Multi-quasiparticle isomers and rotational bands in 181 Re

Abstract

High-spin states in 181 Re have been populated using the 176 Yb( 11 B, 6n) reaction and their decays studied using the CAESAR γ -ray spectrometer. Thirteen bands of rotational states have been observed based on 1-, 3- and 5-quasiparticle structures, including two new 5-quasiparticle isomers, with half-lives of 1.2μs and 22 ns. Angular correlation and distribution coefficients were obtained and γ -ray intensity ratios were used to extract gK-gR|/Q0 ratios. Three K -forbidden decays were observed and their reduced hindrance factors were obtained and found to be consistent with known systematic behaviour. Band crossings were observed between 1- and 3-quasiparticle bands. These rotation-aligned 3-quasiparticle bands appear to have high K , and are identified as t -bands. Band mixing calculations support the assigned K -values. A unique degeneracy was observed for two Iπ=23/2- states at 1883 keV. Show more