β− decay of Tz=+112 isotopes Al

Abstract

β − decay of T z = + 11 2 nuclei, 37 Al and 39 Si, was studied to obtain information about excited states in the daughter and granddaughter nuclei. New information on excited states has been obtained for 37,39 P while level-schemes for 37 Si and 37,39 S were confirmed and expanded on as compared to the most recent investigations. For the nuclei studied, the valence proton and neutron occupy different major shells with opposite parity, hence the β − decay preferentially and primarily populates core-excited 1p1h intruder states with a parity opposite to the ground state of the daughter nucleus. These low-lying intruder states shed light on the N = 20 shell gap and its evolution with neutron number. The β − decay of very neutron rich nuclei also illustrates how the Gamow Teller (GT) strength distribution changes with neutron excess. Comparing β − decay of 37,39 Si presented here with 38,40 Si from a previous study, we clearly see an even-odd effect in the GT strength distribution with the decay from even-even nuclei showing strong low lying strength while for the odd A being very fragmented. Configuration interaction shell model calculations with the state-of-art SDPFSDG-MU effective interaction were performed to understand the structure of the 1p1h states and explore the GT strength distribution.