$\beta$-decay properties of some astrophysically important Sc-isotopes

Abstract

In the late progressive stages of heavy stars, electron capture and ${\beta }^{\pm }$-decay are the governing processes. The weak rates are essential inputs for modeling the stages of high-mass stars before supernova explosions. As per results obtained from previous simulations, weak rates of Scandium isotopes contribute substantially in changing the lepton-to-baryon ratio ($Y_e$) of the nuclear matter in the core. In the present analysis, we report important ${\beta }^{-}$-decay properties of crucial Sc isotopes in an astrophysical environment with mass numbers $49\le A\le 54$. The investigation includes Gamow-Teller (GT) strength distributions, terrestrial half-lives, and stellar rates of electron capture (EC) and ${\beta }^{-}$-decay reactions. The calculations are performed using the proton-neutron (pn) quasi-particle random phase approximation (QRPA) model over a wide temperature range ($10^7$-$3\times 10^{10}$ K) and density range ($10^1-10^{11}$ g/cm${}^3$). Additionally, we compare our calculated results with available experimental and theoretical data. A good agreement is observed between our calculated half-lives and experimentally measured values. Our weak ${\beta }^{-}$-decay and EC rates are compared with those from the Independent-Particle Model (IPM) and Large-Scale Shell Model (LSSM). At high stellar temperatures and densities, our calculated ${\beta }^{-}$-decay rates are smaller than those from the other models.

Comments: 13 Pages, 4 Figures, 4 Tables