Band structure in Rb-83 from lifetime measurements

摘要

Excited states of Rb-83, populated in the Ge-76(B-11, 4n gamma) reaction at a beam energy of 50 MeV, have been studied. The unfavoured signature partner (alpha = - 1/2) of the pi g(9/2) yrast band is proposed up to ail excitation energy of 6669.4 keV and spin (3 1/2(+)). Lifetimes have been estimated for three states belonging to the favoured alpha = +1 /2 band. The B(E2) values deduced from these lifetimes indicate a moderate quadrupole deformation Of beta(2) = 0.20. Theoretical calculations within the framework of the particle-rotor-model suggest that low energy states before the onset of the vg(9/2) alignment at a rotational frequency of similar to 0.5 MeV are prolate while those above this frequency have an ON ate shape. The excited Delta I = I band has been extended up to 5422.7 keV and spin 25/2(-). The B(M 1) rates derived from the measured lifetimes decrease with spin. The results are in general agreement with ail earlier TAC calculation, suggesting the interpretation of these states as arising from magnetic rotation. (c) 2006 Elsevier B.V. All rights reserved.