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The 28th International Scientific Conference of Young Scientists and Specialists (AYSS-2024) will take place from 28 October to 1 November 2024 at the Laboratory of Information Technologies of the Joint Institute for Nuclear Research (JINR, Dubna, Russia).
Please note that remote participation will not be available. Participants are required to attend the conference in person.
The conference is held annually for students, young scientists, and specialists from research centers around the world. Selected papers will be recommended for publication in a peer-reviewed journal. All attendees of the conference will receive participation certificates.
TOPICS
As part of the conference, leading scientists will give lectures on the recent theoretical, experimental, and applied research conducted all over the world with a focus on the major results obtained at JINR. All participants are welcome to submit abstracts on the following topics:
Theoretical Physics
Mathematical Modeling and Computational Physics
High Energy Physics
Particle Accelerators and Nuclear Reactors
Experimental Nuclear Physics
Information Technology
Condensed Matter Physics
Applied Research
Life Sciences
PARTICIPANTS
Students, young scientists, and specialists under 36 from all over the world are invited to participate in the conference with reports and poster presentations.
SCIENTIFIC ADVISORY BOARD: |
ORGANIZING COMMITTEE: |
Co-chairman: Dmitry Kamanin | Co-chairman: Regina Kozhina (LRB) |
Co-chairman: Sergei Nedelko | Co-chairman: Alexander Madumarov (FLNR) |
Grigory Shirkov (JINR Directorate) | Dina Badreeva (MLIT) |
Aleksey Guskov (DLNP) | Dinara Bulatova (JINR Press Office) |
Olga Derenovskaya (MLIT) | Ksenia Ilina (VBLHEP) |
Grzegorz Kaminski (FLNR) | Ekaterina Kolosova (CPED) |
Sergey Kulikov (FLNP) | Igor Pelevanyuk (MLIT) |
Ekaterina Lesovaya (LRB) | Yulia Polyakova (ICD) |
Dmitry Peshekhonov (VBLHEP) | Anna Rybakova (UC) |
Vladimir Rachkov (FLNR) | Daria Shamina (LRB) |
Timur Shneidman (BLTP) | Veronika Smirnova (FLNP) |
Rostislav Sotenskii (DLNP) | |
Alexey Vorontsov (MLIT) |
THE WORKING LANGUAGE of the conference is English.
THE REGISTRATION FEE for participation is 9600 RUB (8000 RUB + VAT 1600 RUB), covering organizing expenses, coffee breaks, the conference dinner, and social program activities. We will publish the payment link for external participants on 1 October. Payments for participants affiliated with JINR will be carried out by internal cashless transactions.
FINANCIAL SUPPORT covering fee, local accommodation, and partial travelling expenses can be provided for a limited number of participants. The selection will be carried out through competition.
SECTIONS
During the conference, the participants will present their reports in one of the nine topical sections. The duration of each sectional talk is 15 minutes, including both the presentation (12 min) and the Q&A session (3 min). For the poster session, the poster size should be A1.
The only way to produce transfermium elements for their study is the accelerator production method in particular multinucleon transfer nuclear reactions with heavy ions1. Neutron-rich isotopes of these elements can be synthesized as a mix of reaction products with predicted half-lives from 1 min to 1 day. Such nuclear physical properties and very similar chemical properties of heavy actinides limit a number of separation methods. A method that meets all the requirements is cation exchange chromatography in α-hydroxyisobutyrate ammonia (α-HIB)2.
We developed the semi-empirical model of predicting the chromatographic parameters, elution and position of actinides peaks on the chromatogram. The validation of the model was performed in application of high-pressure liquid chromatography to separation of Cf and Fm from irradiated uranium target. In this work we irradiated thin 238U target with 1150 MeV Xe ions with an aver-age intensity of 20 nA for 48-72 hours at the U-400 accelerator (FLNR). After cooling for 1 hour, we dissolved U target to make a separation. Radiochemical separation procedure was performed in two steps. Separation of target material, neptunium and plutonium using UTEVA resin followed by cation exchange separation of Cf and Fm fractions with α-HIB. The later followed by prepara-tion of spectrometric sources by LaF3 co-precipitation method. The optimal amount of carrier and the thickness of the spectrometric sources were calculated with the SRIM program taking into account energy losses. Using this approach an energy resolution of 70 keV was achieved. Final samples were analyzed with gamma- and alpha-spectrometry to search isotopes of Cf and Fm, estimate the yield and the cross section.
References
1. Bao X.J., Guo S.Q., Chen P.H.. Phys.Rev. C 2022, 105, 024610
2. Morss L.R., Edelstein N.M., Fuger.J. The Chemistry of the Actinide and Transactinide Elements. Springer Dordrecht, 2010
Swift heavy ion (SHI) irradiation, using Xe ions with 150 MeV energy and varying fluences (5 × 109 – 5 × 1011 ions cm⁻¹) is explored as a method to introduce defects in the hydrothermally synthesized monoclinic BiVO4 (BVO) thin films, aiming to understand its impact on photoelectrochemical (PEC) performance for oxygen evolution reaction (OER). In the near surface region, the irradiation leads to the bismuth rich hillock formation and oxygen depleted ion tracks. 1-hour-long chronoamperometry measurements reveal photocurrent density increase of up to 58.6 % and 25.2 % for 5 × 109 and 1 × 1010 ions cm-1 irradiated samples while sample irradiated with the high fluences shows decrease in activity throughout the whole timeframe. This increase is accompanied by formation of ~150 nm deep and ~50 nm wide holes at the position of original ion tracks. Irradiation induces residual stresses while maintaining the monoclinic scheelite phase and [001] preferential orientation. Notably, high-fluence irradiation leads to amorphization, as confirmed by appearance of new Raman bands at 410 and 910 cm-1. Band gap reduction with increasing fluence, from 2.41 ± 0.06 eV for non-irradiated down to 2.32 ± 0.05 eV for 5×1011 ions cm-1 irradiated BVO, indicates changes in the electronic structure. Overall, the study contributes to the fundamental understanding of SHI-induced modifications in BVO films and lays the foundations for further research aimed at enhancing their efficiency and durability in practical PEC applications.
This research was supported by the Science Fund of the Republic of Serbia, grant No. 6706, Low-dimensional nanomaterials for energy storage and sensing applications: Innovation through synergy of action - ASPIRE.
Austenitic stainless steels are widely used as structural materials in nuclear power engineering, as well as in many other non-nuclear engineering and technological fields. This is due to their good mechanical properties as well as fairly high corrosion and radiation resistance. Recently, much research has focused on nitrogen-containing grades of steels, such as AISI 304 LN. The advantages of nitrogen alloying are stabilization of the austenitic matrix, increased strength of the material, improved corrosion resistance and reduced nickel content in the steel. It is worth considering that neutron irradiation, in particular of austenitic stainless steels, affects the microstructure and mechanical properties of materials. Low temperature irradiation of austenitic stainless steels lead to increase in yield strength and a decrease in plasticity, which is the result of clustering of point defects, particularly dislocation loops. In this work, changes in mechanical properties and microhardness of austenitic stainless steel grades based on AISI 316LN after neutron irradiation in the WWR-K reactor are investigated.
AISI 304 and AISI 316LN austenitic steels were selected as objects of study. 211 L, 212 L and 213 L were produced from AISI 316LN by alloying with nitrogen, manganese, copper and tungsten.. An austenitizing annealing at 1050 °C for 30 min in a vacuum tube (1 Pa) was carried out. In December 2023, irradiation of the samples of the investigated steels was carried out in the WWR-K reactor (Almaty, Republic of Kazakhstan). The samples were irradiated to fluence of Фt = 3.18×1018 n/cm^2. Mechanical tensile tests were performed at room temperature using INSTRON 1195 universal testing machine at a constant strain rate of 0.5 mm/min. Vickers microhardness values of irradiated and unirradiated specimens were measured using a Micro Vicker Hardness Tester at a load of 100g.
As a result of experiments, it was found that: the values of total and uniform elongation of steel AISI 304 are the highest among the studied steels, due to the γ→α transformation. Alloying with nitrogen (N) manganese (Mn) and molybdenum (Mo) reduces plasticity by suppressing the γ→α transformation. Steel 213 L alloyed with tungsten (W) has the highest value of microhardness and the tensile strength of this steel is comparable to that of AISI 304 steel. From this it can be concluded that alloying with nitrogen and tungsten compensates for the loss of strength caused by the suppression of the γ→α transformation. The elongation values, both uniform and total elongation, decreased for all steels after neutron irradiation, except for that of AISI 304 alloy. After irradiation, the microhardness of all the steels studied increased, while the yield strength increased most significantly for 212 L and 213 L steels.
The scientific setup that is intended to be used for studying the nucleons’ spinal structure and other phenomena related to spin is SPD (Spin Physics Detector). It is planned to be placed in one of the two collision points of the NICA collider being built in the International Intergovernmental Scientific Research Organization "Joint Institute for Nuclear Research" (Dubna, Russia).
To facility design, study the possibility of solving the given physical problems and develop methods of registration and identification of processes in experiment, it is necessary to model different detector systems. The work is devoted to the simulation of the SPD muon system, using the software package SpdRoot, and subsequent development of software for processing and analysis of experimental data.
The Spin Physics Detector (SPD) experiment at the Nuclotron-based Ion Collider fAcility
(NICA) is an upcoming project with an extensive physics program aimed at studying the spin
structure of the nucleons. The experiment will record data from the collisions of polarized
proton and deuteron beams. One of the important particles produced in such collisions is the
Λ-hyperon. It is noteworthy because it has already been studied in detail and its polarization
can indicate the polarization of the original process. At the present stage of the experiment, one
of the main tasks is to study the detection of the particles of interest produced in the collisions
at the SPD and to optimize the parameters for their selections. This work presents the results
of the calculations of detection efficiencies of the Λ and anti-Λ hyperons.
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.
In modern conditions of rapid growth of textual information volumes, efficient extraction of named entities becomes a key aspect of data analysis in various fields of science and technology.
The task of text data analysis is extremely relevant for a number of internal services of the Joint Institute for Nuclear Research (JINR), in particular, in the context of development of the JINRex excursion planning and accounting system, which determines the necessity to choose the most efficient methods of information processing.
The comparison of methods of extraction of named entities in the algorithm of processing text data on excursions is carried out. The results of the algorithm allow to obtain statistical information about the conducted events from natural language texts containing a brief description about the name of the excursion and the target audience.
This paper presents a practical comparative analysis of different approaches to the extraction of named entities, with a focus on their applicability in solving the tasks of text analysis and processing within the framework of support and development of JINR internal services.
The integration of different high-energy collision Monte Carlo models into a unified simulation process is inherently time-consuming, largely due to the fact that they are typically developed as monolithic applications. Diverse data formats of the aforementioned models often necessitate the use of numerous converters and supplementary scripts, which can significantly impede the modelling process and potentially introduce unforeseen errors. With this in mind, a lightweight library for organising disparate models was developed with the aim of streamlining future development. The library is based on the principles of modularity and dependency injection (DI) [1]. By organizing models representing different stages of modelling into self-contained modules, it is possible to subsequently combine them into a single program that encompasses the entire modelling pipeline. The resulting program is highly flexible, as the replacement of a module can be completed in a matter of minutes. The standardisation of data format facilitates the troubleshooting of separate modules and eliminates the necessity for converter scripts, which may consequently reduce the prevalence of bugs. A significant proportion of contemporary Monte Carlo code for modelling high-energy collisions is written in C++, largely due to the availability of comprehensive libraries such as ROOT [2] and Geant4 [3]. Accordingly, C++ was selected as the language for the development of this library.
A C++ framework with analogous objectives, JETSCAPE [4], has been in development for several years. In contrast to JETSCAPE, our library does not encapsulate any specific model; rather, it provides interfaces and data objects that are useful for constructing a high-energy collisions model. The installation of modules is fully separated from the library, and therefore, it has no dependencies.
At this point in time, the AAMCC-MST [5] model has been split into several modules to demonstrate the possibilities of this library.
This work was supported by the Ministry of Science and Higher Education of the Russian Federation, Project FFWS-2024-0003.
References:
Baikal-GVD is a neutrino telescope with an effective volume of about 1 km^3 located in Lake Baikal. To enable observations within the framework of neutrino astronomy, the following event processing problems must be solved in the experiment:
1) selection of the neutrino (ν) component against the background of events, caused by extensive air showers (EAS);
2) reconstruction of the parameters of ν events, for example, the energy of the born muon.
In this paper we consider an approach to solving these problems using machine learning (neural networks). For problem 1) it is shown on Monte Carlo simulations of the data that at the level of background suppression of 10^6 times desired for the experiment using convolutional neural networks it is possible to preserve 50% of high-energy neutrino events. For problem 2, a neural network model is created that predicts both the energy itself and the expected error of this prediction for a given event. This is achieved by a loss function of a special kind. On Monte Carlo simulated data we achieve an error factor of 3 for a wide range of energies (from 10 GeV and above) and a factor of 2 for high energies (from 10 TeV and above), which corresponds to the accuracy of standard reconstruction methods. It is shown that the predicted energy error corresponds to one standard deviation of the real error.
Computer simulation of shape effects in electrostatic and magnetostatic interactions
It is well known that an uncharged conductor attracts charged bodies due to electrostatic induction. However, complex-shaped conductors can repel charged bodies. In this case attraction is replaced by repulsion at a certain distance between the bodies. This phenomenon is known as “repulsion effect” [1]. Examples of systems where this amazing effect can occur are known from the literature, in particular, a conducting uncharged hemisphere in the field of a point charge and a conducting uncharged thin plane with a hole in the field of electric dipole. In both cases the repulsive force occurs when a charged object is located in some places near the opening of the conductor. The change in the interaction regime is related to the shape of the conductors and, hence, to the spatial distribution of induced charges on the surface of the conductor. The presence of a hole or cavity in the conductor leads to the "repulsion effect".
In the present work we numerically investigated the "repulsion effect" for various types of uncharged conductors, the shape of which differs from the hemispherical one. The influence of the shape and thickness of the conductor on the repulsion intensity is studied. Using the example of cylindrical conductors, we have shown that a "repulsion effect" is possible for conductors with a through cavity [2]. Most of the conductors under consideration are characterized by axial symmetry. This allows us to consider conductors as a set of parallel uniformly charged thin rings. The charges of the rings were calculated by minimizing potential deviations on the conductor surface. Axial symmetry of the conductor is not necessary for the manifestation of the effect. A system without axial symmetry is presented, wherein the "repulsion effect" is also observed. It is interesting to note that the abandonment of the electroneutrality of the conductor does not lead to a sharp disappearance of the studied effect. If the conductor is slightly charged, then equally charged bodies can attract, and oppositely charged bodies can repel. Moreover, in the case of similarly charged bodies, the interaction regime may change more than once. We also investigated a possibility of the “repulsion effect” in magnetostatics by considering the interaction of a soft magnetic hemisphere with a magnetic dipole.
References
Savin V. P., Koksharov Y. A. Еlectrostatic repulsion between an uncharged or slightly charged conductor and a point charge //Journal of Electrostatics. – 2022. – Т. 120. – С. 103769.
Savin V. P., Koksharov Y. A. Several Features of the Electrostatics of Uncharged Thin-Walled Cylindrical and Conical Conductors //Bulletin of the Russian Academy of Sciences: Physics. – 2023. – Т. 87. – №. 11. – С. 1723-1728.
We consider the phase dynamics in long superconductor-ferromagnet-superconductor $\varphi_0$ Josephson junction described by the modified sine-Gordon equation. In such a junction the Josephson phase and magnetic moment are coupled due to spin-orbit coupling. This allows the manipulation of magnetic properties by Josephson current and vice versa. We investigate the effect of the spin-orbit coupling, Josephson to magnetic energy ratio, and Gilbert damping on the presence of the fluxon states. Also, the magnetic moment dynamics on the fluxon steps are demonstrated. The obtained results can find applications in the field of superconducting spintronics and quantum computing. The calculations were performed on the HybriLIT cluster.
Acknowledgement: The work was carried out with the financial support of Project No. 22-71-10022 of Russian Science Foundation (RSF). Yu. M. Shukrinov and M. Nashaat acknowledge the financial support from collaborative project ASRT, Egypt – JINR, Russia.
The aim of this work was to study the variation of the thermal conductivity of composite materials usually used as glues in experimental setups when exposed to different dose levels of ionizing radiation. The samples under study were epoxy resins filled with diamond powder irradiated with high-energy protons and neutrons. The thermal conductivity of each samples was measured before and after the irradiation. The dose absorbed by the samples was determined by activation analysis of the aluminum foils used as monitors. Additionally, the dose absorption and the radiation damage of the samples were simulated using the FLUKA and MCNPX software packages. The results revealed a significant reduction in the thermal conductivity of the samples after irradiation, highlighting the need for the careful selection and characterization of the materials to be used in high-radiation environments.
The Hubble Crisis -- a large disagreement between different direct and indirect measurements of the present-day rate of the expansion of the Universe $H_0$ -- remains one of the most significant issues in the $\Lambda CDM$ paradigm despite continuing advances in observational techniques. The talk presents the problems plaguing common $\Lambda CDM$ extentions, with the phantom-crossing dark energy models as an example, possible alternative approaches and the difficulties that need to be overcome to explore them. Partially based on the results of https://arxiv.org/abs/2203.03666 (Chudaykin, Gorbunov, Nedelko) as well as on ongoing research.
https://disk.yandex.ru/i/pSD17X2_X5Lw7w
The general theory of relativity, presented in 1915, became
a revolution in theoretical physics due to the beauty of its formulation and the universality of its applicability to the physics of gravitational and cosmological phenomena.For more than a hundred years, Einstein's theory of relativity, as
a relativistic theory of gravitation, has been confirmed in a huge
number of experiments.However, along with the huge successes, the general
theory of relativity has a number of cosmological problems,
primarily related to the need to introduce dark energy and dark matter into the theory, the presence of which, as some hidden mass,
is necessary when describing the evolution of the Universe and the behavior of its large-scale structures.Therefore, it is quite natural to raise the question of the possibility of constructing a theory other than Einstein's theory of relativity, which would be consistent with it in reliably verified aspects, but at the same time would adequately describe those phenomena that are within the framework of
GRT requires the introduction of additional dark sectors, or requires fine-tuning of the initial data.This paper examines some dynamic aspects of the theory proposed in [3], and slightly supplemented in [4],
by Japanese researchers K. Hayashi and T. Shirafuji. They
called this theory New general relativity (we will use
the abbreviation NGR below), it is the simplest generalization of TEGR— the teleparallel equivalent of relativity theory, that is, a theory dynamically completely identical to GRT, but using
torsion instead of curvature as the main geometric characteristic of a spatiotemporal manifold, and the tetrad field as a dynamic variable
instead of a metric.First, we define the basic geometric objects to
be used in the study, illustrate the general properties of teleparallel theories, construct the Lagrangian density
of the action and derive the equations of motion.
Then we show that vacuum static spherically symmetric solutions can be found with arbitrary parameters of the theory. Then we investigate the perturbations of the vacuum equations
of motion over a trivial solution — the Minkowski space. This
makes it possible to determine the number and nature of all degrees of freedom of each of the theories given by the NGR equations of motion, without completely constructing a canonical Hamiltonian formalism.
Within the framework of this work, using a “convenient” tetrad, which does not
generate the antisymmetric part of the field equations, we have found
vacuum static spherically symmetric solutions to the field
equations of NGR theory, and also discuss some of their properties.
We show that the equations of motion can be integrated explicitly in
elementary functions, unlike the nonlinear generalizations of TEGR, where they have not yet been found and will also indicate which of
the solutions satisfy the classical Newtonian limit.
In the course of our work, we determined the type of tetrad that does not generate the antisymmetric
part of the field equations when searching for vacuum static spherically symmetric solutions in NGR, and showed that the field equations in this case allow integration with arbitrary
parameters of the theory. The equations of linearized perturbations of the theory over the Minkowski flat space were obtained and all variables in the tensor, vector and scalar sectors of the tetrad perturbations were classified.
We consider an inflationary scenario in the Sushkov cosmology where the rate of inflaton roll defined by the Hubble flow parameter remains constant. We try to solve Friedmann equations exactly for special values of the constant-roll parameter.
Nanowires are of great scientific interest, both from the point of view of fundamental science and application. For instance, superconducting nanowires serve as elements of a Josephson junction, which is an important component of superconducting and quantum microelectronics, which has been actively developing in recent years. The key areas of development of superconducting microelectronics are increasing the breakdown current and stability in air, as well as increasing the operating temperature and sensitivity to a magnetic field. Indium is a promising material for solving these problems. Due to geometric parameters of nanowires, they exhibit physical properties that are not typical for bulk materials. However, the electrical resistance of indium nanowires has not been measured yet.
Obtaining arrays of indium nanowires by template electrodeposition into a template of anodic aluminum oxide is one of the most effective synthesis techniques since it allows the formation of ordered arrays of cylindrical nanowires with tailored geometric parameters (diameter and length).
In this work arrays of indium nanowires with diameters of 40 nm, 50 nm and 200 nm were fabricated. The technique was proposed for measuring the resistance of single nanowires without removal from the template based on I-U curve analysis. By sweeping the potential up to 1 V, it is possible to register discrete current jumps corresponding to the sequential burnout of nanowires inside the template. This phenomenon allows one to calculate the resistance of a single nanowire (figure 1).
The experimental data were described by the theoretical Fuchs-Sondheimer model:
$\frac{\rho}{\rho_0}=1+\frac{3}{4}(1-p)\frac{l_e}{d}$
where $\rho_0$ is the resistance of a normal material, $\rho$ is the fraction of electrons that are secularly reflected from the surface, d is the width of the wire, $l_e$ is the mean free path in the bulk material. Based on the approximation the electron free path in a bulk indium was estimated to 57 ± 5 nm.
PXI-compatible module combining amplifier, preamplifier, and singe channel analyzer (SCA) for proportional gas counters will be presented. This module is developed for purpose of usage with proportional gas counter sensitive to 14.4 keV and PXI-based Mössbauer spectrometers developed on Palacký University in Olomouc. The module is based on Amptek A225 and Amptek A206 integrated circuits. This allows miniaturization of the spectrometric system, as the amplifier, preamplifier and SCA together are in form of one PXI card and thus built in the compact PXI-chassis. Built-in SCA allows simplification and cost reduction of spectrometric system because much cheaper digital inputs can be used instead of expensive digitizers. There is also no need for the additional power supply, as the developed card is powered by PXI connector from the backpane of PXI chassis. This study will deal with comparison of developed custom SCA board with internal low-level discriminator built-in in A206 integrated circuit, setup with commercially available SCA and setup without SCA using digitizer and multichannel analysis software. The comparison focuses on the signal-to-noise ratio, MCA spectrum and quality and effect of Mössbauer spectrum.
The study of materials for sodium-ion batteries is currently a very promising direction due to the fact that sodium-ion batteries are considered as a real alternative to lithium batteries. Sodium layered transition metal oxides are an important family of cathode materials. Using them, we can potentially reduce the cost of the battery, and at the same time increase the energy density, cyclability and operational safety. [1]
In this work, the object of study is the cathode material - a single-phase layered oxide based on manganese - P2-Na0.7MnO2. In our work, we use planetary milling to study how such processing affects both the morphology of the particles and subsequently the electrochemistry of the material. Theoretically, current values can be increased by reducing the particle size of the material. [2] Moreover, mechanical milling can also be used to solve the problem of slow Na+ diffusion kinetics, since decreasing the particle size results in shorter diffusion paths and an increase in the active surface area of the material in contact with the conductive additives as well as the electrolyte. [3, 4]
REFERENCES
1. Zuo, W., Innocenti, A., Zarrabeitia, M., Bresser, D., Yang, Y., & Passerini, S. (2023). Layered oxide cathodes for sodium-ion batteries: storage mechanism, electrochemistry, and techno-economics. Accounts of Chemical Research, 56(3), 284-296.
2. Yamada, A., Chung, S. C., & Hinokuma, K. (2001). Optimized LiFePO4 for lithium battery cathodes. Journal of the electrochemical society, 148(3), A224.
3. Myung, S. T., Komaba, S., Hirosaki, N., Yashiro, H., & Kumagai, N. (2004). Emulsion drying synthesis of olivine LiFePO4/C composite and its electrochemical properties as lithium intercalation material. Electrochimica Acta, 49(24), 4213-4222.
4. Mi, C. H., Zhao, X. B., Cao, G. S., & Tu, J. P. (2005). In situ synthesis and properties of carbon-coated LiFePO4 as Li-ion battery cathodes. Journal of the Electrochemical Society, 152(3), A483.
The SPD (Spin Physics Detector) is a planned spin physics experiment in the second interaction point of the NICA collider that is under construction at JINR. The main goal of the experiment is the test of basic of the QCD via the study of the polarized structure of the nucleon and spin-related phenomena in the collision of longitudinally and transversely polarized protons and deuterons at the center-of-mass energy up to 27 GeV. The offline software of SPD is being developed now to elaborate the physics research program and to prepare future data processing. Detector description is an essential component in simulation, reconstruction and analysis of experimental data. The first stage SPD detector description based on the GeoModel package will be presented. The using of the detector model in simulation and reconstruction, accessing and navigation amount geometry objects will be discussed.
The integration and application of the CAEN front-end readout system within the miniSPD facility is presented, with a focus on calorimeter modules. The miniSPD is designed for cosmic muon testing of the detectors planned for use in the SPD facility, including straw, silicon, and GEM trackers, along with electromagnetic calorimeters. The main objectives include verifying the functionality and performance of modern electronics, testing the CAEN system’s suitability for miniSPD, and obtaining real cosmic ray data. By using prototype detectors and measuring key detector parameters such as spatial and temporal resolution, efficiency, and stability, this work aims to assess the system's long-term operation reliability. The system was tested to produce key spectra, including the staircase spectrum, Landau distribution, and cosmic ray data, with additional upcoming results focused on SPD calorimeters. The results of using this electronics for straw-tracker prototypes are also presented, where the spectra of Fe-55 and Ru-106 are shown.
The electromagnetic calorimeter ECal of the MPD/NICA multipurpose detector is a modular cylindrical system consisting of 50 half-sectors and containing 38400 towers of the "shashlik" type. The main task of ECal is to determine the energy parameters of photons and electrons. To do this, it is necessary to align the tower responses and energy calibration. As a preliminary alignment of the responses of the calorimeter elements, it is assumed to use alignment on cosmic muons. To get it, tracks should be reconstructed inside each half-sector. In this work, the track reconstruction algorithm used are discussed, which receives an array of reconstructed hits of the interaction of cosmic muons with the detector as input.
The MPD facility of the NICA complex is designed to study heavy ion collisions and should provide accurate determination of events, which is necessary for precise particle identification. Synchronization of all detectors of the MPD will be provided by a trigger system. Due to hardware limitations and signal propagation speed, the detectors are not triggered simultaneously with the moment of particle collision and between themselves. Simulation of the trigger system for the MPDRoot software improve the approximation of the detector response simulation to the real setup.
Conducting research on the morphofunctional state of the central nervous system of small laboratory animals, it is necessary to create a convenient environment for data analysis, including one that allows automating the routine stages of their processing. Сonducting behavioral experiments, researchers face the problem of incorrect detection of an animal in a behavioral test system or maze when using existing software, as well as the task of recognizing individual behavioral patterns on the received videos. The latter is performed manually by experts, which requires a lot of time. The solution to this problem is based on the use of machine learning and computer vision algorithms. The problem of automating the stage of morphological analysis of photographic images of histological slides of the brain is solved using computer vision algorithms and a neural network approach.
The research was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme No. 124092700007-4)
Within the framework of the joint project of LIT and BLTP JINR, a toolkit is being developed for investigation of systems containing Josephson junctions based on Jupyter using Python libraries. It should be noted that a number of tasks require numerous resource-intensive calculations, which leads to the need for significant acceleration of computational schemes implemented in Python and the development of parallel algorithms. The results of investigations will are placed as the Jupyter Book, containing physical and mathematical formulations of problems, developed algorithms, computational schemes, which allows to follow all stages of mathematical modeling with interactive and visual elements, and the user can also download a ready-made Jupyter Notebook for their own research.
In this work we present the results of investigations of controllable magnetization reversal and developed tools for its modeling. The interest in this system is due to the fact that the possibility of developing of cryogenic memory based on the magnetization reversal in a Phi-0 junction has been actively studied recently. In Phi-0 Josephson junctions, the spin-orbit interaction in a ferromagnetic layer without an inversion center provides a mechanism for direct coupling between the magnetization and the superconducting current, which makes it possible to control the magnetic properties by means of the Josephson current, as well as the effect of magnetization on the Josephson current. However, in case of using several Phi-0 junctions in a single chip, there is a need to implement a magnetization reversal in a selected Phi-0 junction. We propose a solution to this problem based on mathematical modeling of the dynamics of a system consisting of three Phi-0 junctions connected via LCR circuits, which is reduced to solving the Cauchy problem.
The results of the development of a toolkit for modeling a controllable magnetization reversal in a chain of Phi-0 junctions using alternating voltage are also presented. It is shown that by applying an alternating external voltage pulse with a frequency coinciding with the eigenfrequency of the LCR circuit, it is possible to realize a magnetization reversal in a selected Phi-0 junction, i.e. the possibility of a controllable magnetization reversal is demonstrated. The influence of system parameters on the magnetization dynamics in each of the Phi-0 junctions is studied in detail. A software module for the performed calculations is developed. The investigations were carried out on the basis of the ML/DL/HPC ecosystem of the heterogeneous HybriLIT platform (JINR LIT).
The work was carried out with the support of the Russian Science Foundation within the framework of project No. 22-71-10022.
A good number of applications in physics (and not only) rely on
random number generation for Monte Carlo purposed (or key distribution,
and other tasks).
Most at hand random servers are hash function based, with carefully
studied and tuned algorithms. Depending on complexity and quality of
the samples produced, they can be very good quality like RANLUX (with
10^171 period), or faster, like the Mersenne Twister (x40 faster).
I present the implementation of a true-random multiplier, a code that
relies on a finite set of true-random numbers from a physical source
(in this case atmospheric noise, set of 0.2 M in the 0 ... 9999 range).
The code produces new numbers by combining any 2 random numbers in the
list, at random distance between their list positions. The random offset
relies on a shift register structure involving both the rand() hash
and numbers from the list itself, thereby producing "non-repetitive
repetitions" - i.e. the multiplier has no known period.
The tests of the multiplier are presented and they show good quality.
The observation of neutrino oscillations provides convincing evidence for non-zero neutrino masses, indicating the existence of a New Physics beyond the Standard Model (SM). A natural generalization on the high-energy scale, theoretically motivated by the idea of Grand Unification, is the left-right symmetry (LR symmetry), in which left- and right- chiral fermions are treated in the same way. Such extension of the SM has several attractive consequences: (1) it provides sources of parity violation that could explain the baryon asymmetry of the Universe, (2) implements the seesaw mechanism that explains the small neutrino masses and neutrino oscillations, (3) predicts the existence of sterile neutrinos, the lightest one is a candidate for the role of a dark matter particle. In our work, we focused on the Minimal Left-Right Symmetric Model (MLRM) with a gauge group $SU(3)_c \times SU(2)_R \times SU(2)_L \times U(1)_{B−L}$ that is broken down to $SU(3)_c \times U(1)_{em}$ due to the non-trivial vacuum structure of the extended Higgs sector. Within this framework, we fixed a set of parameters in the extended Higgs potential by "tuning" them to match the observed Higgs boson mass of 125 GeV, while taking into account existing experimental constraints on the masses of additional non-standard Higgs bosons and massive vector bosons $W_R^{\pm}$ and $Z_R$. We also considered the parameterization of mixing in the lepton sector in detail, investigated the possibility of sterile neutrinos as a warm dark matter, taking into account astrophysical, cosmological, and accelerator constraints.
The main requirement for the formation of vacuum conditions in charged particle accelerators is the reduction of particle losses on residual gas molecules. The rate of losses is determined by both the beam parameters and the composition of the residual gas. As the beam accelerates and accumulates in the accelerator chain, the requirements for the residual pressure change, so to maintain certain beam conditions in the collider, a pressure of about 10 -9 Pa is required.
The Joint Institute for Nuclear Research (JINR) is constructing a heavy ion collider based on the existing superconducting synchrotron, Nuclotron – NICA (Nuclotron based Ion Collider fAcility). It will be a multistage accelerator complex designed to study the interactions of ions with matter.
The report presents the results of the joint commissioning of the BINP SB RAS and JINR power supply for the RF 1 barrier station of the NICA collider
Injection complex is a source of electron and positron beams for both BINP colliders: VEPP-2000 and VEPP-4. Now it covers all consumer needs in beams, however, future BINP projects require operating with higher intensity beams. For this reason building the injection complex damping ring longitudinal coupling impedance model has become important. This work aims at collective effect studies: impedance of vacuum chamber elements calculation and comparison it parameters with beam spectrum, potential-well distortion research; measurements and simulation of beam regrouping from 16th bunch from linear accelerator into 1 single bunch in 1st harmonic damping ring cavity.
To operate the angle of exit of the extracted ion beam, it is necessary to create a magnetic field changing with a frequency of up to 200 Hz. For this purpose the fast scanning magnets were developed and optimized to obtain a given irradiation field extracted ion beam. The shape of the poles is optimized to eliminate heating by eddy currents. Calculation of scanning magnets and magnetic field investigation. Calculations were performed in the COMSOL program.
The generation of polarization radiation by electron beams passing near dielectric objects is attracted the attention of researchers due to the potential for introducing this effect to either measure the beam parameters or generate intense electromagnetic radiation beams in THz and sub-THz frequency range. One of the most interesting forms of this radiation is Cherenkov diffraction radiation (ChDR), which arises when high-energy electrons traverse along a dielectric edge. The characteristics of the generated radiation are dependent on the properties of the charged particles.
By understanding and regulating the properties of the electron beam, it is possible to construct dielectric radiators of varying shapes, which will enable the generation of ChDR with distinct properties. In order to produce such radiators with the requisite degree of accuracy, it is essential to use technology for the fabrication of dielectric samples with complex shapes. This may be done via the application of 3D printing by plastics, specifically fused filament fabrication. However, prior to the implementation of this approach, it is essential to conduct a comprehensive investigation into the dielectric properties of the samples produced through 3D printing.
In this study, a series of experimental samples were produced using the fused filament fabrication technique. The set comprised dielectric wafers printed from a variety of polymers, including polyethylene terephthalate glycol (PETG), polylactide (PLA), acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), styrene-acrylonitrile (SAN) and PLA with differing concentrations of impurities, including copper, bronze, carbon and wood fibre powder. A terahertz laser was applied to measure the refractive index and absorption plus reflection coefficient. Based on the data obtained, the most optimal materials were selected, from which test samples with a special geometry were manufactured for the ChDR generation.
A series of experiments was conducted at the MT-25 microtron in Dubna to investigate the generation of ChDR in the created samples when the electron beam passed parallel to their surface. Subsequently, the super-radiant spectrum of the generated radiation on several harmonic lines was investigated using a spectrum analyser. The data obtained were compared with the ChDR generated under identical conditions by a Teflon radiator manufactured by standard milling from cast material.
This work was partially financially supported by a Program of the Ministry of Education and Science of the Russian Federation for higher education establishments, project No. FZWG-2020-0032 (2019–1569).
High energy and elementary particle physics are the leading fields of science in recent decades. Since this, investigations of the properties of matter and the processes of collision and birth of new particles with subsequent detection and identification of the latter are being held all over the world. One of such mega-science projects is the NICA (Nuclotron-based Ion Collider Facility) founded at the Joint Institute for Nuclear Research (Dubna). Within the framework of NICA project, development is underway to create an MPD (Multi-Purpose Detector) facility for detecting high-energy beam collision products using a TPC (Time-projection chamber), ECal (Electromagnetic Calorimeters) and other subdetectors. The TPC consists of two coaxial cylinders, the space between which is filled with a working gas mixture. The total power of the MPD electronics exceeds 1 MW, so during its functioning, significant heat may be released both inside and outside the volume of the facility. It may lead to a deviation of the thermal stabilization of the working gas volume and, as a result, negatively affect the accuracy of event detection.
To control heat generation on the TPC and ECal subdetectors, the MPD is equipped with a water cooling system for electronics and thermal stabilization of the TPC working gas volume. The cooling system must meet the following requirements:
ensure leakless regime. The coolant pressure in the circuits must not exceed atmospheric pressure. Thus, in case of a mechanical defect in the pipe, the coolant will not leak;
at the same time, as the pressure decreases, the risk of cavitation increases, which is unacceptable.
The presentation describes the design features of the MPD cooling system. The 3D finite-element model of the cooling system was developed and numerical calculations of the coolant flow through it were performed. The model allowed to identify non-compliances with requirements in the initial prototypes of the cooling system, so the new piping layouts were designed. Pipe volumetric flow rates and pressures were estimated, which can be used for calibration and startup of the real system. The results of the numerical experiment were verified using data obtained from a full-scale experiment on a specially designed stand. The presentation also shows the results of a test of the cooling system's resistance to water hammer shock.
Modeling of conformational excitations in a DNA molecule makes it possible to advance the study of fundamental patterns and mechanisms of biological functioning of living systems at the cellular level. Conformational excitations in the DNA molecule are involved in such important processes as transcription, translation, denaturation and replication.
In particular, the course of the replication process is accompanied by a rupture of the hydrogen bond.
Such gaps are called an open state. W. Englander in his model connects the concept of an open state with such a mathematical object as a soliton.
In the framework of this work, the physical model of the DNA molecule
formulated by V. Muto, which is formed by the Todd potential and the Lennard-Jones potential, will be investigated. Although this model is two-dimensional, it retains the main features of dynamics
inherent in volumetric models of conformational excitations of the DNA molecule. The study of a two-dimensional model is significantly simplified, which opens up the possibility of using new mathematical methods for its analysis.
The purpose of the study is to find an open state, the mathematical image of which is - soliton. The methods of wavelet analysis will be used as the tools used.
The authors set the following tasks:
1. Implementation of the dynamics of the Todd-Lennard-Jones model.
2. The use of discrete wavelet transform (DWT) for noise filtering.
3. The use of continuous wavelet transform (CWT) to identify solitons.
4. Estimation of the propagation velocity of the open state.
5. Evaluation of algorithmic complexity.
The presence/absence of solitons in the dynamics of this model will allow us to assess the limits of its
applicability in further research.
Goal of the work:
Prove the following conjecture: The largest maximal subgroup of shifts of a multipermutation system in the Moran covering is isomorphic to the maximal discrete group of displacements (branchings) of Γ(c) To do this, prove the lemma 〖lim〗(n→∞) lim(k→∞)=#Aut(Γ)=ord(1/k)log#G_(n,k). Equivalent to this conjecture is the following statement: the vacuum expectation value of the Wilson loop will reduce to the vacuum expectation value for the maximal compact subgroup of the symmetry group G, that is, 𝑊((𝐶)). Relevance of the work:
This work shows a method for combining topological field theories and knot theory based on the hyperbolic theory of repellers on the spectra of sticky sets with a "gap" condition for conformal reference points using methods of the theory of non-commutative Lie groups. The concept proposed in the work allows more
Results:
1. Examples of invariant knots in SO (4) are constructed
2. The Inono-Wigner contraction for the symmetry group of SO (4) is performed using methods of the theory of non-commutative algebras
3. A new proof of the Brouwer theorem on the shift for a periodic point on the set "disk" is found
4. The Chern-Simons action is modified using the method of Cartan exterior forms, it is shown that translationally invariant components of the Lie algebra can describe a topologically invariant contortion tensor (Cartan tensor)
5. Based on the polysymbolic formalism of the description of the Cachazo-Ye-Yuan equation, a new method for calculating Wilson loops is derived, as applied to three-amplitude fermion Feynman diagrams
6. It is proved that elliptic symplectic compact sets have the specification property.
7. The properties of the symplectic time ordering operator are studied
8. It is proven that the sum of multipermutation subshifts of a topological Markov chain on a Moran cover on a Carathéodory structure in the projective limit converges to an invariant of motion of the type of Randemeister motion
9. It is shown that the extended locality criterion for loops allows one to construct form factors based on a sequence of p-addic numbers
10. The equivalence of the definitions of homeomorphism on pseudoholomorphic curves on elliptic sets for different classes of symplectic capacities is proved.
11.A formulation of the model of the spectrum of sticky sets for conformally symmetric repellers for non-commutative Lie groups is constructed
The aims of the study are to create unique systems for cooling and thermal stabilization of the TPC and ECAL detectors of the MPD experiment (NICA project). The thermal stabilization of the TPC gas mixture Ar/CH4 (90:10) and nitrogen N2 is also an important part for the TPC detector.
The systems are “leakless” type. Cooling water (distilled or deionized) operates at a pressure of up to 0.3 bar (to prevent water leakage inside the MPD experiment). The requirements for cooling pipes are the low radiation length, operation in the radiation environment, pipes must be from nonmagnetic material, small diffusion value through the pipe wall, flexibility for mechanical installation, and low cost. Plastic pipes were chosen.
The FLUKA simulation results for the MPD experiment show that the main problem is neutrons, and 1 MeV neutron equivalent fluence is F = 10 12 n/cm 2 per 10 years of the MPD operation. The candidate pipes were irradiated by neutrons (with an energy max of about 0.6 MeV) with the following fluence values: F1 = 10 9 n/cm2, F2 = 10 10 n/cm2, F3 = 10 11 n/cm2, and F4 = 10 12 n/cm2. A variety of analyses like scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, differential scanning calorimetry (DSC), and direct air leak measurement due to diffusion into the vacuumed pipes before and after irradiation. Also, COMSOL modeling has been done for the selected candidate pipes.
The study of molecular interaction kinetics is of crucial importance for fields such as medical diagnostics, pharmaceuticals, and the food industry. Although label-free biosensing methods, such as surface plasmon resonance, are widely used for kinetic studies, they face significant challenges. These include limitations in scaling to observe multiple interactions simultaneously, the complexity and bulkiness of the equipment, as well as the high cost of sensor chips. In this work, we explore and implement an alternative label-free method, spectral correlation interferometry (SCI), which enables parallel monitoring of multiple molecular interactions in parallel and supports multiplexed biosensing. In our system, the multiplexed SCI-based biosensor generates video output signals that record changes in illumination brightness at each point of the biosensor chip. Using advanced signal processing algorithms, including Fourier transformations, filters, and mathematical operations, we transform the brightness variations in the regions of interest on the chip into measurements of the biological layer’s thickness. The development and application of these signal-processing algorithms are key steps in creating a fully functional multiplexed biosensor, promising for studying the kinetics of thousands of molecular interactions in real time.
The capability to generate DNA molecules of designed architectures has allowed scientists to explore novel applications in various fields, including structural biology, drug delivery and creating new DNA microelectronic devices. The last application requires developing models with a detailed account of both the electronic and structural properties of DNA, as well as its interaction with fluctuating environment. In this work, an electronic hole transfer through artificial DNA is studied based on the tight-binding model accounting a double-stranded structure of DNA chain [1].
As a specific object of application of this model, an artificially created DNA oligonucleotide chain with a homogeneous fragment composed of N identical adenine-thymine pairs (A-T)N is considered. This fragment of a variable length N is enclosed between guanine-cytosine (G-C) end sections, which play the role of donor and acceptor centers for a moving charge. Dissipative dynamics of a hole carrier in this model is described by solving the Lindblad equation for the density matrix of the system, taking into account two types of dissipative processes: (a) a slow attenuation of the wave function of a charged carrier moving from a photo-induced donor to an acceptor, which is due capturing of the carrier by the environment, and (b) the loss of coherence of the carrier wave function caused by the dephasing effect of thermal noise of the environment.
Numerical solutions of the Lindblad equation in the qubit representation are found using the open source LindbladMPO code, which simulates elements of a quantum algorithm on a classical computer [2]. The calculated results are compared to available experimental data [3].
1. Cuniberti, G., Maciá, E., Rodríguez, A., Römer, R.A. Tight-Binding Modeling of Charge Migration in DNA Devices. In: Chakraborty, T. (eds) Charge Migration in DNA. Springer, Ch.1. P. 1-20. 2007.
2. Landa H. and Misguich G. Nonlocal correlations in noisy multiqubit systems simulated using matrix product operators. SciPost Phys. Core. 2023. V. 6. P. 037-38.
3. Giese B., Amaudrut J., Köhler A.K., Spormann M., Wessely S. Direct observation of hole transfer through DNA by hopping between adenine bases and by tunneling. Nature. 2001. V. 412. P. 318-320.
Nanostructured materials based on CuSn(S,Se)2 are of interest in the context of renewable energy. They are effective photoadsorbers [1], and in addition, they have a high structural susceptibility to moisture adsorption. Thanks to the use of nanostructured photo adsorbers, it becomes possible to create a hybrid system that combines the properties of both phototransformers and converters of energy absorption of water molecules into an electric form.
The purpose of this work is to investigate the electrical properties of direct current materials in conditions of different humidity. Crystals of the composition Cu2CdGe100-XSnXSe4 were used as the investigated objects, where x = 10, 20, 30, 40, 50, 60, 70, 80, 90.
Fig. 1. Dependence of the electrical conductivity of Cu2CdGe100-XSnXSe4 samples on humidity.
As can be seen (Fig. 1), there is a tendency to decrease the electrical conductivity of the Cu2CdGe100-XSnXSe4 system with an increase in tin concentration (x%). The maximum value (0.0546 Ohm-1) was recorded for two samples x=10 and x=20 at atmospheric humidity values of 26% and 75%, respectively. It was found that the optimal humidity, where the greatest electrical conductivity is observed for most samples, is 75%.
It was found that the studied compounds of the composition Cu2CdGe100-XSnXSe4 (x=10-90) at relatively high concentrations of dopant in atmospheric humidity conditions of at least 75% have a sufficient level of electrical conductivity and can potentially be used as a functional medium for a combined chemo- and photoconverter for alternative energy sources.
Acknowledgments. The investigation was performed in the scope of the Serbia-JINR cooperation Projects № 50 2024 items 7 and 8, Serbia; Serbia-JINR cooperation Projects № 51 2024 items 4 and 5, Belarus; Serbia-JINR cooperation Projects № 130 2024 items 7 and 8.
[1] Xie H. et al. Impact of Sn (S, Se) secondary phases in Cu2ZnSn (S, Se) 4 solar cells: a chemical route for their selective removal and absorber surface passivation //ACS applied materials & interfaces. – 2014. – Т. 6. – №. 15. – С. 12744-12751.
Ferritin nanoparticles have emerged as crucial components in new recombinant vaccine platforms. As we previously demonstrated in our previous works, the rational design of ferritin-immunogen nanoparticles remains a bottleneck in developing novel tools for drug delivery and immunology [1], [2]. This challenge arises from the stochastic nature of ferritin's self-assembly, which also affects chimeric ferritin-based protein complexes. Consequently, the assembly process can yield nanoparticles with varying stoichiometries, complicating the design of uniform and effective immunogens.
In this study, we engineered several ferritin-immunogen nanoparticles and evaluated their immunogenicity in laboratory mice by measuring antibody titers against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. We assessed different nanoparticle variants, including those with varying stoichiometries. The globular assembly of these nanoparticles was confirmed using small-angle scattering and electron microscopy. Our findings provide valuable insights into the structure-based design of ferritin-based immunogens and offer a deeper understanding of the molecular mechanisms underlying their efficacy.
The study was supported by the Ministry of Science and Higher Education of the Russian Federation (agreement 075-03-2024-117, project FSMG-2021-0002).
Literature
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Nuclear power plants are used to study properties of neutrino oscillation. The intensive antineutrino flux provides the large statistics, the main uncertainties come from systematic.
Usually, the baseline of reactor experiments, the distance between the reactor and the detector, varies from 0.5 km or more. It allows to effectively measure the oscillation parameters $\Delta m^2_{32}$, $\sin^2 2\theta_{13}$. The reactor and detector are considered as point objects.
At the same time, the short baseline experiments, baseline is less than 100 m, are used to precisely measure antineutrino flux (e.g. Taishan Antineutrino Observatory). In the case of the short baseline, it is crucial to take into account the size of the reactor and detector.
This poster will address the impact of spatial distortion of baseline on the effectiveness of measurements of fast neutrino oscillations, comparing measurements with a point model of the reactor and the detector.
The Hartree-Fock (HF) method is one of the most important methods of electronic structure theory. So there is interest in this algorithm, for example, within the framework of a future software ecosystem for high-precision multi-scale ab initio relativistic quantum modeling of atoms, molecules, and materials (part of the BUFO program [1]). But the conventional sequential program implementation of the HF algorithm is too slow and memory-intensive since the evaluation and storage of four-center molecular integrals are needed in HF to obtain the matrix elements of the Coulomb and exchange operators. Therefore, it is considered to be a key bottleneck of the algorithm. Several methods have been designed to speed up this part of the algorithm, one of which is known as resolution of identity approximation (RI) [2]. This method allows to skip evaluation and storage of four-center molecular integrals to vector-matrix operations with two- and three-center integrals and storage of them. The latter can be significantly or sometimes completely organized in RAM of several CPUs or GPUs, unlike four-center integrals. This organization gives a large performance gain because vector-matrix operations to obtain the matrix elements of the Coulomb and exchange operators can be efficiently done in parallel. Thus, if we want to obtain a highly efficient version of the HF algorithm, the most promising option is to develop the RI-HF version. It is done using the libcint library for calculating integrals [3] and using vector-matrix multiplications [4]. The results were compared with those in the ORCA program package [5].
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Over the last few decades, significant progress has been made in the study of the $g$ factor of highly charged ions [1,2]. To date, the experimental accuracy for hydrogen-, lithium- and boron-like ions has reached values in the range of $10^{-9}$ - $10^{-11}$ [3-7]. These studies have provided the most precise value of the electron mass [8, 9]. Additionally, by measuring the $g$ factor of light and heavy highly charged ions, it is possible to determine the value of the fine structure constant, extract nuclear parameters, and explore potential new physics [10-12].
In our investigation, the interelectronic interaction correction to the $g$ factor of ions with the low nuclear charge number $Z$ are investigated for the Coulomb and various screening potentials.
Within the framework of bound-state QED perturbation theory, the contribution of the interelectronic interaction $\Delta g_{\text{int}}$ can be written as a 1/$Z$-parameter expansion:
\begin{equation}
\Delta g_{\text{int}}=(\alpha Z)^2\left[ \frac{1}{Z}B_1(\alpha Z)+\frac{1}{Z^2}B_2(\alpha Z)+\ldots\right].
\end{equation}
The coefficients $B_i$ are expanded in the parameter $\alpha Z$:
\begin{equation}
B_i(\alpha Z) = b_i^{(0)} + (\alpha Z)^2 b_i^{(2)} + (\alpha Z)^4 b_i^{(4)} + \cdots .
\end{equation}
We determine the coefficients $b_k^{(i)}$ in the Coulomb potential and various screening potentials from full numerical calculations of $\Delta g_{\text{int}}$ up to the fifth and third orders respectively. The calculations are based on the dual-kinetic-balance method [13] with a finite basis set composed of B-splines. Corrections due to the interelectronic interaction in the Breit approximation are expanded in powers of $\alpha Z$ for the ground and excited $(1s)^2 2p_{1/2}$ and $(1s)^2 2p_{3/2}$ states. The combination of our results with high precision non-relativistic calculations will enhance the accuracy of theoretical predictions.
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This paper presents a software-hardware complex for measuring the tension of the anode wire in drift tubes used in the SPD experiment's straw tracker at the NICA collider. The tension of the anode wire is critical for ensuring the accuracy of coordinate determination, as it affects electrical stability and the positioning of the wire due to electrostatic and gravitational forces.
The developed complex employs an electromagnetic measurement method, allowing for high-precision control of the tension in thin-walled Mylar tubes. The device measures tension by analyzing wire vibrations. The central component of the system is the STM32L4 microcontroller, which manages the delivery of electrical pulses and performs measurements. The advantages of the complex include ease of setup, a user-friendly interface, and high measurement speed, making it suitable for mass production. Testing confirmed the device's high accuracy and efficiency. Thus, the developed complex represents a significant advancement in the technology for assembling high-precision wire detectors
Gas type detectors nowadays utilise a resistive coating known as DLC (Dimond Like Carbon). It is this coating that acts as a current limiting resistor that not only diverts the electron avalanche after multiplication, but also prevents electrical breakdown in the gas. The resistance of DLC coatings varies over a wide range from units of kOhm to hundreds of Gohm depending on the method of preparation [1]. It is experimentally proved that the stability of electrophysical characteristics of DLC thin films changes with time, which is a critical factor for detector operation for a long time (up to 5 years). For this reason, the actual task is to search for alternative coatings that meet the requirements of long-term operation in the detector without degradation of both the characteristics of the coating and the parameters of the detector itself. It is proposed to use compounds based on nitrides of simple metals (eg, copper (Cu), aluminium (Al)), as these metals are mainly used in the detector and will not contribute to the received signal from the reading electronics.
It has been previously found [2] that the electrical resistivity values characteristic of Cu3N coatings can be varied in the range of hundreds of mOhm to hundreds of Gohm by varying the nitrogen (N$_2$) concentration during sputtering. This flexibility in varying the most important functional characteristic of Cu$_3$N-based coatings is a definite advantage over DLC coatings.
1. With an increase the flow rate 𝐍$_𝟐$ from 3 to 10 l/h from 3 to 10 l/h, the centre of gravity of Cu-N (111) and Cu-N (200) reflections changes towards higher values, indicating the expansion of the crystal lattice.
2. Increasing the flow rate 𝐍$_𝟐$ from 3 to 10 l/h during film synthesis in the Cu-N system leads to a change in the stoichiometric composition of the coatings, manifested by a change in the contribution ratio of the reflex (111) from 45 to 80% and the reflex (200) from 57 to 83%.
3. I-V's Cu-N show a linear character from different 𝐍$_𝟐$ flow rates, but with different slope.
4. The samples show ‘bubbles’ of film delamination from the sample, and the thickness of the thin films varies from 10 to 17 nm.
5. The absolute resistivity R increases from 720 Ohm to 1.34 MOhm with increasing flow rate 𝐍$_𝟐$, and the resistivity increases from 7.2∙10$^{-6}$ to 1.3∙10$^{-2}$ Ohm ∙m.
6. The change in resistivity is directly proportional to the position of the centre of gravity of the Cu-N reflex (111) and (200).
7. The results indicate the possibility of using films based on solid solution in Cu-N system as resistive coatings in gas discharge detectors.
8. Variancing the electrical resistivity of Cu-N thin films will make it possible to study the operation of the resistive electrode in detectors and the mechanism of electron avalanche injection.
The magnetic properties of one-dimensional ferromagnetic nanostructures with diameters in the nanometer range and macrolengths are actively studied and many scientific works are devoted to them due to their non-trivial magnetic behavior due to strong uniaxial shape anisotropy [1]. These nanostructures are a promising material for creating a new kind of magnetic memory, due to the dense manufacturing technology and independent shape anisotropy, these nanostructures can solve the problem of creating a new kind of magnetic memory. In turn, shape anisotropy can be controlled by changes in the geometry of nanostructures. Size effects play an important role in nanostructures, which have a significant impact on their magnetic properties. Studies have shown that such ferromagnetic structures can be used as nanoagents in biomedical applications [2], such as the fight against cancer using hyperthermia and mechanical destruction of tumors, targeted drug delivery, MRI contrast agents. There are many methods for synthesizing various one-dimensional nanostructures [3]. One of them is the method of electrodeposition into porous matrices of aluminum oxide, in which the deposited nanostructures repeat the shape of the pores in the matrix. Under controlled conditions, anodizing aluminum can produce a self-organizing hexagonal ordered array of nano-sized pores [4]. The parameters of porous matrices, such as their porosity, pore diameter and length, and the distance to neighboring pores, can be precisely controlled, which means that the parameters of synthesized ferromagnetic nanostructures can also be controlled, which is why such matrices are attractive for use as membranes.
In this work, ferromagnetic Ni, Fe, Co nanowires were synthesized using porous aluminum oxide matrices as a membrane. Porous matrices of aluminum oxide were obtained under identical conditions in potentiostatic mode with a voltage of 31 V using oxalic acid, to eliminate the influence of differences in the shape of nanowires when comparing them. Nanowires were synthesized by electrochemical deposition in a potentiostatic mode. The morphological and magnetic properties were studied, and X-ray phase analysis of the resulting Ni, Fe, Co nanowires was carried out. Magnetic properties of Co nanowire arrays showed distinctive results compared to Ni, Fe nanowires. Co nanowires showed lower coercivity when the external magnetic field is directed along the long axis of the nanowires compared to Ni, Fe nanowire arrays, and strong interaction fields were observed in Co nanowire arrays, according to FORC research results.
This work was supported by the Russian Ministry of Education and Science (State assignment No. FZNS-2023–0012).
Bibliography
1. Samardak A.S., Ognev A.V., Samardak A.Yu., et al. Variation of magnetic anisotropy and temperature-dependent FORC probing of compositionally tuned Co-Ni alloy nan-owires, Journal of Alloys and Compounds. 732 (2018) 683-693.
2. Mukhtar A., et al. Magnetic nanowires in biomedical applications // Nanotechnology. ‒ 2020. ‒ T. 31, № 43. ‒ C. 433001.
3. Scott J. A., Totonjian D., Martin A. A., et al. Versatile method for template-free synthe-sis of single crystalline metal and metal alloy nanowires. Nanoscale 8 (5) (2016) 2804-810.
4. Ebihara K., Masaichi N., Structure and Density of Anodic Oxide Films Formed on Aluminum in Oxalic Acid Solutions. Journal of the Metal Finishing Society of Japan. 34 (11) (1983) 548–553.
The article presents the results of a study of the mechanisms of coherent transient radiation (CTR) in the sub-terahertz frequency range. This type of radiation can be used to diagnose short electron bunches and can serve as a basis for the development of radiation sources in the THz and sub-THz range. The AREAL linear accelerator with an energy of 3.6 MeV, located at the CANDLE Synchrotron Research Institute in Yerevan, was used as an electron source in the study.
Using an interferometer designed according to the Martin-Applet scheme [1], frequency spectra of radiation were obtained. This made it possible to estimate the length of the electron beam. The radiation was recorded using ZBD-F detectors designed for frequencies in the range from 33.5 to 50 GHz, from 60 to 90 GHz and from 90 to 140 GHz[2].
This work was partially financially supported by a Program of the Ministry of Education and Science of the Russian Federation for higher education establishments, project No. FZWG-2020-0032 (2019–1569).
References:
[1] D.H. Martin; E. Puplett. (1970). Polarised interferometric spectrometry for the millimetre and submillimetre spectrum. , 10(2), 105–109. doi:10.1016/0020-0891(70)90006-0
[2] Virginia Diodes Ltd. https://vadiodes.com/en/zbd
The dynamics of recovery of the open porous structure in HDPE films, which are preliminarily uniaxially deformed in the medium of supercritical $CO_2$ followed by shrinkage in the longitudinal direction, upon their repeated stretching in air is studied by structural mechanical methods. The process of shrinkage is accompanied by the approach of lamellas and the disappearance of the oriented fibrillar structure. The value of relative shrinkage may be as high as 70–80%. According to atomic force microscopy and small-angle X-ray scattering, these polymer films “remember” their previous strain in $CO_2$ and in their repeated stretching in air, which is not a physically active medium, and restore the fibrillar porous structure of crazes with similar parameters. The phenomenon of such a memory makes it possible to use PE films preliminarily formed by the mechanism of intercrystallite crazing followed by their subsequent relaxation in the freestanding state as “precursors” for producing mesoporous materials with the pore volume on the order of 30 vol % for application in various fields, in particular, as vapor permeable membranes.
Transglutaminases (TGases) are a unique group of enzymes that facilitate the post-translational modification of proteins by forming isopeptide bonds. Understanding that diverse processes such as normal and cancerous cell growth, reproduction, and cell death rely on sufficient levels of transglutaminases and that these enzymes can influence the differentiation and proliferation of various cell types has led many researchers to explore these intriguing molecules. Additionally, transglutaminases play a role in several diseases, including celiac disease and neurological disorders. In mammals, nine distinct isoenzymes of TGases have been identified at the genomic level. However, only a limited number of proteins possess reliable structures for future studies, while most have only partial structures.
We have obtained fully resolved models for proteins from the transglutaminase family for the first time using AlphaFold predictions. We constructed theoretical small angle X-ray scattering (SAXS) curves for each model using CRYSOL and demonstrated the ability to distinguish transglutaminase family proteins using SAXS.
We acknowledge the support from the Ministry of Science and Higher Education of the Russian Federation, project FSMF-2023-0010; “Integrated structural biology and genetics for the production of protein preparations and biologically active substances as new food and non-food products.”
One of the key issues in modern physics is understanding strong interactions and, in particular, studying the properties of strongly interacting matter in equilibrium. Strongly interacting matter at extreme densities and temperatures is expected to be in the state of quasi-free quarks and quark-gluon plasma (QGP) [1]. This hypothesis motivates the study of phases (QGP and hadron gas) and transitions between them as a result of particle and nucleus collisions at high energies. Previously, non-trivial dependences of strongly intense variables on the collision energy were obtained in the SMASH, EPOS, UrQMD and PHSD models for p+p and Bi+Bi collisions, namely for Δ[pt,N] [2], Σ[pt, N] [2] and <N>D [pt,N] [3]. The analysis also included the study of second- and third-order cumulants for the transverse momentum. The experimental data show a significant deviation from the basic independent source picture and are supported by experimental data obtained from Au+Au collisions at 200 MeV, indicating the presence of long-range collective correlations and strong final state effects [4]. For UrQMD, PHSD and EPOS in p+p collisions, a smooth change in energy is revealed, but SMASH gives a sharp jump around 3.5-4 GeV. PHSD qualitatively and quantitatively coincides with what the UrQMD model shows in the energy range from 6.3 to 17.3 GeV for the second-order cumulant. In this paper, the energy dependences of highly intense variables and cumulants in Bi+Bi collisions will be investigated depending on the centrality class. Two methods will be proposed for studying highly intense variables and cumulants: a direct method for studying correlations and a subevent method depending on the centrality class. The sub-event method is intended to analyze highly intensive variables and second- and third-order cumulants in two different rapidity intervals, as well as their dependence on the distance between these two intervals, which will allow us to estimate the contribution of short-range correlations depending on the centrality class. A comparison of these two methods will be presented for all four models: SMASH [5], EPOS [6], UrQMD [7], and PHSD [8].
At the commissioning stage of the NICA project, the electronics of the Nuclotron radio frequency (RF) stations are being modernized in parallel. The main achievements to date include the development and commissioning of two key elements of the system: an adjustable amplifier unit with automatic gain control and a remote control unit for RF stations. The remote control unit for RF stations allows centralized control of all stations, which significantly simplifies the operation of the equipment and minimizes the risk of human error. Both units are designed with the ability to be integrated into a single control system for the RF station complex, which will improve control efficiency, automate control and monitoring processes, and provide more flexible adjustment of the equipment to various operating modes.
In the first phase of the SPD experiment, the main tracking system will be supplemented by a Micromegas-based central tracker. When operating in a magnetic field, the performance of Micromegas detectors is largely determined by the gas mixture used. Experimental study results combined with detector simulation are presented.
Geant4 hadronic physics sub-library includes a wide variety of models for high and low-energy hadronic interactions. We report on recent progress in development of the Geant4 nuclear de-excitation module. This module is used by many Geant4 models for sampling of de-excitation of nuclear recoil produced in nuclear reactions. Hadronic shower shape and energy deposition are sensitive to these processes.
We will present de-excitation module structure, and comparisons of Geant4 predictions for the thin target experiments using different Geant4 hadronic physics models for the new Geant4 version 11.3, which will be publicly released in December 2024.
A track scintillation detector based on SiPM matrices has been developed. The detector has two arms oriented at 90 degrees relative to each other. To obtain an image of the particle track, it is necessary to focus the scintillation light on the SiPM matrix. The report describes the measurement process using Fresnel lenses and glass lenses.
In December, 2022 - January, 2023 the BM@N experiment conducted
its first physics run with full detector configuration. Over 500 million
events of Xe+CsI interactions with the Xe beam kinetic energy of
3.8A GeV were collected.
Since then, strong efforts have been put to reconstruct and
analyze the collected data. The current status of this activity will
be presented on the example of the reconstruction of strange
particles weakly decayed to charged hadrons.
This work presents calculations of the bond distances and dissociation energies of LiH, NaH, KH, RbH, CsH, FrH and 119H. The electron configuration of alkali metals contains one open s-orbital, therefore the molecular shells of alkali metal hydrides are closed, which simplifies the study of these molecules’ chemical properties.
To take into account electronic structure we use coupled cluster theory including single, double and perturbative triple cluster amplitudes (CCSD(T)). The calculations are performed within the framework of the relativistic Dirac-Coulomb Hamiltonian, employing the computational software package DIRAC. Based on the obtained results we can make a conclusion that relativistic effects related to contraction of the valence s-orbital are of a high importance for large Z.
SEC-SAXS structural studies of ferritin-based heterooligomers
Oksana M. Tilinova, Margarita S. Gette, Vsevolod V. Sudarev, Yury L. Ryzhykau, Sergey V. Bazhenov, Ilya V. Manukhov, Alexander I. Kuklin, Alexey V. Vlasov
Ferritin is an iron storing protein complex typical for almost all living organisms. Ferritin complex poses the ability to self-assemble into a hollow sphere from 24 identical subunits. Stability of the globule in a wide range of temperatures and pH makes ferritin a promising tool for biomedical applications such as vaccines or drug delivery [1]. Ferritin-based hybrids are the cutting edge of biotechnological applications of this protein complex [2, 3, 4], especially, in case of ferritin from Helicobacter pylori, which is widely utilized as a platform to combat various pathogenic diseases [5]. We suppose that the oligomeric composition of such hybrid molecules might play important role in vaccine efficiency
In this work we investigated hybrid recombinant protein complex based on ferritin subunits from H. pylori and ones fused with a homologue of the Small Ubiquitin-like Modifier protein obtained via pH dis-/reassembly by SEC-SAXS. Small angle X-ray scattering coupled with size exclusion chromatography (SEC-SAXS) allows for obtaining SAXS data of higher quality and precise understanding of every component of the mixture which is crucial in studying hybrid samples [7]. In our case, we defined macro parameters such as Rg, Dmax and Vp for different fractions of the sample of hybrid recombinant protein complex and made further conclusions on the stoichiometry of these hybrid globules. We supposed that these macro parameters in different fractions of SEC correspond to hybrid 24-meric globules, separate monomers of both types of subunits and their dimers. In addition, there is a fraction of SEC that allows for the assumption of the existence of heterodimer in this sample. Its composition is under discussion in this report.
The study was supported by the Ministry of Science and Higher Education of the Russian Federation (agreement 075-03-2024-117, project FSMG-2021-0002)
Literature list
1. Ferritin self-assembly, structure, function, and biotechnological applications / V.V. Sudarev, S.M. Dolotova, S.M. Bukhalovich et al. // International Journal of Biological Macromolecules. — 2023. — Vol. 224.
2. Two-Component ferritin nanoparticles for multimerization of diverse trimeric antigens / I.S. Georgiev, M. G. Joyce, R. E. Chen et al. // ACS Infectious Diseases. — 2018. — Vol. 4.
3. Mosaic nanoparticle display of diverse influenza virus hemagglutinins elicits broad B cell responses / M. Kanekiyo, M.G Joyce, R.A. Gillespie et al. // Nature Immunology. — 2019. — Vol. 20.
4. Apoferritin nanoparticle based dual-antigen influenza conjugate vaccine with potential cross-protective efficacy against heterosubtypic influenza virus / Y. Sheng, J. Wei, Zh. Li et al. // Particuology. — 2022. — Vol. 64.
5. A milk-based self-assemble rotavirus VP6–ferritin nanoparticle vaccine elicited protection against the viral infection / Z. Li, K. Cui, H. Wang et al. // Journal of Nanobiotechnology. — 2019. — Vol. 17.
6. Adding Size Exclusion Chromatography (SEC) and Light Scattering (LS) Devices to Obtain High-Quality Small Angle X-Ray Scattering (SAXS) Data / M. A. Graewert, S. Da Vela, T. W. Gräwert et al. // Crystals. — 2020. — Vol. 10.
The opaque scintillator detector is a novel concept for a new generation of position-sensitive detectors. The main idea is to localize the light near the point of its scintillation via the scattering medium. The first and only published results by the LiquidO collaboration are based on the usage of an opaque liquid scintillator.
Our approach suggests the usage of media based on solid granular organic scintillator and an array of WLS fibers with SiPMs as photodetectors. The report describes the new results obtained during the beam test of different configurations of scintillating and scattering media with external proportional chambers as a tracking system. The results of media comparison and estimation of track reconstruction accuracy are presented.
Ferritin is a protein complex responsible for storing iron in living systems. One of its most remarkable properties is an ability to spontaneously form a spherical hollow protein globule consisting of 24 subunits, this process known as self-assembly [1]. This unique characteristic, combined with ferritin's exceptional stability across a wide range of temperatures and pH levels [2], make it a promising tool in numerous biotechnological applications, including drug delivery, nanotechnology, and vaccine development [3].
Crystallization plays a crucial role in the structural characterization of proteins. Through the formation of ordered structures, the atomic details of proteins can be investigated using X-ray diffraction and other techniques. Understanding the high-resolution structure of ferritin-based complexes can be beneficial for their use in biotechnology, particularly for drug delivery.
In previous work, we developed a model system based on ferritin derived from Helicobacter pylori [4]. In this construct (FerSUMO), ferritin was genetically fused at the N-terminal region with both a His-tag and SMT3 protein, a homolog of the human Small Ubiquitin-like Modifier (SUMO-tag). Small-Angle X-ray Scattering (SAXS) experiments confirmed that under specific expression conditions, the FerSUMO protein assembles into globules containing 24 subunits [4].
In this study, we further investigated the FerSUMO complex. We performed Blue Native PAGE (BN-PAGE), Size-Exclusion Chromatography (SEC), and Negative Stain Transmission Electron Microscopy (NS-TEM) to provide additional information about its structural organization. We also explored the crystallization behavior of the FerSUMO complex using the vapor diffusion method. An extensive screening of crystallization conditions was conducted, followed by an optimization phase. The optimal crystallization conditions for the FerSUMO complex were determined to involve a buffer system containing 100 mM Tris base and BICINE at pH 8.5, along with high-molecular-weight polyethylene glycol (PEG 4000 and PEG 8000). Under these conditions, rhombic crystals with a diameter of about 50 µm were obtained. These crystals require further investigation through X-ray diffraction to resolve the structural details of the protein complex.
This work was supported by the Ministry of Science and Higher Education of the Russian Federation under agreement 075-03-2024-117, project FSMG-2021-0002.
Literature list
1. Zhang, Y. Self-assembly in the ferritin nano-cage protein superfamily / Y. Zhang, B.P. Orner // International Journal of Molecular Sciences. — 2011. — Vol. 12(8).
2. Structure, function, and evolution of ferritins / S.C. Andrews, P.M. Harrison, S.J. Yewdall et al. // Journal of Inorganic Biochemistry. — 1992. — Vol. 47(1).
3. Ferritin self-assembly, structure, function, and biotechnological applications / V.V. Sudarev, S.M. Dolotova, S.M. Bukhalovich et al. // International Journal of Biological Macromolecules. — 2023. — Vol. 224.
4. Ferritin-based fusion protein shows octameric deadlock state of self-assembly / V.V. Sudarev, M.S. Gette, S.V. Bazhenov et al. // Biochemical and Biophysical Research Communications. — 2024. — Vol. 690.
In this work, graphene-based nanostructures on ferrimagnetic substrates such as SmMnC$_3$Cu, EuMnC$_3$Cu, and GdMnC$_3$Cu were investigated. Supercells for the investigated materials were modeled and electronic properties such as the band structure and density of electronic states were calculated using density functional theory. The work was supported by the Ministry of Science and Higher Education of the Russian Federation, project FSWU-2024-0014.
I will present the information about T2K experiment, the near detector ND280 and it’s new subdetector
SuperFGD recently commissioned in the neutrino beam at J-PARC (Japan). SuperFGD is a 3D fine grained scintillating detector. It will detect neutrinos before oscillations and reconstruct kinematic parameters of charged particles with high precision in full solid angle.
Абстракт (Аннотация)
В статье разбирается одна из причин роста продольного эмиттанса в Бустере, возникшая в четвертом пуско-наладочном сеансе, а затем предлагается эффективный способ диагностики. Рассматриваются особенности метода, аппаратное решение и программной обеспечение.
Abstract
The article discusses one of the reasons for the increase of longitudinal emittance in Booster, which appeared in the fourth commissioning session, and then proposes an effective diagnostic method. It describes the features of the proposed method, as well as the hardware and software solutions used.
The adjustable amplifier unit in combination with the automatic gain control unit is designed to regulate and maintain the amplitude of the RF voltage at the accelerating electrode at a predetermined level. The tasks included circuit modernization, installation and bench testing of an adjustable amplifier. The circuit and topology of the board were developed to ensure the uniformity of electronic components. Subsequently, the circuit elements were assembled. Next, the unit was tuned and debugged in bench tests. Bench tests have shown the effective operation of the adjustable amplifier.
One of the SCAN-3 multilayer neutron detectors on the neutron channel in LPI (Troitsk) has been studied. The photodesintegration reaction of a deuteron was used to form a neutron beam. The report describes the procedure for creating a neutron channel, the channel parameters, as well as the results obtained during the work.
In the course of this work, a review of articles on the topic was conducted, some methodological errors were identified and contradictions in the experimental results were revealed. An analysis of the Frank et al. experiment from 2002 was performed. It was shown that the depth of oxide penetration into the protective layer of titanium, which was used in this experiment to prevent gadolinium oxidation, significantly affected the results. An experiment was considered to measure the constant component of the coherent scattering length of natural gadolinium in a geometry where a neutron beam falls on gadolinium through a silicon substrate. To prepare for this experiment, reflection curves with different values of the constant scattering length $b_0$ were calculated. The results obtained are considered preliminary, and their reliability will be confirmed after the experiment is completed.
Time- correlated single photon counting (TCSPC) technique as a powerful analysis tool be used in fluorescence spectroscopy and imaging to measure the fluorescence lifetime of sample. In this report, by analyzing the decay curve of Al2O3 and MgAl2O4 single crystals irradiated by high energy Xe and Bi ions to several fluences. The measurements of the photoluminescence decay curves indicated lifetime increases with emission wavelength increasing in spectral range of 480-660 nm and decreases with ion fluence increasing.
It is suggested that reduction of the decay time with ion fluence is due to growing contribution of nonradiative processes that quench the luminescence yield. The dependence of characteristic lifetimes on registration wavelength is explained by the peculiarities of the charge-transfer processes between defects or defect impurity sites in radiative de-excitation.
This research is dedicated to the problem of strict topologically algebraic proof of discreetness and nondegeneracy of $\mathscr{N} = a^{\dagger} a$ operator in the Hilbert space. It is crucial for building of eigen spaces of operator $\mathscr{N}$ whose direct sum forms the Hilbert space.
The similarity of the effects of ionizing radiation and the effects of aging has been studied by many researchers at different levels of the organization of life, mainly molecular and cellular. Part of the research is aimed at studying radiation-induced changes in the central nervous system, experts in the field of molecular and cellular radiobiology noted the similarity of the identified effects with those observed with aging of the body. Nevertheless, there is practically no data in the available literature on the comparison of functional parameters of small laboratory animals under the influence of AI and aging of the body. The question of the modifying effect of radiation on the processes in the central nervous system associated with age remains open.
In this work, a comparative assessment of behavioral and physiological changes in mice was carried out 10 and 30 days after irradiation of the brain with protons at a dose of 5 Gy, as well as in the aging process. Deviations in the behavior of irradiated mice in the "Open Field" conditions related to the level of anxiety and adaptation, such as acts of grooming and freezing, were found. However, no similar effects were found in older animals.
Bioengineering is the scientific approach that combines engineering principles with the natural sciences to create modified or enhanced systems that address specific challenges. In the context of solar absorbers, bioengineering plays a role in developing solar absorption systems by studying plant mechanisms like photosynthesis, where solar energy is used as the sole energy source to produce a desired by-product. Applying principles derived from these biological processes, along with conventional solar technology, enables the creation of bioengineered solar absorbers for thermal applications. For instance, Yang et al. [1] identified four biochar-based solar absorber variants derived from biomass extracted from E. prolifera, a resource abundant in many coastal regions. The carbonized E. prolifera, with its hierarchically porous and tubular nanostructures, effectively captures solar energy, exemplifying how bioengineering can be applied to develop sustainable solar-thermal solutions.
Keywords: Bioengineered, Solar absorber, Sustainable thermal applications
References
[1] Yang, L. et al., 2019. Sustainable biochar-based solar absorbers for high-performance solar-driven steam generation and water purification. ACS Sustainable Chemistry & Engineering, 7(23), pp. 19311-19320.
In recent years radionuclides or radionuclide pairs applicable for theranostics (a combination of therapeutics and diagnostics in a medical procedure) have gained a lot of interest. Such radionuclides are known with the examples like 67Ga, 117mSn, 123I, 86Y(90Y), 64Cu(67Cu), 124I(131I), 195mPt and are extensively investigated. Radionuclides 195mPt and 193mPt have one of the highest numbers of Auger-electrons which are extremely effective in damaging cancer cell when targeted to an area of a malignancy. The former radionuclide also provides soft -radiation which allows for simultaneous monitoring of the biodistribution of the radiopharmaceutical and thus diagnostics.
In this work we discuss the production of 193mPt and 195mPt by irradiating platinum compounds of natural isotopic composition with bremsstrahlung at the microtron MT-25 (JINR, FLNR) according to the nuclear reactions: 196Pt(γ,n)195mPt, 195Pt(γ,γ’)195mPt, 194Pt(,n)193mPt. The product is obtained with a carrier, so the specific activity is low. The methods of collecting recoil nuclei described in the literature allow increasing the specific activity, but the yield decreases significantly.
To increase the specific activity, we tested a target consisting of a mixture of cisplatin and nanostructured cryptomelane material (K2(Mn4+,Mn2+)8(O,OH)16). Cryptomelane acts as a collector of platinum recoil nuclei. After irradiation, the mixture is extracted, dissolved in water, and the undissolved cryptomelane residue is filtered from the resulting cisplatin solution. Then, cryptomelane is dissolved in a mixture of HCl and H2O2, and platinum is isolated from the manganese solution. This work aims to establish the effectiveness of the proposed materials and the yield of the required radionuclide in the obtained samples.
The continued development of multimodal medical imaging creates demand for contrast agents (CAs) that can be used with multiple imaging techniques. An example of such CAs are Gd-based materials that can be used in magnetic resonance imaging (MRI) and computed tomography (CT), including photon-counting CT. A type of Gd-based material of special interest is nanoparticles with a core-shell structure consisting of a Gd-containing core and a shell formed by amorphous SiO2 with a surface modified with functional groups [1].
The purpose of this work was to produce particles with a core-shell structure Gd2O3@SiO2 and prove their structure for subsequent use as contrast agents for computed tomography and MRI.
Gd2O3 nanoparticles were produced by precipitation of Gd2(C2O4)3*10H2O with subsequent decomposition at 750 °C in an air atmosphere. The particle size, according to scanning electron microscopy (SEM), was 200-500 nm. The particle size in an aqueous suspension, measured by the method of optical scattering of particles suspended in water, was 5-10 μm, which probably corresponds to the size of the associates. Particles with a core-shell structure were produced by treating Gd2O3 with (EtO)3SiC3H6NH2 (ɣ-APTES) and then with H2O vapors in a fluidized bed reactor. In this case, the treatment time with ɣ-APTES was varied from 5 to 30 min, and the temperature of the reactor working zone was varied from 150 to 250 °C [2].
According to IR spectroscopy data, all produced preparations contained a characteristic peak of [SiO4] at 1100 cm-1. According to TG data, the weight loss at 250-600 °C was from 0.8 to 1.2 wt. %, that corresponds to different contents of functional C3H6NH2 groups.
This research was supported by Russian Science Foundation (project number 22-15-00072).
Literature:
1. Evgeniya Suslova, Denis Shashurin, Zukhro Zoirova, Alexey Shumyantsev, Oleg Medvedev, Georgy Chelkov. Gd2O3-based contrasting agents for photon-counting computed tomography: Effect of structure, composition, and particle size. Materials Chemistry and Physics, Volume 313, 2024, 128733, ISSN 0254-0584. https://doi.org/10.1016/j.matchemphys.2023.128733.
2. Amirhossein Mahtabani, Damiano La Zara, Rafał Anyszka, Xiaozhen He, Mika Paajanen, J. Ruud van Ommen, Wilma Dierkes, Anke Blume. Gas Phase Modification of Silica Nanoparticles in a Fluidized Bed: Tailored Deposition of Aminopropylsiloxane. Langmuir 2021, 37, 15, 4481–4492. https://pubs.acs.org/doi/10.1021/acs.langmuir.0c03647.
Forward Hadron Calorimeter (FHCal) is one of the basic detectors at MPD/NICA facility and intended for the measurement of the geometry of heavy nuclei collisions, namely, the centrality and the orientation of reaction plane. FHCal is placed in the forward rapidity region to measure the energy of non-interacting nucleons (spectators) of colliding ions. It consists of two equivalent arms situated symmetrically respective the collision point. Each FHCal part consists of 44 lead/scintillator sandwich modules with fine transverse and longitudinal segmentation. At present, one FHCal arm is assembled and placed in pole of MPD solenoid magnet. We present the construction and expected performance of FHCal. The most attention is devoted to the energy calibration of FHCal modules with cosmic muons. A few approaches of calibration with different muon track geometries are discussed. The results of the energy calibration of FHCal prototype are presented.
Bose-Einstein interferometry of identical hadrons are known to be one of the key experimental tool to study space-time properties of the hot and dense nuclear matter (fireball) in heavy-ion collisions. However, hadron correlations capture the space-time evolution of the source at the freeze-out stage, when final-state hadrons are formed. On the other hand, direct photon correlation are expected to provide important information on the space-time evolution of the fireball on its earliest stages, as direct photons are emitted from the fireball center. Thus, transverse and longitudinal radii of the fireball and their $k_{\text{T}}$-dependence due to fireball radial extension before freeze-out might be measured using two one-dimensional photon-photon correlation functions. The Multi-Purpose Detector (MPD) of the Nuclotron-based Ion Collider facility (NICA) is designed to study the baryon-rich region of the QCD phase diagram, and Bose-Einstein interferometry is an important component of MPD experimental program. In this talk, the possibility to perform measurements of Bose-Einstein photon-photon correlations in Bi-Bi collision at $\sqrt{s_{NN}}$ = 9.2 GeV at MPD using UrQMD model are reported.
Experimental discovery of the resonant-like states in di-J/ψ and J/ψ-ψ(2S) mass specrta in pp-collisions near production threshold suggest the existence of the fully-charmed tetraquarks. Numerous theoretical models that followed the dicovery describe the observed data, speculate on the physics of the new states and predict new observations.
Further studies require precise experimental measurements. The amplitude analysis is one of the approaches to the precise studies of hadron spectra. It allows simultaneous fits of the mass and angular distributions of the decay products, naturally accounts for the sophisticated intereference effects between resonance candidates and background, detector effects, etc.
In this report, the most recent theoretical and experimental results together with their future perspectives and new data analysis techniques are discussed.
Event indexing, or event metadata systems (EMS) are common for particle physics experiments. Their main goal is to keep a searchable catalogue of experimental events from which a subset of data can be extracted based on given filtering criteria. The BM@N experiment's EMS has been designed, developed and deployed previously and is now being improved to increase its performance, convenience for users, as well as fault tolerance. In this talk, the architecture of the current version of the BM@N EMS is reviewed and some recent improvements that have been applied are discussed.
In the course of developing a software ecosystem of the BM@N experiment, a multitude of web services are created, including data processing systems and information resources. A significant challenge is the monitoring of system operational states as an integral component of the maintenance procedure. The report considers implementing a contemporary solution for log management of the BM@N software systems. The utilization of an API Gateway as a singular access point for all web services is highlighted, as it streamlines collections of data regarding incoming requests. Additionally, a system for the collection and storage of logs has been implemented based on the high-performance and cost-effective technology stack of ClickHouse and Datadog Vector. The employment of the Metabase business intelligence platform further facilitates the analysis of the collected logs. Ultimately, the integration of these solutions enhances the resilience of the system and facilitates security auditing. This contributes to improved state tracking of the systems within the information infrastructure of the BM@N experiment.
The BM@N experiment, as part of the NICA complex, produces a substantial quantity of physics data, necessitating the implementation of a sophisticated infrastructure for the efficient storage, processing, and management of the data. In order to address these challenges, a comprehensive set of information systems has been developed. The complex includes an information system representing the Unified Condition Database (UniConDa) that stores necessary parameters of experiment systems; the Configuration Information System (CIS) for managing detector settings and a sequence of software tasks to be used in online; the Geometry Database for operating with information on geometric models of detectors; the Event Metadata System (EMS) for indexing and searching physics events for analysis; and an electronic logbook (e-Log platform) to record information on experiment runs during sessions; and many others. In addition, the BM@N uses various collaboration services, which have been already developed, such as the official website, collaboration forum, document server (Wiki). Security Policy is ensured through the Keycloak, authentication and authorization system, which centralizes access control to BM@N software systems. The report also covers the description of deployed infrastructure on a cluster platform managed by the Proxmox system, which oversees virtualization and containerization of the infrastructure components. An integrated gateway ensures centralized secure access to all software systems of the experiment, while its multi-tier architecture including web interfaces, REST APIs, and backend provides modularity and simplifies component updating. As a result, the developed infrastructure of the information systems and software services ensures the management of information being necessary for physics analysis of experiment data within the BM@N experiment.
Fractals are objects that are fragmented to such an extent that measuring them with the measures we are accustomed to (length, area, volume) gives different results depending on the choice of the measuring segment (scale). The concept of "fractal" was introduced by Benoit Mandelbrot [1], who also laid the foundation for a new "fractal" geometry. Using modeling experiments on small-angle light scattering using the numerical Fourier transform, our team developed a classification of fractal and non-fractal objects in two-dimensional space [2]. Logarithmic fractals are a class of fractals whose representatives have a hierarchical branching structure and obey the law of equality of area at different levels of their hierarchy (different scales).
In our work [3], it was shown that the lateral projection of a mature deciduous tree is a logarithmic fractal. We concluded that during growth and branching, a tree obeys the law of conservation of area when scaling from several meters to several decimeters: the total area of the lateral surface of the "daughter" branches is equal to the surface area of the branch from which they grow. In a huge number of experimental scattering curves in the region of large transmitted impulses (on small scales), a crossover to another regime is observed, which is distinguished by a different exponent when scaling from decimeters to centimeters (the scale of young branches). We proposed a mathematical model that distinguishes the organization of young branches and young trees in general from the structure of an adult tree and adult branches. The model is based not on the law of conservation of area, as for an adult tree, but on the law of conservation of branch volume: the total volume of "daughter" branches is equal to the volume of the branch from which they grow.
We also used the numerical Fourier analysis method for experimental study of the fractal structure of spruce branches. Images of spruce branches of an adult tree over 10 meters in size at different tree heights were studied. Fourier images of photographs of spruce branches demonstrate the same structure of the small-angle scattering curve: the Guinier region, two sections with a linear character of intensity decrease, the Gaussian region. We proposed a mathematical model describing the obtained curves: I(q) = A∙exp((qb)2/3) + P∙q^(-N) in the region of small transmitted impulses (large scales) and I(q) = R∙q^M + S∙exp(-2∙(q - L)^2/F^2 in the region of large transferred impulses (small scales). It is shown that the exponent N is close to 2, which corresponds to a logarithmic fractal, the Gaussian function describing the behavior of the curve in the region of large transferred impulses corresponds to needles. It is shown that since on large scales the spruce paws are formed taking into account the needles covering them, obeying the law of a logarithmic fractal in two-dimensional space, the rule of preserving the area of branches with needles before and after branching is fulfilled for them.
The achievement of high accuracy in theoretical modeling of the electronic structure of materials containing f-elements, in particular lanthanides and actinides, requires simultaneous consideration of relativistic and correlation effects. The most promising method that satisfies this requirement is the relativistic coupled cluster method (RCC), which leads to extremely resource-intensive calculations. It is possible to achieve increased capabilities and reduced computational complexity by using tensor decompositions to store data and optimize the algorithms used in modeling.
For this purpose, a detailed analysis of the efficiency of various tensor decomposition schemes (canonical [1], tensor train [2] and Tucker [3] decompositions) were carried out. Optimal algorithms were found for performing the approximate decomposition of tensors of molecular integrals and cluster amplitudes, and the computational complexity of algorithms implementing the basic operations of the working equations of the coupled cluster method was evaluated.
For the first time, the equations of the coupled cluster method for the ground state were formulated directly in terms of tensor trains, including versions of the method that take into account the contributions of triple excitations of reference functions. Also a software implementation was performed and include to the EXP-T quantum chemical package [4]. Pilot calculations using CCSD method was carried out, in which the superiority of solving the equations of the coupled cluster method in terms of tensor trains was shown.
[1] Kolda T. G., Bader B. W. Tensor Decompositions and Applications // SIAM Review. 2009. V. 51, no. 3. PP. 455–500. doi: 10.1137/07070111X.
[2] Oseledets I. V. Tensor-Train Decomposition // SIAM Journal on Scientific Computing. 2011. V. 33, no. 5. PP. 2295–2317. doi: 10.1137/090752286.
[3] Tucker L. R. Some mathematical notes on three-mode factor analysis // Psychometrika. 1966. V. 31, no. 3. PP. 279–311. doi: 10.1007/BF02289464.
[4] Oleynichenko A. V., Zaitsevskii A., Eliav E. Towards High Performance Relativistic Electronic Structure Modelling: The EXP-T Program Package // Supercomputing. Springer International Publishing, 2020. PP. 375–386. doi: 10.1007/978-3-030-64616-5 33.
Molecules containing heavy element atoms can be utilized to explore "new" physics beyond the Standard Model through precision experiments designed to detect violations of spatial parity (P) and time reversal (T) symmetries in fundamental interactions. One of the most commonly discussed sources of T and P violation in molecules is the electron electric dipole moment (eEDM) [1]. Although a non-zero eEDM has yet to be observed, limits on its value have been established. The most stringent constraint to date was obtained by the JILA group in their experiment with the hafnium monofluoride (HfF+) molecular cation [2]. Additionally, an upcoming experiment with barium monofluoride (BaF) is anticipated to yield a similarly close independent constraint [3].
However, the violation of time reversal (T) and parity (P) symmetries in fundamental interactions within molecules can arise not only from the eEDM but also from the exchange of virtual axionlike particles between electrons and between electrons and nuclei. In this study, we examined this effect in the hafnium monofluoride (HfF+) molecular cation and the barium monofluoride (BaF) molecule. For the electron-nucleus interaction, our calculations accounted for the finite size of the nucleus. By analyzing the molecular parameters related to these interactions, we established constraints on the products of interaction coupling constants that align with the current sensitivity of experiments involving HfF+ [2] and the anticipated sensitivity of future experiments with BaF [3]. The results were published in references [4] and [5]. Additionally, we will discuss new findings on parity violation effects that were not included in those publications.
Calculation of potential energy surface were supported by the Russian Science Foundation Grant No. 24-12-00092. Calculations of matrix elements and development of corresponding code were supported by the Foundation for the Advancement of Theoretical Physics and Mathematics “BASIS” Grant according to Project No. 24-1-1-36-2.
[1] Safronova M.S., Budker D., DeMille D., Kimball D.F.J., Derevianko A., Clark C.W. (2018). Reviews of Modern Physics 90.2: 025008.
[2] Roussy T.S., Caldwell L., Wright T., Cairncross W. B., Shagam Y., Ng, K.B., ... & Cornell E. A. (2023). Science 381.6653: 46-50.
[3] A. Boeschoten et al., arXiv:2303.06402 (2023)
[4] S. D. Prosnyak, D. E. Maison, L. V. Skripnikov, Updated Constraints on T, P-Violating Axionlike-Particle-Mediated Electron–Electron and Electron–Nucleus Interactions from HfF+ Experiment, Symmetry 15(5), 1043 (2023).
[5] S. D. Prosnyak, L. V. Skripnikov, Axion-mediated electron-nucleus and electron-electron interactions in the barium monofluoride molecule, Phys. Rev. A 109, 042821 (2024).
This study investigates the stability of anisotropic collisionless plasma layers to small disturbances within the magnetohydrodynamic (MHD) framework. We focus on the fire hose mode instability, particularly in the context of shear flows in cosmic plasmas. Our analysis is based on moment equations derived from the Vlasov kinetic equation, taking into account heat flow along spatially shearing flows.
We solve the boundary value problem for a smooth hyperbolic velocity profile using WKB approximation, resulting in a general integral dispersion equation. This equation describes various types of body and interface instabilities in the presence of heat flow along the magnetic field. Our findings indicate that reducing the layer width significantly enhances mirror instability while suppressing oblique fire-hose instability.
The study particularly examines how spatial gradients in plasma flow affect the properties of aperiodical oblique fire-hose instability in a limited layer. We demonstrate that spatial gradients in flow velocity greatly enhance this instability. Furthermore, as the shearing layer width narrows and velocity gradients increase, body hose modes transform into surface Kelvin-Helmholtz modes at the interface between flow regions with different velocities.
This research contributes to our understanding of plasma instabilities in cosmic environments, such as the solar wind and astrophysical jets, where anisotropic, collisionless plasmas with shear flows are common.
New data obtained with the Event Horizon Telescope (EHT) for black holes in the galaxy M87 (K. Akiyama, et al., Astrophys. J. 875 (1) L5 (2019)) and in the center of our galaxy Srg A (The Event Horizon Telescope Collaboration, The Astrophysical Journal Letters 930 L17 (2022)) require improvements in theoretical predictions, especially regarding the shadow profiles of black holes (BHs). It was obvious from the outset that both BHs studied are rotating. The rotation velocity of M87* was recently measured (Cui, Y.; others. Nature 621, 711–715, (2023)). At the same time, a direct search for an axisymmetric solution by directly solving the Einstein–Hilbert equations turns out to be not very simple. Therefore, an alternative method (the Newman-Janis algorithm) was proposed to generate rotating solutions from non-rotating ones (Newman, E.T.; Janis, A.I., J. Math. Phys. 6,915–917, (1965)). Recently, simulations were performed for the Bumbelbee model (Capozziello, S.; Zare, S.; Hassanabadi, H., (2023) https://arxiv.org/abs/2311.12896). This paper notes an interesting phenomenon: when a Kerr-type metric with additional parameters (e.g. tidal charge) is considered, these new parameters can change the size and shape of the shadow. Therefore, if (after improving the experimental precision) the EHT finds that the shadow does not exactly match the Kerr metric, this will allow the contribution of the tidal charge to be estimated. This means that the contribution of new physics will be measured.
We obtain black hole rotating solutions for Horndesky theory (specific partial case), bumblebee model and Gauss-Bonnet scalar gravity using the specially improved Newman-Janis algorithm. The shadow profiles for these metrics were calculated. Applying the limitations from the Event Horizon Telescope we find the opportunity to constrain model parameters from considered extended gravity theories. We show that for three considered models two of them (Horndesky theory and Gauss-Bonnet scalar gravity) weaken the effect of rotation and bumblebee model enhances it. This conclusion matches the previously obtained one that extended gravity theories by themselves correct the effect of rotation in both directions.
The use of photon-counting detectors (PCD) in X-ray computed tomography (CT) allows for obtaining specific spectral information about the materials present in the studied object. This provides the capability to detect contrast agents (CAs) based on elements with high atomic numbers, which opens up significant prospects for diagnostics and preclinical trials. This work presents a criterion for the extraction of a contrast agent and the determination of its concentration based on the K-edge absorption. The criterion is built on the study of the spectral characteristics of CAs. It considers scenarios where more than two contrast agents are simultaneously used in a wide range of concentrations in the study. The experiment was conducted using a laboratory microtomographic system based on the Medipix3RX detector family. The criterion utilizes five energy thresholds for the identification of a single contrast agent. Lanthanides were used as contrast agents.
This research was funded by the Russian Science Foundation, grant number 22-15-00072.
Boron and its compounds have distinct properties that allows them to be used extensively in various fields. Their non-toxicity has made them attractive in the healthcare and cosmetic industry [2]. Boron and Boron Carbide nanoparticles synthesized at room temperature by pulsed laser ablation in liquid method have shown to give smaller <100nm non-toxic particles with good chemical stability. These nanoparticles could be explored in the application of boron neutron capture therapy (BNCT). This therapy targets only boron/ boron compound bearing cancer cells through a low-energy thermal neutron beam (0.025 eV) without killing the neighbouring normal tissue [1]. The neutron beam interacts with the deposited boron/ boron compound in the tumor cells, causing it to split into an alpha particle (4He) and the recoiling of lithium nucleus (7Li), which are stable nonradioactive isotopes [2]. Boron target will be synthesized and the nanoparticles shape, size and optical properties characterized for this study.
Keywords: nanoparticles, non-toxicity, laser, ablation, neutron
References
[1]. Cheng, X., Li, F., & Liang, L. 2022. Boron Neutron Capture Therapy: Clinical Application and Research Progress. Current Oncology, 29(10), 7868–7886.
[2]. Tatiya, S., Pandey, M., & Bhattacharya, S. 2020. Nanoparticles containing boron and its compounds—synthesis and applications: A review. Journal of Micromanufacturing,
3(2), 159 –173.
Clinical target volume (CTV) is traditionally defined in radiotherapy, but has several limitations (especially binary concept, variability and uncertainty). Recently was introduced a new continuous probabilistic concept - Clinical Target Distribution (CTD), which should help to eliminate the above limitations. In this paper, we implemented CTD in treatment planning system for proton therapy and compared CTV and CTD in the cases of skull base chordomas. Using new concept we received prescription dose in tumor, satisfied maximal dose constraints for the OAR and got some advantages in dose distribution.
Effective noise amplification has been experimentally demonstrated during the interaction of a relativistic electron beam (electron energy 250 keV, current 1.5 kA, pulse duration 2 ns) with slow plasma waves in a plasma maser, in which a double coaxial waveguide is used as the generator section. The outer and inner electrodes of the section are metal, and the role of the middle electrode is played by tubular plasma. The optimum length of the generator section was determined to create conditions that maximize noise amplification.
As it was shown in [1], the use of such a plasma maser system "makes it possible to increase the electron beam current transported through the system, at which the instability increment and the efficiency of the conversion of the energy of directed motion of electrons also increase". In the process of analyzing experimental data, the dependence of the emission amplitude on the length L of the generator section of the plasma maser was obtained. The measurements were performed at a fixed plasma concentration n = 2·1013 cm3. The emission amplitude grows while changing the length L of the generator section of the plasma maser from 10 to 40 cm, reaches its maximum at L = 40 cm and then decreases, which is typical for microwave devices. The emission frequency of the plasma maser is in the range from 3 to 8 GHz.
Fig. 1. Dependence of the output emission amplitude of a plasma maser with a double coaxial plasma-metal waveguide on the length of the generator section.
As a result of the research, it can be concluded that the presence of the inner electrode not only does not harm the emission of the plasma maser, but also opens the way for promising research on increasing the plasma maser power in a coaxial configuration.
This work was performed under the contract № Н.4к.241.09.23.1050 from 10.04.2023.
References
[1]. I. N. Kartashov and M. V. Kuzelev. The Use of a Coaxial Electrodynamic System for Amplification of Microwave Range Waves During the Development of Beam–Plasma Instability // Plasma Physics Reports, 2021, Vol. 47, No. 6, pp. 548–556.
The LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode material was synthesized by a two-step process, co-precipitation and solid-state methods. The effect of varying the volumes of the chelating (NH4OH) and precipitating (NaOH) agents on the structure, morphology, thermal stability and cycling performance of the prepared NMC811 nanopowders was investigated. The thermogravimetric analysis showed that the NMC811 was stable when annealed with temperatures around 900 ℃. The X-ray diffraction patterns showed that the NMC811 material consists of the hexagon α-NaFeO2 structure. The crystallite sizes ranging from 77 to 101 nm increased with an increase in volumes of the chelating and precipitating agents, respectively. Scanning electron microscopy revealed quasi-spherical shaped secondary particles for the prepared NMC811 nanoparticles. The pyramid-shaped particles changed and appeared to melt together, and irregular polyhedron-like particles crumbled into smaller particles with an increase in the volume of chelating and precipitating agents, respectively. The surface composition of the cathode materials was studied by X-ray photoelectron spectroscopy. The galvanostatic charge/discharge results showed high Coulombic efficiency above 95% after 80 cycles for all samples, and the 20 ml NH4OH sample had the highest discharge capacity of 142 mAh g-1. The EIS results revealed that the chelating agent less affects the resistance at the electrode-electrolyte interface than the precipitating agent. Thus, leading to improved efficiency and performance in applications where rapid charge and discharge cycles are required.
The Highly Granular Neutron Detector (HGND) has now been developed and constructed for the measurements of neutron yields and flow in nucleus-nucleus collisions in the BM@N experiment at the NICA accelerator complex. Its compact prototype was first used in the BM@N experiment to study collisions of 3.8A GeV $^{124}$Xe with a CsI target. The HGHD prototype consists of longitudinally alternating layers of absorber and scintillator with high transverse granularity to ensure an efficient detection of neutrons. Each scintillator layer consists of a 3x3 array of scintillator detectors (40x40x25 mm$^3$) with SiPM individual readout. The time resolution of detectors is about 150 ps, and it allows the measurement of the kinetic energy of neutrons traveled the distance of 8.3 m from the target via the time-of-flight technique providing a good energy resolution.
In this work, the calculated efficiency and geometric acceptance of the HGND prototype in detecting spectator neutrons from hadronic interactions and electromagnetic dissociation (EMD) of $^{124}$Xe are presented. The DCM-QGSM and UrQMD models coupled with the SMM and AMC codes, respectively, to simulate decays of excited spectator matter left after the first fast stage of nucleus-nucleus collisions were used as primary event generators for nucleus-nucleus collisions. The RELDIS model was used to generate EMD events. The systematic uncertainties of the calculated efficiency and acceptance of the HGHD prototype have been estimated and discussed.
One of the current tasks being carried out at the BM@N experiment involves categorizing event based on their centrality by using the energy of projectile spectators as measured by the FHCal. A precise procedure for determining the centrality allows estimating the initial geometry of the heavy ion collision and also gives the possibility to compare the results with model data and other experiments. Determination of centrality using the energy of the spectators can suppress the autocorrelation effect and also become a new alternative way of centrality determination. The purpose of the new method is also related to the large uncertainty of the impact parameter in Glauber model at small multiplicity of charged particles at NICA energy range. A new approach, based on Bayes' theorem and two-dimensional Gamma distribution, for centrality determination with FHCal is proposed. The performance of the proposed approach has been tested on simulation data from the DCM-QGSM-SMM model for Xe+CsI collisions at a beam energy of 3.8A GeV.
The BM@N is a fixed-target experiment aimed at studying of heavy ion collisions at beam energies up to 4 A GeV. The new Highly Granular Neutron Detector (HGND) is being developed for this experiment. This detector will be able to carry unique measurements of flow of the neutrons. Due to these measurements it will be possible to explore the isospin degree of freedom of the QCD phase diagram.
One of the methods to detect neutrons in highly granular detectors is to merge fired cells into clusters, apply selection criteria to these clusters and reconstruct their energy by the time of flight. This talk is devoted to the determining of the efficiency and purity of neutron reconstruction using such an algorithm. The proposed method is verified by Monte-Carlo simulation.
This work is devoted to the search for phi mesons after collision of Xe beams with a CsI target at E = 3.8 AGeV at the BM@N experiment (JINR, Dubna). Both MC and experimental data were analyzed and peaks in the invariant mass distribution corresponding to phi mesons were obtained. The future aim is to increase our understanding of the transition from baryonic matter to (quark-gluon plasma) QGP.
Collective flow is one of the most important observables sensitive to hot and dense matter produced in heavy ion collisions at the beam energy of several GeV. In 2023 Baryonic Matter at Nuclotron experiment conducted the first physical run collecting high-statistics data on Xe+CsI collisions at $E_{kin} = 3.8A$ GeV. We present the first results for directed flow of protons with respect to the spectator symmetry plane and compare the obtained results with existing word data.
The BM@N 8th physics run using Xenon ion beams was successfully completed in February 2023, resulting in the recording of approximately 550 million events. These events were recorded in the form of aproximately 30000 files, with a combined size exceeding 400 TB. The processing of the BM@N files is done in two steps: converting files from Raw format to Digi and on the next step converting from Digi to Dst. This process requires significant computing resources, which is why a distributed infrastructure united by DIRAC was chosen for this task. New methods were developed to make the data processing robust and repeatable. For the first time DIRAC had been used for raw data processing in JINR in production mode. The conversion of BM@N files from Raw to Digi became the most data intensive task solved so far on a distributed infrastractue. A set of approaches, systems, and methods were developed during this data production campaign, whichs help to reduce the efforts required for the next data productions at JINR.
One of the principal technical characteristics of the SPD (Spin Physics Detector) is its triggerless data acquisition. The data acquisition system (DAQ) aggregates data from the detectors of the facility and organizes them into blocks for further primary processing. This approach allows for data arrival rates of up to 20 Gb/sec, with the annual volume of collected data reaching hundreds of petabytes. To address the challenge of detecting and filtering events in the data stream, a specialized computing system, the SPD Online Filter, is being developed.
The "SPD Online Filter" will be a complex of hardware and software designed for the high-throughput processing of primary data from the SPD experimental unit's detection system. The hardware component will comprise a set of multi-core computing nodes, high-performance data storage systems, and a number of control servers. The software component will include not only application software but also a set of middleware that will organize and execute multi-stage data processing steps.
This talk will present a description of the architectural and functional characteristics of a prototype workload management system, together with an account of its current status. The system is designed to facilitate the generation of computational jobs for processing a block of data, the distribution of jobs to computing nodes, and the control of their execution.
Modern experiments in high energy physics are characterized by the need to process huge amounts of data.
SPD (Spin Physics Detector) is a universal detector of the NICA collider (Nucleotron–based Ion Collider fAcility), being built at the Joint Institute for Nuclear Research (Dubna), and designed to study the spin structure of the proton, deuteron and other spin phenomena with polarized beams of protons and deuterons. The expected volume of data collected only at the SPD installation is measured in petabytes per year. To process such volumes of data, it is necessary to combine the resources of several computing centers that can be located remotely, thus forming a geographically distributed computing environment. Given the volume of data and the need for processing in a geographically distributed computing environment, a data management system becomes a key tool for distributing data and ensuring its integrity and accessibility. There is a need for security and access control for this system. In the context of the Rucio Scientific Data management system, as an integral part of the GRID, authentication and authorization are key roles in ensuring security.
This report is devoted to Rucio deployment, configuration and integration with the JINR SSO using JWT-based authentication, and review of the first experience of SPD data management.
Neutron tomography is a powerful tool in material science due to the large penetration depth, sensitivity to light elements and good contrast for elements with close atomic numbers. Such properties of the interaction of neutrons with matter make it possible to obtain data on the internal structure of objects that complement X-ray tomography. However, a significant disadvantage of the method remains the long duration of the experiment. With some exceptions, it takes up to several hours on most installations to obtain the number of radiographic projections satisfying the Nyquist–Shannon theorem. In turn, this does not allow for the study of large series of samples, which is required to obtain statistically significant results in areas such as archaeology. Prolonged exposure to the neutron beam exposes the studied objects to a greater radiation load, which also imposes restrictions on the study of valuable or rare archaeological artifacts. Thus, there is a need for comprehensive development of the neutron tomography method.
One possible way to reduce the time of conducting neutron tomography experiments may be to use fewer radiographic projections. However, tomographic reconstruction from an incomplete data set using standard methods such as filtered back projection (FBP) or simultaneous algebraic reconstruction (SART) leads to low-quality three-dimensional models. Reconstruction methods based on convolutional neural network (CNN) make it possible to circumvent the limitations of classical algorithms. CNNs have proven themselves primarily as a tool for working with images, since they require fewer trainable parameters compared to a fully connected perceptron and reveal the spatial relationship between pixels well.
In this work, the effectiveness of convolutional neural networks in tomography reconstruction algorithms using incomplete data was investigated. Several CNN architectures were compared by test calculations on the Shepp-Logan phantom, as well as on real experimental data. The robustness of the developed algorithms was evaluated with minor fluctuations in the volume of input data. The use of convolutional neural networks made it possible to reduce by 80% the required number of projections for high-quality reconstruction.
The work was supported by AYSS grant No. 24-401-02.
A proprietary method for finding the global minimum to optimise the loss function of a neural network has been developed. The method involves the use of an arbitrary loss function. In this study, a function based on the calculation of the area under the ROC curve (AUC) was implemented. The application of this method in combination with the optimisation of the hyperparameters of the neural network significantly increases its efficiency.
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. Some K-isomers in these nuclei are inspected. It is shown that, in the chain 250−260No, features of 252No and 254No exhibit essential irregularities caused by a shell gap in the neutron single-particle spectra and corresponding break of the neutron pairing. The low-energy pairing-vibrational Kπ = 0+ state is predicted.
[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).
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 lowenergy 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.
References
1. M. Tamkas, E. Aciksoz, J. Issak, T. Beck, N. Benouaret, M. Bhike I.Boztosun, A. Durusoy, U. Gayer, Krishichayan, B.Loher, N. Pietralla, D. Savran , W.Tornow, V. Werner, A.Zilges, M. Zweidinger, Nucl. Phys. A987, 79 (2019).
2. V.O. Nesterenko, P.I. Vishnevskiy, P.-G. Reinhard, A. Repko and J. Kvasil, Eur. Phys. J. 60, 28 (2024).
In an earlier work [1], the calculation of the molecular parameter Wₐ, which characterizes nuclear spin-dependent effects parity violating (NSD-PV) in the ²⁹Si¹⁶O⁺ cation for the ground state, was discussed. One of these effects is the nuclear anapole moment [2], which dominates in NSD-PV [3]. The work [1] lists various sources of contributions and their uncertainties, to which the vibrational correction of the molecule can also be added.
When taking the vibrational correction into account in the first approximation, it becomes clear that to describe it correctly, non-adiabatic effects must be considered. In the adiabatic approximation, the terms of the ground Σ½ state and the excited Π½ state “repel” each other due to spin-orbit interaction. As a result, the function Wₐ(R) (where R is the internuclear distance) has a discontinuity at the “pseudo-crossing” point of these terms, which prevents proper averaging over the vibrational frequencies of the ground state. Therefore, to solve the non-adiabatic vibrational problem using scalar-relativistic calculations, it is necessary to include the non-diagonal matrix element of the spin-orbit interaction between these terms.
In this work, using the coupled-channel method [4], a solution to the non-adiabatic vibrational problem is discussed, and a Python program was written to calculate non-adiabatic vibrational wave functions. The obtained result is essential for the interpretation of an experiment being prepared by a group from MIT [5], which aims to refine the Standard Model in the sector of weak interactions.
Funding The work is supported by the Russian Science Foundation grant no. 24-12-00092 and the “BASIS” grant no. 24-1-1-36-3.
References
A model for the alpha-decay of actinide nuclei has been presented. Within the framework of this model, the fine structure of alpha-decay and its dependence on the spectroscopic factor are studied.
The calculation of the potential energy of the alpha-cluster system and the wave function of the metastable state is performed taking into account the quadrupole and octupole deformation of the daughter nucleus. To calculate the dependence of the spectroscopic factor on angular momentum, the relative motion of the alpha-particle and the daughter nucleus was taken into account. The calculations were performed in the two-potential approach.
The developed model was used to analyze the fine structure of different isotopes of Ra, Th, U and Pu. By comparing the results obtained with experimental data, the parameters of the octupole deformation were estimated.
Представлен метод решения уравнения Шредингера методом кубических сплайнов [1]. Задача сводится к нахождению собственных значений и векторов матрицы, причем применение сплайн-интерполяции позволяет находить кусочно-гладкие решения даже при не очень малом шаге сетки и не очень большом размере матрицы (рис. 1а). Метод применен для решения системы гиперрадиальных уравнений при расчетах энергии и волновой функции (рис. 1б) основного состояния ядра 9Be(α+α+n), 12C(α+α+α) и 6Li(α+n+p) в альфа-кластерной модели с помощью разложения по гиперсферическим функциям [2]. Метод реализован на языке C++ с применением библиотек параллельного программирования (OpenMP, NVIDIA CUDA). Рассчитаны энергия основного состояния ядра, среднеквадратичный зарядовый радиус и зарядовое распределение, получено согласие с экспериментальными значением (см., например, [3]).
1. Г.И. Марчук, Методы вычислительной математики. ‒ М.: Наука, 1980.
2. Р.И. Джибути, К.В. Шитикова, Метод гиперсферических функций в атомной и ядерной физике. ‒ М.: Энергоатомиздат, 1993.
3. В.И. Загребаев, А.С. Деникин, А.В. Карпов, А.А. Алексеев, М.А. Науменко, В.А. Рачков, В.В. Самарин, В.В. Сайко, База знаний NRV по ядерной физике низких энергий, http://nrv.jinr.ru/.
Gamma-cameras are one of the most popular tool in nuclear medicine for the tomography of human organs with the single photons emitted by the radioactive isotopes. As a rule, these cameras consist of a large continuous scintillator or of many small scintillator pixels. Both types have their own advantages and drawbacks. Here we suggest another type of modular gamma-camera that combines the features of the previous two types. Modular structure has a series of advantages, including scaling, simplicity and reproducibility of the parameters of separate elements of gamma camera. We constructed and tested an element of modular camera that consists of inorganic scintillator CsI(Tl) or CsI(Na) with the dimensions 25x25x8 mm3. The light readout is done by 3x3 matrix of 9 silicon photomultipliers with the sizes 6x6 mm2 each. The performance of this prototype was tested with 57Co radioactive source with gamma-ray energy of 122 keV. The obtained energy and spatial resolution are discussed. New algorithms for the reconstruction of gamma interaction point were developed.
Automation and real-time monitoring are hampered by the fact that traditional methods of controlling operations in opaque reactors typically rely on expensive and invasive sensors. This presentation discusses a low-cost, non-invasive technique that provides useful insights into process dynamics using electrical energy analysis. We demonstrate the application of electrical parameter fluctuations such as power and current as indicators of significant process changes in opaque reactors. This method could be of great benefit to the High-Tech industry, where precise process control is required to produce consistent, high-quality products. In our evaluation of the advantages and limitations of the method, we emphasize how the approach can increase production efficiency while reducing the need for human intervention in process control.
Understanding the momentum distributions of the spectator fragments in relativistic nuclear collisions, such as those in the BM@N experiment (NICA), helps to estimate the acceptance of the zero-degree calorimeters and other forward detectors. BM@N is equipped with FHCal and SciWall, which can detect spectator nucleons and at least some spectator fragments [1]. In order to simulate this response, one needs the model which provides realistic momentum distributions of the spectator fragments.
In this work we use the Abrasion-Ablation Monte Carlo for Colliders (AAMCC-MST) model [2] with and without MST clustering as the pre-equilibrium fragmentation model to simulate the production of spectator fragments [3]. The Goldhaber model [4] is used to account for the intranuclear motion of the removed nucleons. The momentum distributions of the spectator fragments were simulated and validated with data from the KLMM collaboration [5, 6]. Then, the momentum distributions of spectator neutrons, protons, hydrogen and helium fragments, light and heavy fragments in 124Xe+CsI collisions at BM@N were calculated for different centrality ranges. It was found that accounting for pre-equilibrium fragmentation increases the mean transverse momentum pT of the spectator fragments and improves agreement with the experimental data.
References
1. M. Kapishin et al., Studies of baryonic matter at the BM@N experiment (JINR). Nuclear Physics A. 982, 967-970 (2019)
2. Svetlichnyi, A.O., Pshenichnov, I.A. Formation of Free and Bound Spectator Nucleons in Hadronic Interactions between Relativistic Nuclei. Bull. Russ. Acad. Sci. Phys. 84, 911–916 (2020)
3. Nepeivoda R, Svetlichnyi A, Kozyrev N, Pshenichnov I. Pre-Equilibrium Clustering in Production of Spectator Fragments in Collisions of Relativistic Nuclei. Particles. 2022; 5(1):40-51
4. A.S. Goldhaber, Statistical models of fragmentation processes. Physics Letters B. 53, 306-308 (1974)
5. M. L. Cherry et al., Fragmentation of the Pb projectile at 158 GeV/nucleon in Pb–Pb interaction. Acta Physica Polonica B. 29, 2155 – 2175 (1998)
6. KLMM Collaboration., Cherry, M.L., Dąbrowska, A. et al. Interactions of 10.6 GeV/nucleon gold nuclei in nuclear emulsion. Z. Phys. C - Particles and Fields 62, 25–29 (1994)
`
This work is devoted to the study of the simplest hypernuclei, namely
3HΛ (consisting of one proton, one neutron, and one Λ-hyperon) and
4HΛ (consisting of one proton, two neutrons, and one Λ-hyperon). They may be one of the possible markers of the phase transition from nuclear matter to quark-gluon plasma in high-energy ion collisions.
The aim of this work is to reconstruct the hypernuclei peak in the invariant mass distribution for simulated data for the BM@N experiment. In the report algorithm of geometrical parameters selection for both decays presented. Estimation of reconstruction efficiency in phase space {pt, y} done. Approach tocalculate lifetime of observed hypernuclei is presented.
Collaborative work on documents is an essential part of scientific research, especially in large collaborations. Various software tools are used to organize and facilitate this process as well as to store files. Some of the most widely used tools in the scientific community include DocDB, XWiki, and the CERN Document Server. Currently, several independent instances of the DocDB system have been deployed at the Joint Institute for Nuclear Research (JINR). However, the use of the system has revealed some issues related to security and reliability, as well as the need for additional features. The support and improvement of this system is a complex process due to its outdated technological foundations. In order to avoid the high efforts associated with addressing the mentioned issues and due to the lack of any suitable alternative, the cloud team has started developing a new platform for scientific documentation. This project aims to develop a more secure, reliable, and feature-rich software platform called “SciDocsCloud” for tracking document in scientific collaboration. It is free and open-source software. Once the core features of the DocDB system have been completed, the platform will be made available in a public repository on GitHub. At the moment, the SciDocsCloud has implemented enough features to cover the most common use cases. This report provides an overview of the service for JINR research groups based on platform, includinginformation about the architecture of the service, its key features, as well as the current status and roadmap.
Тестирование серверного оборудования перед его вводом в эксплуатацию играет весомую роль в обеспечении надежной и бесперебойной работы развернутых систем на Многофункциональном Информационно-Вычислительном Комплексе Объединенного Института Ядерных Исследований (МИВК ОИЯИ). Основной целью тестирования является выявление скрытых дефектов, которые могут возникнуть при критических нагрузках на оборудование. Существуют различные эмпирические методы, описанные в производственных стандартах, используемые для выявления неисправностей оборудования. В докладе представлена система автоматизированного тестирования серверного оборудования, включающая автоматизацию установки средств тестирования, запуск тестов и сбор журналов тестирования. В текущей реализации тестирование осуществляется посредством метода Highly Accelerated Stress Screening (HASS), где в качестве параметров выступает максимальная температура испытуемого компонента в момент нагрузки. Важнейшей частью рассматриваемой системы является подсистема мониторинга, которая требуется для сбора и анализа температурных показателей тестируемых компонентов. Анализ данных мониторинга на этапе тестирования позволяет определить время тестирования с заданной точностью. Помимо инструментов мониторинга Node Exporter, Prometheus, Prometheus Gateway и Grafana, в системе используется Stress ng для нагрузки оборудования синтетическими тестами. Все из рассмотренных подсистем являются свободно распространяемыми, предложенная в докладе система может быть беспрепятственно использована для реализации подобного тестирования в аналогичных инфраструктурах.
Testing of server equipment prior to its operation is crucial for ensuring reliable and uninterrupted performance of deployed systems at the Multifunctional Information and Computation Complex of the Joint Institute for Nuclear Research (MICC JINR). The main purpose of testing is to identify hidden defects that may arise under critical loads on the equipment. There are various empirical methods described in production standards used to detect equipment failures. The paper presents an automated system for testing server equipment, including automation of test installation, launching tests, and collecting test logs. In the current implementation, testing is carried out using the method of Highly Accelerated Stress Screening (HASS), where the maximum temperature of the tested component during loading serves as a parameter. A key part of the considered system is the monitoring subsystem required for collecting and analyzing temperature data from the tested components. Data analysis during the testing phase allows determining the duration of testing with a given accuracy. In addition to the monitoring tools such as Node Exporter, Prometheus, Prometheus Gateway, and Grafana, the system uses Stress ng to load the equipment with synthetic tests. All of these subsystems are freely distributed, and the proposed system can be easily implemented for similar testing in comparable infrastructures.
The phase dynamics and resonance properties of the Phi-0 Josephson junction are investigated. As the Phi-0 junction is considered a superconductor-ferromagnet-superconductor (S-F-S) Josephson junction, in which the symmetry with respect to time inversion is broken and the current-phase relationship has a phase shift by Phi-0 proportional to the magnetization, perpendicular to the gradient of the asymmetric spin-orbit potential. Based on the numerical solution of the equations of the resistive model for the Josephson junction and the Landau-Lifsch-Gilbert equation for magnetization, the manifestation of resonance properties on the volt-ampere characteristic of the Phi-0 junction is shown. The influence of the model parameters on the resonance properties of the Phi-0 junction is demonstrated. An approximate analytical equation similar to the Mathieu equation is obtained, which shows the possibility of realization of parametric resonance in the Phi-0 junction.
In this paper, the Ising model, a classical model of statistical mechanics, is investigated in order to determine its ground (low-energy) state at fixed random interaction constants J and variable direction of spins in the spin lattice. A new algorithm based on a self-learning bilayer neural network implemented on the Keras library is proposed and investigated to efficiently find the ground state of the Ising model.
The network training algorithm consists of predicting possible spin lattice configurations, flipping the spins to minimise the energy of the system and training the neural network based on the obtained data. Numerical experiments have been performed for different spin lattice sizes and J values. The obtained results demonstrate the comparative efficiency of the proposed algorithm in finding the ground state of the Ising model.
In existing studies, convolutional neural networks that perform clustering of spin lattices were used to solve this problem, which allowed increasing the size of the analysed systems, overcoming the limitations associated with computational complexity. Neural networks capable of recovering the temperature of a system based on its spin configuration have also been studied. However, the Metropolis algorithm, known for its tendency to capture local energy minima, was used as a method to find the ground state, which can lead to inaccuracy in determining the true ground state.
The proposed algorithm, based on a self-learning neural network, is a promising method for determining the ground state of the Ising model. In the future, it is planned to extend the model to more complex systems, as well as to increase the size of the spin lattice for a deeper investigation of the behaviour of systems with different characteristics.
Aerosol particles in both outdoor and indoor environments are known to be vehicles for the transfer of radioactivity. It is very relevant to solve the problems of the transfer of contaminants both in the free atmosphere and in premises during accidents and abnormal objects using radioactive substances. However, to date, insufficient attention has been paid to solving these problems. In this work, we propose a model of coagulation between atomic radioactive impurities (ARIs) and aerosol particles of various sizes. For simplicity, it was assumed that the concentration of aerosol particles $c(i)_{g}$ was not very high and coagulation between them might not be taken into account. It was also assumed that the ARI concentration has stabilized and reached steady state; only collisions between aerosol particles and ARP were taken into account, which led to the redistribution of radioactivity on aerosol particles of a certain size g:
$$
\begin{aligned}
& \frac{d c(g, 0, t)}{d t}=-\alpha(g) c(g, 0, t) n+\lambda c(g, 1, t) \\
& \frac{d c(g, i, t)}{d t}=\alpha(g) c(g, i-1, t) n-\alpha(g) c(g, i, t) n-i \lambda c(g, i, t)+(i+1) \lambda c(g, i+1, t) \\
& \frac{d n(t)}{d t}=I-\sum_{i}^{N} \alpha(g) c(g, i, t) n-\lambda n \\
& c(g, t)=\sum_{i}^{\infty} c(g, i, t) \\
& \frac{d n(t)}{d t}=I-\sum_{i}^{N} \alpha(g) c(g, i, t) n-\lambda n \\
& c(g, t)=\sum_{i}^{\infty} c(g, i, t)
\end{aligned}
$$
To solve these equations, the formalism of the generating function was used as [1]:
$$
F(z, t)=\sum_{i=0}^{\infty} c(g, i, t) z^{i}
$$
The corresponding transformations made it possible to find a solution to the system of differential equations, which depends on the initial conditions. If we assume that at the initial moment of time:
$$
c(g, i, t=0)=\delta_{i, 0} c(g, 0)_{0}
$$
That is, at the initial moment of time there were no ARPs deposited on the particles, then the solution can be presented in the form:
$$
F(z, t)=c(g, 0)_{0} e^{\frac{\alpha n}{\lambda}(1-z)\left(e^{-\lambda t}-1\right)}
$$.
This procedure allows one to find all solutions $c(g, i, t)$ by successively differentiating $F(z, t)$ and equating $z=0$. In addition, the system of differential equations was solved numerically using the same initial conditions. It was found that the exact analytical solution is in good agreement with the numerical one.
The corresponding transformations made it possible to find a solution to the system of differential equations, which depends on the initial conditions. If we assume that at the initial moment of time:
$$
c(g, i, t=0)=\delta_{i, 0} c(g, 0)_{0}
$$
That is, at the initial moment of time there were no ARPs deposited on the particles, then the solution can be presented in the form:
$F(z, t)=c(g, 0)_{0} e^{\frac{\alpha n}{\lambda}(1-z)\left(e^{-\lambda t}-1\right)}$.
This procedure allows one to find all solutions $c(g, i, t)$ by successively differentiating $F(z, t)$ and equating $z=0$. In addition, the system of differential equations was solved numerically using the same initial conditions. It was found that the exact analytical solution is in good agreement with the numerical one.
![enter image description here][1]
[1]: https://sun9-51.userapi.com/impg/4NxxLmPOYkhPDgjUdwXWTA55HFTd97ddUPUjfA/OjFPHUD92hQ.jpg?size=427x332&quality=96&sign=3860078bffb9c27dc9fd7ef557ff7d74&type=album
Figure 1. Distribution of activity on particles containing different numbers of ARI.
The graph shows the first 4 dependences of particle concentration with no ARI and with 1, 2, 3 and 4 ARI per aerosol particle. An example is given for the value of the dimensionless parameter $\frac{\alpha(g) n}{\lambda}=1$.
It is also clearly illustrated by graphs in Fig. 1 that at $t \rightarrow \infty$ all concentrations reach a stationary regime; this can also be concluded by consideration of the form of the corresponding differential equations. The asymptotic behavior corresponds to the expressions:
$c(g, i,t\to \infty)=\frac{1}{i!}\left( \frac{\alpha(g)n}{\lambda}\right)^{i}c(g, 0, 0)$
The obtained analytical and numerical solutions complement each other, since when comparing theoretical and experimental data it is necessary to take into account that the number of particle fractions obtained remains finite.
[1] A.A. Lushnikov, Evolution of Coagulating Systems, J. Colloid Interface Sci., 45 (1973) 549 - 556.
Heavy-element-containing compounds and materials are among the most challenging objects for ab initio electronic structure modeling due to the interference of strong relativistic effects, typically multi-configuration nature of electronic states, and high density of levels in their spectra. A thorough modeling of these objects aimed at reliable predictions of their structure and optical, magnetic, and thermodynamical properties clearly requires a set of theoretical methods and software tools implementing them. We present a project of a software ecosystem for multi-scale ab initio modeling of quantum systems from atoms to cluster models of solid-state materials designed at NRC "Kurchatov Institute" – PNPI and Moscow Institute of Physics and Technology. It will include a set of programs focused on objects of different levels of complexity.
The most precise calculations are available within the relativistic multireference coupled cluster (CC) methodology. Its Fock-space version, including up to triple excitations (the FS CCSDT model) was implemented within the EXP-T program package [1]. The manifold of available extensions of the Fock-space coupled cluster method currently also includes its formulations for systems with three unpaired electrons, a special version of the intermediate Hamiltonian technique to resolve numerical stability issues, and finite-field and finite-order approaches to calculate one-electron properties (including transition ones) [2]. Since the coupled cluster method is relatively computationally demanding, its equations were reformulated using the tensor-train decomposition to reduce their formal scaling and implemented as a part of EXP-T. The relativistic CC method was successfully applied recently to predict localized f-d excitations on the Ce3+ and Th3+ impurity ions embedded into the xenotime (yttrium orthophosphate YPO4) crystal matrix [3].
To simulate much larger objects (up to several dozens of atoms), a set of programs implementing the second-order multi-partitioning perturbation theory (MPPT) [4] is currently being developed. Being a genuine multi-state method, MPPT is perfectly suitable to predict excited electronic states and spectra of systems with a pronounced multireference character, including those possessing several unpaired electrons, like materials containing atoms of d- and f-elements (lanthanides and actinides).
Both the CC and MPPT methods employ many-electron Hamiltoniаn integrals over molecular orbitals / spinors; thus, it seems reasonable to design an efficient relativistic Hartree-Fock and density functional program to produce the latter entities. Moreover, it is also necessary to perform preliminary calculations, e.g., geometry optimization, before applying more sophisticated methods. For this purpose, we started the work on the BUFO program, implementing both non-relativistic and two-component relativistic versions [5] of the Hartree-Fock method. It heavily relies on a generalized relativistic pseudopotential (GRPP) concept. It employs the LIBGRPP library to evaluate integrals over the GRPP operator based on atomic Gaussian functions [6]. The GRPP approach, especially its latest versions which account for quantum electrodynamic and Breit effects, is also a cornerstone for modeling of d- and f-element compounds with unprecedented accuracy using the MPPT and CC methods.
The work of A.V.O., A.Z., and A.V.T. at NRC "Kurchatov Institute" – PNPI on developing the coupled cluster program was supported by the Russian Science Foundation under grant no. 20-13-00225, https://rscf.ru/project/23-13-45028/. The work of A.S.R. and A.V.O. at NRC "Kurchatov Institute" – PNPI on developing the tensor-train method and its implementations was supported by the Russian Science Foundation under grant no. 24-73-00076, https://rscf.ru/project/24-73-00076/.
[1] A. V. Oleynichenko, A. Zaitsevskii, E. Eliav. Commun. Comput. Inf. Sci., 1331, 375 (2020).
[2] E. Eliav, A. Borschevsky, A. Zaitsevskii, A. V. Oleynichenko, U. Kaldor, In Comprehensive Computational Chemistry, Elsevier, P. 79-93 (2024).
[3] A. V. Oleynichenko, Y. V. Lomachuk, D. A. Maltsev, N. S. Mosyagin, V. M. Shakhova, A. Zaitsevskii, A. V. Titov. Phys. Rev. B, 109, 125106 (2024).
[4] A. Zaitsevskii, R. Cimiraglia. Int. J. Quantum Chem. 73, 395 (1999).
[5] C. van Wuellen, Z. Phys. Chem., 224, 413 (2010).
[6] A. V. Oleynichenko, A. Zaitsevskii, N. S. Mosyagin, A. N. Petrov, E. Eliav, A. V. Titov. Symmetry, 15, 197 (2023).
Currently, it is of interest to study the magnetic properties of HTSC at the mesoscopic level. One of the best methods of numerical modeling in such cases is the Monte Carlo method. In our work, an attempt is made to apply this algorithm to some unconventional superconductors. Calculations were based on Lawrence-Doniach model, Gibbs free energy was minimized using stochastic method. The survey with 2 different vortex-vortex interaction potentials was carried out. The first one can represent intertype HTSC ($\kappa = \frac{1}{\sqrt{2}}$), and the second one corresponds to ferromagnetic superconductors. Magnetic field distribution and magnetization curves were modelled. As cluster structures were obtained, the dependence of vortex clusterization on the temperature of HTSC in the first potential was investigated. Moreover, the study of behavior of vortex clusters with various configurations of defects was conducted. As for ferromagnetic superconductors, the dependence of the field distribution on magnetic susceptibility has been investigated.
Amorphous and microcrystalline silicon is important in electronics, energy and medicine due to its useful properties. Precisely, microcrystalline silicon is preferred for its high resistivity to degradation, electrical properties and special light absorption. However, producing high quality microcrystalline silicon is challenging. It requires precise control of process of crystallization and grain size.
Laser crystallization and metal-induced crystallization (MIC) are among the most advanced methods. The presence of metals during irradiation of the samples decreases the crystallization temperature and improve the properties of the final material.
In this work, the process of laser heating of an amorphous silicon film with and without a gold layer is modelled. The heat conduction equation is solved by the finite difference method. A finite difference scheme with a time step of 0.01~ns and a spatial step of 0.005~nm provided precise modelling results. This provides high accuracy of the obtained results.
The temperature field in the composite material and dynamics of the thickness of the modified layer are calculated. It was determined that the threshold of modification intensity in the (\alpha)-Si/Au/c-Si structure is 2 times lower than in (\alpha)-Si/c-Si and is (4.3 \cdot 10^{11})~W/m(^{2}) and (2.1 \cdot 10^{11})~W/m(^{2}) for a 1~ns pulse. The modification depth reaches (10-20)~nm at (3.0 \cdot 10^{11}) to (8.0 \cdot 10^{11})~W/m(^{2}) for (\alpha)-Si/Au/c-Si and (7.0 \cdot 10^{11}) to (2.0 \cdot 10^{12})~W/m(^{2}) for (\alpha)-Si/c-Si. The results are in good agreement with the experimental data.
Numerical simulation of the heating of multilayer structures allow to determine the best parameters of laser radiation necessary to achieve the crystallization threshold and further modification of the amorphous phase. The results can be used to optimise the experimental synthesis of microcrystalline silicon at different scales.
Inorganic scintillators BaF2 and LYSO:Ce are considered as candidates for use in the electromagnetic calorimeter of the Mu2e-II experiment. Doping BaF2 with yttrium allows to suppress its slow luminescence component but negatively impacts on radiation hardness of the crystal. In previous work we studied the influence of irradiation with fast neutrons on scintillation properties of the pure BaF2 and doped with 1, 3 and 5 atomic percent of ittrium. In this work we study the influence of gamma irradiation on the light yield,energy resolution and scintillation kinetics of pure and doped with ittrium BaF2 crystals and LYSO:Ce crystals. A special experimental setup with Peltier cooling of PMT have been created to perform this study and especially to study the scintillation kinetics of the samples with delayed coincidence metod.
Exotic hadron states with quark content beyond conventional meson and baryon models are natural laboratory to study the properties of strong interaction. Charmonium-like state $Z_c(4200)$ with a potentially tetraquark structure was found as an intermediate state in $B^0 \to J/\psi K^{\pm} \pi^{\mp}$ decays. The large width of this state leads to significant interference effects with other intermediate states, e.g. $K^{*}$ mesons. The nature of this state and even its existence is still controversial. Further theoretical studies require high-precision measurements of the properties of this state using amplitude analysis methods.
In this report, the current theoretical and experimental status of studying $Z_c(4200)$ exotic state together with prospects for further research will be presented.
Accurate geometric modeling of detector components is essential for optimizing performance and ensuring the reliability of experimental setups in high-energy physics. This report details the geometry simulation of the Zero-Degree Calorimeter (ZDC) which is an important component of the Spin Physics Detector (SPD) at the Nuclotron-based Ion Collider facility (NICA) currently under construction at the Joint Institute for Nuclear Research (JINR), Dubna. Using the latest version of the Geant4 toolkit, this work aims to replicate the particular design of the ZDC, which was engineered to be located at 13 m from the Interaction Point (IP) and placed in between the two beam pipes that are not parallel in that specific position. A precise ZDC geometry description was first created as a GDML solid in a FreeCAD workbench with the aim of being imported in Geant4. The main function of the ZDC consists of detecting neutral particles. Its finely segmented calorimeter design ensures to take part in polarimetry determination and luminosity measurements with high precision. This meticulous modeling of the ZDC's geometry takes into account its electromagnetic and hadronic modules, material composition, and the innovative “growing” design that enhances particle containment. The study also evaluates the detector's response to photons and neutrons with different energies. These results are benchmarked against the specifications outlined in the Technical Design Report (TDR) of the SPD collaboration.
NOvA is an accelerator-based neutrino oscillation experiment. Using Fermilab’s Megawatt-capable NuMI beam and two functionally identical tracking calorimeter detectors, muon (anti)neutrino disappearance and electron (anti)neutrino appearance are studied. Accurate energy estimation is vital to make good measurements of oscillation parameters, since oscillations are a function of neutrino energy. Variables for neutrino energy estimation are outputs of machine learning algorithms, which are utilized to identify events and classify reconstructed particles into either leptons or hadrons. NOvA has specialized estimators for both muon-like and electron-like neutrino events. In this talk, the latest improvements and future opportunities of these estimators will be presented.
В работе Многофункционального информационно-вычислительного комплекса (МИВК) Лаборатории информационных технологий (ЛИТ) Объединенного института ядерных исследований (ОИЯИ) задействован большой объем серверного оборудования, которое обеспечивает вычислительными ресурсами многие научные группы и эксперименты. Некоторые компоненты этого оборудования подвержены износу и должны своевременно заменяться для обеспечения бесперебойной работы комплекса. В МИВК формируется склад запасных частей, что позволяет ускорить процесс замены выходящего из строя оборудования. В докладе рассмотрена рекомендательная система, позволяющая прогнозировать выход из строя компонентов серверов и оптимизировать планирование склада запасных частей. Кроме того, представлены инструменты для сбора показателей работы оборудования, их хранения и последующей обработки, а также примеры статистических методов для прогнозирования отказов. Разработанное решение построено на свободно распространяемых компонентах и может использоваться в аналогичных инфраструктурах. В дальнейшем планируется интегрировать его в систему инвентаризации ОИЯИ.
In the operation of the Multifunctional Information and Computing Complex (MICC) of the Laboratory of Information Technologies (LIT) at the Joint Institute for Nuclear Research (JINR), a large volume of server equipment is utilized, which provides computational resources to many scientific groups and experiments. Some components of this equipment are subject to wear and must be replaced in a timely manner to ensure the uninterrupted operation of the complex. A spare parts warehouse is established within the MICC, allowing for faster replacement of failing equipment. The report discusses a recommendation system that enables the prediction of server component failures and optimizes the planning of the spare parts inventory. Additionally, it presents tools for collecting equipment performance indicators, their storage and subsequent processing, as well as examples of statistical methods for failure prediction. The developed solution is built on freely distributed components and can be used in similar infrastructures. It is planned to integrate it into the JINR inventory system in the future.
The heterogeneous HybriLIT platform is used at JINR to solve various computational tasks, including data collection and processing from experiments, as well as modeling and simulation of physical processes. The main component of the platform is the Govorun supercomputer, which consists of more than a hundred servers that constantly run user programs and communicate with each other over the network. There is a need to monitor the state of computing nodes, including the workload of the central and graphics processors, the use of RAM and permanent memory, network traffic and the temperature of physical components. Thus, it is necessary to develop tools for monitoring the status and usage of components of a heterogeneous platform.
When developing the solution, the advantages and disadvantages of previously used systems were taken into account.
The result was a software product consisting of a server and client part, allowing real-time monitoring of the platform's state through a user-friendly graphical interface.использования компонентов гетерогенной платформы.
При разработке решения были учтены преимущества и недостатки ранее используемых систем.
Результатом стал программный продукт, состоящий из серверной и клиентской части и позволяющий в режиме реального времени следить за состоянием платформы через удобный для пользователя графический интерфейс.
Monitoring of computing cluster resources provides detailed information about the status of various components of computing nodes in real time. Such a tool helps to monitor the status of CPU, RAM, software-defined storage, etc. only at the current moment. To evaluate the efficiency of a computing cluster, it is necessary to analyze the statistics of the use of various components of computing nodes.
The paper presents a developed system for analyzing and visualizing resource usage statistics obtained on the basis of data from the resources and traffic monitoring and analytics system of the heterogeneous HybriLIT platform. The received data is stored in a PostgreSQL database with different levels of aggregation (week, month, year), which allows you to analyze data at different levels of detail. The presentation of the analysis results is based on the locally deployed Yandex DataLens BI platform in the form of a set of informative charts and dashboards displaying statistics on the use of resources of the heterogeneous HybriLIT platform.
The developed system for analyzing and visualizing the use of computing cluster resources allows us to obtain quantitative estimates of the efficiency of various components of the computing cluster, which contributes to its optimization and improved manageability. This system can be used to analyze the operation of other high-performance computing systems.
JINR Institutional repository is built on DSPACE software platform. Repository is a hub of results made by JINR employees, showcase of scientific activities of the Institute.
At the first stage we store publication automatically imported via API from eLIBRARY and INSPIREHEP databases from 2019-2024 yy and then we will continue to go feather into the history. The repository allows users to upload their published works themselves, all data submitted by users will be checked by a moderator. Integration with JINR PIN system, a lot of search possibilities and author profile, these and more features will be presented in the talk.
Nowadays, the successful implementation of a significant part of scientific projects involves the use of a Distributed Information and Computing Environment (DICE) for storing, processing and analyzing data. The JINR DICE initiative is dedicated to the creation, support and development of such an environment by combining the resources of educational and research organizations of the JINR Member States. One of such organizations is the Institute of Nuclear Physics (INP) in Almaty (Kazakhstan). Based on the INP's resources a cloud infrastructure was installed. The necessary services were deployed. The INP cloud was integrated into the JINR DICE. A group of pioneer scientists was selected who start using the INP's cloud resources to conduct research in their areas. Presently, the work is focused on user support.
To date, the European free electron laser is actively used to determine the structure of many materials [1,2]. The advantage of such a laser over other research methods is the ability to generate short beams that make it possible to study the structure without radiation exposure[3]. At the same time, the exposure time of such a pulse is commensurate with the characteristic atomic time, which makes it possible to study molecules without additional preparation, crystallization, etc. This was a revolution in structural biology and not only [4]. However, the difficulty of obtaining and decoding diffraction patterns stops the use of a laser. The complexity of data processing and decoding, namely the phase problem, prevents the widespread use of ultrashort laser pulses to work with molecules[5]. It is necessary to search for new ways to decrypt the received data in order to create an effective three-dimensional visualization method. In the previous work, the method proposed as the basis for decoding experimentally obtained diffraction patterns was described [6]. The method is based on a theoretical description of the interaction of an ultrashort pulse with the substance under study, using numerical modeling and using the Dirac–Hartree-Fock-Slater model. To simplify the decoding of molecular structures, it is proposed to conduct theoretical modeling of the interaction in order to obtain a reference diffraction pattern. In [7], the method was changed, it was proposed to simplify the calculation if there were symmetries or repeating sections in the structure under study. In this paper, the proposed method is tested in more detail on different structures, on a DNA molecule (a larger site), an RNA molecule, and a diamond crystal. All these substances are of great interest in structural biology, medicine and physics. Their research at the atomic level is still difficult, which prompts the development of similar methods of their analysis. The use of the symmetry method will allow calculations to be carried out at the analytical level and reduce processing time. The spectra of the interaction of an ultrashort pulse with molecules and a crystal will be obtained in the article, the proposed theory will be verified by calculating the interaction spectra on these objects. The interaction spectra obtained here will be compared with previous results.
1 Starodub, D., Aquila, A., Bajt, S. et al. Single-particle structure determination by correlations of snapshot X-ray diffraction patterns. Nat Commun 3, 1276 (2012). https://doi.org/10.1038/ncomms2288
2 Neutze, R., Wouts, R., van der Spoel, D., Weckert, E. & Hajdu, J. Potential for biomolecular imaging with femtosecond X-ray pulses. Nature 406, 752–757 (2000).
3 Howells, M. R. et al. An assessment of the resolution limitation due to radiation-damage in X-ray diffraction microscopy. J. Electron Spectrosc. 170, 4–12 (2009).
4 Gisriel, C., Coe, J., Letrun, R. et al. Membrane protein megahertz crystallography at the European XFEL. Nat Commun 10, 5021 (2019). https://doi.org/10.1038/s41467-019-12955-3
5 Pandey, S., Bean, R., Sato, T. et al. Time-resolved serial femtosecond crystallography at the European XFEL. Nat Methods 17, 73–78 (2020). https://doi.org/10.1038/s41592-019-0628-z
6 Johan Bielecki;Adrian P. Mancuso, et al, Struct.Dyn.7, 040901 (2020)https://doi.org/10.1063/4.0000024
7 D. N. Makarov, K.A.Makarova, A.A.Kharlamova “Specificity of scattering of ultrashort laser pulses by molecules with polyatomic structure,” Scientific Reports, vol. 12, pp. 4976, 2022.
8 Kharlamova, A., Makarov, D. Calculation of the Spectrum of Interaction Model with Macromolecules by the Method of Finding Symmetries, Physics of Particles and Nuclei Letters, 2024, 21(4), pp 815–818
Huntington's chorea is a neurodegenerative autosomal dominant disease characterized by impairment of motor and cognitive functions. The disease is caused by the expansion of CAG trinucleotide repeats in the huntingtin protein gene (HTT), leading to elongation of the polyglutamine N-terminal domain, which stimulates the accumulation of defective globules and subsequent neurodegeneration. The molecular and cellular basis of Huntington's disease pathogenesis is not fully understood and is the subject of active and extensive research. Recent studies have demonstrated the pleiotropic role of mitochondrial fusion and fission proteins and cytoskeletal components in a number of processes including mitochondrial metabolism, redox signaling, mitochondrial DNA maintenance and cell death. The existing evidence suggests a connection between Huntington's disease and mitochondria-associated oxidative stress. Since the precise cytophysiological mechanisms underlying the pathogenesis of Huntington’s disease have not yet been discovered, generation of reactive oxygen species and consequent oxidative stress caused by mitochondrial dysfunction associated with huntingtin could be one of the possible explanations.
The aim of this research was to investigate possible changes in the morphological and dynamic parameters of mitochondria in the cells of patients with Huntington's disease, including their branching, intracellular transport and interactions with cytoskeletal components. The cytoskeletal architecture was examined after immunocytochemical staining using wide-field fluorescence microscopy, confocal scanning microscopy, and intravital observations. During the analysis of the results, the following parameters were measured: the number of mobile mitochondria; number of mitochondrial mergers and divisions; the velocity and directionality of intracellular transport; the degree of mitochondrial branching. Obtaining results consistent with data on changes in the dynamics and morphology of mitochondria in other neurodegenerative diseases will allow us to consider not only mitochondria, but also proteins that mediate their connection with the cytoskeleton to be an adequate target for a new type of perspective drugs aimed at preventing the development of Huntington’s disease and relief of its symptoms.
The work was supported by the Lomonosov Moscow State University Development Program (PNR5.13) and the Nikon Center of Excellence at the A. N. Belozersky Research Institute of the Moscow State University named after M. V. Lomonosov.
Among all of the human transglutaminases (TGases), transglutaminase 2 (TG2) is the most present one, existing in all of the tissues and organs of the human body. The protein has several conformations and functions, including protein crosslinking, apoptosis, immune response and calcium signaling. Moreover, TG2 also has the least variability in its coding sequence among the family of proteins, being the most conservative TGase. All of these facts combined highlight the necessity of the protein in the normal development of human organism and show the importance of studying it.
We obtained the first completely resolved TG2 structure using AlphaFold2 and validated it with developed molecular docking and molecular dynamics protocols. We also assembled a library of compounds similar to the existing TG2 inhibitors and verified the efficiency of novel compounds using in silico techniques.
We acknowledge the support from the Ministry of Science and Higher Education of the RF, project FSMF-2023-0010; “Integrated structural biology and genetics for the production of protein preparations and biologically active substances as new food and non-food products.”
Tricritical behavior in systems with an $n$-component order parameter $\varphi = \{\varphi_a, a = 1, \ldots, n\}$ is described by the action $S(\varphi) = \frac{1}{2}\partial_i\varphi_a\partial_i\varphi_a + \frac{\tau}{2} \varphi_a\varphi_a + \frac{\lambda}{4!} (\varphi_a\varphi_a)^2 + \frac{g}{6!} (\varphi_a\varphi_a)^3$, where the coefficients $\tau$, $\lambda$ and $g$ are parameters of the model [1].
Six-loop calculation of the renormalization group functions in the model was carried out in $d = 3 - \varepsilon$ dimensions using the dimensional regularization. The model was renormalized within the minimal subtraction scheme (MS) [1]. All diagrams, except seven diagrams, were calculated with G-functions [2]. For the remaining seven six-loop diagrams, the G-function approach allowed to reduce them to two-loop diagrams, which were computed numerically using the Sector Decomposition method [3]. The results obtained differ from those previously known [4].
The work is supported by the Ministry of Science and Higher Education of the Russian Federation (agreement no. 075–15–2022–287).
[1] A.N. Vasil’ev, Quantum field renormalization group in critical behavior theory and stochastic dynamics. Chapman and Hall/CRC (2004).
[2] K.G. Chetyrkin and F.V. Tkachov, New approach to evaluation of multiloop Feynman integrals: The Gegenbauer polynomial x-space technique. Nucl. Phys. B, 174, 345 -- 377 (1980).
[3] G. Heinrich, Sector Decomposition. Int. J. Mod. Phys. A, 23, 1457 -- 1486 (2008).
[4] J.S. Hager, Six-loop renormalization group functions of $O(n)$-symmetric $\phi^6$-theory and $\epsilon$-expansions of tricritical exponents up to $\epsilon^3$. J. Phys. A: Math. Gen., 35, 2703 -- 2711 (2002).
This project investigates the dissipative properties of an accelerated relativistic medium and their connection to the Unruh effect and effective black hole radiation. The thermodynamic properties in spaces with a horizon is one of the most discussed in modern fundamental physics. A notable 2005 string theory limit sets a minimum shear viscosity. We calculated viscosity in an accelerated frame for a photon medium, where no holographic description exists, treating the black hole horizon as a membrane of finite thickness. While the average viscosity
meets the string theory limit, local values are described by a universal function that is independent of particle spin. Specifically, on the membrane surface, the ratio of local viscosity to local entropy is half the string theory limit. Importantly, this result is gauge-independent, with the positive contribution from gauge fixing exactly canceling the negative contribution from Faddeev-Popov ghosts.
In my talk I will review the hydrodynamical approach to the description of the gravitational chiral anomaly in spacetimes with a non-trivial Ricci tensor proportional to the cosmological constant (so-called Einstein manifolds) and discuss an alternative derivation of the Unruh effect in curved spacetime as a non-trivial consequence of the hydrodynamical description of the axial current.
A model is proposed for a classical bosonic string in d=3 Minkowski space with an action functional that includes Gauss and mean world-sheet curvature. The Lagrangian is invariant under 3d Poincaré transformations modulo total divergence. In addition to the diffeomorphism, the action enjoys the extra gauge symmetry with the second derivatives of the scalar gauge parameter. This symmetry gauges out all the local degrees of freedom (DoF's), while some global DoF's survive. The Hamiltonian constrained analysis confirms that the model does not have any local DoF. The world sheet of the string turns out to be a cylinder with time-like axis. The global DoF's of this string describe one single irreducible massive 3d particle with spin. The particle momentum is a conserved vector directed along the cylinder axis while the momentum square is a fixed constant determined by the parameters in the action. The total angular momentum is a conserved vector that defines the position of the axis of the cylinder whose specific value is defined by initial data, while the spin, being the product of momentum and angular momentum is fixed by the parameters in the string Lagrangian.
We present a method to account for the Coulomb interaction in the ultra-rare leptonic decays $B^0_{s,d}\rightarrow \ell^+\ell^-$ and rare semileptonic $B^0_{s,d}\rightarrow h^0\ell^+\ell^-$, where $h^0 = \{K,\pi^0,\eta,\eta'\}$. Taking into account the Coulomb interaction for the decay of $B^0_{s}\rightarrow \mu^+\mu^-$ reduces the discrepancy between theory and experiment more than twice. The main idea of the work is to change the procedure of secondary quantization - instead of expansion by plane waves the solution of the Dirac equation in an external field (Furry picture) is used. The applicability of the Furry picture is justified on the example of the decay of a hypothetical neutral pseudoscalar particle into two charged scalars $B^0\rightarrow S^+ S^-$.
This work is devoted to the modelling of radiation effects of swift heavy ions in AlN. This material was chosen because it is promising for using in nuclear reactors. The multiscale model was employed. To describe the ions impact and further electron kinetics we use the TREKIS model based on MC-methods. After this, on atomic dynamic stage, MD-methods were applied to trace the atoms movement.
The first step was modelling of ionic impact on material and further electron kinetics of AlN. As the irradiating particles we used ions of Ar, Xe and Bi with energies 100, 158 and 700 MeV respectively. The study shows that electron excitation in the damaged area is faded out to 100 fs after ion impact. The second step of the study was the modelling of ionic subsystem relaxation with molecular dynamics both in the bulk and at the surface. It was found out that in the bulk ion tracks are not formed because of strong recrystallization ability of AlN, only few point defects along the ion trajectory are observed. In contrary, the presence of an open surface allows atoms to go away from the damaged volume including emission of atoms and forming hillocks. As the result, deficiency of the mass in subsurface area, on the one hand, suppresses the processes of recrystallization producing conical hillocks, on the other hand, leads to formation of small cavities. The modelling results are in reasonable agreement with experimental data from the literature.
Ceramics based on mineral-like structures (garnets, scheelites, monazites) are being studied as promising matrices for the immobilization of radioactive waste. This paper presents an investigation of polycrystalline ceramic samples of Y2.5Nd0.5Al5O12 (YAG:Nd) obtained by spark plasma sintering. During the operation of such materials, the matrix structure undergoes intense radiation impact caused by its own residual radioactivity. To test the behavior of materials in such conditions, external irradiation with swift heavy ions (SHI) is used. Therefore, the purpose of this work is to study the effect of SHI irradiation (Xe+, 160 MeV, fluence 10^12 – 10^13 cm^-2) on the structure of the near surface layers of ceramics based on YAG.
The study of structural changes in such ceramics has been carried out both theoretically and experimentally. The method of X-ray diffractometry (XRD) was used in the Bragg-Brentano and grazing incidence geometries [1]. Mathematical modeling of the interaction of SHI with the YAG matrix was carried out using Monte Carlo methods (MC, TREKIS) [2] and molecular dynamics (MD, LAMMPS) [3].
During the XRD experiments, the formation of an amorphous and deformed YAG phase in the disturbed near surface layer was detected. The study of changes in microstructure parameters (degree of crystallinity, crystallite sizes, deformation) from ion fluence was carried out, and the thickness of the disturbed layer was estimated.
To verify the correctness of the results of XRD experiments, MC&MD modeling of the interaction of SHI with YAG was performed. The simulation results qualitatively and quantitatively confirmed the experimental results and made it possible to illustrate the mechanisms of defect formation at the atomic level.
Copper (II) oxide (CuO) is a sustainable, stable, non-toxic photovoltaic material that can be produced using low-cost techniques. The primary objective of this research is to develop a heterostructure based on elongated CuO nanostructures with an inverted and branched architecture. In this heterostructure, the CuO layer serves as both, the support and the absorbing material for solar radiation. This study presents results from CuO nanostructured samples subjected to a sequential thermal treatment. This approach was chosen because it can enhance the structural, electrical and optical properties more effectively than standard thermal treatments by optimizing each step of the thermal cycle. The samples were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). We investigate the structural changes and defect formation in the nanostructured CuO layer resulting from the sequential thermal treatment. The findings indicate a recrystallization process in the CuO layer leading to the improvement of material properties.
There are a lot of studies aimed at replacing lithium-ion batteries (LIB) with sodium-ion batteries (SIB) [1]. Potassium-ion batteries (PIB) are also promising electrochemical devices due to the potassium availability compared to lithium [3]. Unlike sodium, PIBs can use graphite as anode material, suggesting that the well-developed LIB system can be better transferred to the PIB system. Developing efficient cathode materials is an important task for the wide distribution of SIB and PIB. One of the perspective cathode materials are hexacyanoferrates MxFe[Fe(CN)6]·nH2O (Prussian blue analogues, M = Na, K), which have open framework structure and low-temperature synthesis.
A number of samples of KxFe[Fe(CN)6]·nH2O were obtained by hydrochloric acid decomposition of potassium ferrocyanide in aqueous solution. The morphology and crystal structure dependence from synthesis conditions was analyzed. In a pure hydrochloric acid solution, cubic particles of the material are formed. The presence of ascorbic and citric acids does not change the morphology of the samples. An addition of the saturated solution of potassium chloride during acid decomposition leads to the formation of shapeless particles of slightly smaller size compared to the synthesis in the HCl solution.
Samples synthesized in the presence of ascorbic acid with argon purging have a chemical composition of K1.83Fe[Fe(CN)6]·nH2O and cubic morphology with particle face sizes up to 2.2 μm. They have monoclinic structure P21/c, stable during heating up to 250 degrees.
[1] G. Du, H. Pang. Recent advancements in Prussian blue analogues: Preparation and application in batteries // Energy Storage Materials 36 (2021) 387–408
[2] Y. Bai et al. Progress of Prussian Blue and Its Analogues as Cathode Materials for Potassium Ion Batteries // Eur. J. Inorg. Chem. 2023, 26, e202300246
For the demanding of recent research with radioactive ion beams at the new fragment separator ACCULINNA-2 [1], a modular neutron spectrometer based on stilbene crystals and 3” ET-Enterprise 9822B photomultipliers has been routinely employed to study the properties of light exotic nuclei, for instance: 5-7H, 7,9He, 10Li [2-4] lying close to boundary of β-stability. Nonetheless, the detailed characteristics and properties of stilbene scintillator have not been completely studied and well-understood owing to its intricate response by light output anisotropy with reference to the crystalline structure itself. In this work, we determined the light output responses to electrons and charged ions (protons and alpha particles), having the same initial energy but generating different behaviors when they stop in the organic scintillator. In accordance with the detector performance, the energy and time resolution were evaluated at different energy ranges with several gamma sources. Monte Carlo simulations of neutron interactions with stilbene detector were performed to determine the fast neutron registration in the energy range of 3-30 MeV and compared with measured data by the use of 14-MeV “tagged” neutrons, ING-27 [5].
[1] http://aculina.jinr.ru/
[2] A.A. Bezbakh et al., “Study of 10Li low energy spectrum in the 2H(9Li,p) reaction”, Bulletin of the Russian Academy of Sciences: Physics, 84 (2020) 491-494.
[3] A.A. Bezbakh et al., “Evidence for the First Excited State of 7H”, Physical Review Letters, 124 (2022) 022502.
[4] M. S. Golovkov et al., “Observation of a positive-parity wave in the low-energy spectrum of 7He”, Physical Review C, 109, L061602 (2024).
[5] I. N. Ruskov et al., “TANGRA-Setup for the Investigation of Nuclear Fission induced by 14.1 MeV neutrons”, Physics Procedia, 64 (2015) 163-170.
A thorough investigation of neutron-halo nuclear systems such as 7H, which decay through neutron emission, requires the development of a sophisticated system of neutron detectors. At Flerov Laboratory of Nuclear Reactions, a neutron time-of-flight spectrometer of 110 BC-404 plastic-based scintillators was proposed. An individual detector module consists of a 75-mm thick, hexagon-shaped BC-404 scintillator, inscribed in a 100-mm diameter circle and an ET 9822B series PMT. Main characteristics of particular interest to our study are neutron detection efficiency and time resolution of the detector module. Additionally, cross-talk estimation is also of concern for the neutron spectrometer. To maximize neutron detection efficiency, we are required to set a minimal energy threshold, which must be expressed in energy units, typically in MeVee. Time resolution investigation demands amplitude comparison of different detectors in similar energy ranges. Both characterizations require thorough energy calibration. We suggest a semi-automatic procedure to calibrate Compton spectra. In which, the energy spectrum is first simulated with GEANT4 libraries. The optimal values of the Gaussian and calibration coefficients are found through the gradient descent algorithm and initial values are extracted through differentiation of a Fourier-filtered spectrum. A small sample of 15 detector module prototypes has been produced and characterized by time resolution and energy threshold value. To estimate the effect of cross-talk, a measurement was made at Frank Laboratory of Neutron Physics, where we use a 14.1 MeV tagged neutron generator to irradiate a detector module, positioned side-by-side with another module. The result for cross-talk is approximated by the signals detected from the module on the side.
The performance of the Scintillation Wall (ScWall) detector during the first physics run of the BM@N fixed target experiment with Xe+CsI at 3.8 AGeV has been demonstrated. Only charged fragments with charges Z = 1 and Z = 2 were observed in the scintillator detectors of the central part of the ScWall, while fragments with charges up to Z = 5 were also visible close to the beam hole. Comparison of the experimental charge distribution with the results of simulations using the DCM-QGSM-SMM and PHQMD models underestimated the yields of Z = 2 fragments and overestimated those with higher Z, suggesting the need for adjustments to these models to better describe the production of spectator fragments. Centrality evaluation using the correlation of the ScWall total charge with the impact parameter is significantly less sensitive to centrality than that obtained from the correlation of the impact parameter with the Forward Hadron Calorimeter (FHCal) energy deposition. It is shown that to obtain 80% purity in the most central class of events, the width of the centrality class should not be less than 20%. ScWall is effective for event plane estimation, but FHCal provided better resolution of the correction factor for accurate flow measurements at the BM@N.
Neutrino physics has been actively researching for a few last decades and there is a wide variety of open questions. Neutrino oscillation parameters which are supremely important to measure are the charge-parity phase and the neutrino mass ordering. To provide the highest significant level of their values it is necessary to combine data taken from different types of experiments. Currently working neutrino accelerator experiments, NOvA and T2K, have been detecting neutrino interactions in electron neutrino appearance and muon neutrino disappearance modes and these data are the main set to estimate unknown parameters. However, oscillation data from reactor experiments help to reduce some degeneracy in $\chi^2$ calculations. So that the data fitter of accelerator and reactor neutrino experiments is created within GNA. GNA (Global Neutrino Analysis) is a software for neutrino oscillation analysis developed at JINR. One dimensional $\chi^2$ profiles and two dimensional $\chi^2$ contours of neutrino mass differences and mixing angels are plotted based on Monte-Carlo simulation and data taken from NOvA, T2K and Daya Bay experiments.
The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid scintillator detector that is under construction in southern China. One of the main goals of the experiment is to determine the neutrino mass ordering. For this measurement, JUNO will use electron antineutrinos from eight nuclear reactors located at an optimized baseline of 52.5 km. To resolve fast oscillatory pattern in the spectrum and determine the neutrino mass ordering, JUNO will need energy resolution $\sigma$ of 3% at 1 MeV and energy scale uncertainty lower than 1%. This talk will cover the details of JUNO’s sensitivity analysis for neutrino mass ordering.
Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shells and two neutrinos are carried away.
The measurements of the energies of the emitted particles and the half-life of the 2EC2ν decay to the ground state are of great interest to nuclear physics. The model predictions for 2EC2ν half-life are based on the evaluation of form the main source of NME. The NME calculations are complicated and have large uncertainties. Therefore, if retrieved from experiment, half-life values can serve as a test for nuclear theory. In the one model framework some constraints on the 2EC0ν NME can be derived using supposed values of the 2EC2ν NME, so the estimation of 2EC2ν half-life could help to study physics beyond the Standard Model.
This process is being studied on Ar-36 for the first time. We have performed a search for two-neutrino double electron capture in the KK and KL shells of Ar-36 using exposition of about 12 ton-day of data from the DarkSide-50 dark matter detector. As a result of the analysis, no significant excess above background was found, which allowed us to estimate that the half-life limits with CL=90%. We have also evaluated the sensitivity of the DarkSide-20k experiment, which will become operational in the next few years.
Huntington's disease (HD) develops as a result of a polyglutamine mutation (encoded by the CAG triplet) in the huntingtin protein gene (HTT). The juvenile form of the disease evolves with more than 50 number of CAG repeats in htt. HD belongs to the group of neurodegenerative, as it leads to the death of the striatum neurons, and later in the cerebral cortex. HTT has been shown to be involved in a variety of cellular processes, including cellular transport of both individual vesicles and organelles. Microtubules (MT) are involved in these processes. MT polymerize from tubulin, have polarity and dynamic properties. One of their functions is to be "rails" for intracellular transport mediated by motor proteins. There is ample evidence to indicate that the MT dynamics disorders and the MT network intracellular architecture desorganization accompany many diseases, including neurodegenerative ones, which motivated us to investigate changes in their dynamics in patients with HD.
As model systems, we used: (1) fibroblasts isolated from skin biopsies of HD patients with different polyglutamine fragment lengths and healthy donors; cultured (2) neurons and (3) glial cells obtained by directional differentiation from iPSCs of HD patients and healthy donors. The dynamics of the MT network restoration after its disassembly in the cold in skin fibroblasts was analyzed. It turned out that the number of MT growing from the centrosome in the early stages does not differ in the cells of patients with HD and healthy donors (which indicates the absence of the centrosome-located MT organizing centers activation), however the average length of MT increases faster in the cells of patients. To study the dynamic properties of MT, the method of transfection with fluorescently labeled plus-terminal protein EB3-GFP was used, which made it possible to observe the growth and disassembly of the plus-ends of MT in real time. Next, the dynamics of MT were analyzed in the ImageJ program using automatic plugins and manual tracing. The dynamics of MT was studied in various regions of the cell: in the central part (region of the nucleus and centrosome), on the leading edge and in the tail of fibroblasts; in axons, bodies and dendrites of neurons. Interestingly, the dynamic properties of MT at the leading edge and in the tail of skin fibroblasts depended on the CAG repeats number in the HTT gene: with an increase in the repeats number there was an increase in dynamic parameters at the leading edge, whereas in the tail part - on the contrary. In the central part of the cells the tendency to increase growth rates was observed in all cases. Similarly, we observed an increase in growth rates in the bodies and axons of cultured neurons of HD patients, while in dendrites the growth rates did not differ from those in neurons obtained from healthy donors.
The results obtained made it possible for the first time to evaluate in vitro differences in the dynamic properties of MT of cultured fibroblasts and neurons of HD patients and healthy donors, which makes it possible to describe the effect of mutant HTT on the MT dynamics properties as well as to approach the study of MT as targets for HD patients diagnostics and possible therapy.
Acknowledgments: The authors thank the Moscow University Development Program (MSU Development Program PNR 5.13) and Nikon Center of Excellence at A.N. Belozersky Institute of Physical and Chemical Biology for providing research infrastructure.
Ferritin, a globular protein complex essential for iron assimilation and storage within its apoferritin shell, possesses unique biochemical properties and a distinctive topology that make it suitable for diverse applications. This study explores the potential of ferritin as a dietary supplement for iron deficiency and anemia prevention.
We conducted cell cultivation experiments to investigate the efficiency of ferritin expression and iron loading both in vitro and in vivo. Using an E. coli strain engineered to produce ferritin, we loaded ferritin with iron directly within the cells. The degree of iron incorporation was assessed using a commercially available kit, revealing that up to 200 iron atoms were successfully loaded per ferritin molecule. These findings demonstrate that ferritin produced in E. coli can be efficiently iron-loaded, making it a promising candidate for use as an iron supplement. Further research into the molecular mechanisms of iron release from ferritin and its bioavailability in humans is necessary to determine the most effective ways to utilize ferritin for improving human health.
This study was supported by the Ministry of Science and Higher Education of the Russian Federation, project FSMF-2023-0010; “Integrated structural biology and genetics for the production of protein preparations and biologically active substances as new food and non-food products.”.
Functional studies of archaeal cysteine-less LOV domain
Ilia I. Natarov 1, Oleg Y. Semenov 1, Alina A. Remeeva 1, Ivan Y. Gushchin 1
1 Research Center for Molecular Mechanism of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, MIPT, Dolgoprudny 141701, Russia
LOV (Light Oxygen Voltage) domains are sensor modules of photosensitive proteins widespread in bacteria, archaea and eukaryotes. Flavin-binding fluorescent proteins (FbFPs), derived from LOV domains with site directed mutagenesis, can be used as genetically encoded reporters in optogenetics [1] and microscopy [2]. Moreover, oxygen-independent fluorescence of FbFPs and their smaller size represent substantial advantages over green fluorescent protein (GFP). Consequently, FbFPs inclusion in the fluorescence reporter toolbox can be beneficial for imaging in anaerobic biological systems [3].
Conserved cysteine, that forms a covalent adduct with flavin chromophore, plays a crucial role in LOV domains signal transduction [4]. Hence, cysteine knock-out mutants are often used as negative controls in LOV photoreceptor studies. However, recent research [5] specifies that there are biologically active native cysteine-less LOV domains and their signaling mechanism is based on flavin chromophore reduction to the neutral semiquinone radical state.
In this work previously uncharacterized natural cysteine-less LOV domain of BAT (bacterio-opsin activator) protein from thermophilic haloarchaea Halanaeroarchaeum sulfurireducens was successfully cloned and expressed in E.coli, purified and loaded with excess of chromophore. Eventually we studied the photophysics of this LOV domain and verified photoinduced one electron reduction of flavin cofactor to the neutral semiquinone radical state.
Literature list
1. Blue-light receptors for optogenetics / A. Losi, K. H. Gardner, A. Möglich // Chemical reviews. – 2018. – Vol. 118.
2. LOV-based reporters for fluorescence imaging / A. M. Buckley et al. // Current opinion in chemical biology. – 2015. – Vol. 27.
3. Flavin-based fluorescent proteins: emerging paradigms in biological imaging / A. Mukherjee, C. M. Schroeder // Current opinion in biotechnology. – 2015. – Vol. 31.
4. Primary reactions of the LOV2 domain of phototropin studied with ultrafast mid-infrared spectroscopy and quantum chemistry / M. T. A. Alexandre et al. // Biophysical journal. – 2009. – Vol. 97.
5. Signal transduction in light–oxygen–voltage receptors lacking the adduct-forming cysteine residue / Yee E. F. et al. // Nature communications. – 2015. – Vol. 6.
Histidine kinases (HKs) constitute a large family of proteins that play a central role in signal transduction, enabling cells to sense and respond to a wide range of both intercellular and intracellular signals [1]. Although their structural features and distribution are well-studied in prokaryotes, the understanding of histidine kinases in eukaryotes remains incomplete, despite several phylogenetic studies on the subject [2]. Of particular interest are histidine kinase rhodopsins (HKRs), discovered in Green Algae, whose precise biological roles have yet to be fully determined [3].
Green Algae, an important group of autotrophic eukaryotes, are critical to ecosystems by providing habitats, serving as a food source for various organisms, facilitating nutrient cycling, and increasing oxygen levels in aquatic environments through photosynthesis. The ability to sense and respond to light is vital for the photosynthetic processes of Green Algae. Although some of the mechanisms behind these processes have been uncovered [4], further investigation is required.
The main aim of this study was to perform a bioinformatics analysis and explore the structural organization of histidine kinases (HKs) in Green Algae, with a focus on the domains present to infer their possible functions. Amino acid sequences were obtained from the UniProt database using the search query “txid1148[Organism] AND (Histidine[All Fields] AND Kinase[All Fields])” and sequences classified under the EC code for HKs (2.7.13.-). After removing redundant sequences, the remaining data were analyzed using InterProScan-5.66-98.0 [5] to identify the domains within the Pfam collection. Proteins that lacked domains characteristic of HKs were filtered out to minimize the inclusion of incorrect entries. This process resulted in the identification of 458 proteins likely to be HKs.
Within this dataset, two important subgroups were identified. The first subgroup, known as hybrid histidine kinases, consists of proteins that not only possess the histidine kinase domain (HK domain) but also include a receiver (REC) domain. A total of 269 such proteins were identified, representing 58% of all HKs analyzed. The second subgroup, termed histidine kinase rhodopsins (HKRs), consists of hybrid histidine kinases that begin with a rhodopsin-like (Rhd) domain. This subgroup includes 97 proteins, accounting for over a quarter of the HKs studied. We propose that the bacteriorhodopsin-like segment in this subgroup functions as a sensor for external signals, which are then transmitted via the conserved histidine residue to the response regulator. The most prevalent domains and domain architectures were identified for both subgroups. Notably, more than a quarter of the HKRs feature two REC domains instead of one. To better understand the relationships among these proteins, a phylogenetic tree was constructed, offering a visual representation of their evolutionary relatedness within this subgroup.
For the HKRs, three-dimensional protein structures were predicted using AlphaFold3 [6], which largely confirmed the domain identifications. However, in some cases, additional domains were detected that had not been identified by InterProScan. Further analysis with FoldSeek suggested these additional domains could represent secondary REC domains, indicating that the Rhd-HK-REC-REC architecture may be more widespread than previously thought.
In conclusion, our work provides information on the possible and most common domain architectures of histidine kinases. Furthermore, identification of rhodopsin-like domains in a significant proportion of histidine kinases in photosynthetic Green Algae may imply an important functional role for proteins with this architecture in these microorganisms. Additionally, the presence of two REC domains may be a characteristic feature of these proteins, warranting further investigation.
Heavy neutral gauge boson $Z'$ are predicted by many theoretical schemes of physics beyond the Standard Model, and intensive searches for their signatures will be performed at the next-generation high energy electron-positron colliders. It is quite possible that $Z'$ is heavy enough to lie beyond the discovery reach expected at the LHC, in which case only indirect signatures of Z′ exchanges may occur at future colliders, through deviations of the measured cross sections from the Standard Model predictions.
We here assess the identification reaches on Z′ gauge boson pertinent to the SSM, LR, ALR and E$_{6}$ classes of models at the planned International Linear Collider (ILC) and Compact Linear Collider (CLIC).
Based on the previously developed model-independent analysis methodology, model-dependent constraints on the Z′ mass have been derived in this paper.
Prompt heavy quarkonium production is well described within the collinear parton model in the next-to-leading order of perturbaive QCD at kinematical region of $p_T^{} \gg M$ where $M$ is a mass of a quarkonium state. But the region of small $p_T^{}$ is still being researched and the factorisation approach which is valid here is TMD-factorisation (transverse-momentum dependent). We studied $J/\psi$ production in collision of protons at $\sqrt{s} = 200, 27$ and $19.4$ GeV. Certainly, we used Nonrelativistic QCD (NRQCD) as a standard hadronisation model for charmonium production, and we extracted nonperturbative matrix elements for octet color states of the NRQCD from a set of experimental data on prompt $J/\psi$ production because color singlet model can't be considered as sufficient for experimental data description.
The TMD approach is a general factorisation model for $p_T^{} \ll M$ region [1]. One of the realisations of the TMD-factorisation is a so called Soft Gluon Resummation approach [2] where soft gluon emission by partons is considered, evolution of the TMD parton distribution functions is controlled by the Collins - Soper equations [3] though the TMD distribution is partly reduced to the collinear one. We perform our study at the LO$+$LL approximation for now. We describe data from PHENIX Collaboration at $\sqrt{s} = 200$ GeV and from NA3 Collaboration at $\sqrt{s} = 19.4$ GeV and do predictions for future SPD NICA experiments at $\sqrt{s} = 27$ GeV. We considered both gluons and quarks as initial partons, we also estimated a contribution of $P$-wave charmonium production and calculated polarised $J/\psi$ production as an angular coefficient $\lambda$. The Inverse-Error Weighting Scheme [4] is used as an approach for matching of collinear and TMD factorisations.
References:
[1] J. C. Collins. Foundations of Perturbative QCD, Cambridge Univ. Press, Cambridge (2011).
[2] J. Bor and D. Boer. TMD evolution study of the $\cos 2\phi$ azimuthal asymmetry in unpolarized $J/\psi$ production at EIC, Phys. Rev. D 106, 1 (2022).
[3] J. C. Collins, D. E. Soper, and G. Sterman. Transverse momentum distribution in Drell-Yan pair and $W$ and $Z$ boson production, Nuclear Physics B 250 (1-4), 199--224 (1985).
[4] M. G. Echevarria, T. Kasemets, J.-P. Lansberg, C. Pisano, A. Signori. Matching factorization theorems with an inverse-error weighting, Phys. Lett. B 781, 161--168 (2018).
The production of Mueller-Navelet dijets is studied within the framework of the
High-Energy Factorization approach [1,2,3]. Such processes are considered to be
sensitive to the effects of BFKL resummation [4]. In Ref.[5], it was shown
that experimental data for dijets with large rapidity gaps can't be described
using NLO DGLAP based Monte-Carlo generators. In the study, we predict cross
sections for the production of dijets using the Reggeon-Reggeon-Particle and Reggeon-Reggeon-Particle-Particle effective vertices obtained within the formalism of the L.N. Lipatov's Effective Field Theory [6]. Calculations are performed using two different unintegrated PDF sets [7,8].
[1] J. Collins and R. Ellis. Nucl.Phys.B 360 (1991) 3-30;
[2] S. Catani and F. Hautmann. Nucl.Phys.B 427 (1994) 475-524;
[3] L.V. Gribov, E.M. Levin, M.G. Ryskin. Phys.Rept. 100 (1983) 1-150;
[4] A. Mueller and H. Navelet. Nucl.Phys.B 282 (1987) 727-744;
[5] CMS Collaboration. JHEP 03 (2022) 189;
[6] L.N. Lipatov. Nucl.Phys.B 452 (1995) 369-400;
[7] M. Nefedov and V. Saleev. Phys.Rev.D 102 (2020) 114018;
[8] J. Blumlein. DESY-95-121.
Masses of the triply heavy tetraquarks of all flavor contents are calculated within the relativistic quark model, based on the quasipotential approach and QCD, and diquark--antidiquark picture of tetraquarks. The relativistic quasipotential equation takes into account all spin-dependent and spin-independent relativistic corrections and the internal structure of the diquarks. The calculated masses of such tetraquarks are compared with the strong fall--apart decay thresholds into a heavy and heavy--light mesons. The states that could be observed as narrow resonances in other decay modes are determined.
The selection of synthesis methods significantly influences the properties of nanomaterials intended for use in solid-state lighting device applications. In our study, Zinc borate nanophosphors doped with 1 mol% europium (Zn4B6O13:Eu3+) were synthesized using various methods such as the sol-gel, combustion, and solid-state reaction methods. The impact of the various method on the structural and photoluminescence properties of the material is thoroughly investigated. The prepared zinc-borate nanophosphors were successfully annealed at 800 oC. XRD results confirmed a cubic crystal structure formation for all samples. All the synthesized Zn4B6O13:Eu3+ phosphor materials showed a 95% matching score with the JCPDS file (No. 01-076-0917) of the host material. There was a small discrepancy among the crystallite sizes of the nanophosphors, ranging from approximately 95 to 98 nm. The calculated crystallite sizes are very small relative to the literature. Various morphologies were observed through scanning electron microscopy (SEM); polyhedron-like, hexagonal-like, and irregular morphologies for sol-gel, combustion, and solid-state reaction methods, respectively. All samples were distinctly agglomerated into groups. The average particle sizes for the prepared nanophosphors ranged from 500 to 890 nm. Upon excitation at 248 nm while monitoring the highest emission peak at 615 nm, the photoluminescence emission trends were observed to be in this trend: sol-gel > solid state > combustion reaction methods. The highest emission peak was assigned to the europium electric dipole transition, namely: 5D6 → 7F2. The CIE chromacity diagram revealed a reddish colour emission for all the synthesized phosphor materials, which were (0.642, 0.353), (0.641, 0.352), and (0.644, 0.354) for sol-gel, combustion, and solid-sate reaction methods, respectively. The synthesized phosphor materials could be potential candidates for red light-emitting diodes (RLEDs) applications.
Keywords : Zn4B6O13:Eu3+, photoluminescence, synthesis method.
The investigation of nanoscale diamond-like carbon (DLC) coatings on acrylonitrile butadiene styrene plastic (ABS) substrates revealed a linear I-V characteristic, a decrease of resistivity from 12 μOm∙m to 3 μOm∙m, and of wetting angle from 52° to 38° with increasing thickness from 54 nm to 71 nm. The relative dielectric permittivity of the DLC coatings varies from 5.6 to 6.5, and at the high frequency limit is completely determined by the real part. It is proposed to consider the conductivity in the system "DLC-coating//adsorbed layer of $H_{2}O$ molecules" as a combination of two mechanisms: the hopping conductivity of electrons in the volume of the DLC-coating and the proton conductivity by the Grotthuss mechanism in the adsorption layer of water molecules. It is experimentally established that the variation of air humidity in the range of 16% to 95% leads to a decrease in the resistance of the system up to $10^3$ times. The results demonstrate the potential for developing a humidity sensor based on a DLC-coating with a thickness of approximately 50 nm. This technology will be applied in the fabrication of GEM-detectors with optimized resistive coating of the collector electrode.
The crystal and thermodynamic properties of Tb2Ni2X (X = Al, Ga) are reported through measurements of X-ray diffraction (XRD), magnetic susceptibility, χ(T ), magnetization, M(μ0H) and heat capacity, Cp(T ). XRD pattern analysis confirms the orthorhombic W2CoB2-type with the space group of Immm. χ(T ) at high temperature for both compounds follows the Curie–Weiss relationship giving an effective magnetic moment close to that expected for the trivalent Tb ion. The low-temperature χ(T )/Cp(T ) data indicate that both compounds order antiferromagnetically at TN = 41 K / 40.4 K and 41.5 K / 41.4 K for Al and Ga compounds, respectively. Cp(T ) data of the nonmagnetic counterparts Y2Ni2X (X = Al, Ga) are well described by the Debye model given a Debye temperature, θD = 236.9(4) K and 225.3(2) K for Al and Ga compounds, respectively. The low-temperature of the 4f-magnetic contribution to the total heat capacity, C4f (T ) data can be well approximated according to the antiferromagnetic spin–wave dispersion, giving an energy gap Δsw = 4.1(3) meV and 2.2(2) meV for Al and Ga compounds, respectively. The 4f – magnetic entropy S4f (T ) for both compounds reaches the values of 2Rln(2) close to their respective TN values.
The study of spontaneous fission processes in heavy and superheavy nuclei remains an important task in nuclear physics. A Time-Projection Chamber (TPC) is a reliable tool for such investigations, enabling the detection of fission fragment trajectories, fragment energy measurements, and mass distributions of fission fragments. As part of our project, a TPC-based detector is being developed for application at the focal plane of the GRAND separator (SHE Factory). The focus is on the chamber configuration, the use of 3He neutron counters, and evaluating the system’s efficiency. This presentation will cover the operational principles of TPCs and their potential applications for studying the spontaneous fission of short-lived superheavy nuclei.
To understand the possibilities of synthesizing new elements 119 and 120, it is of particular importance to determine the most optimal reactions. This issue depends both on the reaction cross-section value and the availability of the necessary target isotopes and accelerated ions. To do this, it is important to measure the cross sections of reactions that lead to lighter elements, but whose cross sections are obviously higher, for example, $^{242}$Pu($^{50}$Ti,xn)$^{292-x}$Lv and $^{238}$U($^{54}$Cr,xn)$^{292-x}$Lv. The cross sections of these reactions can be compared with, e.g., the cross section of the $^{245}$Cm($^{48}$Ca,2-3n)$^{290,291}$Lv reaction, which could determine the degree of decrease in the production cross section for element 116 during the transition from $^{48}$Ca to $^{54}$Cr. This will help to obtain more reliable information about the process of the compound-nucleus formation (the second stage of the fusion-evaporation process). Note, so far no cross section of the reaction of complete fusion of actinide nuclei with ions heavier than $^{48}$Ca has been measured.
From a comparison of the production cross sections for isotopes of element 116 in reactions with $^{48}$Ca and $^{54}$Cr, it follows that the transition to a heavier particle led to a drop in the cross section by more than factor of 100.
Today, along with standard nuclear reaction approaches such as fragmentation, fission or fusion, the use of multi-nucleon transfer reactions (MNT, MultiNucleonTransfer) is a potential method to reach the field of unknown exotic heavy and superheavy nuclei enriched with protons/neutrons. In addition to studies of the kinematics and cross sections of the formation of products of MNT reactions, the development of suitable methods for separation and registration of heavy nuclei formed in MNT reactions continues. The use of the SHIP kinematic separator (GSI) for the study of MNT reactions has shown that this method is a new approach in the study of MNT reactions.
In May-June 2023, the experiment was conducted at the Laboratory of Nuclear Reactions (LAR) at the U-400 accelerator complex to study MNT reactions in collisions of 26Mg + 238U. The separation of the products of the desired nuclei from the products of side reactions was carried out by the kinematic separator SHELS (Separator for Heavy Element Spectroscopy). After separation, the recoil nuclei fly through a time-of-flight detector and are implanted into a focal two-sided multi-strip silicon detector (DSSD, 128x128 strips), around which 116 proportional neutron counters filled with 3He (SFiNx detection system) are placed. Here, the studied nuclei are registered, as well as the alpha particles emitted by them, fragments of spontaneous fission and neutrons.
During the preprocessing, about 100 spontaneous fission events of various nuclei were recorded. The proposed products in the MNT 26Mg + 238U reactions, which can be seen in the online experiment, are americium isotopes. The statistics are small, but nevertheless, as confirmation that we obtained spontaneously dividing nuclei, we studied the average number of neutrons per fission act (according to preliminary estimates v ̅= 2.68 ± 0.36) and the distribution of neutrons by multiplicity. In order to make concrete conclusions, it is proposed to continue studying this MNT reaction, and process the data more thoroughly.
Structural rearrangements of chromosomes – chromosome aberrations (CA) – are the most sensitive marker of radiation exposure. The analysis of radiation induced CA in metaphase cells of peripheral blood lymphocytes is the only valuable method of human biodosimetry. It allows to estimate the dose to which an individual has been exposed occupationally, accidentally or therapeutically. The advanced method of molecular cytogenetics multicolor FISH (mFISH) based on the whole genome painting allows visualizing all chromosome rearrangements with higher precision than routine methods. CA based biodosimetry relies on accurate calibration curves obtained following exposure to reference radiation, usually γ-rays or 250 kVp X-rays. In recent decade, radionuclide γ-rays sources were replaced in research facilities worldwide with X-ray sources charaterised by lower energy, such as 130 kVp, that deliver X-ray spectrum with substantial component of soft X-rays (20-30 kV). Given multiple reports of increased relative biological efficiency (RBE) of soft X-rays, we aimed to compare CA dose response curves following exposure to X-rays from 130 and 220-250 kVp sources, as well as to X-ray spectrum for manufacturer provided settings and custom-hardened spectrum of 130 kVp X-ray source.
For the first time, we exploited multicolor FISH method to investigate the biological efficiency of different quality X-rays delivered at two LRB facilities that replaced recently deconstructed γ-60Co unit ROKUS-M: CellRad (Precision, USA) and SARRP (Xstrahl, USA) and their suitability as a reference radiation in radiobiological research. For this study, lymphocytes obtained from the blood of one healthy donor were irradiated in vitro with 130 kVp X-rays + 0.5 mm Al manufacturer-supplied filtration or 0.1 mm Cu custom-made filtration (CellRad ) and with 130 kVp X-rays with 1mm Al or 220 kVp with 0.15 mm Cu filtration (SARRP) at doses 1-4 Gy. The cells were harvested after 48 h of post-irradiation culturing and CA in metaphases of the first post-irradiated cell cycle were assessed. The cytogenetic effects of X-ray radiation were compared with the results obtained previously at the γ-60Co unit (ROKUS-M, JINR) and with the results obtained earlier by one of the authors at the 250 kVp X-ray unit (Seifert, GSI, Germany) [1].
Experimental data on mean aberration number at different doses were analysed by non-linear regression using linear-quadratic model, and obtained best-fit parameters compared for different irradiation conditions. Based on the analysis we demonstrated that all X-ray regimes have the higher biological efficiency than γ-60Co. 220 kV regime of SARRP perfectly matched 250 kV Seifert machine giving the same results as previously published [1]. We found no statistically significant difference in biological efficiency of 250 kVp X-rays compared to 130 kVp + 0.1 mm Cu and (p = 0.137) and 220 kVp SARRP (p = 0.143). 130 kVp X-rays filtered with 0.5 mm Al (effective energy 25.6 keV) have the higher biological efficiency than filtered with 0.1 mm Cu (effective energy 38.8 keV) with RBE = 1.11 ± 0.04, p = 0.006). No statistically significant difference, however, was found between 220 kVp X-rays and and 130 kVp X-rays filtered with 1 mm Al (SARRP irradiator). The lower efficiency of SARRP 130 kVp regime, compared to 130 kVp + 0.1 mm Cu, may be explained by using the thicker Al filter (1mm compared to 0.5 mm in CellRad irradiator) which resulted in more efficient reduction of soft X-rays. In summary, our data show that X-rays from both units , 220 kVp SARRP and 130 kVp + 0.1 mm Cu Cell Rad may be used as a reference radiation in radiobiological research.
Noteworthy, the aberration spectra induced by all radiation types used were shown to be similar (~20 % simple breaks, 60% simple exchanges and 20% complex aberrations).
References:
1. Lee R., Sommer S., Hartel C., Nasonova E., Durante M., Ritter S. Complex exchanges are responsible for the increased effectiveness of C-ions compared to X-rays at the first post-irradiation mitosis. Mutat. Res. Genet. Toxicol. Environ. Mutagenes. 2010, 701:52–59. doi: 10.1016/j.mrgentox.2010.03.004.
DNA double-strand breaks (DSBs), defined as the simultaneous damage of the two DNA strands, are considered one of the most complicated types of DNA lesions to repair due to several closely related complications – DNA DSB repair systems restrictions and non-cycling cells. There are two basic cellular mechanisms responsible for DNA DSBs recovery: non-homologues end joining (NHEJ) and homologues recombination (HR). NHEJ is considered to be the main mechanism for DNA DSBs recovery since it does not depend on the cell cycle and repairs the majority of DBS, though it is also error-prone and thus mutagenic. HR, on the other hand, tends to be more accurate; nevertheless, it relies on the second copy of the DNA molecular as a template for the DNA resynthesis step, confining it to G2/M phases of the cell cycle. Providing that radiation exposure generates a lot of DNA DSBs, it is clear that most of them repaired via NHEJ might be repaired incorrectly leading to mutations. However, the DNA damage response is well-tuned and has not precisely been determined in different cell and tissues. For instance, neuron stem cells (NSCs) are incredibly sensitive to genetic mutations making the accurate DNA DSBs repair essential as far as other cell lineages originate in them. It has been shown that stem cells contain 10-times less genetic mutations in comparison with other cycling somatic cells. Whereas non-cycling mature brain neurons are able to withstand the substantial number of DNA damages without disastrous outcomes for brain functions. Moreover, another example of cycling tumor cells might enter the cell cycle with unrepaired DNA DSBs that leads to mutations; yet it does not prevent tumors’ growth. All three examples revealing the complexity of DNA repair machinery in distinctive cell types.
In our work, we compare several cell lines of mammalian and human cells derived from different types of tissues to explore the DNA DSBs repair kinetics after exposure to protons or N15-ions: the cell lines of normal human dermal fibroblasts (NHDF), mouse glioblastoma cells (U87), human melanoma cells (B16), and rat primary hippocampal cell culture (mature hippocampal neurons, astrocytes, NSCs). To analyze the DNA DSBs repair kinetics, the immunofluorescent staining method was utilized with gH2AX or 53BP1 as protein markers of DNA DSBs. Mature neurons, astrocytes and NSCs in the primary hippocampal cell culture were identified by using the cell-type specific markers as MAP2, GFAP, and nestin, correspondingly.
It is shown that the maximum formation of radiation-induced gH2AX and 53BP1 foci in NHDF, B16 and U87 cell lines is revealed at 1 h after proton or nitrogen-irradiation with 1.25 Gy dose. Whilst the peak number gH2AX or 53BP1 foci in the hippocampal cell culture cells shifts towards 4 h post-irradiation. This might demonstrate the difference in DNA repair machinery involved into the DSBs recovery in different cells and tissues, especially in NSCs after nitrogen-irradiation. It was pointed out that nestin-positive cells revealed the lowest number of 53BP1 foci among all tested cell lines. Supposing that NSCs should possess meticulous DNA DSB repair systems, these results might be indicative of the bigger role of HR pathway since 53BP1 protein is known for its role in NHEJ restricting the access to DNA DSB ends from HR proteins.
The radiobiology of TGF-beta 1 is a insufficiently known but promising area of research exploring the role of explores the role of transforming growth factor, a key cellular cytokine, in anticancer therapy. This report will focus on the mechanisms by which TGF-beta 1 regulates cellular processes (such as proliferation, differentiation, and apoptosis) and how it shapes the tumor microenvironment. We will also review the effects of radiotherapy on TGF-beta 1 and its receptors expression and how this knowledge may be used to develop new cancer treatments.
The IBR-2M reactor plant, the complex of technological equipment and the reactor building will develop their final life depending on the operating mode in 2032-2037. One of the proposed options to replace the IBR-2M reactor is the NEPTUNE reactor (average power of 15 MW, pulse duration of 210 μs and an average neutron flux of 1,6 x 1014 n/cm2/s and at peak power of 3,8 x 1017 n/cm2/s), which will for the first time use fuel based on the isotope Np-237.
Nuclear reactors accumulate kilograms of neptunium as a result of irradiation of natural and enriched uranium fuel, and the use of these quantities will give a major boost towards closing the nuclear fuel cycle and reducing the risks of nuclear wastes. Np-237 is a threshold isotope with a fission threshold of 0.4 MeV, lower than the fission threshold of uranium-238 of 2 MeV, which gives it a significant advantage in terms of the possibility of using as a nuclear fuel in pulsed reactors to obtain a very short neutron pulses, have a low background power between pulses and using a new more effective reactivity modulator and control rods.
The report and presentation explain the principle of operation of the reactor, its most important properties, and some of the problems that were discovered during the developing stage, while presenting proposed solutions:
the results of the development of a promising new generation reactor of the IBR type - “NEPTUNE”, are considered in detail. The report will provide an explanation of the components of the research station, clarify in details the components of the reactor core, explain the working principle of the reactor and show the most important characteristics of the reactor;
the report will also illustrate the possibility of partially using low-enriched uranium fuel (with U-235 enrichment less than 20%) in the reactor with the aim of enhancing the safety of the reactor by increasing the generation life time of the neutron;
also review the results of comparing the use of three materials, namely liquid para hydrogen, solid methane, and mesitylene, at temperatures of 20 K, in order to increase the percentage of cold neutrons extracted in the neutron channels.
We investigate a class of strictly four-dimensional, renormalisible gauge-Yukawa theories with all possible dimension 3 and 4 operators which exhibit Asymptotic Safety - their UV behaviour is controlled by an interacting, ultraviolet fixed point. The conformal window introduced by this fixed point is studied in a systematic expansion, provided by the Veneziano limit. Constraints from the strong coupling limit, fixed point mergers and vacuum instability are formulated. We will show that the conformal window lies within a perturbative regime.
The processes of electron-positron annihilation into a virtual photon or a Z-boson is considered. QED radiative corrections due to the initial state radiation in these processes are estimated upto the $\mathcal{O} (\alpha^5)$ order within the leading and next-to-leading logarithmic approximations. The results are relevant for verification of the Standard Model and searches for new physical phenomena at future high-luminosity electron-positron colliders such as the FCC-ee (CERN) and CEPC (China).
We present a detailed study of the T-even lepton angular distribution in the Drell-Yan process, using a leading-order perturbative QCD calculation within the collinear factorization scheme, including the effects of $\gamma/Z^0$ boson exchange. We analyze the $Q_T$ dependence and compare theoretical predictions with available data from the ATLAS and CMS Collaborations at the LHC.
This work is devoted to the study of ion exchange resins Dowex 50WX8 200-400 mesh and Dowex 1X8 100-200 mesh, washed in solutions of iron salts, by nuclear gamma resonance. Unlike crystalline solids, ion exchange resins do not possess long-range order and cannot be described using the phonon concept.Traditionally, the nuclear gamma resonance method is used to study solids. Gel is a three-dimensional matrix, in a certain sense it can be considered as a solid, but without much periodicity. Consequently, Mössbauer spectroscopy can be used as one of the methods for the determination of ionic forms in resins.
The variety of practical applications of materials with f and heavy d elements in the composition requires the development of theoretical methods for their correct interpretation and description. However, when studying optical properties, such as excitation energies, in materials containing lanthanides and actinides, it is almost impossible to achieve reliable, highly accurate results. Currently, such calculations are only possible for molecules with few atoms due to the rapid increase in computational costs with the number of electrons explicitly considered.
For many such applications it is sufficient to simulate the electronic structure of some relatively small fragment of the crystal after performing a preliminary calculation of the periodic structure (crystal), assuming that the rest (environment of the fragment) can be considered as “frozen” with good accuracy. To apply these approaches to crystals, our laboratory has developed a technology for cutting out a fragment from a periodic structure named CTEP (compound-tunable embedding potential) method [1], which provides high accuracy in describing the influence of the environment on the selected fragment.
To analyze the correctness of reproducing the simulated electron density in the vicinity of a heavy nucleus, the chemical shift of lines of the X-ray emission spectra was chosen. For each atom, these spectra are characteristic and highly sensitive to the state of a d- or f-element in a particular compound. Direct methods for calculating the X-ray emission spectra lines are practically unapplicable, therefore a "two-step" method for its calculation was developed [2].
In this work ytterbium halides (YbHal$_n$ Hal=F, Cl, n = 2,3) are investigated by a relativistic version of the CCSD. Since this approach has limited possibilities) because of the rapid growth of its computational complexity with increasing the system size (currently, about 100 electrons can only be correlated simultaneously), therefore, it is important to carry out preliminary calculations on simpler systems and the stoichiometric molecules were chosen for this purpose. In the first part of the work, the calibration of the basic sets on molecular systems was carried out, which showed that when studying the "core-localized properties" on the Yb atom, there is no need to use saturated basic sets on halogens. In the second part of the work, pilot calculations of chemical shifts of X-ray emission spectrum lines for fragments of CTEP crystals were carried out using the relativistic CCSD.
Financial Support. The work was supported by the RSF (project No. 20-13-00225) https://www.rscf.ru/project/23-13-45028 / NRC “Kurchatov Institute” – PNPI.
[1] Shakhova V. M., Maltsev D. A., Lomachuk Y. V., Mosyagin N. S., Skripnikov L. V., Titov A. V. Compound-tunable embedding potential method: analysis of pseudopotentials for Yb in YbF2, YbF3, YbCl2 and YbCl3 crystals // Phys. Chem. Chem. Phys. 2022. V. 24. PP. 19333–19345.
[2] Lomachuk Y.V., Titov A.V. Method for evaluating chemical shifts of x-ray emission lines in molecules and solids// PRA. 2013. V. 88, 6. p. 062511.
Monomolecular films formed on the surface of a liquid by self-organization of amphiphilic molecules are commonly called Langmuir monolayers. The arachidic acid Langmuir monolayers formed on a solution of cerium nitrate were studied in this work. We have identified unusual mode of the structural ordering of such monolayers. The results are based on the analysis of data obtained using the grazing-incidence X-ray diffraction method. The atypical features of the diffraction maps are revealed: the rounding of the Bragg rods, which lie exactly on the circle in reciprocal space. This is atypical for a two-dimensional polycrystalline structure: the classical map for a two-dimensional monolayer generally shows three vertical peaks. The measurements were carried out at the ''Langmuir'' station of the Kurchatov synchrotron radiation source.
For the analysis of 2D diffraction maps, the model of the grazing-incidence X-ray diffraction has been developed to describe the lateral ordering in Langmuir monolayers.
At high surface pressure (compression beyond the collapse point $ \pi \sim 55 $ mN/m), the reorganization of the monolayer structure is observed: a pseudo-herringbone structure is formed in the monolayer and the system becomes corrugated. This is a new type of structural ordering. For the first time, the numerical simulation of two-dimensional diffraction maps reproducing atypical features observed in experimental diffractograms has been carried out and their quantitative description has been performed.
To develop the theoretical model, the conditions of the grazing-incidence X-ray diffraction, the distorted-wave Born approximation (DWBA) and the kinematic theory of scattering on Langmuir monolayers were used. The details of the diffraction model to describe these corrugated Langmuir monolayers and the results of the numerical analysis of the diffraction data are presented in this paper.
Ibuprofen is a representative of the group of non-steroidal anti-inflammatory drugs widely used in modern medical therapy. The drug formulations of Ibuprofen most often contain a racemic mixture of the two enantiomers with the S enantiomer being biologically active and the R being inactive. Cyclic dimers of Ibuprofen can be distinguished in condensed state of this compound that is confirmed by X-ray diffraction analysis. In solvent the formation of dimers with other configurations can be expected: linear and/or cyclic associates with another type of binding. The presence of such dimers will influence the vibrational dynamics of ibuprofen in condensed matter.
The object of present study is ibuprofen enantiomers and their dimers. Both enantiomers (S and R) were taken into account when constructing dimer models. The combination of computational (DFT) and experimental (IR and Raman spectroscopy) methods were used in the study.
For all the dimers studied, the parameters of molecular geometry and characteristics of hydrogen bonding were calculated and analyzed. The strength of the hydrogen bond and the stability of ibuprofen dimers are discussed. It has been shown that the presence of an intermolecular hydrogen bond affects the vibrational frequencies of groups of atoms involved in intermolecular interactions (the carboxyl group). This gives more correct results comparable to the experiment.
The collision of two heavy nuclei takes a special place in nuclear reactions studies due to the collective rearrangement of a large number of nucleons in a very short span of time, typically of the order 10$^{−20}$ seconds. During this collision, a significant number of nucleons are transferred between the projectile and target nuclei due to the influence of different reaction mechanisms [1]. In reactions with heavy ions at energies close to the Coulomb barrier $–$ complete fusion, quasifission (QF), and deep-inelastic collision are competing processes. Therefore, a comprehensive understanding of the reaction dynamics of these processes is one of the key ingredients for the synthesis of Super Heavy Elements (SHE) [2, 3].
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 same fissioning nucleus, $^{224}$Th. The measurements of the reaction binary products were carried out by utilizing the double-arm time-of-flight (TOF) spectrometer $CORSET$ [4]. 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 Mass-Total Kinetic Energy (M-TKE) distributions of the primary binary fragments from $^{224}$Th have been measured. Different aspects of the fission and quasifission reaction dynamics have been studied through detailed multimodal analysis [3] 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 ${\bf 75}$, 064602 (2007).
3. E. M. Kozulin $\textit{et al.}$, Phys. Rev. C ${\bf 105}$, 024617 (2022) and references therein.
4. E. M. Kozulin $\textit{et al.}$, Instrum. Exp. Tech. ${\bf 51}$, 44 (2008).
The knowledge about (n,$\gamma$) and (n,n'$\gamma$) correlations is very useful for understanding the process of inelastic neutron scattering and for estimation of the influence of the direct and compound nucleus (CN) mechanisms on the nuclear reaction. A detailed review of the CN approach is presented in [1], the direct mechanism is described in [2]. The formalism reported in [1] works quite well for low-energy particle scattering, but it fails to describe 14 MeV neutron scattering [3]. There are not too many experiments measuring (n,n'$\gamma$)-correlation with 14 MeV neutrons, and the largest part of them was carried out more than 40 years ago with rather poor accuracy [4,5]. In recent years (n,n'$\gamma$)-correlation in the reaction of inelastic neutron scattering on $^{12}\mbox{C}$ was measured in wide neutron energy range in work [6], but their results don’t generally agree with previous experiments. Thus, it is interesting to obtain data on (n,n'$\gamma$)-correlation with small errors and higher angular resolution.
In Dubna, at the TANGRA setup, an experiment is being carried out to measure angular correlations (n, n'γ) in the inelastic scattering of neutrons with an energy of 14.1 MeV on $^{12}\mbox{C}$ using the tagged neutron method. We use 12 long (1 meter) plastic scintillation detectors with two PMTs. Ten of them are placed around the target in the plane of reaction and two detectors are placed perpendicular to the plane of reaction. These detectors have time resolution about 3ns and space resolution about 20cm that helps us to obtain better angular resolution and separate gamma-rays from neutrons by the time-of-flight. The main idea of all experiments with triple-correlations is to fix plane of reaction made by directions of initial neutron and inelastically scattered neutron. One of the advantages of our setup is a possibility to see the correlation out of reaction plane.
Besides experimental part a theoretical approach will be proposed in this report to describe the differential probability of gamma ray emission in the reaction of inelastic neutron scattering depending on the directions of the initial neutron, scattered neutron and gamma quanta for both direct and CN reaction mechanisms. This approach is based on invariant spherical functions of several vectors - see, for example, [7]. Our formula for angular correlations includes elements of the S-matrix, which can be obtained from the TALYS program, which calculates cross sections for nuclear reactions.
In this work we compare our theoretical approach with experimental data. Parameters of the model in TALYS were adjusted to fit data on neutron inelastic scattering and gamma-quanta angular distribution.
The study of neutron-induced nuclear reactions on carbon is of interest both from the point of view of improving data on the properties of carbon excitation levels and for refining model parameters for describing the neutron interaction mechanism with carbon nuclei. Carbon plays an important role in the process of nucleosynthesis, in particular, according to F. Hoyle, the existence of life on Earth is due to the level of carbon with an energy of 7.65 MeV.
In the framework of the TANGRA project, angular distributions of scattering neutrons on carbon were measured using the tagged neutron method. As the source of neutrons, the ING-27 generator with a built-in 256-pixel alpha-particle detector was used. A graphite plate with dimensions 44x44x2 cm3 was used as a target and was located at a distance of 31.4 cm from the neutron source. Scattered neutrons were measured using 20 plastic detectors located around the target at a distance of ~2 m. The energy of scattered neutrons was determined by the time of flight. Angular distributions for elastic and inelastic scattering for 4.44 MeV, 7.65 MeV and 9.64 MeV states were obtained. Also, the angular distribution of gamma-ray emission were measured. The results were compared with the available experimental data, as well as with theoretical optical model calculations performed with TALYS 1.9 code. A new set of optical parameters was found.
The work will be presented on the development of a system of scintillation detectors for space radiation suppression in the experiment aims to study dd-fusion reactions with the low beam energy (PolFusion). The PolFusion nuclear physics experiment carried out at the Petersburg Nuclear Physics Institute (Gatchi-na), the purpose of which is to study the fusion reaction of 2H (d, p) 3H and 2H (d, n) 3He with polariza-tion of the initial particles at low energies in the range of 10-100 keV. This work includes the following stages: modeling of the central detector system of the PolFusion experiment and the scintillation detector system, development of the design of the scintillation detector system and the results of test measurements of cosmic radiation.
SPD (Spin Physics Detector) is a universal experimental setup that is planned to be installed at the NICA collider under construction. In the first phase of the experiment, the vertex detector will not be used, which will lead to a significant degradation of the momentum resolution and reduce the efficiency of track recognition and secondary vertex reconstruction. To minimize this effect, we propose to supplement the main track system with a Micromegas-based detector located as close as possible to the beam interaction region.
The technology has been improved to clarify a tumor's location and size by utilizing X-ray contrast media in medical CT imaging techniques. In particular, X-ray contrast images of a phantom containing mixtures of contrast agents such as iodine and gadolinium have absorbed the X-rays high and are indicated to produce well-tolerated. Notably, it mentioned that iodinated contrast media is mostly non-ionic and safe to use.
This work focused on evaluating the effect of the X-ray imaging of the simplified phantom containing mixtures of iodine depending on the concentration, materials, and distribution under the CT model of two different types of target sizes are experimental and predictive in the GEANT4 toolkit. The X-ray contrast image on the detector demonstrated different tolerances for each material, and the brightest part was on the bone cortical. For the physical model, the highest contrast effect has been performed on the target with iodine at the highest concentration. However, it could not be demonstrated well in the biological model. The main factor was the contrast effect slightly increased according to the target thickness. Finally, this study indicates the possibility of obtaining CT images for a physical part in potential concentration below the toxic limit of iodine on the body by an in-silico method. We predict it gives potential values between the optimal size of tumor sites and the contrast agent.
The application of copper and silver nanoparticles in the agricultural sector, industry, medicine and commercial products leads to their intentional and unintentional release into the environment. Spearmint (Metha Spicata L.) an important herbal remedy was exposed to root and foliar treatment with silver and copper nanoparticles (PVP-coated) in the concentration range of 1-100 mg/L during 28 days. To determine the content of copper and silver in soils and plant segments inductively coupled plasma optical emission spectrometry and atomic absorption spectrometry technique were used. Transmission electron microscopy allowed to visualize and characterize nanoparticles in solutions. The study revealed the influence of nanoparticles concentration and way of application on their localization in spearmint segments. The preparation of herbal infusion from plants exposed to nanoparticles made it possible to assess the risks to human health through the tea consumption. The percentage of silver and copper extraction into the herbal tea varied depending on the exposure route and nanoparticles concentration in solution. Copper extraction from leaves into the infusion was at the level of 3-64%, while silver extraction was less than 1% (under root exposure), and 22-98% when was applied foliar spraying.
A total of 32 chemical elements in mosses, 33 elements in leaves and 38 elements in soils collected on territory seven Moscow parks (Losiny Ostrov, Victory Park, Ostankino, Sokolniki, Izmailovo, Kuzminki-Lublino and Tsaritsyno) were determined by neutron activation analysis and atomic absorption spectrometry. The high concentrations of some elements in samples indicate significant technogenic impact from the automobile complex, industrial activity and thermal power plants. The ecological and geochemical assessment of the state of three components of the environment applying the total pollution index (TPI) allowed to classify recreational areas of Moscow by the level of pollution and determine the main pollutants. For the three components considered, the level of pollution coincided only at two sites. More than half of the analyzed soils (62%) belongs to a category of high pollution.
Actin is one of the most abundant proteins in a living cell. Actin structures are found in all cells of a living organism and are involved in maintaining and changing the cell shape, exocytosis and endocytosis, cell adhesion to substratum and cell movement, and signal transduction. In mammals, β- and γ-actin are cytoplasmic actin isoforms in non-muscle cells. Despite minor differences in the amino acid sequence, β- and γ-actin localize in different cell structures and perform different functions. While cytoplasmic β-actin is involved in many intracellular processes including cell contraction, γ-actin is responsible for cell mobility and promotes tumor transformation. Numerous studies demonstrate that β- and γ-actin are spatially separated in the cytoplasm of fibroblasts and epithelial cells; this separation is functionally determined. The spatial location of β/γ-actin in endothelial cells is still a subject for discussion. Using super-resolution microscopy, we investigated the β/γ-actin colocalization in endothelial cells. For analysis, we used human pulmonary artery endothelial cells (HPAEC), primary cells isolated from the human pulmonary artery. Colocalization analysis of both wide-field and SIM images was performed using ImageJ software. To find out whether β- and γ-actin are colocalized in a given region, we used the Coloc2 plugin function of calculating the M1 and M2 Manders’ coefficients (i.e., separately for two channels). We showed that β and γ-actin are partially colocalized in certain regions of the endothelial cytoplasm. In HPAEC, the β/γ-actin colocalization degree varies widely between different parts of the marginal regions and near the cell nucleus. In the basal cytoplasm, β-actin predominates, while the ratio of isoforms evens out as it moves to the apical cytoplasm. Thus, colocalization analysis suggests that β- and γ-actin are segregated in the endotheliocyte cytoplasm. The segregation is greatly enhanced during cell activation in the endothelial barrier dysfunction (pathological permeability disorder of the vascular permeability that occurs in a number of acute, life-threatening human states), modelling in vitro, and this data may demonstrate different roles of two cytoplasmic actin isoforms in the functional activity of endothelial cells.
Acknowledgments: The authors thank the Moscow University Development Program (MSU Development Program PNR 5.13) and Nikon Center of Excellence at A.N. Belozersky Institute of Physical and Chemical Biology for providing research infrastructure.
Beams of protons and C-12 nuclei are very effective in treating deep-seated solid tumours, but collateral damage to surrounding healthy tissues is still unavoidable. It has been proposed [1], to reduce this damage by splitting a homogeneous radiation field into arrays of sub-millimetre-wide beams called minibeams. Such minibeams become wider with depth of penetration due to multiple Coulomb scattering and production of secondary particles in tissues and finally overlap in the target tumour volume [2].
In this work, the propagation of minibeams of protons and C-12 in a water phantom was simulated using the Geant4 toolkit [3] of version 10.3. Electromagnetic processes were modelled with the G4EMStandard_opt3 physics list, the Binary Cascade (BIC) model was used for proton- and neutron-induced nuclear reactions, and the Quantum Molecular Dynamics (QMD) model was used for nucleus-nucleus collisions. The modified microdosimetric kinetic model (MKM) was used to calculate the relative biological efficiency (RBE), biological dose and cell survival rate of human salivary gland (HSG) cells [4] representing tissues with normal radiosensitivity.
The hexagonal and rectangular minibeam arrays with individual beams of 0.3 mm and 0.5 mm FWHM with the centre-to-centre distance of 2 mm were considered and compared with a homogeneous radiation field. In all cases the beam energies were adjusted to obtain 60 mm wide spread-out Bragg peaks (SOBP) centered at 130 mm. A higher average cell survival rate was calculated at the entrance to the phantom and at the dose plateau for the arrays of minibeams of protons and C-12 in comparison to the homogeneous irradiation field. While a limited number of cells close to the minibeam central axes receive very high peak dose and thus inactivated, many cells between the minibeams have a high survival probability. At the same time, the cell survival rate in the target volume with minibeams was found to be similar to the survival rate in the homogeneous field. Peak-to-valley dose ratios (PVDR) and dose-volume histograms were also calculated as functions of the depth in phantom and compared for all considered minibeam irradiation geometries and homogeneous field. The calculations demonstrated the advantages of minibeams with respect to homogeneous radiation fields.
This study was funded by the Russian Science Foundation (RSF) grant No. 23-25-00285 ”Modeling of the physical and biological properties of therapeutic minibeams of protons and nuclei”. The authors are grateful to RSF for the support.
References
1. C. Lamirault et al., “Spatially modulated proton minibeams results in the same increase of lifespan as a uniform target dose coverage in F98-glioma-bearing rats,” Radiat. Res. 194, 715 (2020).
2. I. Pshenichnov et al., “Proton and carbon-ion minibeam therapy: from modelling to treatment”, Phys. Part. Nucl. 55, 1083 (2024).
3. J. Allison et al., “Recent developments in Geant4,” Nucl. Instrum. Methods Phys. Res., Sect. A 835, 186 (2016).
4. Y. Kase et al., Microdosimetric measurements and estimation of human cell survival for heavy-ion beams Radiat. Res. 166, 629 (2006).
Fast reactor cores require steels and alloys resistant to high-energy neutron fluxes and capable of maintaining sufficient medium-temperature (300-500°C) strength. EP-450 (1Cr13Мo2NbVB) ferritic-martensitic steel, containing 11-13.5% chromium, is used as an acceptable material for cladding and covers of fuel assemblies (FA) of sodium cooled fast reactors. Its competitive advantage is the high resistance to swelling, especially at elevated core temperatures. One of the problems of ferrite-martensitic steels is that with increasing dose of neutron irradiation the brittle-ductile transition temperature increases, which leads to a sharp decrease in ductility at relatively low temperatures typical of operation.
In this work, samples of EP-450 steel were cut from hexagonal wrappers of fuel assemblies from the BN-350 sodium-cooled reactor located in Aktau, Kazakhstan, in both the unirradiated and neutron-irradiated states to 50.4 dpa. Heat treatment was carried out before irradiation at 1050°C for 30 minutes followed by tempering at 720°C for 1 hour. Uniaxial tensile tests 10×3.5×0.3 mm in size were then carried out at room temperature. Microstructure was investigated using a Hitachi TM-4000 PLUS electron scanning microscope and a JEOL JEM-2100 transmission electron microscope. Vickers microhardness was determined using an eVick-1A microhardness tester.
It was revealed that irradiation of EP-450 steel with fast neutrons leads to a decrease in ductility and increase in strength of the material as expected, though the object of our study was the mechanism. Uniform deformation following irradiation to 50.4 dpa decreases catastrophically to 1-2% due to the effect of low-temperature radiation embrittlement. Deformation was limited to a few ferrite grains favorably oriented to the loading axis. The fracture in the unirradiated steel is ductile, while that of the irradiated steel is brittle-ductile or brittle depending on the irradiation temperature. This paper discusses the influence of irradiation parameters on the strength, ductility and fracture of EP-450 steel.
The previously developed non-destructive method for diagnosing heavy ion beam losses, based on neutron registration, has undergone significant optimization. The main goal of this work was to address identified issues and improve the sensitivity and reliability of the system. During the optimization process, key tasks were solved, including adjusting the operating voltages to enhance detector sensitivity and determining optimal conditions for neutron registration at different beam energies. These measures significantly improved the accuracy and speed of measurements, which is especially important when working with increasing beam energies and intensities.
Additionally, the implementation of continuous monitoring helped minimize data loss and provided more efficient control over beam losses. Experiments conducted at the FLNR accelerator complex confirmed the effectiveness of the improved method, which remains non-destructive—crucial for enhancing the safety of physical installations and improving data quality.
Thus, the optimized diagnostic method has demonstrated its suitability for widespread use in scientific research, including tasks in radiobiology and radiation effect studies, where precise and timely diagnostics are of critical importance.
When a wave propagates in the active line of a spiral high-voltage pulse generator, the electric energy is converted into the energy of the magnetic field, and the electric energy of the coaxial capacitors connected in series. After reflection from the open ends of the line, the energy of the magnetic field in it begins to transform into electric energy, and the wave in the active line changes polarity. When the reflected wave reaches the point where the switch is installed, the voltage between the beginning and the end of the spiral reaches its maximum value.
This paper presents a numerical solution to the problem of the dependence of the voltage at the generator output on time. The process of electromagnetic wave propagation in active and passive lines is described by telegraph equations, and the process of charge draining is described by the model of a classical oscillatory circuit. The solution to wave propagation was found using Godunov's method, and explicit first-order difference schemes were used to calculate the boundary conditions for the spiral generator. The paper also presents experimental results of the distribution of magnetic field induction inside the spiral line in time, obtained by numerical integration of the voltage on the inductive sensor placed inside the generator.
The results of numerical modeling of the spatial distribution of magnetic and electric fields inside and outside the spiral generator are presented. The dependences of the influence of the magnetic circuit on the stabilization of the magnetic field distribution inside the spiral line and on the generator efficiency, respectively, are revealed.
The results obtained in the work allow us to predict and model with sufficient accuracy the physical parameters of spiral generators, which can be used, for example, to manufacture a portable X-ray machine with explosive electron emission.
At the BINP the VEPP-5 injection complex delivers electron and positron beams through transportation channels to the VEPP-4M and VEPP-2000 colliders. There is a necessity to change magnetic field vectors in dipole magnets to deliver particles with different charges, such as positrons and electrons. Because of some physics effects, in order to achieve precise adjustment of field, it's necessary to register not only current in magnet coils, but also the field itself in the transportation channel of the injection complex. The aim of the work is a development of a device which would measure a magnetic field in the injection complex transportation channel with an accuracy more than $10^{-3}$. Hall effect method was chosen. An experiment on Hall sensors resistance to radioactivity was conducted. Two stands for this experiment were created and assembled. Change of Hall parameters due to time spent in radiation was registered. The experiment successfully demonstrated that the hall sensors operate in conditions of the injection complex radiation.
In the context of modern accelerator technology, it is essential to guarantee the specified characteristics of the extracted electron beam. In addition to the information regarding the energy and intensity of the beam, it is crucial to ascertain its spatial and angular distribution [1].
The position of the particle beam in space and its transverse intensity distribution can be determined by means of profilometry. The detectors of profilometers are of various types, dependent on the method employed for the acquisition of the profile. One such method is wire scanning. In order to implement the wire scanning method, it is proposed that a cylindrical ionization chamber can be used as the detecting element, with the detecting device moving linearly in a plane perpendicular to the beam propagation axis. This approach has been put forth due to the notable advantages of ionization chambers, including high radiation resistance, sensitivity to low-intensity radiation, ease of use, and the capacity to collect data in real time.
In order to obtain transverse distributions of the electron beam intensity, it was proposed that the multi-angle scanning method be used [2]. This method entails the rotational movement of the profilometer at different angles relative to the central axis of the beam. The data set obtained in this way represents the dependence of the beam profile on the scanning angle. Through the use of mathematical reconstruction methods, including the inverse Radon transform, the two-dimensional intensity distribution of the beam can be reconstructed.
As part of the study, a wire-scan profilometer utilizing an ionization chamber was developed and evaluated. In order to obtain transverse distributions of the electron beam intensity, a multi-angle scanning device was developed and tested. This included the profilometer described above, which provides linear movement of the detector, as well as a rotation system relative to the central axis of the beam. The prototype of the profilometer and the multi-angle scanning device were tested at the Microtron MT-25 facility (Dubna, Russian Federation) at an electron energy of 7 MeV.
The experimental studies conducted on the electron beam revealed that the ionization chamber is an effective tool for determining the position and measuring the size of the electron beam with high resolution (no worse than 1 mm). Transverse distributions of the electron beam intensity were obtained at varying distances from the microtron output window. The study demonstrated the efficacy of utilizing the ionization chamber in the capacity of a detector for both the profilometer and a multi-angle scanning device.
References:
1. Strehl, P. (2006). Beam instrumentation and diagnostics (Vol. 120). Berlin: Springer.
2. Grigorieva, A. A., Bulavskaya, A. A., Bushmina, E. A., Vorobiev, A. P., Vasilyeva, A. G., Miloichikova, I. A., & Stuchebrov, S. G. (2023). Using Multiangle Scanning to Determine the Transversal Profile of a Carbon Ion Beam. Physics of Particles and Nuclei Letters, 20(5), 1243-1245.
We study the rare decays corresponding to b → d transition in the framework of the covariant confined quark model. The transition form factors for the channels B+(0) →(π+(0), ρ+(0), ω) and B0s → K(∗)0 are computed in the entire dynamical range of momentum transfer squared. Using the form factors, we compute the branching fractions of the rare decays and our results are found to be matching well with the experimental data. We also compute the ratios of the branching fractions of the b → s to b → d rare decays using the inputs from previous papers on b → sℓ+ℓ− using this model.
The pion, as an exchange particle, plays a great role in the description of nuclear dynamics, since it has a small mass compared to other mesons. In the report, the Bethe-Salpeter formalism with a separable kernel is applied to describe the quark-antiquark system. The solution of the Bethe-Salpeter integral equation for the pion vertex function is obtained analytically by applying the separable interaction. Using this solution, the physical constants and dynamical observables of the pion are obtained. The four-dimensional integrals are calculated by using three independent numerical methods: the Cauchy's theorem method, the Feynman parameterization method, and the Wick rotation method. A set of model parameters is selected to describe both physical constants and dynamical observables of the pion decay and scattering in good agreement with experimental data.
The strange baryon production in Bi+Bi collisions at $\sqrt{s_{NN}}=9.0$ GeV is studied applying the PHSD transport model. Hyperon and anti-hyperon yields, transverse momentum spectra, and rapidity spectra are calculated, their centrality dependence and an impact of the rapidity and transverse momentum cuts are investigated. Hydrodynamic velocity and vorticity fields are calculated and the formation of two oppositely-rotating vortex rings moving in opposite directions along the collision axis is found. Hyperon spin polarization induced by the medium vorticity within the thermodynamic approach is calculated and the dependence of the polarization on the transverse momentum and rapidity cuts and on the centrality selection is analyzed. It is shown that for the hyperon polarization mechanism, considered in the paper, the structure of the vorticity field makes an imprint on polarization signal as a function of the azimuthal angle in the transverse momentum plane, $\phi_H$, $\tan\phi_H=p_y/p_x$.
The analysis of two-particle correlations has provided the chief means for determining spatio-temporal characteristics of relativistic heavy ion collisions. We discuss the theoretical formalism behind these studies and the experimental methods used in carrying them out. Recent results from RHIC were put into context in a systematic review of correlation measurements performed over the past two decades. Conservation laws of hydrodynamics have been used and confirmed that the mass before collision is equal to the mass after collision, however, the laws of hydrodynamics are conserved. Various thermodynamic properties such as density, pressure, and velocity profiles were studied, and changes in the flow of gas (in Quark-Gluon Plasma) in the Sod-Tube models were observed from one point to another. The velocity showed a sharp increase with the gas flow.
We investigate the sensitivity of the light nuclei and hypernuclei production to the strongly interacting nuclei matter equation-of-state (EoS) within the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) microscopic transport approach.
PHQMD is an n-body microscopic transport approach based on Quantum Molecular Dynamics (QMD) propagation of baryonic degrees of freedom, where clusters are formed through potential interactions between nucleons and hyperons. The Minimum Spanning Tree (MST) algorithm is employed to identify bound clusters based on the baryon correlations in the coordinate space. In addition to this, a 'kinetic' mechanism for deuteron production is incorporated, utilizing the catalytic hadronic reactions that account for all isospin channels. This approach enhances the deuteron production while considering its quantum nature through the finite-size excluded volume effect and projection of the relative momentum of the interacting pair of nucleons onto the deuteron wave function, leading to a significant reduction of deuteron production, especially at target/projectile rapidities.
We find that static density-dependent and momentum-dependent interactions, although yielding the same EoS for cold matter, have markedly different effects on observables in heavy-ion collisions. We analyze their impact on the flow coefficients, the transverse momentum spectra and the fragment yields of different clusters as a function of rapidity. Our results, compared to HADES and STAR BES data, show a significant sensitivity of the elliptic flow coefficient to the momentum-dependent potential.
Furthermore, we propose a method to experimentally distinguish between various deuteron production mechanisms in heavy-ion collisions across the range of energies from SIS to RHIC.
Spinel-type crystals $\mathrm{AMe_2O_4}$ encompass a wide range of practical applications like photocatalysis or spintronics, but often demonstrate non-trivial electronic and magnetic properties which theoretical description is mitigated. In this work, we performed DFT+U calculations for the most extensive set of neutral point defects in $\mathrm{Fe_3O_4}$ (magnetite) and $\mathrm{FeCr_2O_4}$ (chromite) and investigated all the possible types of cationic and oxygen defects in both spinels. Our results unveil both similarities and principal differences between the defective $\mathrm{Fe_3O_4}$ and $\mathrm{FeCr_2O_4}$, posing chromite as a material less prone to defect formation, and could be a valuable asset to the development of new multiscale models of steel corrosion. For more details, readers are referred to [JETP, 166(3), 347, 2024].
Nickel ferrite spinel $\text{Ni}\text{Fe}_{2}\text{O}_{4}$ promising material in spin-based devices and non-volatile resistive memory. In this work we consider electronic structure of pristine and defective nickel ferrite. The orbital ordering, band gap and charge transfer are studied in the framework of density functional theory with account of strong electronic correlations (DFT+U method). The possibility of changing the type of polaron transport in the presence of oxygen vacancies and nickel antisites has been demonstrated. The corresponding non-adiabatic activation barriers of polaron transport is considered. The resulting hopping energies are in general agreement with experimentally observed activation energies. The highlighted influence of point defects on the polaron conductivity mechanism could be a suitable explanation for the large variability of activation energies in previous experimental works.
The extended version of these findings has been published in the journal Computational Materials Science.
N. A. Fominykh, J. Situmeang, V. V. Stegailov, C.-C. Kaun, Influence
of point defects on charge transport in nickel ferrite NiFe2O4, Compu-
tational Materials Science 246 (2025) 113326.
Silicon (Si) has been considered as one of the most promising materials for photoelectrochemical (PEC) devices due to its low cost, established manufacturing process, and high theoretical photovoltage and saturation current density. However, developing Si-based PEC devices has been challenging, primarily because of silicon highly susceptibility to (photo)corrosion under PEC conditions. To address this, a protective layer is necessary to both prevent corrosion and maintain efficient charge transfer within the photoelectrode. In this study, we prepared high-quality SrTiO3 (STO) thin films on p-Si substrates with reduced graphene oxide (rGO) as an interfacial layer. The STO thin film (~ 10 nm) was deposited using pulsed laser deposition (PLD) on both rGO-buffered and bare Si substrates to explore the effects of epitaxy i.e. crystallinity and interfacial properties on PEC performance. The results showed that the STO layer epitaxially grown on rGO-buffered Si exhibited lower onset potential compared to non-epitaxial counterparts. From linear sweep voltammetry (LSV) and chronoamperometry measurements, we concluded that the epitaxially protected photocathode had significantly improved performance compared to the non-epitaxial sample, thus highlighting the importance of a well-defined interfaces. The smooth surface of high-quality epitaxial STO layer with sub-nano roughness played a crucial role in protecting the underlaying p-Si substrate from corrosion, whereas the presence of pinholes in the non-epitaxial sample resulted in degradation rate similar to that of bare Si substrate without any protection. This study presents a novel approach for preparing a protective layer over the photoelectrode substrate ensuring both high efficiency and long-term stability in PEC devices.
In this study, the effect of proton irradiation on the structure and properties of Al2O3 – YSZ ceramics based on γ+θ-Al2O3 + n% YSZ (n = 0, 1, 5, 10, 15 wt.%) nanopowders was analyzed. The phase composition of the powders, the structure, physical and mechanical properties of the Al2O3 - YSZ ceramics were studied taking into account the YSZ concentration and the pressing pressure. We have found that various crystallization processes occur during the sintering of ceramics and two types of structure are realized: aggregate-hardened and disperse-hardened, depending on the HHP value. It is shown that the processing of compacts under HHP conditions at 600-700 MPa prevents the formation of agglomerates of YSZ grains in the intergranular space of Al2O3, and the maximum values of physical and mechanical characteristics are achieved at concentrations of 10 and 15% YSZ and HHP values of 700 MPa.
Irradiation of the synthesized ceramics of the composition γ+θ-Al2O3 + n% YSZ (n = 0, 1, 5, 10, 15 wt.%) was carried out on an EG-5 electrostatic accelerator. X-ray phase analysis showed that proton irradiation of the composite ceramics of the Al2O3 – YSZ composition did not cause changes in the phase composition of both phases (α-Al2O3 and YSZ) in the ceramic composite. It was also found that irradiation of the ceramics with a proton beam did not lead to the occurrence of macrostress fields (stresses of the 1st kind) on their surface, as indicated by the invariance of the lattice parameters in both phases before and after irradiation. The SEM method revealed the effect of crushing of ZrO2 grains under the action of proton irradiation, which leads to a decrease in the average grain size of the filler of the alumina matrix. Also, the study of the structure of ceramics after exposure to high-energy irradiation showed a strong effect of radiation-accelerated diffusion of zirconium dioxide grains in the aluminum oxide matrix.
The 232Th + 48Ca reaction has been studied at the gas-filled separator DGFRS-2 online to the cyclotron DC280 at the SHE Factory at JINR. At three low 48Ca energies, three new even-even nuclides were synthesized for the first time: a spontaneously fissioning (SF) 268Sg with the half-life TSF = 13 s; an alpha-decaying 272Hs with T = 0.16 s and E = 9.63 ± 0.02 MeV; and 276Ds with T1/2 = 0.15 ms, E = 10.75 ± 0.03 MeV, and an SF branch of 57%. The decay properties of these nuclei are in agreement with the systematics of experimental partial half-lives and alpha-decay energies of heavy known nuclei, as well as spontaneous-fission half-lives. The cross sections of the 4n-evaporation channel of 0.07 pb, 0.7 pb, and 0.11 pb were measured at 231, 238, and 251 MeV, respectively. At two higher projectile energies of 251 and 257 MeV, new isotope 275Ds with the half-life of 0.43 ms and alpha-particle energy of 11.20(0.02 MeV was synthesized in the 48Ca-induced reaction with actinide nucleus and identified by measuring correlated alpha decays ending in known nuclei. The 238U + 40Ar reaction was studied at 212 MeV resulting in observation of 273Ds. The decay properties of nuclei originating from 273Ds and 275Ds are compared with theoretical calculations and decay schemes are proposed. The cross sections of the 232Th(48Ca,5n)275Ds reaction of 0.11 pb and 0.34 pb were measured at excitation energies of the 280Ds compound nucleus E = 51 and 56 MeV, respectively. The cross section of the 5n-evaporation channel of the 238U + 40Ar reaction at E = 49 MeV of 0.18 pb turned out to be comparable to that for 275Ds at close excitation energy.
For the first time since 1983, when the first experiments on the synthesis of Ds isotopes in direct reactions of 40Ar, 48Ca with isotopes of actinide elements (232Th, 235,236,238U) were carried out, the reaction cross section was measured, which turned out to be an order of magnitude smaller than the cross section of the 226Ra(48Ca,4n)270Hs reaction. When moving to heavier elements (Z>110), the cross section increases, reaching a maximum value for elements 114-115, and then decreases by about 30 times for element 118. Such variation is in full agreement with theoretical models predicting shells at Z=108, N=162 and Z=114, N=184.
The performance of a prototype amplifying element for gas-discharge detectors made of polyurethane by a combination of stereolithography, laser drilling and magnetron sputtering has been demonstrated.
An array of 20×20 conical-shaped holes with a solution angle of 78° was formed on an area of 40 mm$^2$. The average diameter of the holes was 300±30 μm on the non-metallised side and 200±20 μm on the metallised side, respectively. The metallisation of the prototype did not result in dusting of the inner surface of the holes.
The prototype amplifying element is characterised by the gas gain coefficient G ≈ 1.3∙10⁴ at electric field strength E ≈ 24 kV/cm, which is comparable to standard detectors. The dependence of G(E) is described by a standard exponential function.
The applied set of technologies allowed to effectively eliminate the disadvantages of already existing analogues: an ordered array of holes without delamination of metallisation along the edges was obtained.
The obtained results confirm the feasibility of using additive technologies and laser drilling to create amplifying elements and can be useful for modernisation of such complexes as NICA, LHC and others.
[1] M. Arif, Zeitschrift Für Physikalische Chemie 237, 809 (2023).
The BM@N experiment, located at the Nuclotron facility of the Joint Institute for Nuclear Research (JINR) in Dubna, is a fixed-target experiment aimed at studying heavy ion collisions at beam energies up to 4 A GeV. One of the primary goals of the experiment is to measure neutron spectra and yields, which are essential for understanding the dynamics of these collisions. To address the challenges of detecting neutrons in the kinetic energy range of 0.5–4 GeV, a Highly Granular Neutron Detector (HGND) is being developed. The detector’s high granularity is critical for precise particle identification and presents a significant design challenge. It features a layered structure with copper absorbers and readout layers consisting of an 11x11 array of plastic scintillators, with a Multi-Pixel Photon Counter (MPPC) readout board and an LED-based calibration board. This report presents status of the design, production, and testing of the readout and calibration boards, along with the development of the mechanical fixtures and support structures required for the detector's assembly.
В рамках научной программы ОИЯИ по исследованиям в области физики высоких энергий ведется работа над проектом создания ускорительного комплекса NICA (Nuclotron based Ion Collider fAcility). Для изучения физических процессов, происходящих при столкновении тяжелых ионов, разработан многоцелевой детектор (Multi-Purpose Detector, MPD), который будет размещен в одной из точек взаимодействия коллайдера NICA. В качестве трекового детектора для экспериментальной установки MPD выбрана Время-проекционная камера (Time-Projection Chamber, TPC), предназначенная для трехмерного трекинга и идентификации частиц. TPC содержит 95232 канала регистрации, включает в себя 1488 карт накамерной электроники (Front-End Card, FEC) и другие модули, сгруппированные в 24 подсистемы сбора данных (Data AcQuisition System, DAQ). Одним из таких модулей является разрабатываемое устройство, предназначенное для обеспечения синхронности работы накамерной электроники и дополнительного канала доступа для цифровой части подсистемы сбора данных. В данном устройстве предусмотрены два функциональных узла, которые будут реализованы на одной печатной плате.
Первый функциональный узел разработан для обеспечения удаленного доступа к микросхемам ПЛИС (Программируемая Интегральная Логическая Схема) элементов подсистемы DAQ, установленных на регистрирующей камере. Разработка данного функционального узла основывается на ранее созданном и протестированном прототипе. Основой элементной базы данной части устройства является микросхема SCANSTA112 на базе интерфейса JTAG (Joint Test Action Group), в функциональном плане представляющая собой коммутатор интерфейса на 7 выходных портов. В схеме устройства используется 11 микросхем, соединённых иерархически, таким образом, что один из выходов каждой вышестоящей микросхемы соединён с входом нижестоящей микросхемы. Такая схема обеспечивает наличие необходимого количества портов JTAG для подключения к 62 картам FEC и контроллеру-концентратору данных, а также запасные порты. Для улучшения качества передачи сигналов JTAG при увеличенной длине линий и увеличенной частоты работы интерфейса были созданы и испытаны конверторы логических уровней LVCMOS-LVDS-LVCMOS (Low Voltage Complementary Metal Oxide Semiconductor, Low Voltage Differential Signaling).
Второй функциональный узел предназначен для синхронизации работы карт FEC на регистрирующей камере и выполняет задачу размножения (fanout buffer) пяти внешних синхросигналов, включая сигнал сброса, триггера данных и три типа опорных тактовых частот. Для этой цели используются специализированные fanout микросхемы, работающие в физическом стандарте LVDS. Разработка данного функционального узла основывается на ранее созданном и протестированном прототипе, выполняющего функцию размножения опорной тактовой частоты трансиверов ПЛИС 62 карт FEC. Для передачи синхросигналов на карты FEC применяются специально разработанные кабельные сборки на основе высокочастотных разъемов и микрокоаксиальных кабелей.
Перед началом разработки устройства были проведены комплексные испытания прототипов функциональных узлов. Полученные результаты испытаний были учтены при проектировании принципиальной схемы устройства. Размер и конфигурация печатной платы устройства, а также ее будущее положение были определены наличием свободного пространства в месте установки элементов подсистемы DAQ. Создание полнофункционального образца устройства и начало его испытаний намечено на вторую половину 2024 г.
The study of light unstable isotopes that decay through the emission of protons or neutrons, is a significant area of interest in modern nuclear physics, as many of these processes remain poorly understood. Some decays, such as the true four-proton decay, are yet to be observed experimentally.
The EXPERT (EXotic Particle Emission and Radioactivity by Tracking) project is a part of the SuperFRS Experiment collaboration at FAIR (Facility for Antiproton and Ion Research), GSI, Darmstadt. The main goal of the project is dedicated to investigating nuclear systems in the vicinity of neutron and proton driplines, and exploring the mechanisms of exotic decays. The EXPERT project employs various detector systems, including silicon microstrip detectors FOOT (FragmentatiOn Of Target).
One of the unknown isotopes is 7C, where a true four-proton decay is expected to be observed. An experiment is planned for next year at the FRS (Fragment Separator) facility to produce this isotope and register the decay products using in-flight tracking technique. Study of the angular correlations of 7C decay products will also help to better understand the properties of its mirror isotope 7H. Recently, a test experiment with a secondary 9C beam has been performed at FRS in order to properly set-up and adjust the entire experiment design for the main experimental run.
This presentation will highlight preliminary results on the simulation of the upcoming experiment with a 9C beam, using the ExpertRoot framework. We will also discuss preliminary analysis of data from the FOOT detectors, including its correlation with the information gathered from the standard FRS detectors, which was acquired at FRS during the test run in February 2024. A primary focus will be on the identification of protons. Additionally, employment of MAPS (Monolithic Active Pixel Sensor) for tracking of particles with Z=1,2,3 will be considered and the initial stages of simulation of these detectors will be shown.
Radon is a naturally occurring noble radioactive gas formed by the decay of radioactive chains of thorium and uranium. Radon and its daughter decay products are being increasingly studied, and their background contribution to low-background experiments for neutrino studies, dark-matter particle searches and other experiments requiring low-background conditions is also being investigated.
At the Dzhelepov Laboratory of Nuclear Problems (DLNP) of the Joint Institute for Nuclear Research (JINR), two compact radon detectors have been developed with an expected sensitivity level of ~1 mBq/m³. The first detector, with chamber volume of 5.8 liters, is based on the electrostatic collection method design of radon daughter products (RDP) on the surface of a silicon detector. The second compact detector, with an internal chamber volume of 0.9 liters, was made using a new method of reverse charge collection of RDP. This scheme is characterized with only a bias voltage applied to the detector. The charge collection field is formed by a grid with high positive voltage around the detector volume. This detector design overcomes several limitations of existing systems and enables efficient assessment of radon and its decay products concentration.
Yeast cells modulate the expression of multidrug resistance (MDR) transporters in response to environmental changes. In our study, we investigate the potential role and localization of MDR transporters in spores, which represent the resting phase of the yeast life cycle. It remains unclear whether spores contain MDR transporters from the ABC or MFS superfamilies. ABC transporters from the PDR family may undergo unhelpful ATP hydrolysis, which may negatively affect spore survival. Conversely, some MDR transporters may promote spore development or aid germination under xenobiotic exposure.
We compared the sporulation efficiency of strains with inactivated (Δpdr1Δpdr3) or overactive (PDR1-3) MDR systems to the wild-type. Intriguingly, both strains showed a stable sporulation percentage, albeit with reduced spores per ascus. Using GFP fusions, we investigated the localization of several mein MDR transporters during meiotic division in S. cerevisiae. We did not detect the presence of Pdr5, Pdr15, Pdr11, Snq2, or Tpo1 proteins in spore and ascus membranes. However, the MFS transporter with broad substrate specificity Flr1-GFP was found to accumulate in spore membranes. To better understand the role of Flr1 in spore development, we compared sporulation efficiency in wild-type, Δflr1/Δflr1, and PTEF-FLR1/PTEF-FLR1 (overexpressor) strains. Our findings suggest that both PDR1/PDR3 and FLR1 play a complementary role in the response to chemical stresses, such as the azole antimycotic fluconazole, in spores.
The study was supported by Russian Science Foundation № 24-74-00050.
Some radiation-induced disorders characterized by memory and learning impairments are associated with a decrease in the number of neural stem cells (NSCs) in the dentate gyrus of the hippocampus after irradiation with 56Fe particles [1, 2]. There are several types of neural stem cells, which differ in their morphology and activation rate of division [3, 4]. At the same time, mathematical models that simulate the dynamics of neural stem cells death after irradiation assume the population of NSCs to be homogeneous [5, 6], that allows for long-term predictions of cell response, but not for short-term responses.
In order to improve the accuracy predicting changes in the neural stem cell population after radiation exposure we have developed a mathematical model that considers the heterogeneity of NSCs based on differences in activation rate of division. The model consists of eleven ordinary differential equations whose parameters were derived from an experiment of chronic intravital imaging to follow individual NSCs [4]. In results, we were able to replicate experimental data on NSCs survival at various time points after exposure to 56Fe particles with a dose of 1 Gy and linear energy transfer of 148 and 240 keV/μm [1, 2]. Further developing of mathematical models that simulate the dynamics of neural stem cells death after irradiation it will allow enhanced therapies for radiation-caused cognitive impairments.
Rivera, Phillip D., et al. "Acute and fractionated exposure to high-LET 56Fe HZE-particle radiation both result in similar long-term deficits in adult hippocampal neurogenesis." Radiation research 180.6 (2013): 658-667.
DeCarolis, Nathan A., et al. "56Fe particle exposure results in a long-lasting increase in a cellular index of genomic instability and transiently suppresses adult hippocampal neurogenesis in vivo." Life sciences in space research 2 (2014): 70-79.
Martín‐Suárez, Soraya, et al. "Phenotypical and functional heterogeneity of neural stem cells in the aged hippocampus." Aging cell 18.4 (2019): e12958.
Electromagnetic radiation in millimetre and sub-millimetre wavelength range is a area of intense studies due to its application for longitudinal beam diagnostics and for generation of intense radiation beams. Transition radiation (TR) appearing when a fast charge particle crosses an vacuum-matter interface is one of the mechanism broadly used for this purpose, because its spectral angular distribution has been invested in details during the past few decades. Deep understanding of TR properties enables us to predict its behaviour in a broad range of electron beam parameters including energy from non-relativistic to ultra-relativistic region, beam sizes form sub-micron to hundreds of microns, angular divergence form micro- to miliradians, etc.
Coherent TR (CTR) is generated when the radiation wavelength is comparable to or larger than the bunch length. In that case all particles emit radiation more or less in phase, and the radiation intensity is proportional to a square of the number of particles in a bunch. However, if we have a sequence of bunches (a train) separated by a fixed distance form one another, the radiation is generated in a so called super-radiant regime [1]. In that case the coherent radiation generated by individual bunches interfere. The radiation spectrum, in this case, is no longer continuous, but represents a set of very narrow lines separated by the bunch sequence frequency, which is proportional (if not equal to) the RF frequency of the accelerating structure. The width of those lines depends on the number of bunches in the train. For example, for 7000 bunches the relative monochromaticity can reach 10^-4 - 10^-7 depending of which radiation harmonic is observed. With modern interferometer based Fourier Transform spectrometers or gratings it is not possible to achieve sufficient resolution.
In this report we will present CTR measurements in super-radiant regime using a horn antenna and a spectrum analyser at MT-25 microtron in Dubna. The measurement system enabled us to precisely resolve several radiation harmonics. We will demonstrate how RF frequency shifts during the acceleration and evaluate the single electron bunch length from the extracted spectrum.
This work was partially financially supported by a Program of the Ministry of Education and Science of the Russian Federation for higher education establishments, project No. FZWG-2020-0032 (2019–1569)
References:
[1] A. Gover, R. Ianconescu, A. Friedman, C. Emma, N. Sudar, P. Musumeci, C. Pellegrini, Rev. Mod. Phys. 90, 035002 (2018).
The NICA accelerator complex (JINR) includes a Heavy ion linear accelerator (HILAC) designed for injection of heavy ions (with the mass to charge ratio A/Z ≤ 6.35) into the storage synchrotron-Booster. Commissioning sessions with accelerated Xe28+ ions showed insufficient beam intensity of the required heavy ion beam parameters for experiments in the Collider. A multiple injection technology has been developed and is currently being implemented for increase of beam intensity. The paper presents the results of 3-fold and 10-fold injection for heavy ion experiments in the NICA collider.
Using first-principle numerical simulations of the lattice $SU(3)$ gauge theory, we study the equation of state of the rigidly rotating gluon plasma. We expand the free energy of the rotating system in a series of angular velocity and measure three coefficients of this expansion. The second order correction is associated with the specific moment of inertia of gluon plasma, while the higher order coefficient describes how the moment of inertia depends on the velocity of rotation due to the mass-energy redistribution.
Using first-principle numerical lattice simulations, we find a new spatially inhomogeneous phase in rigidly rotating gluon plasma. This mixed phase simultaneously possesses both confining and deconfining phases in thermal equilibrium. Unexpectedly, the local critical temperature of the phase transition at the rotation axis does not depend on the angular frequency within a few percent accuracy. An analytic continuation of our results to the domain of real angular frequencies indicates a profound breaking of the Tolman-Ehrenfest law in the vicinity of the phase transition, with the confining (deconfining) phase appearing far (near) the rotation axis.
Phase diagram of two color and three color QCD are reviewed. The dualities of QCD phase diagram are discussed in both two and three color cases. It has been shown that the phase diagram of two color QCD is quite helpful and it has a lot of common features with three color one, and predictions recently made in two color QCD was shown to hold qualitatively in real three color QCD. Showing that two color QCD is indeed great lab to study dense quark matter. The dualities has been shown in two color QCD. Duality between chiral symmetry breaking and charged pion condensation phenomena has been demonstrated from first principles in QCD itself. Also there will be discussed color superconductivity phenomenon and the influence of chiral imbalance on its properties.
Despite the fact that the thermodynamic potential in three color case (N_c=3) does not have properties of all three dualities found in the two-color case, it turned out that the phase portrait qualitatively contains these dualities.