Shell-model calculations of M1 transition probabilities from isobaric analogue states

Abstract

Shell-model calculations of MI transition probabilities within isobaric-spin doublets have been performed for cases without configuration mixing. The Schmidt values and effective values of gyromagnetic ratios have been used. A strong enhancement of MI transition rates for the "parallel" case J= J = l + 1/2 as compared to the "anti-parallel" case J = J = l - 1/2 is obtained. It is also shown that the M I transition probability in a certain single particle orbit is decreasing with increasing isobaric spin. The results are compared with recent experimental data. The positions of 7/2 - states in 31P have been calculated with the modified surface delta interaction for simple three-particle configurations. The wave functions thus obtained have been used to calculate MI transition probabilities between the 7/2 - states in 31P.