New high-spin microsecond isomers, with J π =(31 + ) and J π =(28 − ), have been identified in 206 Bi at 10170 and 9233 keV, respectively, using γ-ray coincidence spectroscopy following deep-inelastic reactions with the 76 Ge+ 208 Pb system. Yrast and near-yrast levels populated in the decay of these isomers have been located and interpreted with the help of shell-model calculations. The states identified at energies up to approximately 7 MeV can be described well in terms of one-protonparticle, three-neutron-hole couplings.

No abstract

The isomeric and β-decay properties of neutron-rich 53−57 Sc and 53,54 Ca nuclei near neutron number N = 32 are reported, and the low-energy level schemes of 53,54,56 Sc and 53−57 Ti are presented. The low-energy level structures of the 21 Sc isotopes are discussed in terms of the coupling of the valence 1f 7/2 proton to states in the corresponding 20 Ca cores. Implications with respect to the robustness of the N = 32 subshell closure are discussed, as well as the repercussions for a possible N = 34 subshell closure.

The K hindrance to the γ decay is studied in the warm rotating 174 W nucleus, focusing on the weakening of the selection rules of the K quantum number with increasing excitation energy. 174 W was populated by the fusion reaction of 50 Ti (at 217 MeV) on a 128 Te target, and its γ decay was detected by the AGATA Demonstrator array coupled to a BaF 2 multiplicity filter at Laboratori Nazionali di Legnaro of INFN. A fluctuation analysis of γ coincidence matrices gives a similar number of low-K and high-K discrete excited bands. The results are compared to simulations of the γ -decay flow based on a microscopic cranked shell model at finite temperature in which the K mixing is governed by the interplay of Coriolis force with the residual interaction. Agreement between simulations and experiment is obtained only by hindering the E1 decay between low-K and high-K bands by an amount compatible with that determined by spectroscopic studies of K isomers in the same mass region, with a similar trend with excitation energy. The work indicates that K mixing due to temperature effects may play a leading role for the entire body of discrete excited bands, which probes the onset region of K weakening.

No abstract