Gamma-widths, lifetimes and fluctuations in the nuclear quasi-continuum

TL;DR

This paper uses the Oslo method to measure nuclear level densities and gamma-ray strength functions, enabling the first evaluation of gamma-widths in the quasi-continuum region, with implications for nuclear structure and astrophysical processes.

Contribution

It introduces a novel approach to evaluate gamma-widths in the quasi-continuum using NLD and gammaSF data, linking nuclear structure to astrophysical reaction rates.

Findings

First evaluation of gamma-widths in the quasi-continuum region.

Measured nuclear level densities and gamma-ray strength functions for several nuclei.

Implications for nuclear reaction rates in neutron star mergers.

Abstract

Statistical $\gamma$-decay from highly excited states is determined by the nuclear level density (NLD) and the $\gamma$-ray strength function ($\gamma$SF). These average quantities have been measured for several nuclei using the Oslo method. For the first time, we exploit the NLD and $\gamma$SF to evaluate the $\gamma$-width in the energy region below the neutron binding energy, often called the quasi-continuum region. The lifetimes of states in the quasi-continuum are important benchmarks for a theoretical description of nuclear structure and dynamics at high temperature. The lifetimes may also have impact on reaction rates for the rapid neutron-capture process, now demonstrated to take place in neutron star mergers.