Extended level structure of Cr51 with measured mean lifetimes of yrast states in agreement with shell-model calculations

An investigation using the ²⁷Al(²⁸Si, 3p1n) reaction and the high-efficiency Indian National Gamma Array has yielded an enriched level scheme for the ⁵¹Cr nucleus. Multiple new γ rays, including high-energy feeders to the yrast states, have been observed. The yrast K^π=15/2^- three-quasiparticle band structure has been extended beyond band termination. Angular correlation and polarization measurements have yielded unambiguous spins and parities to most of the observed yrast states. Unambiguous measurements of mean lifetimes for the yrast states in the K^π=15/2^- band, leading to and even beyond band termination, have been carried out for the first time in this nucleus. This, coupled with the clear identifications of weak intraband crossover transitions, have facilitated profiling of the evolution of $B(E2)$ values along the yrast sequence. Large-scale shell model calculations in the full $fp$ valence space, with no restriction on the occupancy of the valence orbitals, have been performed. The results from such calculations have been found to be consistent with the experimental observations.