Configuration-dependent deformations in 171Re

Abstract

The level scheme of 171 75Re 96, has been studied using (heavy ion, xn yp) reactions. Rotational bands associated with the one-quasiproton Nilsson configurations 5 2 +[402] , 1 2 +[411] and 9 2 −[514] and the “cross-shell” orbitals from the h 9 2 and i 13 2 protons (nominally 1 2 0 −[541] and 1 2 +[660] ) have been identified. Less extensive results for 173Re have also been obtained. Differing (configuration dependent) deformations are required to explain the frequencies and alignment gains in the neutron band crossings. The relative differences are consistent with predicted deformation changes in the “deformation-driving” h 9 2 and i 13 2 (proton) orbitals. Signature splitting in 9 2 −[514] and 5 2 +[402] bands at low spin suggests some γ-deformation. Competing in-band and out-of-band E2 decays in the region of the “real” crossing between the 1 2 +[660] and 5 2 +[402] bands are explained through particle-rotor band-mixing calculations with the ad hoc inclusion of ΔN = 2 mixing. Limited agreement between the observed 1-quasiparticle energies and predicted values underlines the limitation of currently accepted nuclear potentials in this region. Small alignment gains in the 5 2 +[402] and 1 2 +[411] bands, before the AB neutron alignment can be related to the low-spin anomaly in 172Os and explained using three-band mixing. The absence of a similar effect in the 9 2 −[514] band is discussed.