Beta decay of deformed r-process nuclei near A = 80 and A= 160, including odd-A and odd-odd nuclei, with the Skyrme finite-amplitude method

TL;DR

This paper uses the Skyrme finite-amplitude method to calculate beta-decay half-lives of deformed odd-A and odd-odd nuclei near A=80 and A=160, significantly impacting r-process nucleosynthesis modeling.

Contribution

It extends the finite-amplitude method to include odd-A and odd-odd nuclei with deformation, providing more accurate beta-decay half-life calculations for r-process nuclei.

Findings

Calculated beta-decay half-lives differ by up to a factor of seven from previous models.

There is a two to fourfold variation in half-lives depending on the energy-density functional used.

Differences in Q values significantly influence the calculated half-lives.

Abstract

After identifying the nuclei in the regions near A =80 and A = 160 for which beta-decay rates have the greatest effect on weak and main r-process abundance patterns, we apply the finite-amplitude method (FAM) with Skyrme energy-density functionals (EDFs) to calculate beta-decay half-lives of those nuclei in the quasiparticle random-phase approximation (QRPA). We use the equal filling approximation to extend our implementation of the charge-changing FAM, which incorporates pairing correlations and allows axially symmetric deformation, to odd-A and odd-odd nuclei. Within this framework we find differences of up to a factor of seven between our calculated beta-decay half-lives and those of previous efforts. Repeated calculations with nuclei near A = 160 and multiple EDFs show a spread of two to four in beta-decay half-lives, with differences in calculated Q values playing an important role. We investigate the implications of these results for r-process simulations.