K-forbidden transitions from multi-quasiparticle states
Walker PM., Cullen DM., Purry CS., Appelbe DE., Byrne AP., Dracoulis GD., Kibédi T., Kondev FG., Lee IY., Macchiavelli AO., Reed AT., Regan PH., Xu F.
Four-quasiparticle, Kπ = 12+ states in 172Hf and 178W, with half-lives less than 2 ns, are found to decay to their respective Kπ = 0+ ground-state bands, in competition with transitions to intermediate-K, two-quasiparticle structures. All decay transitions are weakly hindered. When taken together with other K-isomer decay rates, an overall trend of decreasing hindrance with increasing excitation energy is evident. Estimates based on density-of-states considerations approximately reproduce the trend of the data, but also indicate the need to include other K-mixing effects. © 1997 Published by Elsevier Science B.V.