Multi-quasiparticle isomers and rotational bands in Re-181

摘要

High-spin states in Re-181 have been populated using the Yb-176(B-11, 6n) reaction and their decays studied using the CAESAR gamma-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 1.2 mu s and 22 ns. Angular correlation and distribution coefficients were obtained and gamma-ray intensity ratios were used to extract g(K) - g(R)/Q(0) 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 I-pi = 23/2(-) states at 1883 keV. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 25]