Spectroscopy of the N=Z-2 nucleus Cr-46 and mirror energy differences

Excited states in $^{46}\mathrm{Cr}$ were sought using the $^{12}\mathrm{C}$($^{36}\mathrm{Ar}$,$2n$) reaction. Gamma rays were detected with the Gammasphere array, and the $Z$ value of the reaction products was determined with an ionization chamber located at the focal plane of the Fragment Mass Analyzer. In addition to the ground-state band observed up to ${I}^{\ensuremath{\pi}}={10}^{+}$ (tentatively ${12}^{+}$), five states are proposed to belong to the ${3}^{\ensuremath{-}}$ band. The mirror energy differences with the analog states in $^{46}\mathrm{Ti}$ present a pronounced staggering effect between the odd and even spin members that is reproduced well by shell-model calculations incorporating the different Coulomb contributions, monopole, multipole, and single-particle effects together with an isospin-nonconserving interaction that accounts for the so-called $J=2$ anomaly. Dramatically different $E1$ decay patterns for members of the ${3}^{\ensuremath{-}}$ band between the $^{46}\mathrm{Cr}$ and $^{46}\mathrm{Ti}$ mirrors are also observed.