Probing role of deformed target on the mass-energy distributions of $^{224}$Th at above Coulomb barrier

19 Oct 2023, 09:40
20m
JINR Club of Scientists

JINR Club of Scientists

Joliot-Curie str., 6 Dubna, Moscow region Russian Federation

Speaker

Aniruddha Dey (JINR)

Description

One of the key ingredients for the synthesis of Super Heavy Elements (SHE) is the target-projectile combination of the reaction. The role of deformed target on the various Compound and non-Compound reaction mechanisms is yet to be explored [1,2]. The synthesis of SHE is further hindered by the Quasifission mechanism that competes with the formation of a Compound nucleus. The investigation of mass-energy distributions of heavy nuclei allows a detailed understanding of the associated various reaction mechanisms, and therefore is highly desirable to study the Quasifission process [3]. Furthermore, the region of neutron-deficient $Th$ nuclei has not been extensively studied for the multimodal fission phenomenon, which further builds on the primary motivation of the present study [4].

The experiment was performed at the Flerov Laboratory of Nuclear Reactions (FLNR), JINR, Russia, using an energetic $^{48}$Ca beam delivered from the $U400$ cyclotron. A thin target of $^{176}$Yb with thickness of about 214 $\mu$g/cm$^{2}$ on 1.5 $\mu$m thick Titanium backing was bombarded with the $^{48}$Ca beam at six different energies in the range of E$_{beam}$ = 188 to 272 MeV. The measurement of the reaction binary products was carried out by utilizing the double-arm time-of-flight (TOF) spectrometer CORSET [5]. Assuming the conservation of mass of the composite system of projectile and target, the double-velocity method was employed to determine the mass and energy of the reaction products.

The present reaction, $^{48}$Ca $+$ $^{176}$Yb, leads to the formation of the composite system, $^{224}$Th above the Coulomb barrier. The Mass-Total Kinetic Energy (M-TKE) distributions of the primary binary fragments from $^{224}$Th have been obtained from the present measurement. The measured M-TKE distribution profiles have been deconvoluted with multiple Gaussian functions to extract the yield contributions of the symmetric and asymmetric components from the fission-like fragments. Due to a comparatively high Coulomb factor, Z$_{1}$Z$_{2}$ = 1400 and a mass asymmetry value of about 0.57, significant suppression of the compound nucleus, $^{224}$Th formation because of enhanced contribution from the Quasifission process is expected. The target nucleus, $^{176}$Yb being highly prolate deformed in the ground state ($\beta_{2}$ = 0.3) when bombarded with spherical projectile beam particles of doubly magic $^{48}$Ca will further allow to investigate the role of deformed target on the reaction mechanism.

References:
1. G. N. Knyazheva $\it{et}$ $\it{al.}$, Phys. Rev. C $\bf{75}$, 064602 (2007).
2. D. J. Hinde $\it{et}$ $\it{al.}$, Phys. Rev. C $\bf{53}$, 1290 (1996).
3. E. M. Kozulin $\it{et}$ $\it{al.}$, Phys. Rev. C $\bf{105}$, 024617 (2022).
4. M. G. Itkis $\it{et}$ $\it{al.}$, Nucl. Phys. A $\bf{654}$, 870c (1999).
5. E. M. Kozulin $\it{et}$ $\it{al.}$, Instrum. Exp. Tech. $\bf{51}$, 44 (2008).

Primary author

Co-authors

Eduard Kozulin (FLNR) Dr Moumita Maiti (Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand, India) Alexey Bogachev (JINR) Mrs Galina Knyazheva (FLNR) Dr I. M. Itkis (Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research) Kirill Kulkov (FLNR JINR) Y. Mukhamejanov (Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research) Kirill Novikov (Joint Institute for Nuclear Research) I. V. Pchelintsev (Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research) R. S. Tikhomirov (Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research) I. V. Vorobiev (Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research)

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