Abstract
The high-spin structure of odd-odd ${}^{86}$Nb was studied with the early implementation of GAMMASPHERE using 36 Compton-suppressed Ge detectors and the MICROBALL, a 95-element full-sphere charged-particle detector array. High-spin states were populated using the ${}^{58}$Ni${(}^{32}$S,$3pn)$ reaction at 135 MeV with beams from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. A number of bands were observed up to spins as high as ${(31}^{\ensuremath{-}})$. The yrast positive-parity band shares many characteristics with the $\ensuremath{\pi}{g}_{9/2}\ensuremath{\bigotimes}\ensuremath{\nu}{g}_{9/2}$ bands in other odd-odd $f$-$p$-$g$ shell nuclei. These similarities include the behavior of the moments of inertia, the magnitude and phase of the signature splitting and its phase reversal near the ${10}^{+}$ state, and the strong alternations in the $B(M1)/B(E2)$ strengths. The moments of inertia in the lowest pair of negative-parity bands start out with a sharp upbend and then gradually fall back to the rigid-body value. New positive- and negative-parity bands appear in the quasiparticle alignment region and eventually become yrast. Some additional positive-parity states around spin $17\ensuremath{\Elzxh}$ are candidates for fully or nearly fully aligned shell-model-like configurations.
Published Version
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