Population Of Yrast States In Os-191 Using Deep-Inelastic Reactions

Several nuclei in the A similar to 190 region have been studied following deep-inelastic reactions using a 460 MeV Se-82 projectile impinging upon a thick Os-192 target. The GASP array (at the Legnaro National Laboratory in Italy) was used to measure the resulting gamma-decays. The previously reported near-yrast structure of Os-191 is extended to a t(1/2) = 61 ns isomer, at an energy of 2640 keV. Branching ratios for Delta I = 1 and Delta I = 2 transitions in the K-pi 11/2(+) band have been measured, giving vertical bar(g(K) - g(R))/Q(0)vertical bar = 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 nu 11/2(+)[615] configuration of the band. Nilsson plus BCS calculations reveal that the isomer is likely to have a {nu 1/2(+)[615] circle times pi 9/2(-)[505] circle times pi 9/2(-)[514]} configuration with J(pi) = K-pi = 31/2(+). This yields an implied reduced hindrance of f(v) = 1.9, in accordance with empirical systematics of K isomers in the A similar to 180-190 region.