является оболочечная модель ядра без инертного кора (NCSM). Эта модель дает возможность довольно точно рассчитывать волновые функции основных и резонансных состояний легких ядер. Непосредственно NCSM не может применяться для расчета распадных характеристик ядерных состояний – асимптотических нормировочных коэффициентов закрытых и ширин открытых каналов фрагментации. Для решения данной задачи, авторами был ранее разработан метод ортогонализированных функций кластерных каналов (CCOFM) [1], что существенно расширило поле применимости ab initio подходов в
исследованиях спектральных свойств ядерных состояний и открыло перспективы для внедрения высокоточных методов в теоретические исследования резонансных ядерных процессов. В первых исследованиях такого рода были получены сечения реакций p(7Li, 4He)4He и n(7Ве, 4He)4He. Проделанные расчеты и их анализ показали как хорошее согласие с экспериментом (дляреакции p(7Li, 4He)4He), так и свои предсказательные возможности для сечения реакции n(7Ве,4He)4He [2].

В данной работе мы демонстрируем возможности разработанного подхода на примере расчета сечения более сложной для теоретического анализа реакции 6Li( 2H,4He)4He и сравнения их результатов с экспериментальными данными. Сложность задачи заключается в том, что данная реакция идет через состояния 0+, 2+ и 4+ 8Ве с чрезвычайно большой энергией возбуждения 22.0 – 25.5 МэВ, плотность которых при данной энергии достаточно велика. Измерения сечения этого процесса демонстрируют два пика — первый их них образуют резонансы 2 +, а второй пик — резонанс 4+. Абсолютная величина сечения в различных экспериментах отличается практически в два раза. В рамках данной работы удалось идентифицировать резонансы, оказывающие определяющее влияние на сечение данной реакции и впервые в рамках теоретического исследования ядерных реакций сделать заключение о достоверности каждой из версий противоречащих друг другу экспериментальных данных.
1. D. M. Rodkin, Yu. M. Tchuvil’sky. Physical Review C 103, 024304 (2021).
2. Доклад в Сарове

Speaker: Dmitry Rodkin (Dukhov Research Institute for Automatics)

94 THEORETICAL STUDY OF THE TRANSFER REACTIONS IN THE D + D SYSTEM

In this work, the D(d, p)T and D(d, n)$^{3}$He transfer reactions are studied by means of the microscopic multichannel cluster approach in the oscillator representation [1–3]. These reactions are of great interest for pure and applied physics. Their total and partial astrophysical S factors are calculated. The contributions of the different channels are discussed, the most important ones are carefully analysed. Manifestations of the nuclear tensor force in dynamics of the studied transfer processes are considered. A comparison of the obtained results with available experimental data demonstrates a good agreement.

1. A. S. Solovyev, Phys. Rev. C 106, 014610 (2022).
2. A. S. Solovyev, Phys. At. Nucl. 86, 24 (2023).
3. A. S. Solovyev, Eur. Phys. J. A 60, 32 (2024).

Speaker: Dr Alexander Solovyev (Dukhov Automatics Research Institute (VNIIA))

95 ИССЛЕДОВАНИЕ РЕАКЦИЙ ПОД ДЕЙСТВИЕМ БЫСТРЫХ НЕЙТРОНОВ НА ЯДРЕ $^{10}B$ С ИСПУСКАНИЕМ ТРИТИЯ C ПОМОЩЬЮ КООРДИНАТНОГО ДЕТЕКТОРА

Взаимодействие быстрых нейтронов с ядром $^{10}B$ при энергиях от 3 до 7 МэВ, сопровождающегося вылетом ядра $^{3}H$, исследуется с целью выделения реакции с рождением ядра $^{8}Be^{*}$ в возбужденном состоянии. Эта реакция выделяется на фоне трехчастичной реакции с вылетом тритона и двух альфа-частиц. Моделирование ионизационных потерь вторичных ядер $^{3}H$ и $^{4}He$ в твердых и газовых слоях двух позиционно-чувствительных многопроволочных детекторов с чувствительными размерами 100х100 и 50х50 $мм^{2}$ показало, что на диаграммах, построенных из потерь в двух газовых слоях, события локализуются в различных областях. Результат эксперимента с детектором 100х100 $мм^{2}$ показал возможность выделения реакции с вылетом ядер $^{3}H$ и $^{8}Be^{*}$. Новый детектор 50х50 $мм^{2}$ содержит два слоя бора‑10 и проволочную систему из двух катодов и двух сеток и поэтому обладает увеличенной эффективностью и селективностью к исследуемой реакции.

Speaker: Dr Станислав Поташев (ФГБУН Институт ядерных исследований Российской академии наук)

Experimental and theoretical studies of nuclear reactions: Gamma-reactions

96 POSSIBILITIES OF PHOTONUCLEAR EXPERIMENTS AT $E_\gamma = (1–4)$ MeV ON COLLIMATED $\gamma$-SOURCES FROM COMPTON BACKWARD-SCATTERING

The possibilities of photonuclear experiments at $E_\gamma = (1–4)$ MeV on collimated gamma-sources from Compton backward-scattering of laser radiation on beams of accelerated electrons are considered. The following items are discussed: operation parameters of such gamma-sources; monitoring of their gamma-beams; types of possible photonuclear experiments, including nuclear resonance fluorescence ones (see, e.g., [1]), total absorption ones using transmission method (see, e.g., [2]), and especially experiments on inelastic scattering of gamma-quanta with population of metastable states of nuclei. As an example, for the last case, there are considered cross-sections of the reaction $^\mathrm{115g}$In ($\gamma$, $\gamma’$) $^\mathrm{115m}$In ($E_{exc} = 336$ keV; T$_{1/2}$ = 4.486 h) in dependence on $E_\gamma$ obtained: a – in [3]; b – in [4] (see fig. 1).

1. S.R.Johnson et al. // Phys. Rev. C. 2023. Vol. 108, 024315.
2. B.S.Dolbilkin et al. // Nucl. Phys. 1965. Vol. 72. P. 137.
3. L.Z.Dzhilavyan. // Phys. Atomic Nuclei. 2015, Vol. 78, P. 624.
4. W.Tornow et al. // Phys. Rev. C. 2018. Vol. 98, 064305.

Speaker: Dr Leonid Dzhilavyan (Insnitute for Nuclear Research of RAS)

97 PHOTONEUTRON REACTION CROSS SECTIONS RELIABILITY IN DIFFERENT TYPE EXPERIMENTS

Absolute majority of data on photonuclear, first of all photoneutron, reaction cross sections was obtained in different type experiments carried out using the beams of quasimonoenergetic annihilation photons and the beams of bremsstrahlung [1]. The methods of receiving the information on reaction cross sections are quite different. On the beams of annihilation photons the cross sections of partial reactions (g,1n), (g,2n), (g,3n),… are directly determined and used for obtaining the total photoneutron reaction cross section σ(g,sn) = σ(g,1n) + σ(g,2n) + σ(g,3n) +… and the neutron yield cross section σ(g,xn) = σ(g,1n) + 2σ(g,2n) + 3σ(g,3n) +… . On the beams of bremsstrahlung the neutron yield cross section σ(g,xn) is determined at first and used for obtaining partial reaction cross sections with the aid of statistical theory corrections and correspondent difference procedures. The differences of the methods used are the reasons for significant disagreements between resulted reaction cross sections in both shape and absolute value. It was found out using the objective physical criteria of data reliability Fi = σ(g,in)/σ(g,xn) for more than 50 nuclei investigated on the beams of annihilation photons and about 10 nuclei investigated on the beams of bremsstrahlung that data obtained using both indirect methods for partial reaction separation contain significant systematic uncertainties which resulted in unreliability of data obtained. Newly evaluated reaction cross sections σ-eval(g,in) = Fi-theor x σ-exp(g,xn) for large number of nuclei from 51V up to 209Bi obtained by the experimental-theoretical method basing on the joint using of the experimental neutron yield cross sections σ-exp(g,xn) and the results of Fi-theor calculations in the combined model of photonucleon reactions (CMPNR) [2] are in serious disagreements with the results of both mentioned experimental methods for indirect unreliable separation of partial reactions. At the same time new evaluated data are in agreement with the results of experiments in which the partial reactions (g,1n), (g,2n), (g,3n),… are separated directly and reliably – the activation method on the beam of bremsstrahlung and the method of direct determination on the neutron multiplicity on the beam of photons from laser Compton backscattering of laser radiation on relativistic electrons [3,4].
The research was carried out in the Department of Electromagnetic Processes and Atomic Nuclei Interactions (Centre for Photonuclear Experiments Data) of the MSU SINP.

1. IAEA Nuclear Data Section database “EXFOR. Experimental nuclear reaction data”, http://www-nds.iaea.org/exfor.
2. B.S.Ishkhanov et al. // Phys. Atom. Nucl. 2008. V.71. P.493.
3. V.V.Varlamov et al. // Phys. Atom. Nucl. 2017. V. 80. P.957.
4. V.V.Varlamov et al. // Moscow University Physics Bulletin. 2023. V. 78. N. 3. P. 303.

Speaker: Prof. Vladimir Varlamov (Skobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State University)

98 THE ISOSPIN SPLITTING OF GDR AND PHOTOPROTON REACTIONS ON MERCURY ISOTOPES

There is very little experimental data on cross sections of photonuclear reactions on mercury in the literature, and for energies of the order of 50-60 MeV there is no data at all. To obtain cross sections for an equivalent quantum during the reactions of ${}^{nat}Hg(\gamma,inkp)$, a sample of natural mercury was irradiated with a beam of bremsstrahlung from the RTM-55 linear electron accelerator of SINP MSU with an upper limit of 55 MeV.

As a result of the experiment, cross sections for an equivalent quantum on a natural mixture of mercury isotopes were calculated using the formula:

$$\sigma^{prod}_q = \frac{\sum_i \eta_i\int_{E_{thresh}}^{E^m} \sigma(E)\cdot W(E,E^m)dE}{\frac{1}{E^m}\int_{0}^{E^m} E\cdot W(E,E^m)dE},$$ in this formula, $W(E,E^m)dE$ is the number of $\gamma$-quanta in the energy range $dE$ per electron of the accelerator hitting the braking target, $\sigma(E)$ is the cross section of the studied photonuclear reaction, $E$ is the energy of $\gamma$-quanta of bremsstrahlung, $E^m=55$ MeV is the kinetic energy of electrons incident on the inhibitory target, $E_{thresh}$ is the threshold energy of the reaction under study, $\eta_i$ is the percentage of the initial nuclei in the natural mixture. The obtained cross sections were compared with the results of theoretical calculations performed using the combined model of photonucleon reactions developed at SINP MSU [1-2] and according to the TALYS program [3]. As can be seen from comparative table 1, the experimental data are in good agreement with calculations within the framework of the CMFR, which takes into account not only the isospin splitting of the giant dipole resonance (GDR) and the quasi-neutron photoabsorption mechanism, but also the contribution to the cross section of the isovector quadrupole resonance and the overtone of the GDR (GDR2). For photoproton reactions, the results obtained under the TALYS program were underestimated. Also, experimentally and using CMFR [1-2], cross sections for an equivalent quantum for $T_>-$ and $T_<-$components were obtained, which allow us to observe the isospin splitting of the GDR.

1. B. S. Ishkhanov and V. N. Orlin, Phys. At. Nucl. 74(1), 21–41 (2011).

2. B. S. Ishkhanov and V. N. Orlin, Phys. At. Nucl. 78(7-8), 601–617 (2015).

3. A. J. Konig, S. Hilaire, and S. Goriely, Eur. Phys. J. A 59: 131 (2023).

Speaker: Olesya Poryadina (Lomonosov Moscow State University, Department of Physics)

99 PHOTOPROTON REACTIONS ON ERBIUM ISOTOPES

This work presents an experimental and theoretical study of photoproton reactions on erbium isotopes. Currently, the nuclear databases (EXFOR) only contain data on photoneutron reactions on a natural mixture of erbium isotopes [1] and on the isotope $^{166}$Er [2]. No data on photoproton reactions is available.
The experiment was performed by irradiating a target made of a natural mixture of erbium isotopes with the bremsstrahlung of the racetrack pulsed microtron RTM-55 of the Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, with a beam energy of 55 MeV. The residual activity spectra were analyzed to identify isotopes formed from photonuclear reactions based on their gamma ray energy and half-life. The cross sections per equivalent photon for a natural mixture of erbium isotopes were calculated based on the induced activity in the target by formula:
\begin{equation}
\sigma_q^{prod}=\frac{\sum_{i} \eta_i \int_{E_{\text{thresh}}}^{E^{m}}\sigma(E)\cdot W(E,E^m)dE}{\frac{1}{E^{m}} \int_{0}^{E^{m}}E \cdot W(E,E^m)dE},
\end{equation}
where $W(E,E^m)$ is the bremsstrahlung spectrum of $\gamma$ produced at the incidence of the beam of accelerated electrons with the energy $E^m$=55 MeV on the bremsstrahlung target, $\sigma(E)$ is the cross section of the studied photonuclear reaction, $E$ is the energy of bremsstrahlung photons, $E_{thresh}$ is the threshold energy of the reaction under study, $\eta_i$ is the percentage of the initial nuclei in the natural mixture of Er isotopes and the index $i$ corresponds to the number of the reaction contributing to the production of the studied isotope.
The experimental cross sections per equivalent photon were compared with calculations using the TALYS program [3] and the combined model of photonucleon reactions (CMPR) [4,5]. In contrast to the TALYS program, the CMPR accounts for the isospin splitting of the giant dipole resonance (GDR), which leads to increased cross sections of photoproton reactions. The comparison of experimental and theoretical data reveals that TALYS significantly underestimates the cross sections of photoproton reactions. The isospin splitting of the GDR should be considered for an accurate description of photonuclear reactions.

1. R. Bergère, H. Beil, P. Carlos, A. Veyssière, Nucl. Phys. A $\textbf{133}$, 417 (1969).
2. B.I. Goryachev, Y.V. Kuznetsov, V.N. Orlin, N.A. Pozhidaeva, V.G. Shevchenko, Yad. Fiz. $\textbf{23}$, 1145 (1976).
3. A.J. Konig, S. Hilaire, S. Goriely, Eur. Phys. J. A $\textbf{59}$, 131 (2023).
4. B.S. Ishkhanov, V.N. Orlin, Phys. At. Nucl. $\textbf{74}$, 19 (2011).
5. B.S. Ishkhanov, V.N. Orlin, Phys. At. Nucl. $\textbf{78}$, 557 (2015).

Speaker: Nadezhda Fursova (Faculty of Physics, Lomonosov Moscow State University, Moscow, Russia; Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia)

100 LIGHT AND MEDIUM–HEAVY NUCLEI PHOTONEUTRON REACTION CROSS-SECTIONS IN BREMSSTRAHLUNG BEAM EXPERIMENTS

In cases for many (~50) nuclei from $^{51}$V to $^{209}$Bi the experimental data on photoneutron partial reactions ($\gamma$,1n), ($\gamma$,2n), ($\gamma$,3n) cross sections directly obtained using beams of quasimonoenergetic annihilation photons [1] do not satisfy objective physical criteria of data reliability [2–5]. The reasons are systematic uncertainties of experimental photoneutron multiplicity sorting method basing on partial reactions separation via measurement of neutron energies. Therefore, the experimental-theoretical method for partial reaction cross-section evaluation basing on physical criteria was used for analysis of reliability of data obtained using quite different method on the beams of bremsstrahlung [6]. Partial reaction cross sections are separated and determined in such kind experiment using statistical theory corrections to the neutron yield cross section $\sigma$($\gamma$,xn) = $\sigma$($\gamma$,1n)+2$\sigma$($\gamma$,2n)+3$\sigma$($\gamma$,3n)+… measured at first. Experimental cross sections of the reactions ($\gamma$,1n) and ($\gamma$,2n) are definitely unreliable in the cases of $^{51}$V, $^{52}$Cr, $^{59}$Co, but enough reliable in the case of $^{90}$Zr. The reason is that the role of two-nucleon reaction ($\gamma$,1n1p) was not taken into account, though this reaction competes with also two-nucleon reaction ($\gamma$,2n). It was shown via the results of calculation in the frame of the Combined photonuclear reaction model [5] that energy positions and amplitudes of cross sections of ($\gamma$,1n1p) and ($\gamma$,2n) reactions are very close to each other in the cases of $^{51}$V, $^{52}$Cr, $^{59}$Co, but in the case of $^{90}$Zr the value of ($\gamma$,1n1p) reaction cross section is very small and could be negligible. This conclusion is analogous to that of the preliminary investigation of the cases of $^{127}$I, $^{165}$Ho, $^{181}$Ta [7]. It means that in the cases of relatively light nuclei $^{51}$V, $^{52}$Cr, $^{59}$Co, as well as $^{58,60}$Ni [8] the reaction ($\gamma$,1n1p) plays important role in nucleus photodisintegration but its contribution is not correctly described by statistical theory corrections.

1. IAEA Nuclear Data Section database “EXFOR. Experimental nuclear reaction data”, http://www-nds.iaea.org/exfor.
2. V.V.Varlamov et al. // Phys. Atom. Nucl. 2017. V. 80. P.957.
3. V.V.Varlamov // Phys. Part. Nucl. 2019. V. 50. P.637.
4. V.V.Varlamov et al. // Moscow University Physics Bulletin. 2023. V. 78. N. 3. P. 303.
5. B.S.Ishkhanov et al. // Phys. Atom. Nucl. 2008. V.71. P.493.
6. A.V.Varlamov et al. Atlas of Giant Dipole Resonances. Parameters and Graphs of Photonuclear Reaction Cross Sections. // INDC(NDS) –394, IAEA NDS, Vienna, Austria, 1999.
7. V.V.Varlamov et al. // Bull. Rus. Acad. Sci. Phys., 2023. V. 87. N. 8. P. 1188.
8. V.V.Varlamov et al. // Bull. Rus. Acad. Sci. Phys., 2023. V. 87. N. 8. P. 1179.

Speaker: Aleksandr Davydov

101 Study of 209Bi(gamma,xn) relative reaction yields in energy range 35-60 MeV

In order to study relative yields of 209Bi(γ,xn) reactions, samples of 99.99% pure bismuth-209 were exposed at LINAC-200 electron beam with tungsten convertor at energies 35, 40, 45, 50, 55, 60 MeV. Activities of obtained products of photonuclear reactions with different neutron multiplicity, from (γ,2n) to (γ,7n) were measured. Relative yields normalized to 206Bi yield were calculated. Obtained yields were compared with the experimental results already available in EXFOR database.
Yields obtained by measurements were compared with the results of theoretical calculations and data from public nuclear databases such as IAEA-2019, LEND-99 and TENDL-2021. Bremsstralung spectra and various systematic effects were simulated by GEANT4.

Speaker: Mikhail Demichev (JINR)

talk-Nucleus24-v001.pdf

102 EXPERIMENTAL STUDY OF RELATIVE PROBABILITY OF HIGH-SPIN ISOMERIC STATES POPULATION IN (α,n)-REACTIONS

Activation techniques for studying nuclear reactions producing high-spin isomeric states are discussed. It is demonstrated that some specific properties of a beam of low-energy alpha particles that make this beam especially interesting for obtaining and studying these states.
Results of the investigations of the yield of high-spin and low-spin isomers in reactions 41K(α,n)44Sc, 86Sr (α,n)89Zr, 112Sn(α,n)115Te, 134Ba (α,n)137Ce in the energy range of the alpha particles 15 – 31 MeV based on off-beam measurements of induced activity of members of the isomeric pair are presented as examples of such unique features. The anomalous behavior of the isomeric cross-section ratio (the presence of a pronounced maximum) for the first of these reactions is confirmed. Uniquely large isomeric cross-section ratios for the second and third ones are obtained. The features of the fourth reaction turned out to be promising for its application in fundamental research. Indeed, this reaction at an energy of 23 – 25 MeV provides the possibility of obtaining, using the secondary acceleration in the frame of the SPIRAL ISOLDE scheme of its products, the purest beams of high-spin isomeric nuclei.

Speaker: Dr T. V. Chuvilskaya (Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University)

103 Stimulation of Re-186m isomeric nuclei de-excitation in high-current Z-pinch plasma at the “Angara-5-1” facility

Recently, in a laser plasma with an average electron temperature
Θ ~ 1 keV and a lifetime τ ≈ 0.3 ns, it was found out the stimulation of de-excitation of nuclear isomers (SDENI) Re-186m (half-life T = 2×10E5 years) to the ground state of the Re-186 nuclei (T = 90 hours) with a probability P ≈ 1·10E(–7), which apparently occurred through an intermediate trigger level with a half-life of ~ 10 days. To increase the SDENI probability, it was proposed to use longer-lived electric discharge plasma instead of laser plasma (see Ref. [1] and references in there).
In Ref. [2], a methodology for SDENI experiments was developed for Re-186m isomers in the Z-pinch plasma of the “Angara-5-1” facility at Troitsk Institute for Innovation and Fusion Research. Plasma was obtained by implosion of a two-cascade cylindrical multiwire assembly (liner) with a current pulse of 4 MA and 1 MV voltage passing through it. The outer cascade of the liner with a diameter of 12 mm and a linear mass of 300 μg/cm was composed of Al-wires with a diameter of 8 μm, and the internal cascade with a diameter of 6 mm and a linear mass of
20 μg/cm was made of W-wires of 6 μm diameter. A Re-layer of 0.5 μm thick with the Re-186m isomer was deposited on W wires by electrolysis. The first experiments showed a SDENI-induced disturbance of the radioactive equilibrium between the isomer and the ground state of the Re-186 nucleus in Z-pinch plasma at Θ = 400 eV and τ = 10 ns. The intensity I of 137 keV γ-quanta of Re-186 decay from a sample of plasma matter after three plasma shots, decreased with time t and reached its stationary value after t ≈ 40 days. Based on the parameters of the I(t) time dependence, we estimated the SDENI probability of P ≈ 2·10 – 7 in the plasma.
The work was supported by the Private Enterprise “Science and Innovations” (ROSATOM) (contract No. 774/569-D).

1. V. Koltsov // “On the stimulation of the de-excitation of nuclear isomers in plasma of a high-current electric discharge”. Plasma Phys. and Techn. 2021. V. 8(1). P. 5.
2. G.S. Volkov, E.V. Grabovski, A.N. Gritsuk, V.V. Karasev, V.V. Koltsov // “On the possibility of observing stimulated de-excitation of nuclear isomer Re-186m in a high-current Z-pinch plasma at the Angara-5-1 setup”. Phys. At. Nucl. 2022. V. 85(9). P. 1486.

Speaker: Vladimir Koltsov (Public corporation “Khlopin Radium Institute”)

Koltsov - Stimulation of Re-186m .pdf

Heavy ion collisions at Intermediate and high energies

104 Analysis of nuclear track emulsion exposed by relativistic hadrons

The recent results of exposure of a nuclear track emulsion (NTE) in a mixed hadron beam is discussed. The purpose of this work is to search and measure the length of short-range tracks of alpha particles produced in the interactions of hadrons and nuclei from the composition of a NTE. Modeling the ionization losses of alpha particles in the substance of a NTE in the SRIM program made it possible to reconstruct their kinetic energies in each found event. Reconstruction of tracks in full 4π-geometry makes it possible to reconstruct the emission angles of alpha particles with high accuracy. In this way, combinatorial spectra of invariant masses of systems of (2-3) alpha particles in the event have been obtained. The angular and energy correlation of the produced alpha particles is presented.

Speaker: Dr MARIMUTHU NATARAJAN (Joint Institute for Nuclear Research)

Nucleus-2024_Marimuthu_020724.pdf

105 Performance study of the anisotropic flow measurements with fixed-target mode of the MPD experiment at NICA

The study of the high-density equation of state (EoS) and the search for a possible phase transition in dense baryonic matter are one of the main goals of beam energy scan programs with relativistic heavy ion collisions at energies $\sqrt{s_{NN}}$=2-5 GeV.
The results of performance study for the differential anisotropic flow measurements of identified charged hadrons at energies $\sqrt{s_{NN}}$=2.5-3.5 GeV will be presented, using a realistic procedure for data simulation and reconstruction in the MPD experiment at NICA working in a fixed-target mode (MPD-FXT).

Speaker: Peter Parfenov (JINR)

Nucleus2024_Parfenov.pdf

106 Cumulative production at central rapidities due to interactions involving fluctons

We study the yields of pions and protons with large transverse momenta at mid-rapidities in the region that is kinematically inaccessible for single nucleon-nucleon interactions (the so-called cumulative region), which may be observed in nuclear collisions by MPD and SPD detectors of the NICA complex. We assume that particles in this kinematic region are formed as a result of scattering from the so-called nuclear “fluctons”, which from a modern point of view can be considered as clusters of cold quark-gluon matter with a high baryon density. We generalize the microscopic quark-parton approach developed in [1-4] for describing the production of cumulative particles in the fragmentation region of one of the colliding nuclei to the case of particle production in this new cumulative region.
For the case of nucleon-flucton interaction, we found that there is a change in the ratio of the proton to pion yield in the region of central rapidities and high transverse momenta compared to the cumulative production in the fragmentation region of one of the nuclei. The reason for this is that in the case of cumulative proton production, the mechanism of coherent coalescence (recombination) of three flucton quarks into a proton dominates, while in the case of cumulative pion production, the fragmentation of a single flucton quark into a pion dominates [3,4,9]. We compare the obtained theoretical results with the results of our preliminary estimates of particle yields in this region based on a more phenomenological approach [5-7].
We show that the study of cumulative phenomena in this new region of central rapidities and large transverse momenta also opens up the possibility of experimentally studying a new interesting process of flucton-flucton interaction in MPD and SPD experiments at NICA, which cannot be studied in the region of fragmentation of one of the nuclei. Note that the study of this process in dd collisions at future NICA SPD has some advantages over MPD. There is no contribution from additional nucleon-nucleon collisions when both deuterons are in the state of 6-quark bags at the moment of collision. This reduces the background and simplifies the registration of a cumulative particle in correlation with particles formed from fragmentation of а flucton residue [8]. An important role in recording rare cumulative processes is also played by the much higher frequency of collisions that the SPD installation can record compared to the MPD.
It is important that studies of particle production in this new cumulative region are available for experimental study only at relatively low initial energies of colliding nuclei of the NICA collider facility and are not available for experimental study at the RHIC and LHC colliders.
The work was supported by the Russian Science Foundation grant 23-12-00042.

1. M.A. Braun, V.V. Vechernin, Nucl. Phys. B 427, 614-640 (1994).
2. M.A. Braun, V.V. Vechernin, Phys. Atom. Nucl. 63, 1831-1834 (2000).
3. M.A. Braun, V.V. Vechernin, Theor. Math. Phys. 139, 766-786 (2004).
4. V.V. Vechernin, AIP Conf. Proc. 1707, 060020 (2016).
5. V.V. Vechernin, Phys. Part. Nuclei 52, 604-608 (2021).
6. V.I. Zherebchevsky, V.P. Kondratiev, V.V. Vechernin, S.N. Igolkin, Nuclear Inst. and Methods in Physics Research A 985, 164668 (2021).
7. V.V. Vechernin, Phys. Part. Nuclei 53, 433-440 (2022).
8. V.V. Vechernin, Phys. Part. Nuclei 54, 528-535 (2023).
9. V. Vechernin, S. Belokurova, S. Yurchenko, Symmetry 16, 79 (2024).

Speaker: Vladimir Vechernin (St. Petersburg State University)

Vechernin_Ядро-2024.pdf

107 Measurement of neutron energy spectra in the region of large angles in Xe + CsI collisions at energy of 3.8 A GeV

Neutron production double-differential cross section was measured for $^{124}\text{Xe}$ + CsI collisions at energy 3.8 A GeV with a compact TOF spectrometer as a part of BM@N setup at external beam channel of the Nuclotron. The aim of this study is to obtain new experimental results on neutron emission from excited spectators of the target nuclei. The measurement was performed at angles θ > $90^0$ and it covers an energy interval of emitted neutrons from 2 to 200 MeV. Neutron detectors based on stilbene with pulse shape discrimination of gamma-rays and a time resolution of 110 ps allow to use short flight distances of ~30 cm and by these to get small contribution from gamma-ray and neutron background. The preliminary results of data analysis are presented and discussed.

Speaker: Nikita Lashmanov (Joint Institute for Nuclear Research)

Nucleus_2024_Lashmanov.pdf

108 Cold Superdense Baryonic Component of Nuclear Matter

Started in the late 1950s at DLNP JINR pioneering experimental studies of proton scattering on nuclei allowed D.I. Blokhintsev assumed the presence in nuclei a lower mass nucleus in a compressed state, i.e. the presence of a cold strongly compressed component in ordinary nuclear matter. The search and study of two- and three-nucleon systems in nuclei continued at DLNP JINR and ITEP (Moscow) and beyond. The investigations were carried out in the kinematic region, outside the kinematic of the nucleon-nucleon interaction. In the future, the processes in this kinematic region were called cumulative processes.
In this report the results of the cumulative processes study outside of the nuclear fragmentation region and with production of particles with the transverse momentum greater than 1 GeV/c is presented. These experiments were carried out with proton and carbon nuclei beams by the IHEP(Protvino) accelerator complex. The data were takeout using the SPIN set up – single-arm magnetic spectrometer. The obtained data showed that the processes of direct knock-out of deuteron and tritium nuclei with momentum up to 6.5 GeV/c are observed. This confirms the presence of deuterons and tritium in the nuclear matter in a highly compressed state, in other words, existing of the cold superdense baryonic component.

Speaker: Stepan Shimanskiy (JINR)

109 Event-by-event determination of thermodynamic quantities at NICA energies

Currently, studies of the properties of a strongly interacting medium in collisions of hadrons and nuclei are actively being carried out in experiments at accelerator complexes at BNL, CERN, and JINR. The NICA collider (Dubna) and the multipurpose detector MPD are expected to be put into operation soon. One of the primary research directions for these experiments involves scanning the phase diagram of strongly interacting matter, investigating the phase transition between hadronic gas and quark-gluon plasma, and searching for the critical point. For these purposes, various fluctuation and correlation observable quantities are used.
The process of nuclear collisions and the evolution of the quark-gluon medium created in them in the energy range of the NICA collider is quite complex, and the thermodynamic equilibrium achieved is only local. All thermodynamic characteristics of the medium undergo unavoidable event-by-event fluctuations. In this regard, it is quite relevant to develop a method for estimating the temperature and baryon chemical potential in each event.
To extract thermodynamic parameters from the particle yields and spectra, the Thermal-FIST package was applied. The average values of temperature (T) and baryon chemical potential ($μ_B$) were extracted from the experimental data of NA61/SHINE and STAR experiments, and the fluctuations of these values were established. Then, it was checked to what extent it is possible to extract event-by-event thermodynamic characteristics, and the method resolution was estimated. The results showed the fundamental applicability of this method in a wide range of (T, $μ_B$).

The reported study was supported by the Russian Science Foundation, project no. 23-12-00042, https://rscf.ru/en/project/23-12-00042/.

Speaker: Vladimir Kovalenko (Saint Petersburg State University)

nucleus2024-3.pdf

110 Self-similarity approach in relativistic nuclear physics

Abstract – A self-similarity approach to description of interaction of accelerated nuclei in the intermediate energy range is presented. This approach represents a relativistically invariant description of angular, energy, and A-dependences of inclusive hadron production cross sections in nuclear collisions. Special attention is paid to the description of cumulative, subthreshold processes at intermediate energies. Quantitative estimates for secondary particle production in fixed-target experiments at extracted beams of the NICA accelerator complex and heavy meson production in collider experiments with heavy nuclei are considered.

Speaker: Elina Baldina (LHEP JINR)

17:00 Coffe break

Applications of nuclear methods in science, technology, medicine and radioecology

111 PROGRAM FOR QUICK CALCULATION OF ABSORBED DOSE DISTRIBUTION BY DEPTH IN HOMOGENEOUS OBJECTS

The use of electron accelerators has become widespread throughout the world, becoming an integral part of scientific and technological development. Currently, accelerator-based installations are used not only in science, but also in medicine, industry, and agriculture. An important parameter for the efficiency of using accelerated electrons is the uniformity of the distribution of the absorbed dose over the volume of the object being processed. Therefore, the development of planning and quick calculation methods is relevant.
Despite the fact that the Monte Carlo method has become widespread for modeling the interaction of ionizing radiation with matter, its use has some limitations. To obtain accurate results and obtain satisfactory event statistics, computer simulation will be required, which can take from several hours to several days depending on the estimated power of the computer used.
It seems interesting to develop a program that allows, based on a database prepared using previously performed modeling, to obtain in a few seconds the distribution of the absorbed dose over depth in an object with a given size and density. Such a program will significantly reduce the planning time for scientific research in the field of application of accelerated electrons.
The goal of this work was to develop a program for calculating the depth distribution of the absorbed dose in a model phantom when irradiated by an electron beam with an energy spectrum in the range from 0.1 MeV to 20 MeV based on a database obtained through detailed modeling using GEANT4. A solution to the inverse problem has also been implemented, when using given distributions of the absorbed dose in water, plastic and aluminum it is possible to reconstruct the energy spectrum of the electron beam.
A comparison was made of the values of the distribution of the absorbed dose over the depth of the object obtained as a result of the created program with the values obtained by direct computer modeling using GEANT4. It is shown that the maximum deviation from the simulation results is no more than 3% over the entire range of energies, thicknesses and materials considered. At the same time, calculations using the developed program were performed on average in 2 seconds, while calculations using GEANT4 took about 7 hours using an average-power personal computer.
The research was carried out within the framework of the Development Program of the Interdisciplinary Scientific and Educational School of Moscow University “Photon and Quantum Technologies. Digital medicine".

Speaker: Felix Studenikin (Lomonosov Moscow State University)

112 Chemical transformations of volatile organic compounds in animal-derived products after irradiation

Radiation technologies are actively used to extend the shelf life of food products and ensure their microbiological safety [1]. However, radiation exposure can cause a variety of physicochemical and organoleptic changes in animal-derived products. This is caused by the intense oxidation of biomacromolecules, such as proteins and lipids, which can change the texture, color, and smell of meat [2]. The intensity of physicochemical processes occurring in biological objects can be assessed by the presence and concentration of volatile organic compounds (VOCs) [3].
This work of scientists from Moscow State University is aimed at identifying and analyzing the physical and chemical changes in products after their radiation processing. In this study, a series of of products - beef, turkey and salmon - was irradiate using the UELR-1-25-T-001 accelerator with a maximum energy of 1 MeV. Also, to explain the dose behavior of the concentrations of volatile organic compounds in products, a series of model studies were carried out on the irradiation of standard samples of volatile organic compounds - 1-hexanol. The concentrations of volatile compounds were determined using a gas chromatography-mass spectrometer Shimadzu GCMS-QP2010 Ultra (Shimadzu, Japan).
Based on the results of the study, a mathematical model was developed that describes the dependence of the concentrations of standard volatile compounds and VOCs identified in food products on the radiation dose.
It was found that aldehydes make it possible to assess how radiation affects the product's lipid and protein components. It has been established that ethanol may indicate a decrease in microbial enzymatic processes occurring in meat products during storage [4].
This research was funded by the Russian Science Foundation, grant number 22-63-00075.
Bibliography
1. Chernyaev, A.P., Radiatsionnye tekhnologii: nauka, narodnoe khozyaystvo, meditsina (Radiation Technologies: Science, National Economy, Medicine), Moscow: Mosk. Gos. Univ., 2019.
2. Indiarto R., Irawan A.N., Subroto E. Meat Irradiation: A Comprehensive Review of Its Impact on Food Quality and Safety // Foods. 2023, Vol. 12(9), p. 1845.
3. Bleicher J., Ebner E.E., Bak K.H. Formation and Analysis of Volatile and Odor Compounds in Meat—A Review // Molecules. 2022, Vol. 27(19), p. 6703.
4. Bliznyuk U et al. Volatile Compound Markers in Beef Irradiated with Accelerated Electrons // Molecules. 2024, Vol. 29(5), p. 940.

Speaker: Victoria Ipatova (Lomonosov Moscow State University)

113 Optimization of radiation treatment of biological objects

To meet the demands of irradiation centers and extend the range of biological objects which can be irradiated for different purposes, our research team has conducted a series of experimental studies to estimate the influence of irradiation parameters as well as physical and chemical properties of bio-objects on the irradiation efficiency. The study focuses on determining the criteria for choosing optimal dose range which would destroy pathogens while preserving essential molecules, such as proteins, lipids, and enzymes.
The study uses real-life objects, such as beef, turkey, chicken, salmon and trout, potato tubers, cereal and oil seeds as well as model objects, such as bacteria, fungi, phytopathogens, standard samples of volatile organic compounds and bovine serum albumin. The methodology of the research involves irradiation of bio-objects using the 1 MeV electron accelerator UELR-1-25-Т-001 (SINP MSU, Russia) and X-ray apparatus DRON YM-2 with X-ray tube BSV 23 with copper anode and X-ray apparatus RAP 100-10 with X-ray tube 1BPV 23-100 with molybdenum anode (Burnazyan Federal Medical Biophysical Center of FMBA, Russia). Irradiation of bio-objects is simulated using GEANT 4 toolkit to estimate the dose uniformity and linear energy transfer (LET) throughout the objects in order to find the most effective irradiation method depending on the objective of irradiation and the distribution of irradiation parameters in the objects.
To determine the optimal dose range limits we applied current physical methods to investigate the biochemical and biophysical changes in biological objects after irradiation. Gas chromatography-mass spectrometry method was used to trace the change in the concentrations of volatile organic compounds in bio-objects since some of these concentrations are highly sensitive bio-markers of lipid, protein oxidation as well as bacterial activity in the irradiated objects. To estimate the change in the native structure of proteins we used high-performance liquid chromatography-mass spectrometry method with tandem mass spectrometric detection and spectrophotometric method for estimation of myoglobin derivative concentrations. Microbiological analysis of bio-objects was carried out to estimate the efficiency of suppressing pathogens by irradiation. The lack of cost-efficient express methods for detecting irradiated objects with a high-water content caused us to apply the kinetic fluorometric fingerprinting technique for recognition of irradiated and non-irradiated bio-objects.
The experiments involved pre-planting irradiation of seeds and root crops to assess the effect of irradiation on the growth and phytosanitary status of agricultural crops. The plants grown from irradiated seeds and root crops were planted and monitored at the experimental sites of the Siberian Federal Scientific Center of Agricultural-Biotechnology of the Russian Academy of Sciences to determine the optimal dose range limits for crops irradiation.
Following the experiments performed by our team it was established that the efficiency of irradiation of biological objects is determined as a function (D) = F(K1(D), K2(D), K3(D)), where K1 is a value determined by the dose uniformity throughout the object and the dose needed to suppress pathogens to the required degree; K2 determines the fraction of pathogens which are suppressed in the biological object irradiated with a certain dose; K3 is radiosensitivity heterogeneity of pathogens across the statistical ensemble.
We have found clear dose and time dependencies of the concentration of lipid and protein oxidation aldehydes as well as the concentration of ethanol alcohol. With a higher irradiation dose ranging from 250 Gy to 10000 Gy a higher peak of lipid and protein oxidation derivatives is detected on day 1 and day 2 after irradiation. On the contrary, the higher the dose the lower ethanol content in biological objects during 4 days of storage after irradiation. Therefore, the concentrations of lipid and protein oxidation aldehydes can serve as markers of lipid and protein peroxidation, while the concentration of ethanol is a marker of efficiency of bacterial suppression as a result of irradiation. For example, when beef tenderloin is irradiated with 1 MeV electron beam with the dose rate of 4 Gy·sec–1, lipid and protein peroxidation is observed in the beef samples irradiated with the doses of 500–1000 Gy and higher, while in the beef samples irradiated with 250–350 Gy the ethanol concentration is 2 times lower than in the non-irradiated beef samples. Therefore, as dose and time dependencies of volatile organic compound markers suggest, the lowest limit of the optimal dose range is 250–350 Gy, and the highest limit is 500–1000 Gy.
The spectrophotometric method for calculating the metmyoglobin concentration in bio-objects containing myoglobin as well as the trypsin hydrolysis of the native structure of bovine serum albumin allow us to quantify the impact of electron beam and X-ray irradiation with different physical parameters, such as dose, dose rate, and the type of irradiation, on protein native structure.
Counting of viable cells in bio-objects after irradiation and assessment of the quantitative damage of protein native structure by irradiation show that the limits of the optimal dose range for beef tenderloin irradiated with 1 MeV electron beam with the dose rate of 4 Gy·sec–1 is 220-854 Gy assuming that the upper limit is determined by the myoglobin oxidation. At the same time, the optimal radiation dose range for beef is 204-755 Gy assuming that the upper limit is determined by the damage of protein native structure. Therefore, the dose ranges determined by measuring the number of viable cells in bio-objects and the damage of protein native structure align well with the ranges obtained by measuring the volatile compound concentrations.
Considering that the rate of indicator reactions involving carbocyanine dyes and oxidizing agents varies depending on physical and chemical properties of bio-objects, kinetic fluorometric fingerprinting technique, which measures the absorption spectrum and fluorescence intensity of extracts made from bio-objects, has proved to be the most suitable express method for recognition of non-irradiated and irradiated animal and plant biological tissues.
Our experimental studies allow to develop practical recommendations on how to improve the efficiency of the bio-object irradiation.
The study is financed by Russian Scientific Foundation (project № 22-63-00075).

Speaker: Dr Ulyana Bliznyuk (Lomonosov Moscow State University)

114 Механизм уточнения энергетических потерь ионов в области низких энергий с помощью измерения эффекта Доплера

Тезис в закрепе. Институтское соглашение получу на следующей неделе.

Speaker: Alexey Grachkov (Dukhov Automatics Research Institute (VNIIA))

GrachkovPresentation.pptx

115 Performance of the Mass Testing Setup for Arrays of Silicon Photomultipliers in the TAO Experiment

Modern neutrino physics detectors often employ thousands, and sometimes even hundreds of thousands, of Silicon Photomultipliers (SiPMs). The TAO experiment is a notable example that utilizes a spherical scintillator barrel with a diameter of 1.8 meters, housing approximately 130,000 SiPMs organized into 4,100 tiles. Each tile with size of 5 × 5 cm^2 consists of a 32-SiPM array functioning as a single detector unit. To achieve an unparalleled energy resolution of 2% at 1 MeV within this volume, the SiPMs must possess cutting-edge parameters, including a photon detection efficiency (PDE) exceeding 50%, cross-talk of approximately 10%, and an extremely low dark count rate (DCR) below 50 Hz/mm^2. Maintaining the setup at a negative temperature of −50◦C is necessary to achieve the desired DCR. This talk presents the setup and methods employed to individually characterize the mass of SiPMs across all 4,100 tiles at the specified negative temperature.

Speaker: Арсений Рыбников (JINR)

Rybnikov-NUCLEUS-2024-SiPM-Mass-Testing-Setup-v3.pdf

116 Evolution of the neutron spectrum during propagation of the neutron flux in solid bodies

The results of numerical modeling of leakage spectra, diffusion time and absorption spectra during propagation of neutron fluxes in solid bodies are presented. The spherically symmetric task of neutron flux diffusion from a central source to the outer surface of spheres, made of various materials, is reviewed. The simulation was carried out using the Monte Carlo method with ABBN-78 neutron group constants.
The task was carried out within the framework of modeling the spectrum of a tungsten-water proton beam target of the pulsed neutron source RADEX,which is used as a proton beam target of the INR RAS proton linear accelerator. Modeling was carried out in order to determine the effect of the target material choice on the neutron spectrum, value of neutron flux and it's diffusion time. Possibility to reconstruct capture spectrum, using experimentally measured leakage spectrum, is discussed.

Speaker: Denis Khliustin (Institute for Nuclear Research Russian Academy of Sciences)

Khliustin_INR_Nucleus2024_pdf.pdf

117 Monte Carlo Simulation Techniques in Radiation Dosimetry: Advancements and Applications

Monte Carlo methods have revolutionized the field of radiation dosimetry by providing a robust framework for simulating the intricate interactions between ionizing radiation and matter. These methods, rooted in probabilistic sampling techniques, offer unparalleled accuracy and flexibility in modeling radiation transport, energy deposition, and dose distribution in diverse applications ranging from medical imaging to radiation therapy[1].
At the heart of Monte Carlo simulations lies the concept of random sampling, where individual interactions of photons, electrons, or other charged particles with tissues and materials are stochastically simulated. The trajectory of each particle is governed by the laws of classical or quantum mechanics, depending on the energy regime and particle type. The probability of interaction events, such as photoelectric absorption, Compton scattering, and pair production, is described by interaction cross-sections derived from fundamental physics principles.
The transport of particles through a medium can be described by the Boltzmann transport equation, which accounts for processes such as scattering, absorption, and production of secondary particles[2]. In a Monte Carlo simulation, the trajectory of a particle is tracked through successive interactions until it is either absorbed or exits the medium. The absorbed dose, defined as the energy deposited per unit mass, is calculated by tallying the energy deposited by all particles within a defined volume.
Validation and benchmarking of Monte Carlo codes are essential to ensure their accuracy and reliability in practical applications. This often involves comparing simulated results with experimental measurements and established dosimetric protocols[3]. By iteratively refining simulation parameters and adjusting models to better match experimental data, researchers can improve the fidelity of Monte Carlo simulations and enhance their predictive capabilities.
In summary, this review provides a comprehensive overview of Monte Carlo methods in radiation dosimetry, emphasizing their foundational principles, applications, validation techniques, recent advancements, and future prospects. By elucidating the role of Monte Carlo simulations in quantifying radiation dose distributions, this review aims to contribute to the ongoing dialogue surrounding radiation safety, treatment planning, and dosimetric accuracy in medical and industrial settings.
REFERENCES

1. Rogers, D.W.O., Faddegon, B.A., Ding, G.X., & Ma, C.M. (1995). BEAM: A Monte Carlo code to simulate radiotherapy treatment units. Medical Physics, 22(5), 503-524.
2. Kawrakow, I., & Walters, B.R.B. (2006). Efficient photon beam dose calculations using DOSXYZnrc with BEAMnrc. Medical Physics, 33(8), 3046-3056.
3. Salvat, F., Fernández-Varea, J.M., & Sempau, J. (2010). PENELOPE-2008: A code system for Monte Carlo simulation of electron and photon transport. OECD Nuclear Energy Agency.

Speaker: Sindorjon Ashurov (National University of Uzbekistan)

Experimental and theoretical studies of nuclear reactions

118 Examination of collective and single-particle models for excited states of $^{13}$C below 10 MeV in nuclear reactions induced by 18 MeV deuteron beam

The first 10 excited states of the carbon isotope were studied in terms of single-particle and collective models of excitation. Experimental cross sections were obtained by the well-known $\vartriangle$E–E method. Elastic scattering data were analyzed using an optical model including a nucleus–nucleus interaction potential, while inelastic scattering data were processed using the coupled-channels approach. For the single-particle model, the spectroscopic amplitudes were obtained through calculations of the large-scale shell model with the YSOXT effective NN-potential. A double folding potential was obtained for the d + $^{13}$C system. A comparison of model calculations with the experimental cross sections was demonstrated.

Speaker: Daniyar Janseitov (BLTP)

119 Observation of positive parity wave in low energy spectrum of 7He

The 7He nucleus was studied using the 6He(d, p)7He reaction in inverse kinematics at 29A·MeV 6He beam delivered by the ACCULINNA-2 fragment separator (FLNR, JINR). The registration of neutrons from 7He → n +6 He decay made it possible to derive the 7He ground state parameters, the decay energy of 0.38(2) MeV and width of 0.11(3) MeV. The forward-backward asymmetry in the neutron emission from unbound states of 7He has been found. That implies the presence of a positive parity wave in the 7He spectrum.

Speaker: Andrey Bezbakh (FLNR JINR)

120 DETERMINATION OF NUCLEAR MATTER RADII USING S-MATRIX FOR ELASTIC SCATTERING OF IDENTICAL NUCLEI

New approach based on combination of the optical model with the modified optical potential and the classical trajectories is proposed for calculations of the effective matter radii of the identical colliding nuclei. The example of the angular distribution for 6Li + 6Li elastic scattering is shown in Fig. 1a. The plot of the value , where is the diagonal element of the S-matrix, is shown in Fig. 1b. The quantum partial reaction probability can be transformed into the semiclassical partial reaction probability

as a function of the minimum distance between the centers of the colliding nuclei depended on energy E and impact parameter b taking into account the relation: . For 6Li + 6Li elastic scattering at Elab = 40 MeV the results of calculations are 5.76 fm and 0.47 fm. The quantity may be interpreted as the sum of the effective matter radii of the identical nuclei . So the determined effective matter radius of the 6Li nucleus is fm, the experimental rms charge radii is 2.589 fm [2]. Similarly, the effective matter radii of the 9Be, 11B, 12C and 16O nuclei were calculated using data from [2], they are 4.0±0.05, 3.3±0.05, 4.0±0.05 and 3.3±0.05 fm, accordingly.

Fig.1. (a) The experimental angular distributions (points) for elastic scattering of 6Li + 6Li at Elab = 40 MeV [1] and the results of calculations in the optical model with modified real part of the optical potential (curve). (b) Comparison of the dependences of the quantum partial reaction probability (solid curve) on the orbital angular momentum l for elastic scattering 6Li + 6Li at Elab = 40 MeV with the semiclassical partial reaction probability (dashed curve).

1. K.W. Potthast, H. Brand, H. Freiesleben, et al, Nucl. Phys., A. 1997, V. 614 P. 95.
2. NRV Web Knowledge Base on Low-Energy Nuclear Physics, http://nrv.jinr.ru/.

Speaker: Viacheslav Samarin (Joint Institute for Nuclear Research, Flerov Laboratory of Nuclear Reactions)

121 Исследование испарительных каналов реакций полного слияния с тяжелыми ионами, приводящих к образованию ядер с 88 ≤ Z ≤ 102.

В рамках экспериментов на пучках тяжелых ионов ускорителей ЛЯР, с использованием сепараторов GRAND 1 и SHELS [2-3], в реакциях полного слияния 26Mg+204,206,208Pb, 48Ca+204,206,208Pb и 40Ar+209Bi измерялись сечения образования ядер-испарительных остатков (ER), в каналах xn, 𝛼xn и pxn (см Рис 1). Изучались свойства радиоактивного распада нейтронодефицитных изотопов 226-230Pu, 249-254No, 246-247Md и их дочерних продуктов.

Рис 1. Функции возбуждения образования испарительных каналов xn и αxn для реакции 26Mg+208Pb. Символы – экспериментальные данные, линии – теоретический расчет, выполненный в программе NRV [4].

1 Kuznetsova A.A., Bulletin of the Russian Academy of Sciences: Physics, 2023, Vol. 87, No. 8, pp. 1105–1111.
[2] Yeremin, A.V., Popeko, A.G., Malyshev, O.N., et al., Phys. Part. Nucl. Lett., 2015, vol. 12, no. 1, p. 35.
[3] Yeremin, A.V., Popeko, A.G., Malyshev, O.N., et al., Phys. Part. Nucl. Lett., 2015, vol. 12, no. 1, p. 43.
[4] https://nrv.jinr.ru/

Speaker: Mrs Алёна Кузнецова (JINR)

122 Measurement and analysis of the 13C(α, α0 )13C reaction cross-section in the energy range of 2.0 – 7.0 MeV

The differential cross-sections of the 13C(α, α0)13C reaction were measured at three angles (130°, 150° and 170°) in the energy range of 2.0-7.0 MeV. The thin layer of 13 С deposited to the beryllium backing was used as a target. The thickness and enrichment of the target were determined by the ion beam analysis methods. The effect of the carbon build-up was taken into account during the data analysis. The measurement results can be used for re-examination of evaluation of the 13C(α,n)16 O reaction cross-section using multi-channel R-matrix calculations.

Speaker: Dr P.S. Prusachenko (Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research)

prusachenko NUCLEUS.pdf

123 Определение низкоэнергетических параметров $pp$-состояния в реакции $d$+$^{1}$H→$p$+$p$+$n$

В работе представлены результаты исследования реакции $d$+$^{1}$H→$p$+$p$+$n$ на ускорителе У-120 НИИЯФ МГУ. В кинематически полном эксперименте, проведенном при энергии дейтронов 15.3 МэВ, регистрировались в совпадении протон от развала синглетного $pp$ $^{1}$$S$$_0$ состояния и вторичный нейтрон. В результате анализа формы энергетического спектра "развальных" протонов определены низкоэнергетические параметры $pp$-состояния: величина энергии виртуального синглетного $pp$-состояния и соответствующее ей значение $pp$-длины рассеяния.
Исследование выполнено в рамках научной программы Национального центра физики и математики, направление № 6 «Ядерная и радиационная физика».

Speaker: Вячеслав Мицук (ИЯИ РАН)

124 Исследование вариации МНД

Исследования вариаций МНД на источнике ИРЕН

Shakir Zeynalov1 and Olga Sidorova1,2

1 ОИЯИ, Лаборатория нейтронной физики им.И.М.Франка, г. Дубна
МО,141980
1,2 Государственный университет Дубна, Московская область,

Аннотация

Исследование процесса эмиссии мгновенных нейтронов деления в реакциях деления, индуцированного нейтронами необходимо для понимания общих закономерностей деления ядер и процессов распределения энергии между фрагментами. Процесс деления ядра рассматривается как эволюция заряженной жидкой капли в процессе конкуренции между кулоновскими силами отталкивания и ядерными силами притяжения, приводящей в результате к разрыву ядра на пару осколков деления (ОД). Большая часть энергии возбуждения делящегося ядра передается мгновенным нейтронам деления (МНД), испущенными ОД после полного ускорения кулоновскими силами. Экспериментальные исследования различных характеристик эмиссии МНД необходимы для понимания динамики деления ядра плоть от седловой точки до разрыва. Одним из интересных наблюдений явилось увеличение   из тяжелого ОД при увеличении энергии возбуждения делящейся системы [1], которое до сих пор не нашло ясного объяснения. Поэтому необходимы дальнейшие систематические исследования корреляций между характеристиками фрагментов деления и эмиссией МНД. Исследования процесса эмиссии МНД в делении, индуцированном нейтронами

Ключевые слова: деление, вызванное нейтронами, 235U, эмиссия мгновенных нейтронов деления МНД, множественность МНД, массовое распределение ОД, распределение ОД по суммарной кинетической энергии, спонтанное деление.

Speaker: Shakir Zeynalov (JINR)

Experimental and theoretical studies of nuclear reactions: Gamma-reactions/Multinucleon transfer reactions

125 Investigation of (γ,xn)-reactions on natural iridium at 55 MeV bremsstrahlung energy

The study of photonuclear reactions is an important fundamental task for obtaining information about the structure of the nucleus and the nature of the nuclear forces. At present, only reactions involving the escape of one or two neutrons in the giant dipole resonance region are well studied. We have studied the flux-weighted average cross sections of (γ,xn) reactions on natural iridium at bremsstrahlung with an end-point energy of 55 MeV.
The determination of the flux-weighted average cross sections of the studied photonuclear reactions was carried out by activation analysis methods. The source of the 55 MeV bremsstrahlung was a racetrack microtron of the Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics. In the experiment, an assembly of an iridium target and a tantalum monitor target was irradiated for one hour. The irradiated targets were then measured using Ortec® and Canberra® semiconductor spectrometers with ultrapure germanium detectors having an energy resolution of 1.8-2.0 keV for 1333 keV 60Co gamma radiation. The detection efficiency of the spectrometers was determined using standard calibration sources 152Eu, 226Ra, 137Cs.
The table summarises the experimental values of the flux-weighted average cross sections of the photonuclear reactions studied on natural iridium. The experimental values obtained were compared with theoretical values calculated in the framework of the constant temperature Fermi gas model and the Gogny-Hartree-Fock-Bogoluybov temperature-dependent density model using the Talys 1.96 program code.

Speaker: Vladimir Pupyshev (Lomonosov Moscow State University)

126 Исследование угловых распределений и сечений излучения гамма-квантов на ядрах Si, O и C в реакциях с быстрыми нейтронами

Ядерные реакции, происходящие под действием быстрых нейтронов с различными веществами, важны как для практического применения, так и с точки зрения фундаментальных исследований. На базе Лаборатории Нейтронной Физики им. И.М.Франка (ОИЯИ) реализуется международный проект «TANGRA» (TAgged Neutrons and Gamma RAys) по изучению рассеяния меченых нейтронов на атомных ядрах. В рамках проекта создано несколько многофункциональных конфигураций экспериментальных установок, в основе которых лежит использование метода меченых нейтронов (ММН). [1,2,3]
Одна из целей проекта «TANGRA» - создание и развитие базы данных по сечениям реакций взаимодействия нейтронов с энергией 14.1 МэВ с ядрами различных элементов и характеристическим γ-линиям для расширения применимости метода меченых нейтронов для элементного анализа различных материалов и веществ. На его базе ведётся поиск и систематизация экспериментальных результатов по угловым распределениям и сечениям излучения γ-квантов.
Данная работа посвящена измерению этих характеристик для ядер Si [1], O [2], C [3], испускаемых в ходе девозбуждения ядер-продуктов реакций с быстрыми нейтронами. Измерения этих характеристик производились на новой конфигурации установки «TANGRA», состоящей из двух полупроводниковых HPGe детекторов, которые имеют высокое энергетическое разрешение и четырёх сцинтилляционных детекторов LaBr. Такая комбинация детекторов позволяет измерять малоинтенсивные γ -линии с помощью детекторов высокого разрешения и угловые распределения для наиболее выраженных γ-переходов.

Работа поддержана грантом РНФ № 23-12-00239
Литература
1. Fedorov N.A, Grozdanov D.N., Bystritskiy V.M., Kopach Yu.N., etc all Measurements of the gamma-quanta angular distributions emitted from neutron inelastic scattering on 28Si//EPJ Web Conf. 2018, 177 02002 DOI: 10.1051/epjconf/201817702002
2. Грозданов Д.Н., Н.А Федоров, В.М. Быстрицкий и др. Измерение угловых распределений гамма-квантов в реакциях неупругого рассеяния нейтронов с энергией 14.1 МэВ на ядрах углерода и кислорода// Ядерная физика. 2018, Т. 81, №5. С. 548–554.
3. Kopatch Yu.N., Bystritsky V.M., Grozdanov D.N., Zontikov A.O., Ruskov I.N., Skoy V.R., Rogov Yu.N., Sadovsky A.B., Barmakov Yu.N., Bogolyubov E.P., Ryzhkov V.I., Yurkov D.I. Angular Correlation of Gamma-Rays in the Inelastic Scattering of 14.1 MeV Neutrons on Carbon.// Proc. of ISINN-23. 2015, http://isinn.jinr.ru/proceedings/isinn-23/pdf/Kopatch.pdf

Speaker: Alexander Andreev (JINR,FLNP)

127 Role of entrance channel angular momentum on the mass-energy distributions of $^{224}$Th

In heavy-ion induced reactions, the interaction mechanism is primarily governed by the projectile beam energy and angular momentum ($L$) of the composite system. The angular momentum brought in by the projectile have significant influence on the fission barriers [1-3]. The effects of $L$ on fission have been less investigated due to the difficulty of producing the same compound nucleus (CN) via different projectile-target combinations [4]. Therefore, an attempt has been made to produce a fissioning nucleus through different entrance channels at similar excitation energies in order to investigate the role of entrance channel angular momentum.

The experiments were performed at the Flerov Laboratory of Nuclear Reactions (FLNR), JINR, Russia, using energetic beams of $^{16}$O and $^{48}$Ca delivered from the $U400$ cyclotron. The thin targets of $^{208}$Pb and $^{176}$Yb were bombarded with the $^{16}$O and $^{48}$Ca beams, respectively at different energies above the Coulomb barrier to produce the fissioning nucleus, $^{224}$Th. The measurements of the reaction binary products were carried out by utilizing the double-arm time-of-flight (TOF) spectrometer CORSET [5]. Assuming the conservation of mass of the composite system of projectile and target, the double-velocity method was employed to determine the mass and energy of the reaction products.

The reactions, $^{16}$O + $^{208}$Pb and $^{48}$Ca + $^{176}$Yb, lead to the formation of the same composite system, $^{224}$Th above the Coulomb barrier. The Mass-Total Kinetic Energy (M-TKE) distributions of the primary binary fragments from $^{224}$Th has been obtained from the present measurement. The latter reaction is subject to significant influence of quasifission reaction mechanism in addition to fusion-fission process. Subsequently, the events corresponding to fusion-fission process only were selected on the measured M-TKE distribution profiles to investigate the role of angular momentum on the fission reaction mechanism. Detailed multimodal analysis has been carried out on the experimental mass and energy distributions of the fission fragments.

References:
1. R. Vandenbosch, J.R. Huizenga, Nuclear Fission, Academic, New York (1973).
2. G. N. Knyazheva $\textit{et al.}$, Phys. Rev. C $\textbf{75}$, 064602 (2007).
3. A. Dey $\textit{et al.}$, Phys. Lett. B $\textbf{825}$, 136848 (2022).
4. F. Plasil $\textit{et al.}$, Phys. Rev. C $\textbf{29}$, 1145 (1984).
5. E. M. Kozulin $\textit{et al.}$, Instrum. Exp. Tech. $\textbf{51}$, 44 (2008).

Speaker: Dr ANIRUDDHA DEY (Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research)

128 Experimental study of MNT process in the reaction 209Bi + 238U at energy 1.85 GeV

Nowadays multinucleon transfer reactions (MNT) are considered as a perspective way to synthesize and investigate heavy and superheavy nuclei. Synthesis of superheavy elements in the MNT reactions in collisions of uranium ions with actinide nuclei is of particular interest. However, it is also important to obtain the experimental data in the reactions like $^{209}$Bi + $^{238}$U for deeper understanding of the MNT mechanisms and planning the future experiments.

The $^{209}$Bi + $^{238}$U reaction at $^{209}$Bi beam energy of 1.85 GeV was measured at the Flerov Laboratory of Nuclear Reactions with CORSET setup [1] to investigate mass and energy distributions of fragments formed in the MNT reactions. Primary and secondary mass and energy distributions of survived binary products (projectilelike and targetlike MNT fragments) have been obtained as a result of the measurements. Simultaneous using of three time-of-flight arms with energy measurements (ToF-E arms) allowed us also to register three body events: light MNT fragment and both products of sequential fission of excited heavy MNT fragment. As a result, primary mass distributions of fissioned targetlike MNT fragments have been recovered using ToF-E method. The obtained experimental results will be presented.

References:
[1] E. M. Kozulin et al., Instrum. Exp. Tech. 51, 44 (2008).

Speaker: Igor Vorobev (FLNR)

129 Competition between deep-inelastic transfer and fragmentation reactions in heavy-ion collisions at Fermi energy region

Experimental data in the reaction 40Ar+9Be at projectile energy 36 MeV per nucleon obtained at the wide-aperture magnetic mass separator COMBAS were analyzed to investigate the competition between different collision reaction mechanisms in the Fermi energy region. As was shown in our previous papers velocity distributions of the forward-emitted fragments in the reactions at this energy range exhibit a very asymmetric shape, revealing the presence of at least two main components in the reaction mechanism. The right one with the peak at projectile energy is assumed to rise from direct (fragmentation) processes and is described by the Goldhaber distribution, the contribution of the left-hand side of the velocity distribution is connected with dissipative processes, it is naturally to assume that the main contribution to the dissipative processes responsible for the decrease in the velocity is made by deep-inelastic transfer reactions. Taking the ratio of these two contributions, we conclude that both mechanisms play approximately equal role in the reaction mechanism at projectile energies at the Fermi energy region. The results of modeling isotope distributions in different transport approaches and EPAX, AA and HIPSE models are presented and discussed.

Speaker: Эрдэмчимэг Батчулуун (JINR, FLNR)

130 STUDY OF NUCLEON TRANSFER PROCESSES IN THE REACTIONS 48 Ca + 197 Au, 48 Ca + 9 Be

In this work, we present the results of studying nucleon transfer processes in the
reactions 48 Ca +  197 Au, 48 Ca +  9 Be at energies above the Coulomb barrier. The
experiments were performed at the Flerov Laboratory of Nuclear Reactions,
Joint Institute for Nuclear Research, Dubna. A 48 Ca beam with an energy of 400
MeV was accelerated by the U-400 cyclotron and transported to the reaction
chamber of the high-resolution magnetic analyzer MAVR [1]. The measured
angular distributions of the products of the reaction 48 Ca + 197 Au are presented in
Fig. 1. For isotopes of K, Ar (Fig. 1(a)) and Sc, Ti (Fig. 1(b)) corresponding to
few-nucleon transfer, maxima are seen in the vicinity of the grazing angle; for
isotopes of S, P (Fig. 1(a)) and V, Cr (Fig. 1(b)) corresponding to multinucleon
transfer, the angular distributions are practically isotropic. This behavior is
consistent with the observations described in detail in review [2]. The obtained
experimental data will be analyzed based on numerical solution of the time-
dependent Schrödinger equation for nucleons [3].

1. V.A. Maslov, V.I. Kazacha, I.V. KoIesov, S.M. Lukyanov, V.N. Melnikov,
   N.F. Osipov, Yu.E. Penionzhkevich, N.K. Skobelev, Yu.G. Sobolev, E.I. Voskoboinik.
   // J. Phys. Conf. Ser. 2016. V. 724. P. 012033.
2. V.V. Volkov, Nuclear physics research with heavy ions (JINR, Dubna, 2023).
3. V.V. Samarin et al. // Phys. At. Nucl. 2018. V. 81. P. 486.

Speaker: Ksenia Molotorenko (JINR)

131 exotic structure studies of light neutron-rich nuclei via transfer reactions

In order to study the exotic structures in unstable nuclei at around N = 8, we develop a silicon + CsI(Tl) detection array with large acceptance[1,2], which is suitable for the transfer reactions induced by radioactive beams on the proton and deuteron targets in inverse kinematics. First of all, 57(7)% d-wave and 19(7)% s-wave intruder components in the g.s. of 12Be are deduced from a new 2H(11Be, p) 12Be reaction, which is dramatically different from the g.s. of the one-neutron halo nucleus 11Be with a dominant s-wave intrusion[3,4]. Lately, 12(2)% d- and 5(2)% s-wave intruder strengths in the g.s. of 13B are determined from a new 1H(13B, d)12B reaction. The sudden change of the intruder sd-wave intensity between 13B and 12Be needs further theoretical interpretation[5]. Moreover, a new resonant state at 3.21+ 0.12− 0.04 MeV, located just 40 keV above the one-neutron separation threshold, was observed for the first time in 12Be from the 2H(11Be, p) reaction. This state is assigned a spin-parity of 0− according to the systematics of the level scheme of the N = 8 isotones and decay width analysis[6]. Recently, another new resonant state at Ex = 4.8 ± 0.1 MeV with an intrinsic width of 0.42 ± 0.28 MeV is populated by the 2H(13B, 3He) reaction via a l = 1 proton transfer for the first time.The spin-parity of 2+ is tentatively assigned to this resonance according to the analysis of its angular distributions as well as the theoretical calculations[7].
[1]Li G, Lou J L, Ye Y L, et al. Nucl Inst & Meth A, 2021, 1013, 165637.
[2]Hong‑Yu Zhu, Jian‑Ling Lou, Yan‑Lin Ye et al.,Nucl. Sci& Tech, 2023, 34,159.
[3]Chen J, Lou J L, Ye Y L, et al. Phys Lett B, 2018, 781, 412–416.
[4]Chen J, Lou J L, Ye Y L, et al. Phys Rev C, 2018, 98, 014616.
[5]Liu W, Lou J L, Ye Y L, et al. Phys Rev C, 2021, 104, 064605.
[6]Chen J, Wang S M, Fortune H T, Lou J L et al. Phys Rev C, 2021,103: L031302.
[7]Liu W, Lou J L*, Ye Y L, et al. Phys Rev C, 2022, 105, 034613.

Speaker: Jianling Lou (Peking university)

Heavy ion collisions at Intermediate and high energies

132 Charged fragments-spectators measurements with Scintillation Wall in the BM@N experiment Xe+CsI@3.8 AGeV

The report presents the performance of the BM@N Scintillation Wall (ScWall) achieved during the first physics run at the Nuclotron accelerator with Xe+CsI at 3.8 AGeV collisions. The report is devoted to the design of the ScWall and its capability to differentiate charged fragments produced in nucleus-nucleus collisions. The measured charge spectrum and the ability of the ScWall to measure nucleus-nucleus collision geometry are presented. In addition, a comparison between the experimental data and the simulation is provided.

Speaker: Mikhail Mamaev (NRNU MEPhI)

Volkov_Mamaev_02_07.pdf

133 Peeling away surface neutrons from $^{209}$Bi in asymmetric collisions

The ratio of neutron to proton densities increases toward the periphery of heavy nuclei. While this leads to a subtle difference (~0.5 fm) in the mean square radii of neutrons and protons, the thickness of such a neutron skin (NS) is very sensitive to the nuclear symmetry energy term in the equation of state (EOS) of nuclear matter important for both nuclear physics and astrophysics [1]. There have been several measurements of the NS thickness in $^{208}$Pb, see e.g. [2, 3], but their results diverge. In this respect, the estimation of the NS thickness in a neighboring nucleus such as $^{209}$Bi by new methods may help to solve the puzzle.
In this work, by means of Abrasion-Ablation Monte Carlo for Colliders (AAMCC) model [4] with MST-clustering [5] we simulate the emission of free spectator neutrons and protons in ultracentral collisions of $^{209}$Bi with target nuclei equal to (Bi) or smaller (Au, W) than $^{209}$Bi. It is expected that an excited donut-shaped spectator mater can be produced in such asymmetric ultracentral collisions. Then, an immediate break-up to free spectator neutrons and protons is predicted, and the detection of these neutrons and protons can provide a unique possibility to analyze the n/p ratio at the nuclear periphery.
The multiplicity distributions of spectator neutrons and protons were calculated with and without neutron skin in $^{209}$Bi. It was found that the neutron multiplicity distributions are different in Bi-Bi, Bi-Au and Bi-W collisions and they are sensitive to the presence of neutron skin in the projectile nucleus. The average neutron yield was calculated as a function of the volume of spectator matter in the considered ultracentral collisions.
The studies of ultracentral $^{208}$Pb–$^{208}$Pb collisions at the LHC were proposed previously [6] to identify the presence of NS in $^{208}$Pb. The ultracentral $^{96}$Zr–$^{96}$Zr and $^{96}$Ru–$^{96}$Ru collisions were also investigated at RHIC [7]. In all these cases the collisions of equal mass nuclei were investigated. In this work the method of Ref. [6] was extended to collisions of $^{209}$Bi with lighter projectiles. The yields of spectator nucleons in ultracentral collisions and the n/p-ratio of released spectator nucleons were studied as a probe of NS thickness.
As known, the BM@N experiment is equipped with forward detectors capable of detecting spectator nucleons and fragments from $^{209}$Bi projectiles [8]. In view of further upgrades of the BM@N setup one can rely on the possibility to disentangle free spectator neutrons from protons to conduct the measurements proposed in the present work.
[1] C.A. Bertulani, J. Valencia, Phys. Rev. C 100, 015802 (2019)
[2] C.M. Tarbert et al., Phys. Rev. Lett. 112, 242502 (2014)
[3] D. Adhikari et al., Phys. Rev. Lett. 126, 172502 (2021)
[4] A. Svetlichnyi et al., Bull. Russ. Acad. Sci. Phys. 84, 911 (2020)
[5] R. Nepeivoda et al., Particles 5, 40 (2022)
[6] N. Kozyrev et al., Eur. Phys. J. A 58, 184 (2022)
[7] L. Liu, et al., Phys. Rev. C 106, 034913 (2022)
[8] F. Guber et al., JINST 15 C05020 (2020)

Speaker: Aleksandr Svetlichnyi (Institute for Nuclear Research, Russian Academy of Sciences, Moscow Institute of Physics and Technology)

Svetlichnyi_NUCLEUS_2024_v2.pdf

134 Reconstruction of strange particle decays from Xe+CsI interactions with the BM@N spectrometer

In December, 2022 - January, 2023 the BM@N experiment performed
its first physics run with full configuration. Over 400 million
events of Xe+CsI interactions with the Xe beam kinetic energy of
3.8A GeV were collected.

Since then, the collaboration put strong efforts to reconstruct and
analyze collected data. The current status of this activity will
be presented with the emphasis given to the ability of the experiment
to reconstruct strange particles via their weak decays to charged hadrons.

Speaker: Alexander Zinchenko (Joint Institute for Nuclear Research)

AZ_BMN_Nucleus_2024.pdf

135 Lobachevsky geometry in relativistic nuclear physics. Directed nuclear radiation

Abstract – Application of the Lobachevsky geometry for solution of some problems in relativistic nuclear physics is discussed. Geometric description of the problem of particle production and the idea of “elementary particle” is considered. The geometric properties of particle distributions in relativistic nuclear reactions and the new regularities based on the properties of the Lobachevsky space are presented. The results of analysis are illustrated by a vast experimental material acquired in the bubble chamber experiments.

Speaker: Dr Anton Baldin (LHEP JINR)

136 Anisotropic Collective Flow at High Baryon Density

The anisotropic collective flow is one of the important observable sensitive to the equation of state (EOS) and transport properties of the strongly interacting matter created in relativistic heavy-ion
collisions. In this work we discuss the recent flow measurements from the Beam Energy Scan programs at SIS, SPS and RHIC and anticipated performance of the BM@N and MPD experiments at Nuclotron-NICA.

Speaker: Аркадий Тараненко (VBLHEP JINR)

Nucleus2024_Taranenko.pdf

Nucleus2024_Taranenko.pptx

137 Recent PHENIX results on identified charged hadron production

Quark gluon plasma (QGP) is a deconfined state of matter, which exists at the temperatures T>170 MeV and energy densities ϵ~1 GeV/fm$^{3}$. Initially it was thought that such conditions can be reached only in the relativistic heavy ion collisions (e.g. Au+Au, Cu+Cu, Cu+Au and U+U collisions), while in small collision systems such as p+Al, p/d/$^{3}$He+Au conditions are not sufficient for QGP formation. Observation of signatures for QGP formation in p/d/$^{3}$He+Au collisions by the PHENIX experiment in 2019 has renewed interest in small collision systems and hadronic matter phase diagram studies.
One of the probes for studying the phase transition between hadronic and quark-gluon matter is identified charged hadron ($π^±$, $K^±$, $p$, $\bar{p}$) production. Enhancement of proton to π-meson yields ($p/π$) measured in the intermediate $p_T$ range (1.5 GeV/c≲ $p_T$≲ 4 GeV/c) in heavy ion collisions in comparison to the ones measured in p+p collisions is usually attributed to the recombination. Recombination implies the formation of hadrons as a result of combining quarks located nearby in phase space. Formation of QGP in the collision significantly increases the probability of recombination. In collisions where QGP is not formed (p+p collisions), hadrons are mainly produced as a result of string breaking, known as fragmentation.
The talk presents latest PHENIX results on $π^±$, $K^±$, $p$ and $\bar{p}$ measurements in p+Al, $^{3}$He+Au, Cu+Au collisions at the energy of $\sqrt{s_{NN}}$ = 200 GeV and in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV. It was obtained, that in central Cu+Au, $^{3}$He+Au and U+U collisions recombination plays an important role, while in p+Al collisions and peripheral $^{3}$He+Au, Cu+Au, and U+U collisions fragmentation dominates over recombination. The conclusions are supported by comparison with theoretical predictions based on the AMPT and PYTHIA models, as well as by comparison with the results of neutral meson production measurements. The possible role of radial flow in particle production at intermediate $p_T$ range will also be highlighted.

Speaker: Daria Larionova (Peter the Great St.Petersburg Polytechnic University (SPbPU))

Wednesday 3 July

Heavy ion collisions at Intermediate and high energies

138 Is there diffraction dissociation of nuclear nucleons in nucleus-nucleus interactions

In nucleon-nucleon collisions there are processes: diffraction dissociations of projectile nucleon (PrD), dissociation of target nucleons (TrD), meson exchange processes (ME) and non-diffractive interactions. Correspondently, $\sigma^{in}\ =\ \sigma_{PrD} + \sigma_{Trd} + \sigma_{ME} + \sigma_{ND}$. Perhaps there is only one possibility to estimate these cross sections in reggeon approach. According to the approach, $\sigma_{ME}$ fast decreases with energy grouth. $\sigma_{PrD}$ and $\sigma_{Trd}$ grouth logorithmically as the elastic cross section. $\sigma_{ND}$ has a weak logorithmical grouth. Multiplicities of produced particles in the processes are related as $M_{ME}\ < \ M_{PrD}, \ M_{TrD} \ <\ M_{ND}$. In nucleus-nucleus (AA) interactions these relations and thier energy dependences can be changed.If one neglects PrD and TrD processes, $\sigma^{in} \simeq \sigma_{nd}$, multiplicities of produced particles will be overestimated. In other case, the multiplicities will be underestimated. These limiting situations are implemented in various Monte Carlo event generators. In the presentewd report, we propose a "soft" sheme of accounting of the diffraction processes in AA interactions. As a result, we have an acceptable description of experimental data of NICA BMN and NA61/SHINE collaborations (at higher energies). Details of the sheme will be considered in the report.

Speaker: Владимир Ужинский (LIT, JINR)

Uzhinsky.pptx

139 Status and preparations for the first physics with the MPD experiment at NICA

The Multi-Purpose Detector (MPD) is the main heavy-ion experiment of the NICA complex under construction at JINR. With collisions of heavy-ions in the energy range $\sqrt{s_{NN}}=4-11$ GeV, MPD will scan the region of high net baryon density of the QCD phase diagram to look for the critical end point and study the first order phase transition predicted to occur in that region. The commissioning of the MPD and first data taking with Xe-Xe or Bi-Bi collisions at ~ 7 GeV is foreseen to start in 2025. The MPD comprises a rich physics program that includes the study of hadron spectra and hyper-nuclei production, collective flow, correlations and fluctuations, hyperon global polarization, electromagnetic probes, open charm production. In this talk, we present the status of the project, its competitiveness and its physics measurements feasibility with the first beams.

Speaker: Oleg Golosov (NRC "Kurchatov Institute", MEPhI)

Golosov_MPDstatus_nucleus2024.pdf

140 Towards understanding of $K^0_s meson production in hadronic interactions

Recently, the NA61/SHINE collaboration has presented experimental data on $K^0_s$ meson productions in proton-proton interactions at projectile momenta ($P_{lab}$) of 31, 40 and 80 GeV/c [1]. Earlier, the collaboration obtained the analogous experimental data at
$P_{lab}$=158 GeV/c [2]. As it was shown in [1,2] , there are no Monte Carlo models that can well describe all the experimental data. Only at $P{lab}$=158 GeV/c, the EPOS model reproduces reasonably well the experimental data.

The description of the experimental data of the NA61/SHINE collaboration by the Geant4 FTF model [3] will be given in our report. According to the FTF model, $K^-$ mesons are mainly produced by the fragmentation of quarks and antiquarks. Productions of $K^+$ mesons are connected with the fragmentation of di-quarks. The $K^0_s$ meson yields are coupled with the fragmentation of either quarks/anti-quarks or di-quarks.

Earlier, we have described [4] experimental data on $K^+$ and $K^-$ meson productions in the proton-proton interactions measured by the NA61/SHINE collaboration. In that study, the main problem that we have identified was the tuning of the fragmentation of di-quarks for $K^+$ mesons. The experimental data on $K^0_s$ meson production allowed us to check our tuning. Now, we have reached the best description of $K^0_s$ yields in the proton-proton collisions.

The mechanism of the $K^0_s$ meson production can be studied using two-particle transverse-momentum correlations proposed by us in [5]. The correlations between $K^0_s$ mesons and $\Lambda$ hyperons, protons, $К^-$, $\pi^-$ mesons produced in proton-proton interactions at center-of-mass energy of NN collisions of 10 GeV have been calculated in the Geant4 FTF and Pythia 6.4 models. The strong $P_T$ correlations between $K^0_s$ mesons and $\Lambda$-hyperons, $K^+$ mesons, protons have been found. The two-particle $P_T$ correlations can be studied at NICA SPD experiment. The study of the two-particle correlations can help to clarify the mechanism of quark-gluon string fragmentation.

[1] NA61/SHINE Collaboration (N. Abgrall et al.), arXiv: 2402.17025
[2] NA61/SHINE Collaboration (A. Acharya et al.), Eur. Phys. J. C82 (2022) 1.
[3] Geant4 Collaboration (J. Allison et al.) Nucl. Instrum. Meth. A835 (2016) 186.
[4] A. Galoyan and V. Uzhisnky, XXV International Baldin Seminar on High Energy Physics Problem, Sept. 2023, Dubna, Russia
[5] A.Galoyan, A.Ribon, V.Uzhinsky, MDPI Physics 5 (2023) 3, 823-831

Speaker: Aida Galoyan (Veksler and Baldin Laboratory of High Energy Physics)

Galoyan_Ks0_corr.pptx

141 The MPD-ITS project. Status and Perspectives.

The Inner Tracking System (ITS) of the Multipurpose Detector (MPD) will be a vertex silicon detector designed for the efficient registration of short-lived products of nucleus–nucleus interactions and it is planned to be built using the novel technology of monolithic active pixel sensors (MAPS) following the corresponding know-how and technological transfer from CERN’s ALICE-ITS upgrade project (ALICE-ITS2) to JINR to create a large-area MAPS-only tracker at NICA. The project is being implemented as a collaboration of several institutions from Russia and China lead by JINR and the Central China Normal University (CCNU) respectively. This sophisticated and ambitious project represents equally the possibility of implementing at JINR the latest technology on components and production process, and the necessity of creatively overcoming the many obstacles for getting access to such technologies from Russia the current geopolitical conditions. During the presentation current status of the multiple aspects of the project will be reviewed along with the perspectives for the use of the MAPS technology at NICA.

Speaker: Dr Cesar Ceballos Sanchez (JINR)

MPD-ITS_Status-20240703.pdf

142 Feasibility study for directed flow measurements in the BM@N experiment

Baryonic Matter at Nuclotron is a fixed target experiment designed to probe the properties of the strongly interacting matter at the region of high baryonic densities. We report a feasibility study for measuring the directed and elliptic flow with respect to spectator symmetry plane for the recent physical run at the BM@N facility. The new results will extend the existing data available from the previous measurements of $v_1$ and $v_2$ in heavy ion collisions at the beam energy of several GeV. The system size and passing time dependency of $v_1$ are discussed.

Speaker: Mikhail Mamaev (NRNU MEPhI)

NUCLEUS_2024_07_03.pdf

143 VARIATION OF THE SOURCE VELOCITY IN COLLITIONS OF 2.1 GeV PROTONS WITH GOLD TARGET

In the present work the source characteristics of multifragmentation are investigated for the p+Au collisions at 2.1 GeV. Beam of 2.1 GeV protons were obtained from the Dubna superconductind accelerator NUCLOTRON. Source velocities of carbon and lithium fragments were measured with the 4-pi device FAZA.
It was found decreasing source velocities as the charge of fragment is decreasing.
The research was supported by the Russian Science Foundation, Grant No. 23-22-00160.

Speaker: Сергей Авдеев (ОИЯИ)

Avdeyev.pptx

144 Unstable nuclei 8Be and 9B and the Hoyle state in relativistic nuclear fragmentation

The BECQUEREL experiment is aimed at solving topical problems in nuclear clustering physics. The used method of nuclear track emulsion (NTE) makes it possible, due to its unique sensitivity and spatial resolution, to study in a unified approach multiple final states arising in dissociation of relativistic nuclei. Currently, a research focus is on the theoretical concept of α-particle Bose-Einstein condensate (αBEC) - the ultra cold state of several S-wave α-particles near coupling thresholds. The unstable 8Be nucleus is described as 2αBEC, and the 12C(0+2) excitation or Hoyle state (HS) as 3αBEC. Decays 8Be → 2α and 12C(0+2) → 8Beα can serve as signatures for more complex αBEC decays. Thus, the 0+6 state of the 16O nucleus at 660 keV above the 4α threshold, considered as 4αBEC, can sequentially decay 16O(0+6) → α12C(0+2) or 16O(0+6) → 28Be(0+).
The consideration of αBEC as an invariant phenomenon indicates possibility of its search in the relativistic fragmentation. A practical alternative is provided by NTE layers longitudinally exposed to relativistic nuclei. The invariant mass of ensembles of He and H fragments can be determined from emission angles in the approximation of conservation of momentum per nucleon of a parent nucleus. Owing to extremely small energies and widths, the 8Be and HS decays, as well as 9B → 8Bep, are identified in fragmentation of light nuclei by an upper constraint on the invariant mass.
Having been tested, this approach has been used to identify 8Be and HS and search for more complex states of αBEC in fragmentation of medium and heavy nuclei. Recently, based on the statistics of dozens of 8Be decays, an enhancement in probability of detecting 8Be in an event with an increase in number of relativistic α-particles was found. A preliminary conclusion is drawn that contributions of 9B and HS decays also increase. The exotically large sizes and lifetimes of 8Be and HS allowing suggesting possibility of synthesizing αBEC by successively connecting the emerging α-particles.The main task of the forthcoming stage of the project is to clarify the relation between the appearance of 8Be and HS and α-ensemble multiplicities and search on this basis for decays of the 16O(0+6) state. Currently, the BECQUEREL experiment aims to measure multiple channels of 84Kr fragmentation below 1 GeV per nucleon. Searches for αBEC lead to the study of nuclear matter with temperature and density ranging from red giants to supernovae. In this respect NTE layers exposed to heavy nuclei at several GeV per nucleon of the NICA accelerator complex will make it possible to study relativistic ensembles of H and He isotopes of unprecedented multiplicity under optimal conditions.
[1] P.I. Zarubin, Lect. Notes in Phys. 875, Clusters in Nuclei, Volume 3. Springer Int. Publ., 51 (2013); arXiv: 1309.4881
[2] D.A. Artemenkov et al., Eur. Phys. J. A 56 (2020) 250; arXiv: 2004.10277
[3] A.A. Zaitsev et al., Phys. Lett. B 820 (2021) 136460; arXiv: 2102.09541
[4] D.A. Artemenkov et al., Phys. At. Nucl. 85, 528 (2022); arXiv: 2206.096

Speaker: Pavel Zarubin (Joint Institute for Nuclear Research)

Yadro-2024_Zarubin_210624.pdf

Neutrino physics and nuclear astrophysics: Neutrino physics

145 On the possibility of the Majorana nature of neutrinos

One of the most popular explanations for the smallness of the neutrino mass is the seesaw mechanism [1], in which the neutrino should be a Majorana fermion. The concepts of C and CPT conjugations play an important role in the theory of Majorana fermions. We have shown that in the literature there are five nonequivalent concepts of charge conjugation (C1 - C5) and, accordingly, five possible types of Majorana fermions:
1. A fermion coinciding with its conjugate according to Pauli [2].
2. A fermion coinciding with its charge conjugate according to Majorana [3] and Kramers.
3. A truly neutral fermion coinciding with its antiparticle [3].
4. A fermion coinciding with its conjugate according to Schwinger [4].
5. A fermion coinciding with its charge conjugate with charge conjugation by means of creation and annihilation operators.

Previously, we have proven that Majorana fermions of the second type cannot be physical particles [5]. In this work, we analyze the possibility of a neutrino being a Majorana fermion of the other types.
We have proven that the non-QFT Pauli conjugation operator C1, defined in the framework of the theory of “holes” in the Dirac Sea, is equivalent to the QFT conjugation operator C4. Charge conjugation C3 is equivalent to the CPT inversion with reversal of the sign of the spin projection and chirality. The most commonly used in QFT conjugation C4 is antiunitary, reverses the particle chirality, and is not a charge conjugation. Its result coincides with the C5 charge conjugation only for chiral symmetric fermions.
We have proven that a comparison of operators in the coordinate representation and the representation of occupation numbers allows us to uniquely determine the phases of the operators P and C, up to sign, and limit the number of variants of charge conjugation and Majorana spinors.

1. R. N. Mohapatra, G. Senjanovic. Phys. Rev. Lett. 1980, 44, 912-915.
2. W. Pauli. Annales de l'Institut Henri Poincare, Physique Theorique 1936, 6, 109-136.
3. E. Majorana. Nuovo Cimento 1937, 14, 171-184.
4. J. Schwinger. Phys. Rev. 1948, 74, 1439-1461.
5. V.Monakhov. Space, time and fundamental interactions 2023, 3, 221-227.

Speaker: Prof. Vadim Monakhov (Saint Petersburg State University)

146 TUNED ELECTRON-NUCLEUS RESONANCE AS A TOOL OF PRODUCING THE 229Th ISOMER

Much attention is paid to the problem of creating nuclear optical clocks and, accordingly, the next generation frequency standard. Record samples of atomic clocks demonstrate an error within several units of 10−18, while in order to solve challenging fundamental and applied problems it is necessary to further reduce the errors by another order of magnitude. The development of heavy-ion clocks has good prospects. A further reduction in the error would allow to resolve the long-standing question about the possible drift of the fundamental constants. The most pressing task of modern physics is the search for dark matter and energy. Here the fundamental idea is to detect wave oscillations of particles of ultralight matter in its interaction with ordinary matter. And their use to search for the drift of fundamental constants has irreplaceable features, since the contribution from the nuclear component, compared to the Coulomb component, to the transition frequency is much stronger than in optical ones. Some projects are based on the joint use of atomic and nuclear clocks, using the specified features of the latters.
The number one candidate for the creation of nuclear clocks is the unique nuclide of 229Th, whose excited state 3/2+[631] lies at a height of only 8.355740(3) eV above the ground state 5/2+[633] [7]. The possibility of further refining its energy by means of resonance optical pumping is discussed. Attention is focused on considering the broadening of the resonance in order to reduce scanning time. The two-photon method proposed exploits the radical broadening of the isomer line due to mixing with the electron transition. This is not burdened with the cross-section reduction, in contrast with internal-conversion-based resonance broadening or intended extra-broadening of the spectral line of a pumping laser. In the case under consideration, according to the calculations, it turns out to be two orders of magnitude more efficient. It is applicable to both ionized and neutral thorium atoms. Realization of the method supposes excitation of the both nucleus and electron shell in the final state.

Speaker: Fedor Karpeshin (Mendeleyev Institute for Metrology)

КАРПЕШИ24.pptx

147 Capture of neutrinos from the accelerator by Iodine-127 nuclei

Current studies of neutrino-nucleus interactions have come to a situation where it has become both possible and necessary to study in detail the capture of neutrinos by nuclei. In this paper we study the interaction of high-energy neutrinos from the SNS accelerator with the detector based on the Iodine-127 [1]. We calculate the resonance structure of the charge-exchange strength function S(E) and its influence on the neutrino capture cross sections of the $^{127}$I nucleus. Three types of isobaric resonances: the giant Gamow-Teller resonance (GTR) [2], the analog resonance and the low lying pygmy resonances [3] are investigated in the framework of the self-consistent theory of finite Fermi systems [4]. The calculations of neutrino capture cross sections $\sigma(E)$ for the $^{127}$I nucleus have been carried out taking into account the resonance structure of the strength function S(E) and the influence of GTR on the energy dependence of $\sigma(E)$ has been analyzed and it has been obtained that the contribution of GTR exceeds 80% in the calculations of the cross-section $\sigma(E)$. The contribution of high energy neutrinos to the neutron emission process with the formation of $^{126}$I and $^{125}$I isotopes has been analyzed.
These results can be used to interpret experimental data and modeling results for planning new-generation experiments on the detection of rare events, such as SNO+ [5], LEGEND [6], CUPID [7], and others.

1. P. An et al. // Phys. Rev. Lett. 131, 221801 (2023).
2. Gaponov Yu. V., Lyutostanskii Yu. S. // JETP Lett. V. 15. P. 120. (1972).
3. Lutostansky Yu. S. // JETP Lett. V. 106, P. 7. (2017).
4. Migdal A. B. Theory of Finite Fermi Systems and Applications to Atomic Nuclei (Nauka, Moscow 1965; 1983, 2nd ed.; Interscience Publishers, New York, 1967).
5. Andringa S., Arushanova E., Asahi S. et al. // Adv. High Energy Phys. V. 2016. P. 6194250. (2016).
6. Cattadori C. M., Salamida F. // Universe V. 7. P. 314 (2021).
7. Alfonso, K., Armatol, A., Augier, C. et al. // J. Low Temp. Phys. V. 211. P. 375. (2023).

Speaker: Almaz Fazliakhmetov (Kurchatov Institute, INR RAS)

148 Применение кристаллов ZnSe в калибровочных экспериментах

С.В. Семенов
Курчатовский Институт

Характеристики реакции поглощения нейтрино ядром 82Se – низкое значение порога, образование гамма-кванта с энергией 75 кэВ одновременно с возникновением электрона [1], высокое значение сечения поглощения нейтрино, излучаемых источником 51Cr [2], делают кристаллы Zn82Se перспективным материалом для поиска новых типов нейтрино в калибровочных экспериментах. В модели (3+1) для сферической геометрии получено выражение для длины пробега нейтрино в установке при наличии осцилляций. Предложена схема эксперимента, позволяющего исследовать область m2>1 эВ2.

1. D. Frekers et al, Phys. Rev. C, Vol. 94, 014614 (2016)
2. S.V. Semenov, Phys. Atom. Nucl., Vol. 85, No. 11, p. 1832 (2022).

Speaker: Сергей Семенов (Национальный исследовательский центр "Курчатовский Институт")

149 Измерение квенчинг-фактора α-частиц в теллурсодержащих жидких сцинтилляторах

Тезисы и разрешения в прикрепленных файлах

Speaker: Ivan Suslov

YADRO_Suslov_24.pptx

150 𝑺𝒓𝑰𝟐(𝑬𝒖) scintillation neutrino detector with ultra-low energy threshold

A concept of SrI2(Eu) scintillation neutrino detector with ultra-low energy threshold is being developed in INR RAS to detect recoil electrons with energy lower than 1 keV. The detector will have a simple scalable structure and consist of 64-channel layers of scintillation detector modules. The modules consist of four small SrI2(Eu) crystals with SiPM readout. The detector can be used to study neutrino spectrum at low-energy range for isotope decay and reactor neutrinos. The SrI2(Eu) scintillator has light yield of up to 120 p.e./keV that provides the ability to detect extremely low energy deposition. Setting detection threshold of 6 photoelectrons allows to detect energy deposition greater than 100 eV, if SiPMs photon detection efficiency (PDE) is 50%. SrI2(Eu) emission spectrum aligns well with SiPM maximum PDE. SiPMs operation temperature below -60 ensures the suppression of dark current rate (DCR) of used SiPM-matrixes and satisfies the low threshold measurement requirement. SiPMs DCR waste studied for different temperatures and operating voltages. The parameters of detector modules were studied for few samples of scintillators produced by different companies. The measurements show satisfactory light yield of tested samples.

Speaker: Alexander Strizhak (INR RAS)

Strizhak - Nucleus,2024.pdf

151 High-energy neutrino generation at jets from supermassive black holes

The famous Blandford-Znajek mechanism or process (Blandford R.D., Znajek R.L. Mon. Not. R. Astr. Soc. 179 433 (1977)) explains the formation of relativistic jets from the fast-rotating accreting black hole due to the electric current trough black hole event horizon. The working efficiency of the Blandford-Znajek mechanism is justified recently by numerous numerical simulations of the General Relativistic Magnetohydrodynamics (GRMHD) accretion onto rotating Kerr black hole at the most powerful supercomputers in the world. In this process the acceleration of protons and other nuclei is impossible due the energetic losses in the powerful radiation field from the accretion disk.
From physical point of view the favorable place for acceleration of protons and other nuclei are the outflowing jets from accreting supermassive black holes, hitting the dense plasma clouds along the jets. It must be happened far enough from the black hole e vent horizon, radiation field from the accretion disk becomes a rather weak (at the distance ~1 pc or more). Therein is the generation of high-energy neutrino as secondary particles.
The maximum energy of these neutrinos estimated by the method (or criterium) by Hillas (Hillas A.M. Annu. Rev. Astron. Astrophys. 22 425 (1984)), may reach 1015 eV. These high-energy neutrinos are accessible for observations by the largest neutrino telescopes, such as IceCube at the South Pole and Baikal Neutrino Telescope (Baikal Gigaton Volume Detector, Baikal-GVD).

Speaker: Konstantin Prokopev (INR RAS)

K. Prokopev Nucleus-2024.pdf

152 Поиск одно- и трех-нуклонных распадов 76Ge в эксперименте GERDA

А.А.Смольников от имени коллаборации GERDA
Объединенный институт ядерных исследований

Возможность одно- и трех-нуклонных распадов, нарушающих сохранение барионного числа, предсказывается в нескольких расширениях Стандартной модели. Основной целью эксперимента GERDA (GERmanium Detector Array) был поиск безнейтринного двойного бета-распада 76Ge. Помимо этого, были получены другие результаты GERDA по поиску различных процессов за пределами Стандартной модели. В том числе исследуется возможное проявление инклюзивного, т.е. независимого от мод, распада одиночных нейтрона и протона, а также определенные моды трех-нуклонных распадов в ядре 76Ge.
По данным эксперимента GERDA исследуется возможное исчезновение одиночного нуклона в 76Ge, проявлением которого был бы β-распад основного состояния 75Ge на возбужденное состояние 75As, совпадающий с γ-квантами, испускаемыми при последующем де-возбуждении 75As. В результате распада протона может сначала образоваться нестабильное ядро 75Ga, которое затем распадается за счет β-излучения до 75Ge. Трех-нуклонные ppp-, ppn- и pnn-распады 76Ge приводят к образованию ядер 73Cu, 73Zn и 73Ga, соответственно. Эти ядра нестабильны и в конечном итоге переходят за счет последовательных β-распадов в 73Ge. Таким образом, проводится поиск распада 73Ga, который преимущественно заселяет возбужденное состояние 73mGa с энергией 66,7 кэВ. Наш анализ также включает в себя nnn-распад, происходящий через 73mGe.
Кандидатов ни для одно-, ни для трех-нуклонных распадов 76Ge обнаружено не было. Это приводит к ограничениям на время жизни инклюзивного распада одиночного нуклона в 76Ge: для нейтронов τ(n) > 1,5×10^24 лет и для протонов τ(p) > 1,3×10^24 лет при 90% CI. Это первый предел, полученный для 76Ge. Получен предел на сумму ширин распада четырех инклюзивных трех-нуклонных распадов, соответствующий нижнему пределу на время жизни 1,2×10^26 лет (90% CI). Этот результат улучшает предыдущие пределы для трех-нуклонных распадов от одного до трех порядков величины.

Speaker: A.A. Smolnikov (JINR)

Smolnikov _Nucleon Decay.pdf

Nuclear structure: theory and experiment

153 ON THE STRENGTH DISTRIBUTION OF ISOSCALAR GIANT MONOPOLE RESONANCE IN MEDIUM-HEAVY SPHERICAL NUCLEI

Being associated with breathing modes of high-energy nuclear excitations,the Isoscalar Giant Monopole Resonance (ISGMR) is the object of permanent experimental and theoretical studies [1, 2]. In studies of Ref. [2], the detailed theoretical description of ISGMR (together with L=1,2,3) isoscalar GRs) in medium-heavy closed-shell nuclei have been proposed within the semi-microscopic Particle-Hole Dispersive Optical Model (PHDOM). Although this model is not fully self-consistent, it demonstrates unique abilities in describing main characteristics (strength distribution, transition densities, probabilities of direct one-nucleon decay) of various GRs in the above-mentioned nuclei (Refs. [2, 3] and references therein). These abilities appear due to specific features of PHDOM, in which the main relaxation modes of collective (p-h)-type states associated with GRs (Landau damping, coupling these states to single-particle continuum and to many-quasiparticle configurations (the spreading effect)) are together taken into account. In particular, these modes are the main contributors to formation of the GR total width.

In this report, we present a comparison of the strength functions of ISGMR in 48Ca, 90Zr, and 208Pb evaluated within PHDOM [2] and cRPA (continuum-random-phase approximation) with the strength distributions deduced from an analysis of the respective (α,α’)-reaction cross sections [4, 5, 6]. In neglecting contribution of pair correlations to formation of the ISGMR strength function (this effect is expected to be weak), a similar comparison is done for open-shell nuclei 58Ni and 120Sn (experimental data are taken from Refs. [5, 6]). As a result, one can conclude that due to the above-mentioned features of PHDOM it is possible within this model to describe reasonably the strength distribution of ISGMR in medium-heavy spherical nuclei. Respective results of other theoretical approaches are also discussed.

1. Garg, U. and Colo, G., Progr. Part. Nucl. Phys., 101, 55 (2018).
2. Gorelik, M. L. and Shlomo, S. and Tulupov, B. A. and Urin, M. H., Phys. Rev. C, 103, 034302 (2021), Phys. Rev. C, 108, 014328 (2023).
3. Bondarenko, V. I. and Urin, M. H., Phys. Rev. C, 106, 024331 (2022), Phys. Rev. C, 109 (2024) (in press, https://arxiv.org/abs/2309.17173 ).
4. Olorunfunmi, S. D. and Neveling, R. and Carter, J. and von Neumann-Cosel, P. and Usman, I. T. and Adsley, P. and Bahini, A. and Baloyi, L. P. L. and Brummer, J. W. and Donaldson, L. M. and Jivan, H. and Kheswa, N. Y. and Li, K. C. W. and Marin-Lambarri, D. J. and Molema, P. T. and Moodley, C. S. and O'Neill, G. G. and Papka, P. and Pellegri, L. and Pesudo, V. and Sideras-Haddad, E. and Smit, F. D. and Steyn, G. F. and Avaa, A. A. and Diel, F. and Dunkel, F. and Jones, P. and Karayonchev, V., Phys. Rev. C, 105, 054319 (2022).
5. Bahini, A. and Neveling, R. and von Neumann-Cosel, P. and Carter, J. and Usman, I. T. and Adsley, P. and Botha, N. and Brummer, J. W. and Donaldson, L. M. and Jongile, S. and Khumalo, T. C. and Latif, M. B. and Li, K. C. W. and Mabika, P. Z. and Molema, P. T. and Moodley, C. S. and Olorunfunmi, S. D. and Papka, P. and Pellegri, L. and Rebeiro, B. and Sideras-Haddad, E. and Smit, F. D. and Triambak, S. and Wiedeking, M. and van Zyl, J. J., Phys. Rev. C, 107, 034312 (2023).
6. Bahini, A. and von Neumann-Cosel, P. and Carter, J. and Usman, I. T. and Arsenyev, N. N. and Severyukhin, A. P. and Litvinova, E. and Fearick, R. W. and Neveling, R. and Adsley, P. and Botha, N. and Brummer, J. W. and Donaldson, L. M. and Jongile, S. and Khumalo, T. C. and Latif, M. B. and Li, K. C. W. and Mabika, P. Z. and Molema, P. T. and Moodley, C. S. and Olorunfunmi, S. D. and Papka, P. and Pellegri, L. and Rebeiro, B. and Sideras-Haddad, E. and Smit, F. D. and Triambak, S. and Wiedeking, M. and van Zyl, J. J., Phys. Rev. C, 109, 014325 (2024).

Speaker: Mikhail Gorelik (Moscow Economic School)

154 Microscopic description of isoscalar giant monopole resonance in spherical nuclei

A comprehensive analysis of the isoscalar giant monopole resonance (ISGMR) has long been a subject of extensive theoretical and experimental research [1,2]. The ISGMR properties are presently an important problem not only from the nuclear structure point of view [2,3] but also because of the special role they play in many astrophysical processes such as prompt supernova explosions [4] and the interiors of neutron stars [5].

The random phase approximation (RPA) with the Skyrme-type energy-density functional (EDF) is the most widely used theoretical model for describing the ISGMR [2,3]. The study of the monopole strength distribution in the region of giant resonance involves taking into account a coupling between the simple particle-hole excitations and more complicated (two- and three-phonons) configurations [3,6].

In the present report, we discuss the effects of the coupling between one-, two-, and three-phonon terms in the wave functions on the monopole strength distribution in the double-magic nuclei 40,48Ca and 208Pb. Using the same set of parameters, we describe available experimental data [7,8]. The effects of the phonon-phonon coupling (PPC) [9] lead to a redistribution of the main monopole strength to lower energy states and into higher energy tail [8,10]. In particular, the PPC predictions of the fine structure of the ISGMR in the Ca isotopes are in good agreement with the fine structure which is extracted from experimental data analysis [11].

The research was supported within the framework of the scientific program of the National Center for Physics and Mathematics, topic No. 6 "Nuclear and Radiation Physics" (stage 2023–2025).

[1] M.N. Harakeh and A. van der Woude, Giant Resonances (Clarendon Press, Oxford, 2001).
[2] Z.Z. Li, Y.F. Niu, and G. Colò, Phys. Rev. Lett. 131, 082501 (2023).
[3] N.N. Arsenyev, and A.P. Severyukhin, Universe. 7, 145 (2021).
[4] H.A. Bethe, Rev. Mod. Phys. 62, 801 (1990).
[5] N.K. Glendenning, Phys. Rev. Lett. 57, 1120 (1986).
[6] N.N. Arsenyev, A.P.Severyukhin, R.G. Nazmitdinov, JETP Letters, 118, 718 (2023).
[7] S.D. Olorunfunmi et al., Phys. Rev. C. 105, 054319 (2022).
[8] A. Bahini et al., Phys. Rev. C. 109, 014325 (2024).
[9] A.P. Severyukhin, V.V. Voronov, and N.V. Giai, Eur. Phys. Jour. A. 22, 397 (2004).
[10] N.N. Arsenyev, and A.P. Severyukhin, Phys. At. Nucl. 85, 912 (2022); 86, 465 (2023).
[11] S.D. Olorunfunmi et al., in preparation.

Speaker: Nikolay Arsenyev (Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research)

155 Dipole electric and magnetic strengths in 156Gd

In connection with recent NRF experiment for dipole spectra in 156Gd [1], various E1 and M1 excitations in this nucleus are investigated in the framework of the fully self-consistent quasiparticle random phase approximation (QRPA) with Skyrme forces [2]. The low-energy pygmy dipole resonance (PDR), isovector E1 giant dipole resonance (GDR), isovector M1 low-energy orbital scissors resonance (OSR), M1 spin-flip giant resonance (SFGR) are covered. Besides, we consider a toroidal E1 resonance and low-energy M1 spin-flip states. The deformation splitting and dipole-octupole coupling of electric excitations are analyzed. Our calculations show a good agreement with E1 NRF data but disagree with M1 data at 4-6 MeV, where, in contradiction with our calculations and previous (p, p′) data, almost no M1 strength was observed.

Speaker: Petr Vishnevskiy

156 Spin-dipole strengths and neutron skin thickness of 90Zr, 132Sn, 208Pb

I. N. Borzov 1), 2)*, S. V. Tolokonnikov 1), 3)
1) National Research Center “Kurchatov Institute", Moscow, Russia.
2) Bogolubov Laboratory of Theoretical Physics, JINR, Dubna, Russia.
3) Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia.

The strength functions of charge exchange spin-dipole (SD) excitations are calculated in the continuum quasiparticle random-phase approximation based on the Fayans density functional DF3-f with modified isovector part [1]. An impact of the isovector parameter h2− of the functional on the charge-exchange spin-dipole excitations (0-, 1-, 2-) are studied for 208Pb, 132Sn and 90Zr. The sum rules are calculated using both ground state radii and direct integration of the total SD strength distributions [2]. A comparison with the experimental SD sum rule in 90Zr [3] gives one an additional possibility to check previously estimated h2− values [1] which described well the recent combined estimate for the neutron skin thickness ∆Rnp in 208Pb and corresponding parameters of nuclear matter equation of state - symmetry energy J (ρ0) and a slope parameter L (ρ0) [4].
1. I.N. Borzov, S.V. Tolokonnikov, Physics of Atomic Nuclei 86 (3) 304-309 (2023).
2. Shi-Hui Cheng, JingWen, Li-Gang Cao, Feng-Shou Zhang, Chin. Phys. C 47, 024102 (2023).
3. K. Yako, H. Sagawa, and H. Sakai, Phys. Rev. C 74, 051303 (2006).
4. R. Essick, P. Landry, A. Schwenk, and I. Tews, Phys. Rev. 104, 065804 (2021).

Speaker: Sergei Tolokonnikov (National Research Centre "Kurchatov Institute")

157 SOME FEATURES OF BETA-DECAY STRENGTH FUNCTION IN HALO NUCLEI

The probability of the $\beta$-transition is proportional to the product of the lepton part described by the Fermi function $f( \textit{Q}_{\beta} - E)$ and the nucleon part described by the $\beta$-decay strength function $S_{\beta}(\textit{E})$ . Until recently, experimental investigations of the $S_{\beta}(\textit{E})$ structure were carried out using total absorption gamma-ray spectrometers $(TAGS)$ and total absorption spectroscopy methods, which had low energy resolution. With $TAGS$ spectroscopy, it became possible to demonstrate experimentally the resonance structure of $S_{\beta}(\textit{E})$ for Gamow–Teller ($GT$) $\beta$-transitions [1]. However, $TAGS$ methods have some disadvantages arising from low energy resolution of $TAGS$ spectrometers. Modern experimental instruments allow using nuclear spectroscopy methods with high energy resolution to study the fine structure [2] $S_{\beta}(\textit{E})$.
In this report the fine structure of $S_{\beta}(\textit{E})$ in halo nuclei is analysed. When the parent nuclei has $nn$ Borromean halo structure, than the Gamow-Teller resonance and pygmy resonances in $GT$ $\beta$-decay strength function $S_{\beta}(\textit{E})$ in daughter nuclei may have structure corresponding to $np$ tango [3,4] halo. When neutron excess is high enough, resonances in $S_{\beta}(\textit{E})$ may simultaneously have both $nn$ Borromean halo component and $np$ tango halo component and form so-called mixed halo [3,4]. Analysis of the $S_{\beta}(\textit{E})$ structure in halo nuclei allow to determine the most suitable region for the Wigner $SU(4)$ spin-isospin symmetry. Value $Z/N \approx\ 0.5 - 0.6$ may correspond to the $SU(4)$ spin-isospin symmetry region.

1. Yu.V. Naumov, A.A. Bykov, I.N. Izosimov, Sov.J.Part.Nucl., $\textbf{14}$, 175(1983).
   https://www.researchgate.net/publication/233832321
2. I.N. Izosimov, V.G. Kalinnikov, A.A. Solnyshkin, Phys. Part. Nucl., $\textbf{42}$, 1804(2011). DOI: 10.1134/S1063779611060049
3. I. N. Izosimov, Physics of Particles and Nuclei Letters $\textbf{16}$, 754 (2019). DOI: 10.1134/S1547477119060207
4. I. N. Izosimov, EPJ Web of Conferences $\textbf{239}$, 02003 (2020).
   DOI: 10.1051/epjconf/202023902003

Speaker: Igor Izosimov (Joint Institute for Nuclear Research)

158 Muon capture measurements with Ba-136 target.

The large energy and momentum transfer of ordinary muon capture makes it an excellent tool to study the nuclear structure at conditions similar to neutrinoless double beta decay and benchmark the corresponding nuclear matrix elements. The MONUMENT collaboration is performing a set of muon capture experiments at the Paul Scherrer Institute in Switzerland. In the report, the measurement principle, the setup and preliminary results performed with Ba-136 target are presented. These measurements will benefit future calculations for leading double beta decay experiments.

Speaker: Maria Fomina (JINR)

FominaM_Nucleus2024_final.pdf

159 Investigation of low-energy spectrum in 250-260No chain

The low-energy multipole spectrum in isotopes 250-260No is investigated in the framework of fully self-consistent Quasiparticle-Random-Phase-Approximation (QRPA) method with Skyrme forces [1,2]. The representative set of Skyrme parametrizations (SLy5, SLy6, SkM* and SVbas) is applied. The main attention is paid to nuclei 252No and 254No, where we have most of the experimental spectroscopic information [3,4]. In addition to low-energy one-phonon collective states (lm=20,22,30,31,32) and their rotational band, the isomeric states are inspected. In general, a good agreement with the experimental data is obtained. It is shown that, a shell gap in the neutron single-particle spectra of 252No and 254No can lead to specific properties of these two nuclei. In connection with the first experimental evidence of the scissors mode in the 254No [5], the distribution of M1 strength in this nucleus is analyzed.
[1] P.-G. Reinhard, B. Schuetrumpf, and J. A. Maruhn, Comp. Phys. Commun. 258, 107603 (2021).
[2] A. Repko, J. Kvasil, V.O. Nesterenko and P.-G. Reinhard, arXiv:1510.01248[nucl-th].
[3] R.-D. Herzberg and P.T. Greenlees, Prog. Part. Nucl. Phys. 61, 674 (2008).
[4] R.-D. Herzberg, arXiv:2309.10468[nucl-ex].
[5] F.L. Bello Garrote et all, Phys. Lett. B834, 137479 (2022).

Speaker: Mariia Mardyban

11:30 Coffee break

Heavy ion collisions at Intermediate and high energies

160 NEGATIVE PION PHOTOPRODUCTION ON THE TENSOR-POLARIZED DEUTERON AT VEPP-3

The results of measurement of the T20 component tensor analyzing power in incoherent π--meson photoproduction on the deuteron in the photon energy range of 300–650 MeV are presented. Experimental statistics of the reaction under study was isolated from the experiment that was designed to investigate photodisintegrathion on deuteron. In this experiment two protons were recorded by the upper and lower arms of the detecting system. The measured asymmetries of the yields with regard to the change in the sign of tensor polarization of deuterons were used to calculate the T20 component of the tensor analyzing power of the reaction under investigation. A detailed description of the experimental setup and detection equipment is provided in [1-3].
The obtained experimental data are compared with the results of statistical simulation. The event generation was followed by verification that it belongs to the permissible region of the kinematic phase space. After the generation of independent kinematic variables, the reaction amplitude was calculated. The model described in [4] was used to calculate the amplitude of the neutral pion photoproduction. In the framework of the model, the quasi-free pion photoproduction on nucleons that form the deuteron and the contribution of nucleon-nucleon and pion-nucleon rescattering were considered. The measurements cover the photon energy range of (300-650) MeV. In general, there is a qualitative agreement between experimental and available theoretical predictions. It is planned to give further attention to extraction of the experimental data on the reaction from the experimental statistics accumulated at VEPP-3 in 2023 using the photon tagging system.

Speaker: Dr V.V. Gauzshtein

161 Photodisintegration of polarized deuteron. Status of the experiment at the VEPP-3 storage ring.

The experiment on photodisintegration of tensor-polarized deuteron is in progress. It is carried out at VEPP-3 storage ring using the internal polarized gas target technique. The component of tensor analyzing power T20 is obtained by measurement of the target polarization asymmetry for deuteron photodisintegration in the photon energy range 400 – 640 MeV. Photon energy is defined by the system for tagging almost-real photons was developed at the BINP. We discuss the results of the last run at VEPP-3 and the future plans to study this physical process.

Speaker: Yuri Shestakov (Budker Institute of Nuclear Physics of Siberian Branch Russian Academy of Sciences (BINP SB RAS))

162 Relativistic equation for four-nucleon system

The paper generalizes the four-particle integral Faddeev-Yakubovsky equation to the
relativistic case. The obtanied system of integral equations is solved by the iteration method
and the binding energy and amplitudes of states of the helium-4 nucleus are found. The rank-
one separable Yamaguchi potential is used as the NN interaction potential. In the calculations
the only states with zero orbital momentum are considered - S states. The results of the
calculation are compared with non-relativistic calculations and experimental value.

Speaker: Sergey Yurev (JOINT INSTITUTE FOR NUCLEAR RESEARCH)

163 Covariance and noncovariance of relativistic spin equations

To solve difficult problems of nuclear spin physics like the proton spin crisis physicists should perfectly understand what spin is. There are a few correct definitions of the relativistic spin operators [1]: Dirac spin definition and two Foldy-Wouthuysen spin definitions coupled with the center-of-charge and center-of-mass position operators. The conventional definition explicitly or implicitly uses the Foldy-Wouthuysen representation and presents the total angular momentum as a sum of the orbital angular momentum defined in the laboratory frame and the spin defined in the particle rest frame. It has been proven [2] that this definition leads to noncovariant spin equations. Two other definitions result in covariant spin equations but are not convenient.

[1] Liping Zou, Pengming Zhang, and A. J. Silenko, Position and spin in relativistic quantum mechanics, Phys. Rev. A 101, 032117 (2020).

[2] A. A. Pomeransky, R. A. Senkov, and I. B. Khriplovich, Spinning relativistic particles in external fields, Usp. Fiz. Nauk 43, 1129 (2000) [Phys. Usp. 43, 1055 (2000)].

Speaker: Alexander Silenko (Joint Institute for Nuclear Research)

Nucleus2024Silenko.pdf

164 О проблеме происхождения массы нуклона

Проблема происхождения массы нуклона является одной из наиболее значительных проблем современной физики. Уже в конце прошлого века происхождение этой массы было признано как результат непертурбативного взаимодействия глюонов и токовых кварков при нарушении киральной симметрии. Однако механизм такого взаимодействия остаётся открытым в отличие от механизма возникновения массы лептонов и токовых кварков. Поэтому поиск такого механизма необходим для понимания происхождения основной наблюдаемой массы современного мира, образованного нуклонами. Интенсивность такого поиска в настоящее время несравнимо мала по сравнению с интенсивностью исследований, которые привели к открытию механизма Браута-Энглера-Хиггса и его экспериментальному подтверждению. Тенденция к изменению этой парадоксальной ситуации может возникнуть только на базе изучения процессов с участием конституентных кварков, образующих нуклоны. Экспериментальным подходом для этого может стать изучение неупругих центральных нуклон-нуклонных соударений при сравнительно невысоких энергиях. В этом отношении уникально благоприятны условия, возникшие в настоящее время на экспериментальном комплексе NICA в ОИЯИ.

Speaker: Vladimir Komarov (JINR)

165 Создание теоретической базы данных сечений редких ядерных процессов, рассчитанных в модели ядерных реакций кваркового уровня CHIPS

Разрешение в процессе оформления, поэтому будет прикреплено позже.

Speaker: Mikhail Kosov (Dukhov Automatic Research Institute (VNIIA))

Ядро2024_CHIPS(Kosov).pdf

Ядро2024_CHIPS(Kosov).pptx

Ядро2024_CHIPS(Косов).pdf

Ядро2024_CHIPS(Косов).pptx

166 Dualities in heavy-ion collisions

The interplay between different theoretical descriptions of nuclear matter is considered. The statistical approach based on Zubarev density matrix appears to be dual to the geometrical one based on conical singularities for accelerated media. The new phase transition in accelerated media is predicted in both approaches which may explain the hadronization and fast thermalization.

Speaker: Oleg Teryaev (JINR)

teryaev0307b.pdf

167 Magnetic moment and polarizability of the vector strange mesons from lattice QCD

We explore the ground state energy behaviour of the vector $K^*$ mesons in external abelian magnetic field of QCD scale in SU(3) lattice gauge theory. We calculate the magnetic polarizability of the neutral and magnetic moment of the charged $K^{*}$ mesons by background field method and investigate the dependence of these physical quantities from the value of $m_s/m_d$ ratio.

Speaker: Prof. Oleg Teryaev (Joint Institute for Nuclear Research)

teryaev0307c.pdf

Neutrino physics and nuclear astrophysics: Neutrino physics

168 STATUS AND RESULTS FROM NUGEN EXPERIMENT AT KALININ NUCLEAR POWER PLANT

The experiment nuGeN investigates neutrino properties at Kalinin nuclear power plant (KNPP, Udomlya, Russia) [1]. The experimental setup was installed under the third unit of the KNPP at a distance of 11.1-12.2 m from the reactor core. The enormous antineutrino flux at this place of (3.6 - 4.4)*10$^{13}$ $\nu$/(cm^2 sec), good overburden of 50 m w.e. and suitable background conditions provide the one of the best places for search of coherent elastic neutrino scattering, magnetic moment of neutrino and other rare processes. The signals are recorded by a specially designed low-background, low-threshold, 1.4 kg germanium detector. The surrounding of the detector by active and passive shielding allows to mitigate background from external radiation. Special techniques were developed to detect nuclear recoils with energy depositions below 300 eV. The detection efficiency for signals from events with energy higher than 250 eV is more than 80 %. The spectrometer demonstrates good and stable performance. More than 1600 kg•days of data has been accumulated so far. A detailed overview of the experimental setup, the current status of measurements, and the new results will be presented at the conference.

Speaker: Алексей Лубашевский (JINR)

lubashevskiy_NUCLEUS.pdf

169 Investigation of reactor antineutrino in the DANSS experiment

Detector DANSS detects antineutrino flux from the 3.1 GW industrial nuclear reactor VVER-1000 of the Kalinin Nuclear Power Plant at distances 10.9, 11.9, 12.9 meters over 8 years. By 2024 statistics of more than 8 million inverted beta decay events have been collected. New analyses of the data exclude a large area of parameters for hypothetical short base reactor neutrino oscillations to sterile state. Additionally, a new study of high energy part (8-12 MeV) of reactor antineutrino spectrum was carried out. The neutrino spectrum dependence on the 239Pu fission fraction and the ratio of cross sections for 235U and 239Pu will be shown. A status of the DANSS upgrade will be reviewed. Twice better energy resolution of 12% at 1 MeV and increased by 70% sensitive volume will provide more sensitive and precise studies of reactor antineutrino in the DANSS experiment over next years.

Speaker: Igor Zhitnikov (JINR)

2024-07-03-danss-nucleus2024-zhitnikov.pdf

170 A search for corellation of neutrino events in the Borexino detector with transient astrophysical phenomena.

The Borexino detector was a low-background real-time liquid scintillator setup with primary focus on solar neutrino spectroscopy. The detector has been in operation since May of 2007 up until October of 2021 at the underground facilities of Gran-Sasso National Laboratory.
Here, we present the results of our search for correlations between Borexino signals and known astrophysical transients (such as fast radio bursts, gamma-ray bursts and gravitational waves) that has been registered within the same time period.

Speaker: Evgeniy Unzhakov (Petersburg Nuclerar Physics Institute - NRC Kurchatov Institute)

Nucleus_2024_Unzhakov_BX_vs_transients_v1_1.pdf

171 Search for Sterile Neutrino with the Daya Bay full dataset

on behalf of Daya Bay Collaboration

Modern neutrino physics contains a few anomalies that can not be described by the three-neutrino mixing and oscillation framework. Reactor neutrino experiments observed a deficit of the anti-neutrino flux at $2.5 \sigma$ level with respect to the prediction (Huber-Mueller model). Gallium detectors for solar neutrinos observed a deficit of events from radioactive calibration sources of neutrino ($^{37}$Ar and $^{51}$Cr) at $2.3 \sigma$ level.
These anomalies could be explained with one or more sterile neutrinos, which interact only gravitationally.
The reactor experiment Daya Bay has stored $5.55 \cdot 10^6$ IBD candidates from the interaction of electron antineutrinos. The statistics have been accumulated on a distance from 400 m to 2 km between reactor and detectors. It makes the experiment sensitive to sterile neutrino in a wide range of sterile mass splittings $\Delta m^2_{41}$.
Since no significant signal of sterile neutrino was observed, it enables us to exclude a large region of sterile neutrino parameter space. The sensitivity to sterile amplitude $\sin^2 2\theta_{14}$ achieves $5 \cdot 10^{-3}$ with 95% confidence level in a region of $2\cdot 10^{-4}$ eV$^2 < \Delta m^2_{41} < 2 \cdot10^{-1}$ eV$^2$.
The overview of the experiment and results of the analysis of the full dataset of Daya Bay will be presented.

Speaker: Vitalii Zavadskyi (JINR)

Zavadskyi_NUCLEUS-2024-07-03_.pdf

172 Classification of tau-neutrino events in the Scattering and Neutrino Detector using kinematic information

The SHiP (Search for Hidden Particles) experiment is a new fixed-target experiment to be installed at the CERN SPS ring with a 400 GeV proton beam energy. The primary goal of the experiment is to detect signals from the Hidden Sector particles, introduced to describe dark matter, baryon asymmetry, and small neutrino masses. To suppress background, an iron magnetized hadron absorber and a muon shield are utilized, along with several veto systems, aiming to reduce the experiment's overall background to zero over 5 years of operation.

SND (Scattering and Neutrino Detector) is the SHiP detector project designed to detect neutrinos of all flavors and direct signals from Light Dark Matter (LDM) interactions. An updated design for SND@SHiP includes a high-granularity hadron calorimeter achieved using scintillating fibers (SciFi) and scintillator layers (Sci).

This work aims to verify the possibility of classification:
1. Signal from inelastic interaction of tau-neutrinos via charged current on nuclei followed by tau lepton decay in the leptonic channel (CC DIS $ \nu_{\tau} N \rightarrow \tau + X \rightarrow \mu \nu_{\tau} \nu_{\mu}+ X $) against the background of signal from inelastic interaction of muon neutrinos via charged current on nuclei (CC DIS $ \nu_{\mu} N \rightarrow \mu + X $).
2. Signal from inelastic interaction of tau-neutrinos via charged current on nuclei followed by tau lepton decay in the hadronic channel (CC DIS $ \nu_{\tau} N \rightarrow \tau + X \rightarrow hadrons + X $) against the background of signal from inelastic interaction of muon neutrinos via neutral current on nuclei (NC DIS $ \nu_{\mu} N \rightarrow \nu_{\mu} + X $ ).
The search for tau-neutrino signal was performed using reconstructed kinematics of secondary particles and detector response. Inelastic neutrino interaction events from the SHiP experiment spectrum on nuclei were simulated using the GENIE package, and secondary particles were passed through the detector using the GEANT4 package. A classifier was developed using machine learning methods trained on kinematic variables, capable of accurately classifying event types. To assess the required accuracy and resolution of the detector, the model was tested on blurred data and demonstrated stability under the assumed detector resolution.

Speaker: Vasilisa Guliaeva (MSU, NUST MISIS)

Nucleus2024July_statistical_nutau.pdf

173 ACTIVE AND STERILE NEUTRINO OSCILLATIONS INSIDE THE SUN IN A PHENOMENOLOGICAL (3+1+2)-MODEL

The phenomenological model with three active and three light sterile neutrinos is considered taking into account terrestrial experimental data, which indicate anomalies at short distances beyond the minimally modified Standard Model with three massive active neutrinos [1, 2, 3, 4]. One of the sterile neutrinos is assumed in this work to have comparatively different mass versus masses of two others, that is corresponding to a (3+1+2)-model of neutrinos. Model parameters values used for the description of oscillations of both active and sterile massive neutrinos into the Sun are chosen. Oscillation characteristics of solar neutrino together with sterile neutrino contributions have been evaluated taking into account the neutrino interaction with the matter inside the Sun. We use the standard solar model (SSM) [5, 6, 7]. Results obtained are in harmony with observational data and can be used for development of sterile neutrinos models.

References
1. Abazajian K.N. Neutrinos in astrophysics and cosmology // arXiv: 2102.10183 [hep-ph].— 2021. — P. 1 — 45.
2. Khruschov V.V., Fomichev S.V. Oscillations of active neutrinos at short baseline in the model with three decaying sterile neutrinos // Universe.— 2022.—V. 8.— # 97.— P. 1 — 13.
3. Khruschov V.V., Fomichev S.V. Active and sterile neutrino oscillations inside the Sun in a phenomenological (3+1+2)-model // arXiv: 1310.5817v3 [hep-ph] .— 2015. — P. 1 — 7.
4. Acero M.A., Arguelles C.A., Hostert M. et al. White paper on light sterile neutrino searches and related phenomenology // arXiv: 2203.07323 [hep-ex] ].— 2022. — P. 1 — 206.
5. Bahcall J.N., Serenelli A.M., Basu S. New solar opacities, abundances, helioseismology, and neutrino fluxes // Astrophys. J.— 2005.—V. 621.— P. L85 — L88.
6. Bahcall J.N., Serenelli A.M., Basu S. 10000 standard solar models: a Monte-Carlo simulation // Astrophys. J. Suppl.— 2006 — V. 165.— P. 400 — 431.
7. Vinyoles N. et al. A new generation of standard solar models // Astrophys. J. — 2017.—V. 835.— # 202.— P. 1 — 16.

Speaker: Viacheslav Khruschov (NRC Kurchatov Institute)

Nuclear structure: theory and experiment

174 Delineating the island of deformation in the light gold isotopes by means of laser spectroscopy

Optical spectroscopy is able to measure subtle shifts in the energy of the atomic electron levels, arising from changes in the charge distribution of the nucleus [1]. For a given isotopic chain, this effect, known as the isotope shift (IS), arises due to changes in the nuclear mass and size. From this, the change in mean-square charge radius ($\delta\langle r^2\rangle$) can be extracted in a nuclear-model independent way. Similarly, spin ($I$), magnetic dipole ($\mu$) and electric quadrupole ($Q$) moments can be deduced from the hyperfine splitting of optical lines. The optical spectroscopy is therefore a sensitive and direct method of probing the nuclear ground and metastable states that enable to obtain a wealth of new information about shape evolution across the nuclear landscape.

In this contribution, we present the results of the optical spectroscopy measurements for neutron deficient Au isotopes performed at the ISOLDE facility (CERN). In order to study very neutron deficient isotopes with low yield, it was necessary to use the most sensitive laser spectroscopy method: in-source resonance-ionization laser spectroscopy [2]. The advanced atomic calculations of the factors needed for extraction of the nuclear observables from the measured IS’s, enable us to decrease substantially the uncertainties of the $\delta\langle r^2\rangle$ values.

Evolution of deformation in the gold isotopic chain proves to be different from that found earlier in the adjacent chains: shape staggering for Hg and Bi [3] isotopes, gradual increase of deformation in Pt or Po isotopes, retention of the near spherical shape in Pb and Tl nuclei. Thus, the small changes in $N$ and/or $Z$ in this region lead to the dramatic variations in the pattern of the shape evolution which make these data a stringent test of the theory.

The experimental results are compared to mean-field calculations [4], that reproduce the unusual behavior of $\delta\langle r^2\rangle$ fairly well only when the nuclear ground states are chosen in accordance with experimental spin and magnetic moments rather than in accordance with the energy of the corresponding levels. This observation reveals the fundamental deficiency of the current mean-field approaches.

1. P. Campbell et al., Prog. Part. Nucl. Phys. $\bf{86}$, 127 (2016).
2. G.D. Alkhazov et al., Nucl. Instrum. Methods Phys. Res. B $\bf{69}$, 517 (1992).
3. A. Barzakh et al., Phys. Rev. Lett. $\bf{127}$, 192501 (2021).
4. J.G. Cubiss, et al., Phys. Rev. Lett. $\bf{131}$, 202501 (2023).

Speaker: Pavel Molkanov (Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, Russia)

175 In-source laser photoionization spectroscopy of heavy (N > 126) Bi isotopes

Nuclei in the "lead region" of the nuclide chart ($Z$ close to 82) are of particular importance for nuclear physics. Nuclides in the vicinity of neutron mid-shell $N$ = 104 exhibits striking effects such as shape coexistence, shape staggering $etc$. The heavier isotopes ($N$ > 126) are also of great interest. One of the reasons is so-called "shell effect" in charge radii [1]. This effect consists in the presence of the characteristic kink in the charge radii at the $N$ = 126 neutron shell closure.

Studies of the heavier isotopes $^{214-218}$Bi (including isomers) were performed at the ISOLDE facility (CERN) using the in-source photoionization laser spectroscopy. The changes of the mean square charge radii and electromagnetic moments were measured.

The observed deviation of the behavior of the magnetic moments from the trend for the lighter isotopes and other isotopic chains may indicate structural changes in the heavy Bi isotopes.

The isomer $^{215}$Bi$^m$ ($I$ = 25/2...29/2) is of particular interest. Measurement of the isomer shift $\delta \langle r^2 \rangle_{215,215m}$ enables checking the hypothesis of the determinative role of the $\nu 1i_{11/2}$ occupancy in the formation of the kink in charge radii when crossing $N$ = 126, since the main peculiarity of this isomer is the presence of the unpaired neutron on the $i_{11/2}$ shell.

It's commonly accepted that the kink in charge radii appears only when the neutron $1 i_{11/2}$ shell is substantially occupied in nuclei with $N$ > 126 [2]. In particular, this kink is quite successfully reproduced in Covariant Density Functional Theories (CDFT) with the variety of covariant energy density functionals [3]. HBF calculations with an additional density-dependent term to the spin-orbit interaction (proposed by Nakada and Inakura [4]) also reproduced more rapid rise of the radii in the heavier isotopes ($N$ > 126). Nevertheless, the first rude estimations based on the sign and amplitude of the $\delta \langle r^2 \rangle _{215,215m}$ are in favor of the CDFT approach.

1. A.E. Barzakh, D.V. Fedorov, V.S. Ivanov, P.L. Molkanov, F.V. Moroz, S.Yu. Orlov, V.N. Panteleev, M.D. Seliverstov, and Yu.M. Volkov, Phys. Rev. C $\bf{97}$, 014322 (2018).
2. P.M. Goddard, P.D. Stevenson, and A. Rios, Phys. Rev. Lett. $\bf{10}$, 032503 (2013).
3. M.M. Sharma, G.A. Lalazissis, and P. Ring, Phys. Lett. B $\bf{317}$, 9 (1993).
4. H. Nakada and T. Ikamura, Phys. Rev. C $\bf{91}$, 021302(R) (2015).

Speaker: Maxim Seliverstov (Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, Russia)

176 Nuclear electromagnetic moments and radii near N = 126 neutron shell

Nuclear electromagnetic moments and radii near N = 126 neutron shell

I.N. Borzov, 1, 2, ∗ and S. V. Tolokonnikov 1, 3, †
1) National Research Centre”Kurchatov Institute”, Moscow, Russia
2) Bogolubov Laboratory of Theoretical Physics, JINR, Dubna, Russia
3) Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia

Charge radii of Tl, Pb and Bi isotopic chains and magnetic moments of the ground state Jπ=1/2 + (Tl g ) and 11/2 – (Tl m ) isomeric states are calculated. The self-consistent Theory of Finite Fermi Systems (TFFS) based on the modified Energy Density Functional DF3-a by Fayans et al. is used. The calculated ground-state charge radii of Tl, Pb and Bi isotopic chains reveal distinctive kink at the N = 126 shell closure which has a similar magnitude, as in the neighboring mercury, lead and bismuth isotopic chains. For Tl isotopic chain, the experimental kink indicators ξ = δ<r2>128/126 / δ<r2>126/124 [1] are described by the present calculation. Taking into account the meson exchange in the external field operator and in the effective spin dependent NN -interaction, as well as the regular effects of np-nh configurations and non-regular phonon-coupling (PC) corrections enables an improved description of the ground state magnetic moments in the long isotopic chain of thallium isotopes. Calculated magnetic moments agree fairly well with the isotopic trend and qualitatively reproduce the “asymmetric” jump at N = 126 revealed by the experiment [2]. For N = 82−126, “parabolic” N- dependence of the 11/2 − Tl m isomeric state magnetic moments and its value [1] is well reproduced without phonon-coupling (PC) corrections.
1. A. E. Barzakh, D. V. Fedorov, V. S. Ivanov, et.al. Phys.Rev. C 97, 014322 (2018).
2. Z. Yue, A. N. Andreyev, A. E. Barzakh , I. N. Borzov , J. G. Cubiss et.al. Physics Letters B 849, 138452 (2024).

Speaker: Ivan Borzov (NRC KI and JINR)

177 Evolution of neutron shell structure of N = 14, 16 isotones

The evolution of neutron single-particle characteristics of isotones with N = 14, 16 was studied in the dispersive optical model /1/ in Z region from 7 to 20. The calculation was performed with the parameters both extrapolated in accordance with the global parameters KD (KDUQ) /2, 3/ and with the diffuseness parameter $a_{HF}$ depending on the neutron excess. With an increase in the neutron excess, the energy gap N = 14 and N = 16 is reduced and widens respectively. In addition, the deviation $\Delta_F=|〈E_{1d_{5/2}},E_{2s_{1/2}}〉-E_F|$ of the middle between the $1d_{5/2}$ and $2s_{1/2}$ energies from the Fermi energy $E_F$ increases for N = 14 isotones. It reflects the disappearance of N = 14 magicity when approaching the neutron drip line. While, the deviation $\Delta_F=|〈E_{2s_{1/2}},E_{1d_{3/2}}〉-E_F|$ for isotones with N = 16 decreases. An increase in the $a_{HF}$ parameter for unstable isotones enhances this effect. The obtained results are consistent with the double magicity of $^{24}$O (N = 16) and $^{34}$Ca (N = 14) nuclei. As an example, Fig.1 shows the evolution of neutron single-particle energies $E_{nlj}$ near the Fermi energy of isotones with N = 14. The deviation $\Delta_F$ is represented relative to the value of particle-hole energy gap $G$.

References
1. C. Mahaux, R. Sartor Adv. Nucl. Phys. 1991. V.20. P.1.
2. A.J. Koning, J.P. Delaroche. Nucl. Phys. A. 2003. V. 713. P. 231.
3. C. D. Pruitt J. E. Escher, and R. Rahman, Phys. Rev. C. 107, 014602 (2023).

Speaker: Olga Bespalova (Scobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State Unoversity)

178 Single-particle structure of mirror nuclei near $^{48}$Ni

The radial wave functions and the energies of the protons and neutrons in the same states of the corresponding mirror nuclei differ due to the Coulomb interaction. Mirror energy difference (MED) between the energy of protons and neutrons in these states depend on angular momentum (the Thomas-Ehrman effect $[$1]). The single-particle structure of the mirror nuclei $^{52}$Ni-$^{52}$Cr, $^{50}$Ni-$^{50}$Ti, and $^{48}$Ni-$^{48}$Ca was studied within the dispersive optical model [2]. The parameters of the imaginary part of the potential were determined according to the global parameters [3]. MED of 2$\textit{p}$ valence states with low angular momentum ($\textit{l}$ = 1) was shown to be less than that of 1$\textit{f}$ states ($\textit{l}$ = 3) (Fig 1, a). In Fig. 1,b the calculated difference $\Delta r_{np}$ between the root mean square radii of protons and neutrons in 1$\textit{f}$, 2$\textit{p}$ states of the investigated mirror nuclei is presented. The difference is greater for 1$\textit{p}$ states compared to 1$\textit{f}$ states. The effect is enhanced approaching the proton drip line. Taking into account such effects is important for more accurate prediction of the features of drip-line nuclei such as double magic $^{48}$Ni nucleus.

References:
1. J.B. Ehrman, Phys. Rev., 81 (1951), pp. 412-416, R.G. Thomas, Phys. Rev., 88 (1952), pp. 1109-1125
2. Mahaux C., Sartor R., Adv. Nucl. Phys., 20, 1 (1991)
3. A. J. Koning, J.P. Delaroche, Nucl. Phys. A., 713, 231 (2003)

Speaker: Anna Klimochkina (Physics Department of Lomonosov Moscow State Universiry; Scobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State Unoversity)

179 Investigation of 1^+ excitations in light and medium nuclei within shell model

This work examines the excitation of anomalous parity levels 1^+ in some light and medium nuclei with filled or partially filled shells. Nuclei {12}^C, {16}^O, {18}^O, {28}^Si, {48}^Ca are considered. The wave functions of excited states were calculated within the framework of the shell model using the NuShellX program [1]. Within the framework of this program, the calculation of excited states is performed taking into account the connection between the proton and neutron components of the nucleus. In addition, using this program, single-particle transition densities of the considered excitations were also calculated. Wave functions are tested using the values of the reduced probabilities B(M1) of radiation transitions, as well as when describing the differential cross sections of inelastic scattering in the reactions (p,p') and (e,e') with excitation of the levels under consideration. The fragmentation of the strength of the magnetic dipole transition is studied, as well as the contribution of the spin excitation component in the transitions under consideration.

1. B. A. Brown and W. D. M. Rae, The Shell-Model Code NuShellX. Nuclear Data Sheets 120, 115 (2014).

Speaker: Mikhail Onegin (Petersburg Nuclear Physics Institute of NRC KI)

14:00 Lunch

Design of new experimental facilities

180 IP vertexing – a novel idea

A new vertexing algorithm is presented, applicable to IP determination, based on the linear extrapolation of tracks in the vicinity of the IP. The algorithm considers the tracks as infinitely elongated ellipsoids, reducing the problem to the vertexing of a set of points of given ellipsoid error matrices. We have implemented the idea in C++, which works with our previously reported NXV4 package for vectors and matrices (available in JINRLIB).

Speaker: Maria Dima (JINR - MLIT)

DIMA MARIA.pptx

181 Microtron based VEGA-m spectrometer for study of the shape isomers decays.

In the series of experiments performed at the beam of the MT-25 microtron in FLNR, JINR, the break-up of fission fragments (FFs) while they pass a solid-state foil in the timing detector, placed at four meters from the actinide target was observed [1-3]. The results were obtained using the VEGA (V–E Guide based Array) setup. The FFs from photo-fission reactions were captured by an electrostatic guide system (EGS). The guide is a cylindrical capacitor of four meters long with a thin wire as a central electrode. Some part of the FFs were captured in EGS and transported to the time-of-flight mass-spectrometer at the opposite side of the guide, where the break-up of part of the FFs took placed. The mean time-of-flight of the FFs in the EGS exceeded 400 ns. The effect was treated as a break-up of the FF born in a long-lived shape isomer state at the stage of binary fission of mother nucleus in the target and was observed for the first time.
The main problem that was encountered during the experiment was the background noise from the accelerator. To radically improve the situation, a new VEGA-m project is underway. The guide of about 6 meters long will now be positioned vertically and therefore will enter the second floor of the microtron hall, passing about 2 m of concrete, which will protect from the radiation. Essential upgrade of both the spectrometer electronics and data processing is also being planned.

Speaker: Alexey Solodov (JINR FLNR)

182 Misalignment influence on the track reconstruction in the MPD TPC

A method of determining the position of the readout sectors of a time projection chamber using experimental data is proposed. Considering the results of modeling the response of sensitive elements of the time projection chamber of the multipurpose detector (MPD), three types of tracks were reconstructed: cosmic muons, beams of the laser detector system, and muons from the interaction of nuclei. The accuracy of the MPD TPC alignment finding is investigated in MC events with different types of tracks. For the Time Projection Camera, a measure of deviation of the used alignment from the real one is introduced. The simulation of track reconstruction shows the dependence of track parameter errors on the accuracy of knowledge of the real alignment of the detector. The found dependencies allow to correct systematic errors during track reconstruction.

Speaker: Dr Valentin Kuzmin (NIINP Moscow State University)

nucleus24.pdf

183 Detector setup optimization based on training artificial neural-networks

We apply artificial neural networks (ANN) to event-wise analysis of simulated data from a microchannel plate detector (MCP)[1] being considered for installation in future experiments on NICA collider [2]. We have demonstrated, that neural networks can estimate the parameters of the collision not only from spatial distribution of particles, but also benefit from high resolution time-of-flight distributions that can be obtained from MCP. From this data we estimate the impact parameter and the collision point of an event. We have performed the analysis based on several Monte-Carlo models of the event. Even though the quality of the existing event models is not sufficient for a reliable model-independent estimation of the event parameters, the proposed parameter reconstruction procedure allows us to evaluate - and to optimize - the technical characteristics of the detector. These characteristics include the geometry of the device, its placement, the number of sensors, and the time resolution.

In [3, 4, 5] we have demonstrated that - subject to the detector geometry - the collision point and the impact parameter of each event can be estimated quite accurately only from the raw detector data. Our approach exploits Monte-Carlo models of high energy collisions. As we have demonstrated in [3, 4, 5], the data from QGSM generator[6] allows us to estimate the impact parameter within an uncertainty of about 1 fm, and to reconstruct the collision point with uncertainty about 1 cm. This result, however, is model-dependent, and processing data from alternative generators [7, 8] leads to different ANN parameters. Despite this model dependence of the ANNs, the detector parameters providing the best reconstruction of the event parameters do not depend on the Monte-Carlo model of the event.

We report the results of ANN training and suggest the optimal MCP configuration which is model-independent and, thus, can be used in future detector specification.

References
[1] A.A.Baldin, G.A. Feofilov, P. Har'yuzov, and F.F. Valiev,
// Nucl. Instrum. Meth.A 2020, V.958,P.162154. https://doi.org/10.1016/j.nima.2019.04.108
[2] https://nica.jinr.ru/
[3] K.A. Galaktionov, V.A. Roudnev, and F.F. Valiev, Neural network approach to impact parameter estimation in high-energy collisions using the microchannel plate detector data,
// Moscow University Physics Bulletin 2023, V. 78, P. S52-S58
[4] Galaktionov K.A., Roudnev V.A., Valiev F.F. Artificial Neural Networks Application in Estimating the Impact Parameter in Heavy Ion Collisions Using the Microchannel Plate Detector Data: Physics of Atomic Nuclei.
//Phys. At. Nucl. 2023 V.86(6), P.1426-1432. https://doi.org/10.1134/S1063778823060248
[5] Galaktionov, K., Roudnev, V., Valiev, F., Application of Neural Networks for Event-by-Event Evaluation of the Impact Parameter,
// Physics of Particles and Nuclei 2023 ,V. 54, P. 446-448
[6] Amelin N. S., Gudima K. K., Toneev V. D. Ultrarelativistic nucleus-nucleus collisions within a dynamical model of independent quark - gluon strings // Sov. J. Nucl. Phys. 1990. V. 51(6), P. 1730-1743
[7] Werner, Klaus and Liu, Fu-Ming and Pierog, Tanguy Parton ladder splitting and the rapidity dependence of transverse momentum spectra in deuteron-gold collisions at the BNL Relativistic Heavy Ion Collider
// Physical Review C 2006, V. 74
[8] Aichelin, J. and Bratkovskaya, E. and Le Fèvre, A. and Kireyeu, V. and Kolesnikov, V. and Leifels, Y. and Voronyuk, V. and Coci, G. Parton-hadron-quantum-molecular dynamics: A novel microscopic n-body transport approach for heavy-ion collisions, dynamical cluster formation, and hypernuclei production
// Physical Review C 2020, V. 101

Speaker: Kirill Galaktionov (Saint Petersburg State University)

184 Исследование наноуглеродных центров спонтанной эмиссии на катодах многопроволочных пропорциональных камер мюонных детекторов LHCb

Практика работы экспериментов на Большом адронном коллайдере (БАК) показала, что основной проблемой эксплуатации многопроволочных пропорциональных камер (МПК) являются спонтанные самоподдерживающиеся токи (ССТ) [1,2]. Их появление вызывает либо аварийное отключение детекторов, либо понижение значений поданного на них напряжения, что приводит к уменьшению эффективности соответствующих детекторных систем.

Исследование МПК, работавшей в составе Мюонной системы эксперимента LHCb на БАК, где регулярно возникали ССТ показало, что причиной эффекта являются точечные центры эмиссии электронов на катодных плоскостях [3]. Причиной возникновения центров эмиссии оказалось образование на катодах МПК островковых наноструктур, включающих в себя углерод, фтор и кислород. Представленная работа демонстрирует сформировывавшиеся путем осаждения из газовой фазы на катоды МПК наноструктуры. Поиск и исследование центров эмиссии проводились путем последовательного применения методов атомно-силовой микроскопии, начиная с полуконтактных фазовых и топографических измерений, и заканчивая измерениями токовых характеристик на предварительно выделенных участках поверхности катода МПК.

1. The LHCb collaboration et. al. // JINST. 2008. 3 S08005.
2. The CMS collaboration et. al. // Nucl. Instrum. Meth. A494:504-508, 2002.
3. Albicocco F.P., Anderlini L., Anelli M. et al. // JINST. 2019. V.14. Art. P11031.

Speaker: Alexey Dzyuba (NRC «Kurchatov Institute» - PNPI)

Dyzuba_Nucleus2024.pptx

185 Integration of the HGND readout into the B@MN experiment data acquisition system

The new high granular time-of-flight neutron detector (HGND) is being developed for the BM@N (Baryonic Matter at Nuclotron) experiment to identify neutrons and to measure their energies in heavy-ion collisions at ion beam energies up to 4 AGeV. The HGND consists of about 2000 scintillator detectors (cells) with a size of 40X40X25 mm^3 and with individual light readout with EQR15 11-6060D-S photodetectors. The readout board with a 100 ps FPGA-based TDC (Time to Digital Converter) is currently under development. The HGND will have eight such readout boards, each comprising three Kintex 7 FPGAs for reading out 252 channels. The TDC operates on the standard LVDS 4x asynchronous oversampling and is synchronized with the experiment timestamp using the White Rabbit link. The two-channel TDC prototype demonstrates a time resolution of 42 ps. The FPGA-TDC principle of operation and tests results, readout board topology, and the readout software architecture will be discussed.

Speaker: Dmitry Finogeev (INR RAS)

HGND_RD_NUC_2024_Finogeev.pdf

186 Экспериментальное обоснование необходимости исследования радиационных свойств материалов: графит, тантал, висмут, золото, уран, торий, актиниды, ленты втсп, с целью создания технологий для работы реакторов работающих в электроядерном (АДС) варианте.

Эксперименты проводились в рамках программы электроядерных исследований на ускорителях ОИЯИ на экспериментальных комплексах ЛЯП и ЛФВЭ ОИЯИ, созданных на базе ускорителей, в «on-line» и «off-line» режимах.
В докладе описана методика экспериментов, как при использовании урановой сборки
«Квинта», так и при облучении на прямом пучке ускорителей ОИЯИ, описана работа и полученные результаты на многодетекторном спектрометре ФАЗА.(См.рис.)
Рассматриваются протекающие реакции, а также структура образующихся и исследу- емых ядер. Особое внимание уделено реакциям мультифрагментации идущих при боль- ших (более 1 Гэв) энергиях. Представлены результаты исследований с мишенями
графита, золота, урана, актинидов. В докладе делаются экспериментальные оценки образования и наработки быстрых нейтронов необходимых для протекания реакций деления. Рассматриваются планы дальнейших экспериментов,(см.доклад).
1. S.I. Tyutyunnikov, V.I. Stegailov et al. «Nucleus-2023». Sarov. 2023. P.17-18.
2. S.I. Tyutyunnikov, V.I. Stegailov et al. «Nucleus-2020». St-Petersburg. 2020. P.117-118.
3. S.P. Avdeyev, W. Karcz, V.I. Stegailov et al. // Bull. Russ. Acad. Sci. Phys, 2020, 84, P. 979–980.
4. S. Kilim, S.I. Tyutyunnikov, V.I. Stegailov et al. XXIII Inter. Baldin Seminar, Dubna, 2016, P. 80-81.

Speaker: Mr Владимир Стегайлов (ОИЯИ)

187 Cryogenic gas stopping cell testing with alpha source and Monte Carlo simulations

The new experimental setup for the high-precision mass measurement of the heavy and the superheavy nuclei is being built in the Flerov Laboratory of Nuclear Reactions (Dubna). The crucial part of the setup for stopping and thermalization of the reaction products is the cryogenic gas stopping cell (CGSC). The CGSC consists of the stainless steel outer and inner chambers. The outer chamber is at the vacuum pressure and works like the thermal insulation. It also reduces the radiation heat transfer to the inner chamber by the insulation foil. The temperature inside of the outer chamber is the room temperature (293 K). The inner chamber is filled by the helium buffer-gas and it is also platted from the outside by the copper for the homogenous distribution of the temperature. The inner chamber is cooled to the 40 K by the cryocooler. The set of the cylindrical and the conic electrodes are installed inside of the inner chamber. The isotopes for the testing of the CGSC is possible to get from the alpha source with the intensity below the minimally significant activity according to the radiation safety rules. There are stopped in the active volume of the inner chamber and guided by the electrical field to the supersonic nozzle and then extracted and filtered by the radio frequency quadrupole. The alpha source 227Th decays by alpha decay to the 223Ra, 219Rn, 215Po and 211Bi. The measuring is performed at the pressure 50 Torr for the room temperature (293 K) and the 5 Torr for the 40 K. The simulations of the extraction time from the CGSC were performed. The internal software using the Monte Carlo method and based on the SRIM and the Geant4 was used in the simulations.

Speaker: Aleksey Novoselov (FLNR JINR)

Neutrino physics and nuclear astrophysics: Astrophysics

188 NUCLEOSYNTHESIS IN A LOW-MASS NEUTRON STAR CRUST. STRIPPING MODEL.

The lanthanides traces discovery in the kilonova spectra after recording a gamma-ray burst and gravitational waves [1] confirmed theoretical scenarios for the development of the r-process [2], associated with the neutron stars merger at the end of a close binary system evolution. After successful r-process simulation that occurs as a result of the neutron stars merger and observing these events, it became clear that this scenario is crucial for the heaviest nuclei formation. However, the neutron stars evolution in close binary systems strongly depends on their masses. With a large neutron stars masses difference, a stripping scenario is implemented instead of merging [3], which, in particular, has different heavy elements nucleosynthesis path [4,5].
In this work the nucleosynthesis in the low-mass neutron star crust, which loses mass due to accretion onto a larger companion and explodes upon reaching a hydrodynamically unstable configuration [3] is discussed.
It is shown that in the stripping scenario the exploded residue substance expands and, while its density is high, new elements nucleosynthesis occurs. In the inner crust it originates mainly due to the r-process with characteristic values of electrons to baryons initial ratio Ye<0.3. Nucleosynthesis in the outer crust in the scenario under consideration occurs mainly due to explosive nucleosynthesis with a sharp increase in temperature caused by a shock wave. Various decompression options for subnuclear density matter in the inner crust, preceding nucleosynthesis and forming the initial seed nuclei, are considered. The amount of heavy elements formed in a neutron star crust is M ~ 0.041Mʘ, which is at least an order of magnitude greater than the yield of heavy elements in the close masses neutron stars mergering scenario [6].
The work was carried out within the state assignment framework of the National Research Center «Kurchatov Institute».
1. N. R. Tanvir, A. J. Levan, C. González-Fernández, et al. // AJ. 2017. V. 848. P. L27.
2. J. Cowan, et al. // Rev. Mod. Phys. 2021. V. 93. id. 15002.
3. S. I. Blinnikov, D. K. Nadyozhin, N. I. Kramarev, A. V. Yudin // Astronomy Reports. 2021. V. 65. P. 385.
4. I.V. Panov, A.V. Yudin // Astronomy Letters. 2020. V. 46 P. 518.
5. A. Yudin, N. Kramarev, I. Panov, A. Ignatovskiy // Particles. 2023. V. 6. P. 784.
6. S. Rosswog, et al. // Astron. Astrophys. 1999. V. 341. P. 499.

Speaker: Anton Ignatovskiy (MIPT; Kurchatov Institute - ITEP)

Ignatovskiy_StrippingModel_NUCLEUS2024.pptx

189 Ricci-Gauss-Bonnet gravity, cosmology, and nuclear astrophysics

Ricci-Gauss-Bonnet (RGB) gravity based on a pure geometric Lagrangian that is defined by a specific dimensionless combination of the Ricci (R) and Gauss-Bonnet (G) scalars is suggested and discussed as a possible viable generalization of the General Relativity (GR). Within the Parameterized Post-Newtonian (PPN) formalism it is shown that RGB gravity has the same values of PPN parameters as in the GR. As well in RGB gravity there is no ghosts, or unstable perturbations. With no need in cosmological constant and dark matter RGB gravity well agrees with the solar system data, cosmological data, and with the spectral scalar index defined by evolution of the random metric fluctuations at the inflation stage of the primordial Universe. The physics of the gravitational field arising from RGB gravity is considered in contexts of the cosmology, black holes, supernovae stars, neutron stars, compact binary systems, galaxy rotation curves, and weak-field gravity. Finally, RGB gravity is shown to exhibit a number of interesting phenomena in each of the topics mentioned above, and it is discussed for prediction of new possible experiments.

Speaker: Dr Yury Pokrovsky (National Research Center “Kurchatov Institute”)

190 Об особенностях гиперонных взаимодействий в нейтронных звёздах

Изучение свойств барион-барионных взаимодействий является на сегодняшний день актуальной темой исследований в области ядерной физики. При этом гиперон-нуклонные и, тем более, гиперон-гиперонные взаимодействия изучены гораздо хуже, нежели нуклон-нуклонные. Подходящей средой для изучения свойств барионных взаимодействий являются нейтронные звёзды, поскольку их материя состоит из барионов и лептонов и может быть описана с помощью методов ядерной физики. Более того, экстремальные условия, реализующиеся внутри нейтронных звёзд, такие как сверхвысокие давление и плотность, позволяют исследовать различные особенности барионных взаимодействий, которые не проявляются в нормальных условиях.
В данной работе мы концентрируемся на изучении свойств гиперонных взаимодействий в нейтронных звёздах. Предполагается, что материя нейтронных звёзд состоит из нуклонов, лептонов и гиперонов. Для описания взаимодействия используются силы Скирма, а для расчёта масс и радиусов нейтронных звёзд — уравнение Толмана-Оппенгеймера-Волкова.
Мы исследуем влияние зависимости от плотности гиперон-нуклонного взаимодействия на характеристики нейтронных звёзд. Также рассматривается вопрос о плотности, при которой появляются гипероны в нейтронных звёздах. Эта характеристика, по нашему мнению, имеет важное значение для описания нейтронных звёзд, в материи которых присутствуют гипероны [1, 2]. В связи с этим изучается зависимость плотности в точке появления гиперонов от свойств гиперон-нуклонного взаимодействия. Наконец, мы исследуем вопрос о зависимости от плотности гиперон-гиперонного взаимодействия и предлагаем новый способ описания этого взаимодействия в нейтронных звёздах.
Исследование выполнено за счет гранта Российского научного фонда № 24-22-00077.

[1] L.T. Imasheva, D.E. Lanskoy, T.Yu. Tretyakova. Physics of Atomic Nuclei. 82 (2019) 402.
[2] S. Mikheev, D. Lanskoy, A. Nasakin, T. Tretyakova. Particles. 6 (2023) 847.

Speaker: Mr Semyon Mikheev (Skobeltsyn Institute of Nuclear Physics (SINP MSU), Moscow)

Nucleus_Mikheev_2024 (1).pdf

191 Neutrino magnetic moments and high-energy neutrinos flavour composition

Neutrino propagation in the Galactic magnetic field is considered. To describe neutrino flavour and spin oscillations on the galactic scale baselines an approach using wave packets is developed. Evolution equations for the neutrino wave packets in a uniform and non-uniform magnetic field are derived. Analytical expressions for neutrino flavour and spin oscillations probabilities accounting for damping due to wave packet separation are obtained for the case of uniform magnetic field. It is shown that for oscillations on magnetic frequencies $\omega_i^B = \mu_i B_\perp$ the coherence lengths that characterizes the damping scale is proportional to the cube of neutrino average momentum $p_0^3$. Probabilities of flavour and spin oscillations are calculated numerically for neutrino interacting with the non-uniform Galactic magnetic field. Flavour compositions of high-energy neutrino flux coming from the Galactic centre are calculated accounting for neutrino interaction with the magnetic field. It is shown that for neutrino magnetic moments $\sim 10^{-13} \mu_B$ and larger these flavour compositions significantly differ from ones predicted by the vacuum neutrino oscillations scenario.

Based on:
1) A.Popov, A.Studenikin, "High-energy neutrinos flavour composition as a probe of neutrino magnetic moments", arXiv: https://arxiv.org/abs/2404.02027.
2) A.Popov, A.Studenikin, Manifestations of nonzero Majorana CP-violating phases in oscillations of supernova neutrinos, Phys.Rev.D 103 (2021) 11, 115027.
3) A.Popov, A.Studenikin, Neutrino eigenstates and flavour, spin and spin-flavour oscillations in a constant magnetic field, Eur.Phys.J.C 79 (2019) 2, 144.

Speaker: Artem Popov (Moscow State University)

Popov_Nucleus.pdf

192 SATURNE: Current Status and Physics Potential

The Sarov tritium neutrino experiment (SATURNE) is part of the scientific program of the National Center for Physics and Mathematics (NCPM) [1] that was founded in Sarov in 2021. The experiment is under preparation, with the first taking of data expected for 2025 and the data collection expected to be completed by 2032.

SATURNE is motivated by fundamental problems in neutrino physics. Specifically, it will primarily search for neutrino electromagnetic interactions [2,3] in elastic and ionizing neutrino-atom collisions. The experiment will employ a high-intensity tritium neutrino source, with an initial activity of at least 10 MCi and possibly up to 40 MCi. The tritium source will be used in combination with the He-4, Si and SrI$_2$(Eu) targets in order to study the elastic and ionization channels of neutrino-atom collisions at unprecedentedly low energies.

The Si and SrI$_2$(Eu) detectors with record low-energy thresholds for such detector types will measure the ionization channel of neutrino-atom collisions. With the 1-year data from either detector, one may expect to achieve a sensitivity on the order of $\sim10^{-12}\,\mu_B$ at 90% C.L. to the neutrino magnetic moment $\mu_\nu$, which is the most studied theoretically and actively searched experimentally among the neutrino electromagnetic properties.

The measurements with the liquid He-4 detector in a superfluid state are expected to provide the first observation of coherent elastic neutrino-atom scattering (CE$\nu$AS) [4,5]. This will bring the experimental studies of coherent elastic neutrino-nucleus scattering (CE$\nu$NS) [6] to a qualitatively new level, namely when one will be able to explore the neutrino elastic scattering not only on a nucleus as a whole, but also on an atom as a whole. With the 5-year data using the liquid He-4 detector, it is also expected to achieve a record-high $\mu_\nu$-sensitivity of $\sim10^{-13}\,\mu_B$ at 90% C.L.

References
[1] А.А. Yukhimchuk et al., FIZMAT 1, 5 (2023) (in Russian).
[2] C. Giunti and A. Studenikin, Rev. Mod. Phys. 87, 531 (2015).
[3] A.I. Studenikin and K.A. Kouzakov, Mosc. Univ. Phys. Bull. 75, 379 (2020).
[4] Yu.V. Gaponov and V.N. Tikhonov, Sov. J. Nucl. Phys. 26, 314 (1977).
[5] M. Cadeddu, F. Dordei, C. Giunti, K. Kouzakov, E. Picciau, and A. Studenikin, Phys. Rev. D 100, 073014 (2019).
[6] V. Pandey, Prog. Part. Nucl. Phys. 134, 104078 (2024).

Speaker: Prof. Konstantin Kouzakov (Lomonosov Moscow State University)

193 The Signature of Neutron Fluences of the Artificial Pulse Nucleosynthesis

An extreme high intensive neutron pulses ensure the conditions for pulse
nucleosynthesis realized in nature (at neutron concentration >10E+19 cm-3): at different mechanism of supernova explosions, in very massive stars, at merging and destroying of neutron stars). In the artificial condition the nucleosynthesis can occur in the close zone of nuclear/thermonuclear explosions where the neutron fluxes reach the units of 10E+24 cm-2 during the short pulse ~10E-6 s (pr- promt rapid process). The purpose of executed experiments on nucleosynthesis were production of transuranic elements by multiple (n,?)-captures in the irradiated target (manufactured from the 238U or more heavy/mixture isotopes as 232Th, 237Np, 238U, 242Pu and 243Am). The first time the creation of isotopes with neutron excess up to mass A = 255 was obtained and discovered in the Mike experiment [1]. During the Plowshare scientific program and some next USA nuclear tests (as Anacostia, Kennebec, Par, Barbel, Tweed, Cyclamen, Kankakee, Vulcan and Hutch) the transuranium isotopes up to A=257 was registered [2-4].
Basing on the proposed ABM-model it was simulated the transuranium isotope yields for five large scale pulse experiments (Mike, Anacostia, Barbel, Par and Vulcan) for creation of uranium isotopes up to A=257. The model target irradiated by sequential (n,?)-neutron captures is the mixture of 238U (main isotope) with admixture of the 239Pu injected into the plasma ball [5,6]. The model includes the elements of the dynamics
with temperature decrease down to ~2 keV and expansion of the matter with linear velocity ~190 km/s. The obtained results indicated on the roughly linear dependence of the isotope Y-yield relations from the neutron fluence [7]. It were considered the next pairs of neighboring isotopes with atomic masses A=245 and 244, A=246 and 245, A=247 and 246.The relation 246/245 (i.e., yields with masses A=246 and 245)
depending on the fluences is the most strong demonstrator of the linear dependence. The analysis of transuranic isotope yields and them relation can be sensitive signature of the fluences realized in artificial nucleosynthesis.
[1] Dorn D.W. Phys Rev 1962;126:693
[2] Hoff R.W., Dorn DW. Nucl Sci Eng 1964;18:110.
[3] Dorn D.W, Hoff RW. Phys Rev Lett 1965;14:440.
[4] Los Alamos Radiochemistry Group. Phys Rev Lett 1965;14:962.
[5] Lutostansky Yu.S, Lyashuk V.I, Panov I.V. Bull Russ Acad Sci: Phys 2010;75:533.
[6] Lyashuk V.I. Bull Russ Acad Sci: Phys 2012;76:1182–6.
[7] Lyashuk V.I., Results in Physics 2024; 56:107234.

Speaker: Dr Vladimir Lyashuk (Institute for Nuclear Researches of the Russian Academy of Sciences, Moscow)

194 Effects of neutrino electromagnetic properties and spin state in elastic neutrino-nucleon scattering

Electromagnetic neutrino properties can be a manifestation of new physics [1]. We study electromagnetic contribution to elastic neutrino-nucleon scattering processes. Following our approach developed for the case of elastic neutrino-electron [2] and neutrino-proton [3-6] collisions, in our formalism we account for possible electromagnetic form factors of massive neutrinos: the charge, magnetic, electric, and anapole form factors of both diagonal and transition types. Considering Dirac neutrinos from an astrophysical source arriving at a detector on Earth, we assume them to have arbitrary spin polarization due to effects of neutrino spin oscillations induced by neutrino magnetic moment interactions with magnetic fields both in the astrophysical source and in the interstellar environment. When treating the nucleon electromagnetic vertex, we take into account not only charge and magnetic form factors of a nucleon, but also its electric and anapole form factors. We numerically examine how the effects of electromagnetic properties and spin polarization of the cosmic neutrinos can influence the differential cross sections of their elastic scattering on nucleons in the detector.
[1] C. Giunti and A. Studenikin, Neutrino electromagnetic interactions: A window to new physics, Rev. Mod. Phys. 87, 531 (2015), arXiv:1403.6344.
[2] K. Kouzakov and A. Studenikin, Electromagnetic properties of massive neutrinos in low-energy elastic neutrino-electron scattering, Phys. Rev. D 96, 099904 (2017), arXiv:1703.00401.
[3] K. Kouzakov, F. Lazarev, and A. Studenikin, Electromagnetic neutrino interactions in elastic neutrino-proton scattering, PoS(ICHEP2020) 205 (2020).
[4] K. Kouzakov, F. Lazarev, and A. Studenikin, Electromagnetic effects in elastic neutrino scattering on nucleons, J. Phys.: Conf. Ser. 2156, 012225 (2021).
[5] K. Kouzakov, F. Lazarev, and A. Studenikin, Neutrino electromagnetic properties in elastic neutrino-proton scattering, Phys. Atom. Nucl. 86, 257 (2023)
[6] K. Kouzakov, F. Lazarev, and A. Studenikin, Elastic neutrino–nucleon scattering and electromagnetic properties of neutrinos, Moscow Univ. Phys. Bull. 78, 797 (2023)

Speaker: Fedor Lazarev (MSU)

Nucleus24Lazarev.pdf

Nuclear structure: theory and experiment

195 Spin scissors mode in Actinides

The scissors mode is investigated in the actinide region, including even-even superheavy nuclei up to $^{256}$No, within the Time Dependent Hartree-Fock-Bogoliubov (TDHFB) approach. The solution of TDHFB equations by the Wigner Function Moments (WFM) method predicts a splitting of the scissors mode into three intermingled branches due to spin degrees of freedom [1]. Both the calculated energy centroid and integrated $M1$ strength in $^{254}$No are in good agreement with the results of recent measurements performed by the Oslo method [2]. The energy centroids and summed $B(M1)$ values for other transuranium nuclides are predicted.

The calculations are performed also for $^{232}$Th and $^{236,238}$U isotopes. The scissors resonance in many actinide region nuclei exhibits a prominent double-hump structure [3,4]. The WFM analysis allows to assume that the observed splitting of scissors resonance can occur due to the separation of conventional scissors and spin-scissors excitations.

[1] E. B. Balbutsev, I.V. Molodtsova, A. V. Sushkov, N. Yu. Shirikova, P. Schuck, Phys. Rev. C 105, 044323 (2022)
[2] F. L. Bello Garrote, A. Lopez-Martens, A.C. Larsen, I. Deloncle, S. Peru et al.,
Phys. Lett. B 834, 137479 (2022)
[3] A. S. Adekola, C. T. Angell, S. L. Hammond, A. Hill, C. R. Howell, H. J. Karwowski, J. H. Kelley, E. Kwan, Phys. Rev. C 83, 034615 (2011)
[4] M. Guttormsen, L. A. Bernstein, A. Gorgen, B. Jurado, S. Siem et al., Phys. Rev. C 89, 014302 (2014)

Speaker: Irina Molodtsova (Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna)

196 Separable forces approximation in the generalized theory of finite fermi systems.

In a series of papers [1], a generalization of the theory of finite fermi systems (TFFS) was developed within the framework of the Green's function method to consistently account for complex configurations with phonons. However, quantitative estimates of the effects obtained there were not carried out due to the large quantitative difficulties. It seems that these difficulties can be circumvented or greatly reduced if to use the separable forces approximation applied, for example, in the well-known quasiparticle-phonon model (QPM) [2]. In the non-self-consistent QPM, the parameters of separable multipole forces are usually adjusted according to experimental data, in particular, for the lowest-lying $2^+$ and $3^-$-phonons, and a good description of many other excited states of spherical and deformed nuclei is obtained, for more details see [2].
We used "our" separable forces adjusting their two parameters in the corresponding equation for the effective field (vertex) [3, 4] and proceeding from fixed effective quadrupole charges based on the general formula we derived for them. In particular, for $e^{n, p}_{eff}$ =1 and 2 at $\omega$ =0 in $^{208}Pb$, we obtained that two separable forces parameters are equal.
Within the framework of this approach, a simple and useful relationship between $e^{p, n}_{eff}$ and two parameters of separable forces, that approximate the full amplitude $\Gamma$ in the standard TFFS, is also obtained.
The results obtained are used to quantify new effects in the generalized TFFS: equations for the regular part $\Gamma^r$ of the amplitude $\Gamma$, the ratios of various phonon-exchange interactions, the equation for the two phonon creation amplitude, which is contained in the concept of tadpole, and other effects.

1. S. P. Kamerdzhiev, M.I. Shitov, Phys. At. Nucl. 84 No.6, 804 (2021); 84 №5, 649 (2021); 85 №5, 425 (2022).
2. V. G. Solovʹev, Theory of Atomic Nuclei, Quasi-particle and Phonons, Institute of Physics Pub., Bristol; Philadelphia, 1992.
3. A. B. Migdal, The theory of finite Fermi systems and the properties of atomic nuclei (2nd revised and enlarged edition), Nauka, Moscow, 1983.
4. S. P. Kamerdzhiev, Sov. J. Nucl. Phys. 5, 971 (1967).

Speaker: Сергей Kamerdzhiev (Kurchatov Institute)

197 ИССЛЕДОВАНИЕ СВОЙСТВ УРОВНЕЙ НЕЧЕТНО-НЕЧЕТНОГО ЯДРА ГОЛЬМИЯ С А=160.

Для установления структуры низколежащих состояний нечетно-нечетного ядра гольмия с A=160 и объяснения т.н. f-запрещенных переходов в этом ядре измерены времена жизни уровней, интенсивно заселяемых электронным захватом и одновременно, используя вариационный принцип Хартри-Фока-Боголюбова, с целью уточнения квантовых характеристик и структуры ядер в этой области, ведутся расчеты свойств среднего поля.
Вместе с тем, в последних экспериментах по исследованию распада облученной протонами (Еp=660 Мэв) на фазотроне мишени гольмия с А=165 обнаружен распад гамма перехода с Е=857 кэв, принадлежащего распаду 160Ho, (см.рис.) с периодом равным 3.5мин., т.е. в ядре 160Ho найдено новое изомерное состояние. Анализ экспериментальных данных
продолжается.
Критерием достоверности полученных результатов служит проведённая таким же образом обработка интенсивных, незадержанных мгновенно совпадающих между собой и с собственными Kx и Lx лучами переходов 86.6, 197.0 кэВ при распаде 160Ho и 98.9, 218.2 кэВ при распаде 158Ho.
1. S.I. Tyutyunnikov,V.I.Stegailov et al. // Book of abstracts and articles of Int. Conf. "Modern Problems of Nucl. Energ. and Nuclear Technologies", 84-85, Tashkent, 23-25 November, 2021.
2. S.I. Tyutyunnikov, V.I. Stegailov, V.G. Kalinnikov и др. // Тез.докл.межд.конф. по ядерной
физике (Саров, 2006), с.82-83.
3. В.Г.Калинников и др. //Тез. докл. меж. конф. по яд.физике (С.-Петербург, 2005), с.58.
4. В.И.Стегайлов и др. // Тез. докл. меж. конф. по яд.физике (С.-Петербург, 2005), с.72.
0510152025303540455055606570100101102857.6 keV распад160Ho~3.5 min 160Ho (8+)CountTime, minute 160Ho (8+ -> 6+) Т1/2 =25 мин

Speaker: Mr Владимир Стегайлов (ОИЯИ)

198 Appearance of superconducting pair correlations in spherical even-even nuclei

The formation of superconducting pair correlations
between like nucleons in the ground state of spherical
even-even nuclei is considered within a special Bogoliubov
transformation.
The influence of the monopole pairing interaction on
the energy of single-particle states is taken into account.

It is shown that the emergence of pair correlations
depends on the particle number and shell structure.

In open subshell nuclei the correlations exist at any
attractive monopole interaction.
In this case, nucleon pairs are distributed over all
subshells participating in the pairing interaction.

The closed shell nuclei are considered within simplified
model with constant pairing interaction.
It is confirmed that the superconducting
pair correlations appear if the coupling constant $G$
exceeds a certain threshold value.
Rough upper and lower estimates are obtained
for the threshold value.

Speaker: Vladimir Kuz'min (BLTPh, JINR)

199 Модифицированные массовые соотношения GKT и GKL

Локальные массовые соотношения Гарви-Келсона GKT и GKL, предложенные в работе [1], широко использовались для изучения свойств ядерного взаимодействия, нуклонных корреляций, а также для предсказания масс неизвестных ядер. GKT и GKL представляют собой простые арифметические соотношения между массами 6 соседних ядер, выполняющиеся с точностью около 200-300 кэВ на всей совокупности измеренных масс средних и тяжелых ядер. В последние годы интерес к массовым соотношениям этого типа связан с разработкой новых статистических методов анализа данных, позволяющих выявлять закономерности и связи между различными элементами ядерных массовых моделей.

В данной работе рассматриваются модифицированные соотношения VGKL и VGKT с дробными значениями коэффициентов, полученные исходя из условия оптимальности. На основе новых массовых соотношений и экспериментальных данных AME2020 рассчитаны удовлетворяющие им массовые таблицы. В области масс $A \ge 40$ среднеквадратичное отклонение значений новых соотношений VGKT и VGKL примерно на 10% меньше соответствующих значений GKT и GKL, но при этом среднеквадратичное отклонение значений масс в полученных с их помощью массовых таблицах, равняется, соответственно, 204 и 260 кэВ, что в несколько раз меньше значений RMS массовых таблиц GKT и GKL. Новые массовые соотношения в значительно меньшей степени чувствительны к энергии Вигнера при $N = Z$.

1. G. T. Garvey and I. Kelson, Phys. Rev. Lett. 16, 197-200 (1966).

Speaker: Константин Стопани (Научно-исследовательский институт ядерной физики им. Д. В. Скобельцына)

200 СРАВНЕНИЕ МЕТОДОВ ДИАГОНАЛИЗАЦИИ ГАМИЛЬТОНИАНА БКШ С ТОЧНЫМ СОХРАНЕНИЕМ ЧИСЛА ЧАСТИЦ

Традиционным методом определения собственных функций и собственных значений гамильтониана модели Бардина-Купера-Шриффера является квазичастичный подход с приближенным сохранением числа частиц. Однако в ряде случаев этот подход оказывается недостаточно точным. Тогда необходимо воспользоваться методами с точным сохранением количества частиц. Один из таких подходов [1] основывается на представлении основного состояния сферической системы из $N$ частиц ($N$ четное) в виде
$$\left| N \right\rangle ={{\left( {{S}^{+}} \right)}^{N}}\left| 0 \right\rangle,$$ где $S^{+}=\sum\limits_{i}\beta_{i}\left( a_{i}^{+}a_{i}^{+} \right){J=0}$ –- оператор рождения коррелированной пары частиц c моментом $J$, $a{i}^{+}$–- оператор рождения частицы на уровне $i$. При этом построение возбужденных состояний с четным количеством частиц сводится к замене одного из операторов рождения пары частиц на произвольный двухчастичный оператор. Количество таких двухчастичных операторов можно увеличивать, что ведет к появлению различных возбужденных состояний. Недостатком этого подхода является заданный вид волновой функции, а достоинством — возможность использования удобного формализма симметрических полиномов. Однако по мере увеличения количества неспаренных частиц удобство метода уменьшается. Другой подход [2] заключается в построении волновых функций четных систем без использования операторов $S^{+}$ на основе $N$ операторов $\left( a_{i}^{+}a_{i}^{+} \right)_{J=0}$, распределенных в основном состоянии по одночастичным уровням согласно вариационному принципу. Построение возбужденных состояний сводится или к изменению распределения этих операторов, или к появлению состояний с ненулевым сениорити $s$. Для низколежащих состояний этот метод требует больше вычислительного времени, однако по мере перехода к высоколежащим состояниям трудоемкость обоих методов сближается, но второй точнее, так как не использует заранее заданного вида волновой функции $\left| N \right\rangle$. Проведены расчеты перекрытия волновых функций, полученных в рассматриваемых подходах в зависимости от количества и положения одночастичных уровней, количества частиц, константы парного взаимодействия и величины $s$, а также сравнение вычислительного времени.

1. Vlasnikov A.K., Mikhajlov V.M. // Ядерн. спектр. и структ. ат. ядра. Тез. докл. межд. совещ. СПб: Наука, 1994. С. 126.
2. Лунёв А.В., Власников А.К., Михайлов В.М. // Изв. РАН. Сер. Физ. 2015. Т. 79. С. 997.

Speaker: Dr Alexandr Vlasnikov (St.Petersburg State University)

201 ZEEMAN EFFECT IN NUCLEI

Wigner Function Moments method is applied to solve Time Dependent Hartree-Fock-Bogoliubov equations. The dynamical equations for the second rank irreducible tensors are derived. Their solution for $^{164}$Dy produces fourteen energy levels: ten high lying ones with $E>10$ MeV (including isoscalar and isovector Giant Quadrupole Resonances) and four low lying $K^{\pi}=1^+$ ones with $E<4$ MeV. Three low lying levels represent three types of nuclear scissors modes: orbital (conventional) one and two spin ones. Fourth level is disposed below all scissors modes and has the electrical (non magnetic) feature. Its nature can be understood after solving dynamical equations for irreducible tensors with $K^{\pi}=2^+$ and $K^{\pi}=0^+$ and studying the deformation dependence of the found low-lying levels. The results of calculations for $^{164}$Dy demonstrate in an obvious way that the lowest $1^+$ state is just one of three ($K^{\pi}=0^+, 1^+, 2^+$) branches of $I^{\pi}=2^+$ state, which can exist in a spherical nucleus (and which is split due to deformation into these three branches). It is discovered that the antiferromagnetic properties of nuclei predicted in [1], where they were called as "intrinsic angular momenta", lead to the splitting of $2^+$ states already at the zero deformation. So, we predict the existence inside of nucleus the phenomenon, which is known in atomic physics as the Zeeman effect [2]!

[1] E. B. Balbutsev, I.V. Molodtsova, P. Schuck, Phys. Rev. C 91, 064312 (2015).
[2] E. B. Balbutsev, I.V. Molodtsova, Eur. Phys. J. A 59, 207 (2023).

Speaker: Evgeny Balbutsev (JINR)

17:00 Coffe break

Design of new experimental facilities

202 The first results of test of the SPD Beam-Beam Counter scintillation detector prototype

The Spin Physics Detector is a collider experiment at NICA designed to study the spin structure of the proton and deuteron and other spin-related phenomena using polarized beams. One of the subsystems of the SPD is the Beam-Beam Counters (BBC). Two scintillator-based BBC detectors will be installed symmetrically upstream and downstream the interaction point and will serve as a tool for beam diagnostics including local polarimetry. The BBCs will be designed as high granularity scintillation detector.
In this talk, we present the tests of a BBC prototype based on the scintillation tiles produced by Uniplast (Vladimir). The prototype was equipped with the Saint-Gobain Crystals green wavelength shifter, 1x1 mm2 SensL SiPM, and CAEN FERS-5200 front-end readout system. The first obtained results are disscussed.

Speaker: Aleksey Tishevsky (JINR)

Tishevsky_nucleus2024.pdf

203 Performance of the Time-of-flight system at the BM@N experiment

The BM@N is the first experiment at the NICA accelerator complex. It is focused to study baryonic matter at high density which provides the opportunity to investigate both the EOS, and to explore the degrees-of-freedom of this matter, including the search for new phases of high-density matter. For the purpose of charged particle identification in the BM@N, two time-of-flight systems TOF400 and TOF700 are used. To perform particle identification, it is necessary to measure the time of flight as precisely as possible. To maintain the systems’ good time resolution, a sequence of calibrations has to be done. Firstly, it is the calibration of the integral nonlinearity of TDC channels, secondly, it is cable length correction, thirdly it is geometry alignment of the system, then time-amplitude correction using Time-Over-Threshold method and finally “time shift” correction. The procedure for calibration and final performance of TOF400 and TOF700 systems will be presented.

Speaker: Irina Zhavoronkova (JINR)

BM@NPerf_Zhavoronkova.pdf

204 Экспериментальная установка для прецизионного измерения зарядового радиуса протона

Представлена экспериментальная установка для прецизионного измерения радиуса протона в упругом ep-рассеянии с регистрацией протона отдачи в активной водородной мишени в диапазоне по Q2 ~ 0.001–0.04 GeV2. Установка включает в себя активную водородную мишень - время-проекционную камеру (TPC – time projection chamber), разработанную для регистрации протонов отдачи, совмещенную в одном корпусе с высокоточным трекером рассеянных электронов на основе многопроволочных пропорциональных камер (MWPC – multiwire proportional chamber). Установка, работающая при давлении газов 20 bar, позволяет измерять в ТРС угол и энергию отдачи протона одновременно с углом рассеяния электрона в MWPС. Одним из ключевых элементов эксперимента является трековая система MWPC, работающая в аргон/метановой смеси высокого давления. Трекер из восьми детекторов измеряет с высокой абсолютной точностью X и Y координаты трека электрона, а также формирует быстрые сигналы для триггерной системы. Результаты испытаний трекера и регистрирующей электроники приведены в докладе.

Speaker: Dr Gennadii Gavrilov (PNPI NRC "Kurchatov Institute")

NUCLEUS_Gavrilov_24_06_30.pdf

205 Front-end electronics and mechanical design of the HGND for BM@N experiment

High Granularity (time-of-flight) Neutron Detector (HGND) is the newest addition to the BM@N (Barionic Matter (at) Nuclotron) experiment, designed to identify neutrons and to measure their energies in heavy-ion collisions at ion beam energies up to 4AGeV. This work covers the mechanical design, developed to host ~2000 individual scintillatior cells with a size of 40x40x25 mm3, together with their readout electronics, data gathering equipment as well as power and monitoring devices. This work also includes a discussion on the design of the front-end analog electronics, responsible for photo-electronic conversion, based on the EQR15 series SiPMs, and implementation of the Time-over-Threshold (ToT) conversion.

Speaker: Aleksandr Makhnev (INR of RAS)

nDet Nucleus 2024.pdf

206 About the efficiency of the Electron Beam Ion Sources and Traps (EBIS/T)

The ion source of the electron beam type (ESIS, which is the EBIS in certain condition of the reflex mode of operation) will be used at NICA acceleration complex. Thus the research of the EBIS theoretycal efficiency is important and relevant. The talk presents the results of analysis and numerical computer simulation of the efficiency of an ion trap for the production of highly charged ions formed by the space charge of an electron beam, depending on its parameters and ionization conditions. The efficiency is defined as the product of the degree of compensation of the ion trap by ions and the relative number of ions with the required charge in the full charge spectrum. According to the numerical simulation the maximum number of ions with the required charge is possible only at a strictly specified pressure of the cooling substance, which is called optimal and depends on the electron current density and the composition of the cooling substance. At optimal coolant pressure, the efficiency is almost independent of the current density in the ion trap, but strongly depends on the charge state of the ions. A significant drop in the efficiency of the ion trap is shown with an increase in the ion charge.

Speaker: Александр Рамздорф (JINR)

207 ПРИМЕНЕНИЕ МИКРОСТРИПОВЫХ КРЕМНИЕВЫХ ДЕТЕКТОРОВ ДЛЯ ИССЛЕДОВАНИЯ РАСПАДОВ С ИСПУСКАНИЕМ ПРОТОНОВ

Исследование различных механизмов распадов лёгких нестабильных ядер с испусканием протонов либо нейтронов представляет значительный интерес для современной ядерной физики, поскольку эти процессы пока мало изучены. Некоторые из них, такие как истинный четырёхпротонный распад, до сих пор не регистрировались в экспериментах.

Проект EXPERT (EXotic Particle Emission and Radioactivity by Tracking) является частью коллаборации SuperFRS (Super-conducting FRagment Separator) Experiment, который реализуется в рамках FAIR (Facility for Antiproton and Ion Research). Основной целью проекта является исследование малоизученных ядерных систем, находящихся вблизи границ нейтронной и протонной стабильности, а также изучение экзотических распадов, таких как испускание нескольких протонов или нейтронов. В рамках проекта EXPERT используются различные детекторные системы, включая кремниевые микростриповые детекторы FOOT (FragmentatiOn Of Target).

Одним из изотопов, который до сих пор не был обнаружен, является ⁷С. В нём ожидается наблюдение истинного четырёхпротонного распада. В следующем году на фрагмент-сепараторе FRS (FRagment Separator) в GSI планирутся проведение эксперимента по получению данного изотопа и регистрации продуктов распада с помощью метода трекинга на лету. Последующее изучение угловых корреляций продуктов его распада также поможет лучше понять свойства зеркального ему изотопа ⁷H. В недавнее время был проведён тестовый эксперимент со вторичным пучком ⁹C, предназначенный для отладки всей схемы эксперимента.

В данной работе представлены предварительные результаты по симуляции предстоящего эксперимента во фреймворке ExpertRoot, а также по сравнению симуляционной модели и экспериментальных данных, полученных в ходе тестового эксперимента.

Speaker: Булат Хамидуллин (Joint Institute For Nuclear Research)

Neutrino physics and nuclear astrophysics: Astrophysics

208 The Fayans energy-density functional in applications to neutrons stars

The energy-density functional in the form proposed by Fayans has proved to be convenient and efficient for describing a large class of nuclear phenomena from nuclear masses and radii to proton and neutron density distributions and decay probabilities. Originally the parameters of the potential functional (FaNDF0) were tuned to reproduce the variational calculations of the nuclear equation of state with the v_14 potential and Urbana three-nucleon forces. Nowadays the parameter set DF3 has become very popular. We study the compositions and mass-radius relations of neutron stars using these two parameterizations. We find general relations between parameters of the functions and the expansion parameters of the nuclear equation of state at the saturation density. We set bounds on the Fayans functional parameters so that the corresponding maximum masses and radii of neutron stars satisfy new empirical constraints.

Speaker: Dr Evgeni Kolomeitsev (BLTP, JINR, Dubna and Matej Bel University, Slovakia)

Kolomeitsev-Fayans-Functional-Nucleus24.pdf

209 Neutrinos from dynamo-driven supernovae

The dynamics of neutrinos in hot and dense magnetized matter, corresponding to dynamo-driven supernova explosion, is considered. It is shown that taking into account fluctuations in the interaction of neutrinos with matter leads to the Fokker-Planck equation for the dynamics of the distribution function in the phase space. The component of the kinetic equation additional to the transfer effect [1] is determined by straggling in neutrino collisions in a magnetized nucleon gas due to the Gamow-Teller neutral current interaction. The effect of fluctuations leads to an additional increase in the hardness of the neutrino spectra. The effects of neutrino oscillations in magnetic field and dense matter on detection by the KM3NeT and Baikal-GVD observatories are discussed. It is shown that the applications of the k-fold coincidence technique in data processing makes it possible to increase the upper limits of the distance for the observation threshold by a factor of 1.5√k.
1. Kondratyev V. N. Magnetorotational Supernova Neutrino Emission Spectra and Prospects for Observations by Large-Size Underwater Telescopes // Phys. At. Nucl. – 2023. – V. 86. – P. 1083-1089.

Speaker: Vladimir Kondratyev (BLTP JINR)

210 Crust of accreting neutron stars

The report presents the results of a series of papers on modelling the nuclear physical processes in the outer layers (crust) of neutron stars in low mass X-ray binaries. In these systems, material is transferred from the companion star to the neutron star, a process known as 'accretion' in astrophysical literature. As a result, the original crust is replaced by accreted material.

We demonstrate that the presence of free neutrons (unbound in atomic nuclei) in the inner crust plays a crucial role in the nuclear physical process of forming the accreted crust. Neutrons redistribute rapidly between the layers of the inner crust due to superfluidity and diffusion (with diffusion being important near the boundary between the outer and inner crust, where neutrons are not superfluid). This effect was not considered in
previous models developed over approximately 40 years. It leads to a radical change in the nuclear reactions
chains and the composition of the crust.
Consequently, several previously accepted statements are shown to be incorrect. For instance, it was previously believed that the main reactions in the inner crust were electron capture and neutron emission, and the transition to the inner crust was associated with reaching the neutron drip line. In our work, we demonstrate that reverse reactions occur in the inner crust (neutron capture and electron emission), and the boundary between the inner and outer crusts is determined by the redistribution of free neutrons in the crust and the star's core, maintaining diffusion-hydrostatic equilibrium.

The heating efficiency of the crust has been shown to be significantly lower than previously estimated. We confront these results with observations of accreting neutron stars.

The work was supported by the Russian Science Foundation, grant 22-12-00048.

Speaker: A.I. Chugunov (Ioffe Institute)

Chugunov_AccrNS_Jadro24.pdf

Nuclear structure: theory and experiment

211 Investigation of the properties of the first excited 1^- states of even-even nuclei

Various relationships between the characteristics of low-lying
states of even-even nuclei, including the first excited 1- state, are
derived and discussed. Checking them
can become part of the program of experimental research on the created
at the National Center for Physics and Mathematics Compton Source of
monochromatic photons.

Speaker: Rostislav Jolos (JINR BLTP)

212 Spectroscopy of transfermium elements @GRAND/SHELS

At FLNR JINR experiments are carried out to investigate the radioactive decay properties (α, β, γ spectroscopy) and the cross section measurements of transfermium elements synthesised in the fusion-evaporation reaction of an accelerated heavy ion beam with target nuclei using the kinematic separator SHELS [1,2] at the cyclotron U-400 and the gas-filled separator GRAND, located at the Factory of Superheavy Elements. A number of experiments have been devoted to the study of the radioactive decay properties of No and Rf and their daughter nuclei. No and Rf isotopes are produced as a result of the evaporation of one to four neutrons from compound nuclei in the reactions of $^{204}$Pb($^{48}$Ca,(1–3)$\textit{n}$)$^{251,250,249}$No [3,4], $^{238}$U($^{22}$Ne,4$\textit{n}$)$^{256}$No [5], $^{204}$Pb($^{50}$Ti,1$\textit{n}$)$^{253}$Rf [6], $^{207}$Pb($^{50}$Ti,2$\textit{n}$)$^{255}$Rf [7], $^{208}$Pb($^{50}$Ti, 1$\textit{n}$)$^{257}$Rf [8], respectively. These transfermium isotopes have sufficiently high production cross sections to allow us to collect good statistics for the study of decay properties by methods of α, β, and γ spectroscopy. No and Rf isotopes are interesting because of the possibility to study changes in radioactive decay properties around the neutron subshell N=152, which could provide data necessary to understand how the properties of heavy element isotopes behave in the region of the neutron subshell N=162.

References
1. Yeremin A. et al. First experimental tests of the kinematic separator SHELS (Separator for Heavy ELement Spectroscopy). // EPJ Web Conf. 2015. Vol. 86. P. 4–6.
2. Yeremin A. V. et al. Experimental tests of the modernized VASSILISSA separator (SHELS) with the use of accelerated 50Ti ions // Phys. Part. Nucl. Lett. 2015. Vol. 12, № 1. P. 43–47.
3. Svirikhin A.I. et al. The New 249No Isotope // Phys. Part. Nucl. Lett. 2021. Vol. 18, № 4. P. 445–448.
4. Tezekbayeva M.S. et al. Study of the production and decay properties of neutron-deficient nobelium isotopes // Eur. Phys. J. A. Springer Berlin Heidelberg, 2022. Vol. 58, № 3.
5. Kessaci K. et al. Evidence of high-K isomerism in 256No // Phys. Rev. C. 2021. Vol. 104, № 4. P. 044609:1-6.
6. Lopez-Martens A. et al. Fission properties of Rf 253 and the stability of neutron-deficient Rf isotopes // Phys. Rev. C. 2022. Vol. 105, № 2. P. 1–5.
7. Chakma R. et al. Investigation of isomeric states in Rf 255 // Phys. Rev. C. 2023. Vol. 107, № 1. P. 1–11.
8. Hauschild K. et al. Alpha-decay spectroscopy of 257 Rf // Eur. Phys. J. A. Springer Berlin Heidelberg, 2022. Vol. 58, № 1. P. 1–7.

Speaker: Dr M.S. Tezekbayeva (Joint Institute for Nuclear Research)

213 Nucleon-pair approximation with particle-hole excitations

In this talk I shall give a brief introduction to the nucleon-pair approximation of the shell model [1], as well as its extended version with particle-hole excitations included [2]. Some applications of the method will also be presented.
[1] Y. M. Zhao, A. Arima, Nucleon-pair approximation to the nuclear shell model, Phys. Rep. 545, 1 (2014).
[2] Y. Y. Cheng, Y. M. Zhao, A. Arima, Nucleon-pair approximation with particle-hole excitations, Phys. Rev. C 97, 024303 (2018).

Speaker: Yiyuan Cheng

214 Empirical systematics of spontaneous fission half-lives of heavy and superheavy nuclei

The exact calculation of half-lives in spontaneous fission remains an open problem in nuclear physics. In this work, a new systematics of half-lives in spontaneous fission was proposed. For nuclei with the same value of neutron excess (isospin) and charge numbers $90\leq Z \leq 102$, a linear correlation was found between the decimal logarithm of the half-life of spontaneous fission and the alpha decay energy. An empirical formula has been proposed to determine the half-life of spontaneous fission of even-even nuclei depending on the alpha decay energy and neutron excess. We then extended this formula to calculate the half-lives for odd-$A$ and odd-odd nuclei, as well as for nuclei with $Z \geq 103$. The experimental half-lives were reasonably reproduced using this formula with average deviations of $1.15$ for $105$ experimentally known nuclei, which means that the formula is reliable for predictions.

Speaker: Nikita Moiseev (Lomonosov Moscow State University, Joint Institute for Nuclear Research)

215 Size, shape and deformation of nuclei

In the framework of the semi-empirical quark model of nuclear structure that is based on the quark model of the nucleon, the Strongly Correlated Quark Model (SCQM) we construct nuclei from light to heavy ones, including halo nuclei. Nucleons inside nuclei are bound due to junctions of SU(3) color fields of quarks [1]. According to SCQM, arrangement of nucleons within nuclei reveals the emergence of the face-centered cubic (FCC) symmetry [2]. The model of nuclear structure becomes isomorphic to the shell model and, moreover, composes the features of cluster models. Binding of nucleons in stable nuclei are provided by quark loops which form three and four nucleon correlations. Three nucleon correlations are responsible for the structure of “halo” nuclei. Quark loops leading to four-nucleon correlations are responsible for the binding energy enhancement in even-even nuclei which are composed by virtual alpha clusters. Namely virtual alpha-clusters are responsible for experimentally observed peculiarities of central nuclear density distribution. The model describes well quadrupole moments of nuclei (Fig. attached), although, as demonstrated, deformation of nuclei is much more complicated. Moreover, it shows that neutron and correspondingly matter distributions are deformed essentially larger. The role of the “pairing” effect and structure of isomers are discussed.

References
[1] G. Musulmanbekov in Frontiers of Fundamental Physics, New York, Kluwer Acad/Plenum Publ., 2001, p. 109 - 120.; PEPAN Lett., 2021, v.18, N5, p. 548-558.
[2] G. Musulmanbekov and N.D. Cook, Phys. Atom. Nucl. 71, 1226, 2008

Speaker: Mr Genis Musulmanbekov (Joint Institute for Nuclear Research)

Musulmanbekov.ppsx

Poster session

Thursday 4 July

Plenary

216 The Tagged Neutron Method and its Application for Nuclear Physics Studies and Applied Research

The Tagged Neutron Method (TNM), sometimes also called Associated Particle Technique consists in irradiating the object of study with fast neutrons with an energy of about 14 MeV, which are formed in the reaction d+t→α+n [1]. Neutron tagging is carried out by registering an alpha particle with a special position sensitive detector built into the neutron generator. The use of TNM in experiments studying nuclear reactions with fast neutrons provides a number of important advantages, in particular, a decrease in the background due to the registration of events coinciding with α-particles. The study of the spectra of gamma rays produced in the reactions of inelastic neutron scattering makes it possible to carry out an elemental analysis of the irradiated object. Currently, TNM technology is widely used in various practical applications for remote non-destructive analysis of the elemental composition of a substance.

The TANGRA (TAgged Neutrons and Gamma Rays) project at JINR is aimed at investigations of the neutron-nuclear reactions using the tagged neutron method. An overview of recent activities in the framework of the project will be presented with an emphasis on the measurements of the gamma-ray emission cross sections and angular distributions from (n,xγ) reactions with 14.1 MeV neutrons using the tagged neutron method, as well as on the development and use of the TNM for non-destructive elemental analysis of various objects [2].

References:

1. V Valkovic. 14 MeV Neutrons. Physics and Applications. — CRC Press, New York. 2015.
2. Yu.N.Kopach, M.G.Sapozhnikov, Physics of Particles and Nuclei, 2024, Vol. 55, No. 1, pp. 55–102.

Speaker: Yuri Kopatch (Joint Institute for Nuclear Research)

217 Manifestation of chaos in nuclear structure phenomena

The description of giant dipole (GDR) and monopole (GMR) resonance decay widths requires to trace the spreading of the highly excited, collective states along the hierarchy of particle-hole configurations with various degree of complexity. Naturally, one would expect that chaotic component of intrinsic structure of a finite many-body quantum system, exhibited in its spectral properties at low excitation energy, may transform from the secondary constituent to the dominant one in basic characteristics of the considered system with increase of the excitation energy. Indeed, our analysis of the dipole and monopole strength distributions in the lead region indicates on the onset of statistical properties close to those of the Gaussian Orthogonal Ensembles (GOE) of the Random Matrix Theory (RMT). We show that employment of the random distribution for the coupling between microscopic one-phonon states and two-phonon states, generated by the GOE distribution, gains a better insight into the description of general properties of the decay widths. Our microscopic calculations (based on the Skyrme forces) demonstrate that Landau damping of the one-phonon states is the basic mechanism of the decay widths of the GDR in heavy nuclei around 208Pb [1]. However, the incorporation of ideas, borrowed from the RMT, providing the effective counting of the two-phonon
configurations, contributed additionally to redistribution of the isovector dipole strength distribution. On the other hand, it is found that the main contribution into the decay of the GMR in this nuclear region is determined by a small number of two-phonon states strongly coupled to low-energy surface vibrations [2]. While a vast majority of the coupling matrix elements (that are small in value and following the GOE distribution) are responsible for the fine structure of the GMR decay width. A remarkable agreement between the results of the full microscopic calculations (based on QRPA phonons coupled by means of the microscopic coupling matrix elements with calculated two-phonon states) with those of the developed approach confirms the vitality of the proposed ideas.

1. A.P. Severyukhin, S. Åberg, N.N. Arsenyev, R.G. Nazmitdinov,
   Phys. Rev. C, 104, 044327 (2021).
2. N.N. Arsenyev, A.P.Severyukhin, R.G. Nazmitdinov,
   JETP Letters, 118, 718 (2023).

Speaker: Dr Rashid Nazmitdinov (BLTP, JINR&lt; Dubna)

218 БАЗА ДАННЫХ И СИСТЕМАТИКА МАГНИТНЫХ МОМЕНТОВ ЯДЕР

На основе компиляции [1] и файла ENSDF [2] создана новая база данных MagDa свойств ядерных состояний, для которых экспериментально определены магнитные моменты. Программа-интерфейс к этой базе данных позволяет делать выборки спектроскопической информации по различным параметрам, к которым относятся не только спин, энергия возбуждения, время жизни состояния, но и метод измерения и дата публикации результата. Для отобранных состояний можно получить подробную информацию о структуре и распадных свойствах. Программа-интерфейс представляет информацию не только в виде таблиц, которые могут далее использоваться по усмотрению пользователя, но и в виде графиков. Последнее свойство очень полезно при поисковых запросах.
На первом этапе была проведена систематика магнитных моментов ядер в основном состоянии. На рисунке показаны традиционные зависимости наблюдаемых магнитных моментов от спинов в А-нечетных ядрах.
В приближении сферической симметрии (непрерывные линии на рисунке, «ограничивающие» значения магнитных моментов) проведено описание магнитных моментов легких (Z<20) и околомагических ядер. Значение магнитного момента часто является решающим при определении конфигурации основного состояния нечетно-нечетного ядра.

1. N.J.Stone. Table of recommended nuclear magnetic dipole moments, IAEA Technical Report, INDC(NDS)-0794 (2019).
2. ENSDF: Evaluated Nuclear Structure Data File Search and Retrieval
   https://www.nndc.bnl.gov/ensdf/

Speaker: Prof. Иван Митропольский (Петербургский институт ядерной физики им.Б.П.Константинова НИЦ Курчатовский институт)

11:00 Coffee break

Plenary

219 Electromagnetic neutrinos: The basic interaction processes and constraints from laboratory experiments and astrophysics.

We start with an introduction to the theory of neutrino electromagnetic properties [1]. Then we consider experimental constraints on neutrino magnetic µν and electric dν moments, millicharge qν, charge radii <rν2> and anapole aν moments from the terrestrial experiments (the bounds from MUNU, TEXONO, GEMMA, Super-Kamiokande, Borexino, COHERENT, XENON1T, CONUS and the most recent bounds from XENONnT [2] and LUX-ZEPELIN [3]).
Then we focus on the main manifestation of neutrino electromagnetic interactions, such as: 1) the radiative decay in vacuum, in matter and in a magnetic field, 2) the neutrino Cherenkov radiation, 3) the plasmon decay to neutrino-antineutrino pair, 4) the neutrino spin light in matter, and 5) the neutrino spin and spin-flavour precession are discussed. Phenomenological consequences of neutrino electromagnetic interactions (including the spin light of neutrino) in astrophysical environments are also reviewed. The best bounds from laboratory experiments and astrophysical observations on neutrino electromagnetic properties are confronted with the predictions of theories beyond the Standard Model.
[1] C.Guinti, A.Studenikin, Neutrino electromagnetic interactions: A window to new physics, Rev.Mod.Phys.87(2015)531.
[2] A.Khan, Light new physics and neutrino electromagnetic interactions in XENONnT, Phys.Lett.B837(2023)137650.
[3] M.Atzori Corona et al., New constraint on neutrino magnetic moment from LZ dark matter search results,Phys.Rev.D107(2023)053001.
[4] [4] S.Jana and Y.Porto, Resonances of supernova neutrinos in twisting magnetic fields, Phys. Rev. Lett. 132 (2024) 101005.

Speaker: Alexander Studenikin (Department of Theoretical Physics, Moscow State University)

220 The JUNO Experiment: Current Status and Prospects

The Jiangmen Underground Neutrino Observatory (JUNO) represents a groundbreaking experiment currently under construction in China. Featuring a central detector with a diameter of 35.4 meters and containing 20 kilotons of liquid scintillator, which is read out by 17,612 large and 25,600 small Photomultiplier Tubes (PMTs), JUNO promises to deliver unprecedented statistics, high-energy resolution (σ = 3% @ 1 MeV), and a remarkably low energy threshold (approximately 0.2 MeV), thereby enabling a diverse physics program.
The primary objective of JUNO is to determine the neutrino mass ordering and precisely measure neutrino oscillation parameters. This will be achieved through the observation of over 100,000 reactor electron antineutrinos emitted from the Yangjiang and Taishan nuclear power plants over 6 years. Additionally, JUNO will provide high-statistics data on solar neutrinos, including those from ⁷Be, and ⁸B sources, as well as geo-neutrinos with a measurement uncertainty of 8% over a data-taking period of 10 years with a known Th/U ratio. Furthermore, JUNO will capture atmospheric neutrinos in both sub-GeV and GeV ranges, detect the diffuse supernovae neutrino background with a significance of 3σ over a 3-year period, and observe neutrinos from core-collapse supernovae.
In tandem with the central detector, JUNO will be supported by the Taishan Antineutrino Observatory (TAO) detector. TAO's main function will be to measure the antineutrino spectrum from the Taishan nuclear power plant with an energy resolution of σ < 2% @ 1 MeV and a statistical uncertainty of 1%. This satellite detector will aid in mitigating systematic uncertainties associated with the primary antineutrino spectrum from the reactor and facilitate measurements of short-baseline sterile neutrino oscillation, up to differences in squared masses of ~ 8 eV². To achieve its unparalleled energy resolution, TAO will utilize Silicon Photomultipliers with a High Photon Detection Efficiency of approximately 50%, operating at a temperature of -50°C.
This presentation will provide an overview of the current status of the JUNO experiment, highlighting its groundbreaking capabilities and prospects.

Speaker: Dr Nikolay Anfimov (Joint Institute for Nuclear Research)

Anfimov_JUNO_Nucleus2024.pdf

221 Pre-supernova (anti)neutrino emission via weak processes with hot nuclei

(Anti)neutrino luminosities and spectra arising from neutral- and charged-current weak reactions with a hot nucleus $^{56}$Fe are computed for pre-supernova conditions and compared with the contribution of thermal processes [1,2]. It is found that thermodynamically consistent consideration of thermal effects within the thermal quasiparticle random phase approximation produces a higher luminosity and a harder spectrum of electron neutrinos, compared to the standard technique based on the large-scale shell model weak-interaction rates. It is shown that in the context of electron antineutrino generation, the neutrino-antineutrino pair emission via nuclear de-excitation (ND) is at least as important as the electron-positron pair annihilation process. We also show that flavor oscillations enhance the high-energy contribution of the ND process to the electron antineutrino flux. This could potentially be important for pre-supernova antineutrino registration by the Earth's detectors.

1. A.A. Dzhioev, A.V.Yudin, N.V. Dunina-Barkovskaya, and A.I. Vdovin, Particles 6 (2023) 682-692
2. A.A. Dzhioev, A.V.Yudin, N.V. Dunina-Barkovskaya, and A.I. Vdovin, Monthly Notices of the Royal Astronomical Society 527 (2024) 7701-7712

Speaker: Alan Dzhioev (Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics)

13:00 Excursion along the Volga River by boat

18:15 Banquet

st. Moskovskaya, 2, Dubna

Friday 5 July

Plenary

222 MODERN DETECTOR TECHNOLOGIES FOR NUCLEAR PHYSICS EXPERIMENTS AND DIAGNOSTIC STUDIES IN NUCLEAR MEDICINE

Today, one of the nuclear physics tasks of experiments at high-energy accelerator complexes is the study of the superdense nuclear matter phase diagram. It is assumed that during the formation of such matter there will be an increased yield of particles, which include heavy c- and s-quarks. Due to the short life-time of these particles for precise reconstruction of their decay vertex the new tracking detector systems are needed. In this work a new concept of a vertex detector for the MPD (Multi-Purpose Detector) experiment at the NICA collider is proposed. In this detector, 3 inner layers based on monolithic active pixel sensors are maximally close to the collider beams interaction point and consist of a large area flexible ultra-thin silicon wafers. For the proposed concept the evaluation of the spatial resolution has been done. It was shown that the transition to such thin inner layers with smaller radii allowed reconstructing the decay vertices of Ds+, D0 and D+ mesons.
In this work also an overview of modern detector technologies using silicon pixel sensors is provided for development of proton computed tomography for the diagnostics of tumor in hadron therapy methods. The development of new detector systems for digital track calorimeters will be shown, both for reconstruction of a large number of proton tracks and for proton energy measurements.
The results of experimental work (proton beams of 100 - 200 MeV) on the creation of digital track calorimeters will also be presented, together with the results of properties and characteristics studies of silicon pixel sensors in the context of high accuracy charged particle tracks reconstruction tasks.
The reported study was supported by the Russian Science Foundation, project no. № 23-12-00042, https://rscf.ru/en/project/23-12-00042/

Speaker: Dr Vladimir Zherebchevsky (Saint-Petersburg State University)

223 Modern nuclear physics research in radiation medicine

Thanks to the studies of the structure of matter at the beginning of the 20th century and subsequent significant discoveries in particle physics, today people have a powerful tool in the form of ionizing radiation both for scientific purposes and for various sectors of the world economy. The development of radiation technologies has allowed nuclear physics methods to become firmly entrenched in human life and become an integral part of many areas of human activity. One of the most important such areas is the application of radiation technologies in medicine. The public's interest in radiation medicine is growing every year, as evidenced by the growth of scientific publications, radiotherapy centers, medical accelerators and other medical equipment based on ionizing radiation. However, with increasing interest, there is also increase number of tasks requiring modern nuclear physics research and new solutions to further improve the effectiveness of radiation technology. For example: in the field of radiation therapy, it is necessary to improve the efficiency of irradiation on electron and photon beams, as well as new methods of dosimetry on medical accelerators, in the field of radiation diagnostics, it is necessary to improve image quality and its automatic processing (removal of artifacts, segmentation, etc.), in the field of medical radioisotopes, research is underway in terms of obtaining radioisotopes in new ways. The question of the effect of ionizing radiation on structural changes in the blood is no less important. It is also necessary to study the biophysical aspects of radiation treatment of food products, since human health directly depends on the quality of food consumed. Currently, all of the above-mentioned studies are conducted all over the world, including in the Department of Nuclear Physics Methods in Medicine and Industry of the Moscow State University Research Institute of Nuclear Physics.
Thus, this report is devoted to modern nuclear physics research in radiation medicine, which is a key aspect of the successful application and development of this field.

Speaker: Prof. Alexander Chernyaev (Department of Physics, Lomonosov Moscow State University)

224 The MONUMENT (Muon Ordinary capture for the NUclear Matrix elemENTs in ββ decays) project's overview and advantages

The main idea of the MONUMENT project is carrying out experimental measurements of muon capture at several daughter candidates for 0n2β decay nuclei. Obtained results are used to check the nuclear matrix elements calculations. In addition, the nuclear structure and the information of the particle's angular correlations of that process could be clarified.

Speaker: Dr Mark Shirchenko (Joint Institute for Nuclear Research)

11:00 Coffee break

Plenary

225 High-Granular Time-of-Flight Neutron Detector HGND for the BM@N experiment

A new high-granular time-of-flight neutron detector HGND (High Granural Neutron Detector) is being developed and constructed in order to measure azimuthal neutron flow in nucleus-nucleus interactions within at the BM@N experiment (JINR). The detector consists of alternating layers of copper absorber plates and matrices of scintillation cells with individual light readout by silicon photomultipliers. The HGND detector will be used in the fixed target BM@N experiment to identify neutrons and to measure their energy in heavy-ion collisions with energies up to 4 GeV per nucleon. The ratios of direct and elliptic azimuthal neutron flow to the corresponding proton flow, which can be measured by the magnetic spectrometer of the BM@N facility, should be sensitive, as shown in a number of models, to the symmetry energy in the equation of state (EoS) of high dense nuclear matter. Measuring these ratios is also important in astrophysics for understanding the structure of neutron stars, processes during supernova explosions and merging of double neutron stars.
The performance studies based on the results of simulations of the new HGND detector at the BM@N experiment will be presented. Results of time resolution measurements of scintillation cells will be shown.

Speaker: Sergey Morozov (Institute for Nuclear Research RAS)

Slides_HGND_Morozov_v3.pdf

226 Heavy-ion physics results by the CMS experiment

Recent results from the Compact Muon Solenoid (CMS) Collaboration at the LHC (CERN) on heavy-ion physics will be presented.

Speaker: Dr Sergey Petrushanko (M.V.Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics)

Petrushanko_Nucleus2024.pdf

227 ПАК для поиска и идентификации гамма-излучающих нуклидов на основе машинного обучения - результаты 2022-2024 годов.

Доклад будет посвящен результатам
почти 2х лет разработки
программно-аппаратного комплекса для
идентификации гамма-излучающих
нуклидов, работающего на основе
методов машинного обучения для
идентификации радиоизлучающих
нуклидов на примере анализа
гамма-излучения. Буду приведены
метрики сравнения с классическими
методами, а также продемонстрированы
примеры работы алгоритмической части.

Speaker: И.С. Бредихин (ООО "Гамматек")

12:50 Lunch

Experimental and theoretical studies of nuclear reactions

228 Исследование альфа кластерных структур в ядре 46Ti

В данной работе представлены результаты экспериментальных и теоретических исследований влияния кластеризации на структуру спектра возбужденых состояний 46Ti. Ядра 46Ti получались в реакции подхвата протона 45Sc(3He, d)46Ti при энергии пучка 3He 30 МэВ [1]. В спектре возбуждения ядра 46Ti наблюдались уровни в широкой области значений энергии от 2 до 16.7 МэВ. Уровни с энергией от 10.4 до 16.7 МэВ наблюдались впервые и заселялись с высокой вероятностью. Расчеты в рамках модели двойной ядерной системы показали [2], что заселение высоковозбужденных состояний с энергией Ex≥10 МэВ в 46Ti и их структура могут быть объяснены формированием альфа-кластерной системы 42Ca+4He, отвечающей супердеформированному состоянию 46 Ti. Проанализирована структура альфа-кластерных состояний в изотопной цепочке 44-52Ti. Результаты сравниваются с экспериментальными данными о формировании альфа-кластерных двойных систем в 44,46,52Ti, полученными ранее в реакциях 40,42,48Ca(7Li,tα)40,42,48Ca [3].

Speaker: Talgat Issatayev (JINR,FLNR)

229 TARGET DEPENDENCE OF THE ISOTOPE DISTRIBUTIONS IN HEAVY-ION REACTIONS AT FERMI ENERGIES

Heavy-ion reactions at Fermi energies are a tool to produce new isotopes far from stability line. Previous experiments show that the production of neutron-reach isotopes is enhanced when the heavy target is used instead of the light one. In this report we compare isotope distributions calculated in transport-statistical approach BNV-SMM with the three frequently used models: empirical EPAX , geometrical-macroscopic Abrasion-Ablation and phenomenological HIPSE, and experimental data obtained in collisions of 18O projectile on 181Ta and 9Be targets at 35 MeV per nucleon obtained at COMBAS set-up in FLNR, JINR. The experimental ratio of cross-sections obtained in the reactions on heavy 181Ta and light 9Be target in the collision with the same projectile and the same ratio obtained as model predictions is discussed. Some explanations of the observed features are presented.

Speaker: Tatiana Mikhaylova (LIT, JINR)

Mikhailova_Nuc24.pdf

230 Study of the Coulomb decay of light fragment procuced in the ternary fission of $^{252}$Cf

Theoretical analysis of experimental data on the ternary fission of $^{252}$Cf is performed in the semi-classical trajectory approach. The energy and angular distributions, total kinetic energies of the fragments in the ternary fission of $^{252}$Cf are obtained in this model using the Monte-Carlo simulations. The calculations well reproduce these experimental data with the same set of the model parameters for different types of the lightest fragments, i.e. hydrogen, helium, lithium, beryllium isotopes. As earlier suggested in [1], there is a contribution of short-living isotopes to the energy spectra of $^{4,6}$He, such as $^{5}$He and $^{7}$He. Using the estimated [2] decay width of $^{7}$He we have calculated the energy and angular distribution of the $^{4}$He fragment obtained in the 4$n$ decay of $^{8}$He emitted in the ternary fission. The energy and angular distributions of the neutrons om this decay are also estimated. We can conclude, that study of neutron and fragment energy and angular distributions in ternary fission may provide the information on decay of neutron-rich short living isotopes as $^{8}$He.
[1] Yu. N. Kopatch et al., Phys.Rev. C 65(2002), 044614
[2] M. Pfutzner et.al., Rev. Mod. Phys. 68(2012), 567

Speaker: Юлия Парфенова (Joint Institute for Nuclear Research)

231 Detection system of the DGFRS-2 setup: first applications in long term irradiations with intense heavy ion beams at DC-280 cyclotron

Double Side Silicon Detector (DSSD) based spectrometer of the DGFRS-2 setup has been applied in a different heavy ion induced complete fusion nuclear reactions leading to formation of superheavy nuclei. Nuclear reactions with 48Ca, 40Ar, 54Cr projectiles were used [1,2]. Materials of206Pb, natYb, 232Th, 238U, 242Pu, 243Am were used as targets. We report about different stability tests during these long term experiment. Radiation damage induced of achange in leakage current values of DSSD detectors are under consideration.Formation of the evaporation residue (ER) registered energy spectrum measured with DSSD focal plane detector is presented. Comparison with the PC-based simulation code for these spectra generation is made for different cases. A specific of application of “active correlation” real-time method is reported in brief too [3]. Review of the design of the DGFRS-2 spectrometer is preceding the main results [4-6].
References
[1] Yu. Ts. Oganessian et. al., Investigation of 48Ca-induced reactions with 242Pu and 238U targets at the JINR Superheavy Element Factory, Phys. Rev. C 106, (2022) 024612.
[2] Yu. Ts. Oganessianet. al., First experiment at the Super Heavy Element Factory: High cross section of 288Mc in the 243Am +48Ca reaction and identification of the new isotope 264Lr, Phys. Rev. C 106, (2022) L031301.
[3] Yu. S. Tsyganov et al., Detection system for heavy element research: present status, Nucl. InstrumentsMethods Phys. Res. Sect. A Accel. Spectrometers, Detect. Assoc. Equip. 525, (2004) 213-216.
[4] D. Ibadullayev, Y.S. Tsyganov, A.N. Polyakov, A.A. Voinov and M.V. Shumeiko, Specific moments in detection of superheavy nuclei: DGFRS-2 spectrometer, JINST, 18 P05010, 2023
[5] Yu. S. Tsyganov, D. Ibadullayev et. al., New analog spectrometer of the DGFRS2setup for real-time searching of ER-α and α–α correlated sequences in heavy-ion induced complete fusionnuclear reactions, Acta Physica Polonica B Proceedings Supplement. 14, (2021) 767-774.
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Speaker: Mr Yury Tsyganov (JINR)

232 Study of the break-up of fission fragments in solid-state foils using double-hit experimental approach

In our previous publications [1-4], we discussed various manifestations of the decay channel of low excited heavy nuclei, called collinear cluster tri-partition (CCT). The break-up of the fission fragment was observed while the fragment passes a solid-state foil. The bulk of the results were obtained in the framework of the so-called missing mass method when only two fragments are directly detected, and a deficit between their total mass and the mass of the mother system serves as a sign of a multibody decay. In order to increase reliability of identification of such events so called ”double-hit” experimental approach was applied in our recent experiments at the COMETA setup in FLNR (JINR). COMETA is a double-armed mosaic time-of-flight spectrometer of fission fragments [2]. Digital images of all the signals from PIN diodes and micro-channel plates based “start” detector were obtained using multichannel fast flash-digitizer. Off-line processing of the recorded data allowed us to select the decay events where two fragments were detected in the same PIN diode (” double-hit” event) during the time-selection gate of 200ns. For the selected events, the prescission configuration of the mother nucleus seems to be a chain which includes different magic nuclei.

References
1. Yu.V. Pyatkov et al., Eur. Phys. J. A 45, 29 (2010).
2. Yu.V. Pyatkov et al., Eur. Phys. J. A 48, 94 (2012).
3. Yu.V. Pyatkov et al., Phys. Rev. C 96 (2017) 064606.
4. Yu.V. Pyatkov et al., Eurasian Journal of Physics and Functional Materials
v.4 №1 (2020) 13-18

Speaker: Dmitry Kamanin (Joint Institute for Nuclear Research)

15:20 Closing