Coupling highly excited nuclei to the atomic shell in dense astrophysical plasmas

TL;DR

This paper investigates how coupling between highly excited nuclei and atomic shells in dense astrophysical plasmas affects neutron capture processes, finding that the impact of nuclear excitation by electron capture is minimal for stellar nucleosynthesis.

Contribution

It introduces an analysis of nuclear excitation by electron capture in dense plasmas and quantifies its limited effect on neutron capture and gamma decay sequences.

Findings

Nuclear excitation by electron capture has a small effect on neutron capture.

Coupling to atomic shells slightly influences gamma decay sequences.

The impact is less significant compared to photoexcitation effects.

Abstract

In dense astrophysical plasmas, neutron capture populates highly excited nuclear states close to the neutron threshold. The impact of additional low-energy nuclear excitations via coupling to the atomic shell on the ability of the so-formed compound nucleus to retain the captured neutron is investigated. We focus on the mechanism of nuclear excitation by electron capture in plasmas characterized by electron fluxes typical for the slow neutron capture process of stellar nucleosynthesis. The small effect of this further excitation on the neutron capture and gamma decay sequence relevant for nucleosynthesis is quantified and compared to the corresponding effect of an additional low-energy photoexcitation step.