# Gamma strength functions and the Brink-Axel hypothesis

## TL;DR

This paper discusses experimental tests of the Brink-Axel hypothesis using high-resolution inelastic proton scattering to validate gamma strength functions and level density models in the pygmy dipole resonance region.

## Contribution

It introduces a new experimental approach with proton scattering at high energies and forward angles to test the Brink-Axel hypothesis independently.

## Key findings

- Validation of the Brink-Axel hypothesis in the pygmy dipole resonance region
- Independent determination of gamma strength functions and level densities
- Assessment of model-dependent decomposition in the Oslo method

## Abstract

Experimental tests of the Brink-Axel hypothesis relating gamma strength functions (GSF) deduced from absorption and emission experiments are discussed. High-resolution inelastic proton scattering at energies of a few hundred MeV and at very forwrd angles including $0^\circ$ presents a new approach to test the validity of the BA hypothesis in the energy region of the pygmy dipole resonance. Such data not only provide the GSF but also the level density and thus permit an independent test of their model-dependent decomposition in the Oslo method.