Spectroscopy in theZ=49108,110Inisotopes: Lifetime measurements in shears bands

Abstract

Excited states have been populated in ${}^{108}\mathrm{In}$ and ${}^{110}\mathrm{In}$ in complementary backed- and thin-target experiments using the Stony Brook and the $8\ensuremath{\pi}\mathrm{Ge}$-detector arrays. The level schemes for both isotopes have been extended and modified, including the first observation of $\ensuremath{\Delta}I=2$ bands in ${}^{110}\mathrm{In}.$ Lifetimes of states in four $\ensuremath{\Delta}I=1$ bands and one $\ensuremath{\Delta}I=2$ band have been measured using the Doppler-shift attenuation method. Experimental total angular momenta and reduced transition strengths for the $\ensuremath{\Delta}I=1$ bands have been compared with tilted axis cranking predictions for shears bands with configurations involving one proton ${g}_{9/2}$ hole and one or three valence quasineutrons from the ${h}_{11/2}$ and ${g}_{7/2}{/d}_{5/2}$ orbitals. The $\ensuremath{\Delta}I=2$ bands have been compared with principal axis cranking predictions for configurations with two ${g}_{9/2}$ proton holes and a ${g}_{7/2}$ or ${d}_{5/2}$ proton and one- or three-quasineutron configurations involving the ${h}_{11/2}$ and ${g}_{7/2}{/d}_{5/2}$ orbitals. In general, there is good overall agreement for both the angular momenta and reduced transition strengths. The $\ensuremath{\Delta}I=1$ and $\ensuremath{\Delta}I=2$ bands have large ${\mathcal{J}}^{(2)}/B(E2)$ ratios as expected for the shears mechanism. The $B(M1)$ strengths deduced for the $\ensuremath{\Delta}I=1$ bands show a decreasing trend as a function of spin, which is also a feature of the shears mechanism. Configuration assignments have been made for most observed bands based on comparisons with theory and systematics of neighboring nuclei.