Damping of giant dipole resonance in highly excited nuclei

TL;DR

This paper models how the giant dipole resonance's width and shape in excited nuclei change with temperature and angular momentum, using the phonon damping model, and compares predictions with experimental data.

Contribution

It introduces the phonon damping model to describe GDR properties at finite temperature and angular momentum, and compares it with experimental systematics and other theories.

Findings

GDR width increases with temperature and saturates at high T.

Thermal pairing keeps GDR width nearly constant below 1 MeV.

Predictions of nuclear viscosity from GDR data.

Abstract

The giant dipole resonance's (GDR) width and shape at finite temperature and angular momentum are described within the phonon damping model (PDM), which predicts an overall increase in the GDR's total width at low and moderate temperature T, and its saturation at high T. At T< 1 MeV the GDR width remains nearly constant because of thermal pairing. The PDM description is compared with the experimental systematics obtained from heavy-ion fusion, inelastic scattering of light particles on heavy targets, and alpha induced fusion reactions, as well as with predictions by other theoretical approaches. The results obtained within the PDM and GDR's experimental data are also employed to predict the viscosity of hot medium and heavy nuclei.