Population of yrast states in 191Os using deep-inelastic reactions

Several nuclei in the A ∼ 190 region have been studied following deep-inelastic reactions using a 460 MeV 82 Se projectile impinging upon a thick 192 Os target. The GASP array (at the Legnaro National Laboratory in Italy) was used to measure the resulting γ-decays. The previously reported near-yrast structure of 191 Os is extended to a t 1 /2= 61 ns isomer, at an energy of 2640 keV. Branching ratios for ΔI = 1 and A/ = 2 transitions in the K π = 11/2 + band have been measured, giving |(g K - g R )/Q 0 | = 0.022(3) and 0.024(7) for transitions from the 17/2 + and (19/2 + ) states respectively. These are consistent with the theoretical calculation for the proposed v11/2 + [615] configuration of the band. Nilsson plus BCS calculations reveal that the isomer is likely to have a {v11/2 + [615] ⊗ π11/2-[505] ⊗ π9/2-[514]} configuration with J π = K π = 31/2 + . This yields an implied reduced hindrance of f v = 1.9, in accordance with empirical systematics of K isomers in the A ∼ 180-190 region.