Microscopic description of Gamow - Teller transitions in middle pf-shell nuclei by a realistic shell-model calculation

Abstract

Gamow - Teller (GT) transitions in N = 28 - 30 nuclei are studied in terms of a large-scale realistic shell-model calculation, by using Towner's microscopic parameters. values to low-lying final states are reproduced with a reasonable accuracy. Several gross properties with respect to the GT transitions are investigated with this set of wavefunctions and operator. While the calculated total strengths show no apparent disagreement with the measured ones, the calculated total strengths are somewhat larger than those obtained from charge-exchange experiments. With respect to the Ikeda sum rule, the proportionality of to (N-Z) persists to an excellent approximation, with a quenching factor of 0.68. For the relative strengths among possible isospin components, the lowest isospin component gathers a greater proportion than expected by the squared CG coefficients of the isospin coupling. It turns out that these relative strengths are insensitive to the size of the model space. The systematics of the summed values are discussed for each isospin component.