Isospin dependence of nuclear level density at A≈ 120 mass region

Abstract

Nuclear level density and the level density parameter of 115,119,127Te isotopes are experimentally determined by analyzing the backward angle neutron energy spectra from 4He+112,116,124Sn reactions. Measurements are done in the compound nuclear excitation energy range of 25-42 MeV. Statistical model analysis is performed to test different phenomenological prescriptions of the level density parameter. Our data efficiently scan the explicit dependences of level density on three key factors: nuclear deformation, neutron-proton asymmetry, and the separation from the most stable isobar. It is observed that the experimental data are best described when deviation in atomic number from the corresponding β-stable isobar is explicitly taken into account. Further, nuclear level densities determined from the measured spectra show a reduction for 115,127Te in comparison to that of 119Te, which lies closer to the β-stability line.