Spectroscopy of proton-rich 66Se up to Jπ = 6+: Isospin-breaking effect in the A = 66 isobaric triplet

Abstract : Candidates for three excited states in the 66Se have been identified using the recoil-β tagging method together with a veto detector for charged-particle evaporation channels. These results allow a comparison of mirror and triplet energy differences between analog states across the A = 66 triplet as a function of angular momentum. The extracted triplet energy differences follow the negative trend observed in the f7/2 shell. Shell-model calculations indicate that the strength of the Coulomb isotensor part alone is not sufficient to account for this trend in the case of the A = 66 triplet.