Rotational structure of [formula omitted] and [formula omitted] bands in the [formula omitted] nucleus 62Ga

Abstract

The rotational behavior of T=0 and T=1 bands in the odd–odd N=Z nucleus 62Ga is studied theoretically using the spherical shell model (laboratory frame) and the cranked Nilsson–Strutinsky model (intrinsic frame). Both models give a good description of available experimental data. The role of isoscalar and isovector pairing in the T=0 and T=1 bands as functions of angular momentum is studied in the shell model. The observed backbending in the T=0 band is interpreted as an unpaired band-crossing between two configurations with different deformation. The two configurations differ by 2p–2h and are found to terminate the rotational properties at Iπ=9+ and Iπ=17+, respectively. E2-decay matrix elements and spectroscopic quadrupole moments are calculated. From the CNS calculation, supported by shell model results, it is suggested that the low spin parts of the bands with T=0 and T=1 correspond to triaxially deformed states with the rotation taking place around the shortest axis (positive γ) and intermediate axis (negative γ), respectively. At lower spins the configuration space pf5/2g9/2, used in the shell model calculation, is found sufficient while also f7/2 becomes important above the backbending.