Identification of yrast high-K isomers in 177Lu and characterisation of 177mLu

Long-lived high-K states have been identified in Lu-177, including an isomer with tau > 10 mus, placed at 3530 keV and associated with the yrast K-pi = 39/2(-), 5-quasiparticle state predicted in multi-quasiparticle-state calculations. The gamma-decay of the isomer exposes the rotational band based on the 160-day 23/2(-) isomer, Lu-177m, with band properties which support its proposed configuration. A 90-ns isomer at 1325 keV is associated with the predicted 3-quasiparticle K-pi = 25/2(+) state while a 5-quasiparticle 33/2(+), 902-ns isomer with highly-hindered decays is identified at 2771 keV. Both exhibit rotational bands whose properties are used to support the assigned configurations. The possibility that the K-pi = 39/2- isomer found in this work should be identified with a beta-decaying isomer, proposed recently to populate the 51-min 37/2(-) isomer in Hf-177, is discussed in terms of the implied log f t values, configuration changes, and hindrances for K-forbidden gamma-decays. (C) 2004 Elsevier B.V. All rights reserved.