Structural properties of hot deformedXe122at high spins

Abstract

TheXe nucleus is investigated using statistical theory for studying intrinsic properties as a function of temperature and spin assuming the nucleus to move in a triaxially deformed Nilsson potential. The single particle level density parameter is extracted as a function of temperature for various spins and is found to reach a constant value at higher temperature. The excitation energy is calculated as a function of angular momentum for different entropies and temperatures. The spin cutoff parameter as a function of angular momentum is determined for various temperatures from the rotational energy. The shell correction as a function of angular momentum is determined. The variation of proton and neutron Fermi energies with temperature and angular momentum is studied. The effect of the variation of nuclear level density with excitation energy on nuclear temperature is verified for difFerent spins. PACS number(s): 24.60. -k, 21.10.Ma, 27.60. +jThe inHuence of rotation on nuclear structure [1 -3] and shape has opened up a large Geld for studying intrinsic properties of nuclei. The production of hot nuclei has caused considerable interest in the study of nuclear shapes and recently a study of such properties in the A = 120 region was done by Ragnarsson et aL [4]. The interplay of angular momentum generated by the alignment of single particle spins or by the increase of collective rotational angular momentum due to deformation with temperature is very important in understanding the nuclear structure. The experimental searches [5 -7] for a high spin shape transition in the barium nuclei are inconclusive. In I nuclei, oblate to prolate shape hindrance has been studied and for Z = 53 iodine nuclei shape coexistence has been reported [8,9]. A dynamical triaxial deformation in the mass region A = 120 -140, in particular, Xe and Ba nuclei, is observed [10]. In this work, an attempt has been made to study the intrinsic properties of the Xe nucleus as functions of temperature, spin) and deformation.The statistical theory given in Ref.[11] is used for this purpose and the applicability of thermodynamical concepts at very high temperature is known from Ref. [12]. The main assumption for statistical analysis is microscopic equilibrium which means that all the states with the same excitation energy E* are equally populated.The single particle level density parameter is studied as a function of temperature and spin [13] and is found to reach a constant value at higher temperatures for all spins.The constant entropy lines are drawn in the excitation energy E* versus the angular momentum plane. Prom these lines it is evident that backbending and yrast traps are absent in Xe. By calculating the rotational energy as a function of angular momentum, the spin cutoff parameter is determined for various spins at different temperatures. The variation of proton and neutron Fermi energies with temperature and angular momentum is studied. The shell correction [14] as a function of angular momentum is calculated for this nucleus by extending t...