Updated nuclear level density parameters of 153Sm nucleus within the back-shifted Fermi gas model

Abstract

The present work re-evaluates the level density parameter a, asymptotic level density parameter a_asy, and back-shifted energy parameter E₁ within the back-shifted Fermi gas model (BSFG) for the ¹⁵³Sm nucleus. This reevaluation is based on the experimental nuclear level scheme extracted from the ENSDF library, the average level spacing at the neutron binding energy (D₀ value), and the latest updated nuclear level scheme obtained from an experimental gamma cascade experiment, which was performed at the Dalat Nuclear Research Reactor using the thermal neutron beam. The updated values of the BSFG level parameters are: (1) a=18.09±0.25 MeV^-1 and E₁=-0.92±0.07 MeV for the energy-independent level density parameter; and (2) a_asy=15.00±0.20 MeV^-1 and E₁=-0.81±0.08 MeV for the energy-dependent level density parameter. It has been found that the total nuclear level densities calculated using these updated parameters agree with the experimental data better than those using parameters taken from the nuclear reference database RIPL-3. These updated parameters are more accurate and reliable than those extracted from RIPL-3 and are, therefore, highly recommended for all the applications hereafter.