Investigating the effect of nuclear deformation on $\beta$-decay half-lives of neutron-rich nuclei

TL;DR

This study explores how nuclear deformation influences the beta-decay half-lives of neutron-rich nuclei, revealing significant variations that impact nucleosynthesis modeling under terrestrial and stellar conditions.

Contribution

It introduces a comprehensive analysis of deformation effects on beta-decay properties using multiple models, highlighting the importance of deformation in nuclear decay predictions.

Findings

Deformation significantly alters beta-decay half-lives and stellar rates.

FRDM deformation values yield the most accurate half-life predictions.

Nuclear shape transitions can change stellar beta-rates by over an order of magnitude.

Abstract

We examine the effect of nuclear deformation on the calculated $\beta$-decay half-lives of 55 neutron-rich nuclei. The deformation values were computed using DD-PC1 and DD-ME2 interactions in the Relativistic Hartree-Bogoliubov model. Yet another set of deformation was adopted from the Finite Range Droplet Model (FRDM). The model-dependent deformation values were used as a free parameter in the proton-neutron quasiparticle random phase approximation model to calculate the $\beta$-decay properties under terrestrial and stellar conditions. The Gamow-Teller strength distributions, branching ratios, half-lives and stellar weak rates of selected nuclei were later investigated. It was concluded that the $\beta$-decay properties of neutron-rich nuclei changed with nuclear deformation. The FRDM computed deformation values provided the best predictions for calculated half-lives followed by the DD-ME2 functional. The terrestrial $\beta$-decay half-lives changed up to 3 orders of magnitude and the stellar $\beta$-rates within a factor of 2 as the neutron-rich nuclei switched their geometrical configurations. For magic number nucleus $^{138}$Sn, the stellar rates changed substantially by more than 1 order of magnitude as the nucleus transitioned away from the spherical shape. Our investigation might prove useful for a realistic modeling of nucleosynthesis calculation.