Shell evolution of N=20 nuclei and Gamow-Teller strengths of $^{30,32,34}$Mg by the deformed QRPA

TL;DR

This paper investigates the Gamow-Teller strength distributions in Mg isotopes using deformed QRPA, revealing shell closure breaking at N=20 due to shape deformation and analyzing its impact on nuclear structure and excitations.

Contribution

It introduces a deformed QRPA approach to study shell evolution and Gamow-Teller strengths in Mg isotopes, highlighting the role of shape deformation in shell closure breaking.

Findings

N=20 shell closure is broken in Mg isotopes due to prolate deformation.

Low-lying GT states shift to higher energies with deformation.

Comparison shows different approaches agree on shell evolution trend.

Abstract

Gamow-Teller (GT) strength distributions of Mg isotopes are investigated within a framework of the deformed quasi-particle random phase approximation(DQRPA). We found that the N=20 shell closure in $^{28 \sim 34}$Mg was broken by the prolate shape deformation originating from the {\it fp}-intruder states. The shell closure breaking gives rise to a shift of low-lying GT excited states into high-lying states. Discussions regarding the shell evolution trend of single particle states around N=20 nuclei are also presented with the comparison to other approaches.