Discovery of a non-yrast K=8 isomer in Dy and the influence of competing K-mixing mechanisms on its highly forbidden decay
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چکیده
The Gd(Be,α3n)Dy reaction has been used to study high-spin states in Dy. Pulsed beam conditions were utilised for enhanced isomer sensitivity. An isomer at 2188.1(3) keV with a half-life of 8.3(3) μs has been discovered and assigned K= 8 with a 2-quasineutron configuration. Among eleven γ-ray decay branches, an E2, ∆K= 8 transition to the ground-state band was observed with a reduced hindrance of fν=35, agreeing well with systematics correlating fν with the product of the valence neutron and proton numbers (NpNn) over an extended N,Z range. Small deviations from NpNn dependence are analysed for a range of 2-quasiparticle isomer decays, and interpreted as arising from a weak dependence on the isomer excitation energy relative to the yrast line.
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تاریخ انتشار 2011