Nuclear expansion and symmetry energy of hot nuclei

TL;DR

This study investigates how the symmetry energy of hot nuclei decreases primarily due to expansion and density reduction, not temperature increase, supported by experimental data and microscopic calculations, and proposes an empirical relation for finite nuclei.

Contribution

It provides new insights into the factors affecting symmetry energy in hot nuclei and introduces an empirical relation for its study across different mass regions.

Findings

Symmetry energy decreases with excitation energy mainly due to expansion.

Results align with microscopic Thomas-Fermi calculations.

Proposes an empirical relation for symmetry energy in finite nuclei.

Abstract

The decrease in the symmetry energy of hot nuclei populated in $^{58}$Ni + $^{58}$Ni, $^{58}$Fe + $^{58}$Ni and $^{58}$Fe + $^{58}$Fe reactions at beam energies of 30, 40, and 47 MeV/nucleon, as a function of excitation energy is studied. It is observed that this decrease is mainly a consequence of increasing expansion or decreasing density rather than the increasing temperature. The results are in good agreement with the recently reported microscopic calculation based on the Thomas-Fermi approach. An empirical relation to study the symmetry energy of finite nuclei in various mass region is proposed.