Beta-decay half-lives at the N=28 shell closure

Abstract

Measurements of the beta-decay half-lives of neutron-rich nuclei (MgAr) in the vicinity of the N=28 shell closure are reported. Some 22 half-lives have been determined, 12 of which for the first time. Particular emphasis is placed on the results for the Si isotopes, the half-lives of which have been extended from N=25 to 28. Comparison with QRPA calculations suggests that 42Si is strongly deformed. This is discussed in the light of a possible weakening of the spin–orbit potential.