First-forbidden $\mathbf{\beta}$-decay rates, energy rates of $\beta$-delayed neutrons and probability of $\beta$-delayed neutron emissions for neutron-rich nickel isotopes

TL;DR

This paper calculates first-forbidden and Gamow-Teller beta-decay rates, energy rates of beta-delayed neutrons, and neutron emission probabilities for neutron-rich nickel isotopes, highlighting the importance of these transitions in astrophysical processes.

Contribution

It introduces a comprehensive calculation of beta-decay properties including deformation effects for neutron-rich nickel isotopes, improving agreement with experimental data.

Findings

Calculated half-lives match experimental measurements.

Deformation effects significantly influence beta-decay rates.

Enhanced beta-decay rates can accelerate r-process nucleosynthesis.

Abstract

First-forbidden (FF) transitions can play an important role in decreasing the calculated half-lives specially in environments where allowed Gamow-Teller (GT) transitions are unfavored. Of special mention is the case of neutron-rich nuclei where, due to phase-space amplification, FF transitions are much favored. We calculate the allowed GT transitions in various pn-QRPA models for even-even neutron-rich isotopes of nickel. Here we also study the effect of deformation on the calculated GT strengths. The FF transitions for even-even neutron-rich isotopes of nickel are calculated assuming the nuclei to be spherical. Later we take into account deformation of nuclei and calculate GT + unique FF transitions, stellar $\beta$-decay rates, energy rate of $\beta$-delayed neutrons and probability of $\beta$-delayed neutron emissions. The calculated half-lives are in excellent agreement with measured ones and might contribute in speeding-up of the $r$-matter flow.