Damping of giant dipole resonance in hot rotating nuclei

TL;DR

This paper extends the phonon damping model to include angular momentum effects at finite temperature, studying how giant dipole resonance damping in hot, rotating nuclei varies with temperature and angular momentum, revealing saturation behaviors.

Contribution

The study introduces an extension of the phonon damping model to account for angular momentum at finite temperature, providing new insights into GDR damping in hot rotating nuclei.

Findings

GDR width increases with temperature and angular momentum.

At high T and M, GDR width saturates in Sn106 and Mo88.

Maximal angular momentum values are estimated to avoid violating shear viscosity bounds.

Abstract

The phonon damping model (PDM) is extended to include the effect of angular momentum at finite temperature. The model is applied to the study of damping of giant dipole resonance (GDR) in hot and noncollectively rotating spherical nuclei. The numerical results obtained for Mo88 and Sn106 show that the GDR width increases with both temperature T and angular momentum M. At T > 4 MeV and M<= 60 hbar the increase in the GDR width slows down for Sn106, whereas at M<= 80 hbar the GDR widths in both nuclei nearly saturate. By adopting the nuclear shear viscosity extracted from fission data at T= 0, it is shown that the maximal value of the angular momentum for Mo88 and Sn106 should be around 46 and 55 hbar, respectively, so that the universal conjecture for the lower bound of the specific shear viscosity for all fluids is not violated up to T= 5 MeV.