Test of the Brink-Axel hypothesis for the pygmy dipole resonance

TL;DR

This study tests the Brink-Axel hypothesis for 96Mo by comparing gamma strength functions from inelastic scattering and gamma decay, confirming its validity in the Pygmy Dipole Resonance energy region.

Contribution

It provides experimental validation of the Brink-Axel hypothesis for 96Mo using high-resolution (p,p') reaction data and gamma decay comparisons.

Findings

The gamma strength function in 96Mo is independent of nuclear state structure.

The results support the use of the Brink-Axel hypothesis in astrophysical models.

Independent confirmation of gamma strength and level density separation methods.

Abstract

The gamma strength function and level density of 1- states in 96Mo have been extracted from a high-resolution study of the (p,p') reaction at 295 MeV and extreme forward angles. By comparison with compound nucleus $\gamma$ decay experiments, this allows a test of the generalized Brink-Axel hypothesis in the energy region of the Pygmy Dipole Resonance. The Brink-Axel hypothesis is commonly assumed in astrophysical reaction network calculations and states that the gamma strength function in nuclei is independent of the structure of initial and final state. The present results validiate the Brink-Axel hypothesis for 96Mo and provide independent confirmation of the methods used to separate gamma strength function and level density in $\gamma$ decay experiments.