Isospin symmetry breaking in the T=1, A=70 triplet

Excited states in the Kr70 and Br70 nuclei were populated via the Ca40(S32,2n)Kr70 and Ca40(S32,pn)Br70 fusion-evaporation reactions at the Accelerator Laboratory of the University of Jyväskylä. The 2+⟶0+ and 4+⟶2+ transitions in Kr70 have been found to be 881(1) keV and (tentatively) 1037(2) keV, respectively. Several new γ-ray transitions were also identified in Br70, and the T=1 band has been tentatively extended up to Jπ=10+. The newly observed transitions in Kr70 and Br70 resolve discrepancies in the previously reported results for these nuclei. The experimental Coulomb, triplet, and mirror energy differences are compared with the results of two independent shell-model calculations. The comparisons aim to investigate the shape evolution and the role of the isospin breaking interactions in this mass region.