Intrinsic states, high-spin rotational bands and rotation alignment in 177Os and 179Os

Low-lying intrinsic states and their associated rotational bands have been identified in 177Os and 179Os. They are the mixed isub(13/2) neutron states and the 1/2-[521] states in 177Os and 179Os, as well as the 5/2-[512] state in 177Os and the 7/2-[514] state in 179Os. The 1/2- state in each case is assumed to be the ground state, the other intrinsic states giving rise to isomers. The in-band decay properties of the 7/2-[514] band, and the isub(13/2) bands show the effect of mixing. In the rotational bands in 177Os a low frequency backbending anomaly is observed but no anomaly is observed in the isub(13/2) band. In 179Os the isub(13/2) band does backbend but at a higher frequency than in the yrast bands of the even neighbours. The systematics of the backbending frequencies, and the effects of blocking, are discussed. The rotation aligned angular momentum is deduced, and a comparison made between the isub(13/2) bands and the s-bands in the even neighbours. The results broadly support the identification of the s-bands with the aligned (isub(13/2))2 configuration. (orig.)