Giant dipole resonance in highly excited nuclei

TL;DR

This paper models the evolution of the giant dipole resonance in highly excited nuclei using the phonon damping model, successfully matching experimental data and predicting nuclear viscosity at high temperature and angular momentum.

Contribution

It extends the phonon damping model to include angular momentum effects and compares its predictions with experimental data and other theoretical approaches.

Findings

Excellent agreement between PDM predictions and experimental data.

Extended PDM accurately describes GDR width and shape at finite T and J.

Predictions of nuclear viscosity at high T and J.

Abstract

The evolution of the giant dipole resonance's (GDR) width and shape at finite temperature $T$ and angular momentum $J$ is described within the framework of the phonon damping model (PDM). The PDM description is compared with the established experimental systematics obtained from heavy-ion fusion and inelastic scattering of light particles on heavy target nuclei, as well as with predictions by other theoretical approaches. Extended to include the effect of angular momentum $J$, its strength functions have been averaged over the probability distributions of $T$ and $J$ for the heavy-ion fusion-evaporation reaction, which forms the compound nucleus $^{88}$Mo at high $T$ and $J$. The results of theoretical predictions are found in excellent agreement with the experimental data. The predictions by PDM and the heavy-ion fusion data are also employed to predict the viscosity of hot medium and heavy nuclei.