Excitation energy and angular momentum dependence of the nuclear level density parameter around A$\approx $110

TL;DR

This study investigates how excitation energy and angular momentum influence the nuclear level density parameter around mass 110, revealing an increase in the inverse level density parameter with excitation energy and spin, supported by experimental and theoretical analysis.

Contribution

It provides new experimental data and analysis on the dependence of the nuclear level density parameter on excitation energy and angular momentum around A≈110.

Findings

Inverse level density parameter increases with excitation energy.

Parameter also increases with nuclear spin.

Experimental results agree with microscopic statistical-model calculations.

Abstract

Neutron kinetic energy spectra in coincidence with low-energy $\gamma $-ray multiplicities have been measured around $A\approx $ 110 in the $^{16}$O, $^{20}$Ne + $^{93}$Nb reactions in a compound nuclear excitation energy range of $\approx $ 90 - 140 MeV. The excitation energy (temperature) and angular momentum (spin) dependence of the inverse level density parameter $k$ has been investigated by comparing the experimental data with statistical Hauser-Feshbach calculation. In contrast to the available systematic in this mass region, the inverse level density parameter showed an appreciable increase as a function of the excitation energy. The extracted $k$-values at different angular momentum regions, corresponding to different $\gamma $-multiplicities also showed an overall increase with the average nuclear spins. The experimental results have been compared with a microscopic statistical-model calculation and found to be in reasonable agreement with the data. The results provide useful information to understand the variation of nuclear level density at high temperature and spins.