High-spin states, particle-hole structure, and linked smooth terminating bands in doubly odd112Sb

Abstract

Excited states in ${}^{112}\mathrm{Sb}$ have been observed with the Stony Brook array of six Compton-suppressed HPGe detectors and the ${}^{103}\mathrm{Rh}{(}^{12}\mathrm{C},3n)$ reaction at 60 MeV using a thick target. New excited states which decay solely towards the ${\ensuremath{\tau}}_{m}=773$ ns, ${I}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ isomer have been identified using time-correlated spectroscopy. The previously known level scheme has also been extended and corrected. In total, five rotational bands are observed, consisting of the two previously known strongly coupled bands based upon one-particle--one-hole (1p-1h) proton excitations across the $Z=50$ shell gap and three newly observed decoupled bands based upon 2p-2h proton excitations. The 1p-1h bands are interpreted as deformed rotors, although there is a possibility that a shears mechanism like that observed in the lead region may also play a role. Results from a thin-target measurement using the Eurogam-II spectrometer and the ${}^{90}\mathrm{Zr}{(}^{31}\mathrm{P},2\ensuremath{\alpha}n)$ reaction at 150 MeV are also presented. These data have been used to extend the decoupled bands up to $I\ensuremath{\sim}40\ensuremath{\Elzxh}$, a spin regime where the bands exhibit the features of smooth band termination. The combined results from the two experiments have enabled two of the bands to be connected by discrete $\ensuremath{\gamma}$-ray transitions to the low-spin level scheme, thereby determining their spins and parities. This allows for a definitive comparison with the results of cranked Nilsson-Strutinsky calculations and excellent agreement is obtained. Further confirmation of the terminating band configuration assignments is obtained from an analysis of the relative alignment properties of pairs of bands in the chain ${}^{110--112}\mathrm{Sb}$.