Evidence for a K≈39/2 β-decaying isomer in 177Lu

Deep-inelastic collisions of 136Xe ions with tantalum and tungsten targets have been used to study high-spin isomers in neutron-rich A≈180 nuclei at the GSI on-line mass separator. Gamma-rays associated with the decay of the well known Kπ=37/2−, 51-minute isomer in 177Hf were observed, but with different half-life characteristics and an unexpectedly high yield. These features are interpreted as evidence for a hitherto unrecognized isomer in 177Lu. A two-component half-life analysis of the 177Hf γ-ray intensities gives a first component of 6−2+3 min, when the second component is fixed at 51 min. Comparison with multi-quasiparticle calculations suggests the possibility of a Kπ=39/2− isomer in 177Lu, which β-decays to the 177Hf isomer. This would be the highest-spin β-decaying state yet identified.