K-FORBIDDEN TRANSITIONS FROM MULTI-QUASI-PARTICLE STATES

Four-quasiparticle, K-pi = 12(+) states in Hf-172 and W-178, with half -lives less than 2 ns, are found to decay to their respective K-pi = O + ground-state bands, in competition with transitions to intermediate- K, two-quasiparticle structures. All decay transitions are weakly hind ered. When taken together with other K-isomer decay rates, an overall trend of decreasing hindrance with increasing excitation energy is evi dent. Estimates based on density-of-states considerations approximatel y reproduce the trend of the data, but also indicate the need to inclu de other K-mixing effects. (C) 1997 Published by Elsevier Science B.V.