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

Abstract

Shell-model calculations of M1 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 M1 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 M1 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 M1 transition probabilities between the 7 2 − states in 31P.