Abstract
Isovector E2 and M1 transitions from isobaric analog states of the N=29 isotones to low-lying states in the N=28 isotones are discussed by making use of the shell model. The j and the +j configurations are assumed for the N=29 and N=28 isotones, respectively, where j denotes one of the , , and orbits. First, the model space is restricted to j= only, and it is extended to include all the , , and orbits, in order to study stepwise the role of the various wave function components. For the isovector E2 transitions, it is confirmed that the major components of the wave functions play a decisive role for the allowed transitions in the single-particle shell model and the use of the good isospin wave functions is indispensable for the forbidden ones. For the isovector M1 transitions, it is shown that the spin-nonflip → transition, which is introduced by the neutron-excited components in the wave functions of the N=28 isotones, plays a very significant role: It gives rise to the important cancellation which is responsible for the strong suppression of the M1 transition strength in comparison with the simple shell-model prediction, and it becomes the leading term in the l- and j-forbidden M1 transitions. Similar discussion holds for the Gamow-Teller beta decays between the levels of the N=28 and N=29 nuclei.
- Received 3 February 1988
DOI:https://doi.org/10.1103/PhysRevC.38.1058
©1988 American Physical Society