Deformed i 13 2 bands and prolate-oblate shape coexistence in 185Tl and 187Tl

Abstract

High spin states in the very neutron-deficient isotopes 185Tl and 187Tl have been identified from γ-γ coincidence measurements performed with the reactions 154Gd(35Cl, 4n) and 159Tb(32S, 4n). Unambigous mass assignments were obtained using a Fragment Mass Analyzer and the reactions 154Gd(36Ar, p4n and 155Gd(36Ar, p3n). Struvtures are observed corresponding to both an i 13 2 proton coupled to a prolate deformed core, and also h 9 2 and i 13 2 protons coupled to an oblate defo rmed core. The proposed 13 2+[606] intrinsic states are isometric, with meanlives of 12±2 ns in 185Tl and 1.0±0.2 ns in 187Tl. Eq uilibrium deformation calculations for the excitation energies of intrinsic states reproduce general trends, but overestimate the bandhead energies of high-j states. Show more