Beta-decay study of $T_z=-2$ proton-rich nucleus $^{20}$Mg

TL;DR

This study provides detailed spectroscopic data on the beta decay of the proton-rich nucleus $^{20}$Mg, revealing new decay pathways and resonance information relevant for astrophysical processes, using a specially developed detection system.

Contribution

It introduces a novel detection setup for charged-particle decay studies and offers new insights into the decay scheme and resonance states of $^{20}$Na from $^{20}$Mg decay.

Findings

Observation of a new proton branch in $^{20}$Na decay

Improved measurements of half-life, excitation energies, and branching ratios

Reproduction of isospin asymmetry in mirror decays

Abstract

The $\beta$ decay of the drip-line nucleus $^{20}$Mg gives important information on resonances in $^{20}$Na, which are relevant for the astrophysical $rp$-process. A detailed $\beta$ decay spectroscopic study of $^{20}$Mg was performed by a continuous-implantation method. A detection system was specially developed for charged-particle decay studies, giving improved spectroscopic information including the half-life of $^{20}$Mg, the excitation energies, the branching ratios, and the log $ft$ values for the states in $^{20}$Na populated in the $\beta$ decay of $^{20}$Mg. A new proton branch was observed and the corresponding excited state in $^{20}$Na was proposed. The large isospin asymmetry for the mirror decays of $^{20}$Mg and $^{20}$O was reproduced, as well. However, no conclusive conclusion can be draw about the astrophysically interesting 2645~keV resonance in $^{20}$Na due to the limited statistics.