Isospin symmetry in the T = 1, A = 62 triplet

Abstract

Excited states in the Tz = 0, −1 nuclei 62Ga and 62Ge were populated in direct reactions of relativistic radioactive ion beams at the RIBF. Coincident γ rays were measured with the DALI2+ array and uniquely assigned to the A = 62 isobars. In addition, 62Ge was also studied independently at JYFL-ACCLAB using the 24Mg(40Ca,2n) 62Ge fusion-evaporation reaction. The first excited T = 1, Jπ = 2+ states in 62Ga and 62Ge were identified at 979(1) and 965(1) keV, respectively, resolving discrepant interpretations in the literature. States beyond the first 2 + state in 62Ge were also identified for the first time in the present work. The results are compared with shell-model calculations in the f p model space. Mirror and triplet energy differences are analyzed in terms of individual charge-symmetry and charge-independence breaking contributions. The MED results confirm the shrinkage of the p-orbits’ radii when they are occupied by at least one nucleon on average.