K-hindered decay of a six-quasiparticle isomer in Hf176

Abstract

The structure and decay properties of high-K isomers in Hf176 have been studied using beam sweeping techniques and the Gammasphere multidetector array. A new ΔK=8 decay branch, from a Kπ=22⊃-, six-quasiparticle, isomeric (t1/2=43μs) state at 4864 keV to the 20⊃- state of a Kπ=14⊃- band, has been identified. The reduced hindrance factor per degree of K forbiddenness for this decay is measured to be unusually low (fν=3.2), which suggests K mixing in the states involved. The deduced interaction matrix elements are discussed within the context of relevant K-mixing scenarios. The 3266-keV state, previously interpreted as a Kπ=16⊃+ intrinsic state, is reassigned as the Jπ=16⊃+ member of the band based on the Kπ=15⊃+ state at 3080 keV. The systematics of fν values as a function of the degree of forbiddenness is discussed in light of this change. © 2010 The American Physical Society.