Deformation dependence of 2p-radioactivity half-lives: probe with a new formula across the mass region with Z < 82

Abstract

Effect of deformation on half-life of two-proton (2p) radioactivity is investigated across the periodic chart for nuclei with Z&lt;82. 2p-decay half-lives are estimated by employing our newly proposed semi-empirical formula wherein the nuclear deformation has been incorporated in a phenomenological way. Robustness of the formula is demonstrated as it estimates the measured values quite accurately and, hence, reliably applied to predict the other possible 2p-emitters. For many proton rich nuclei for which experimental data on the decay energies are not available, we have used the theoretical values obtained from our calculations using the relativistic mean-field (RMF) approach. The uncertainties in the theoretical decay energy values are minimised by machine learning (ML) technique. Correlation of 2p-radioactivity with 2p-halo and deformation is probed. Our calculations show the phenomenon of shape coexistence in several 2p-emitters, wherein the prolate shape is found to be more predominant for the ground state.

The Nuclear Reaction Network WinNet

“…This decay would be most relevant for nucleosynthetic paths along the proton-dripline at low mass numbers. There are some works on predicting the half-life of this decay (e.g., Basu et al 2005;Bhattacharya & Gangopadhyay 2007;Dong et al 2009;Qi et al 2012;Saxena et al 2023). However, proton-emission is somewhat more complex to describe and depends more strongly on the Q-value as well as on often unknown properties, such as the angular momentum transfer of the decay.…”