Beta decay of Neutron-Rich 53-56Ca

TL;DR

This study measures beta-decay properties of neutron-rich calcium isotopes, providing new half-life data, identifying gamma emissions, and comparing results with shell model calculations and theoretical predictions to understand nuclear structure.

Contribution

First-time determination of half-lives for 54Ca, 55Ca, and 56Ca, and revised half-life for 53Ca, with comparison to shell model calculations and beta-decay theory.

Findings

Half-lives for 54Ca, 55Ca, 56Ca measured for the first time.

Revised half-life for 53Ca is significantly longer than previous reports.

Beta-decay properties support the existence of a subshell gap at N=32.

Abstract

Beta-decay properties of neutron-rich Ca isotopes have been obtained. Half-life values were determined for the first time for 54Ca [86(7) ms], 55Ca [22(2) ms], and 56Ca [11(2) ms]. The half-life of 230(6) ms deduced for 53Ca is significantly longer than reported previously, where the decay chain 53K -> 53Ca -> 53Sc was considered. A delayed gamma ray with energy 247 keV as identified following beta decay of 54Ca, and is proposed to depopulate the first 1+ level in 54Sc. The beta-decay properties compare favorably with the results of shell model calculations completed in the full pf-space with the GXPF1 interaction. The half-lives of the neutron-rich Ca isotopes are also compared with gross beta-decay theory. The systematic trend of the neutron-rich Ca half-lives is consistent with the presence of a subshell gap at N=32.