Rotational structures in doubly odd 198Tl

Abstract

States of 198Tl, excited through the 197Au(α, 3n) reaction at E α = 30 to 55 MeV, were studied using in-beam γ-spectroscopic techniques. Excitation functions, γ-ray angular distributions, γ-γ coincidences, half-lives in the nsec and μsec regions and conversion electron spectra were measured. As expected, due to the different type of experiment, a completely new scheme was found as compared to the known data. Two “rotational-like” structures were found based on isomeric states at 934.3 keV (I π = 8 −, T 1 2 = 12.3±0.3 nsec) and 687.1 keV (I π = (5) +, T 1 2 = 150±40 nsec) . The intrinsic structure of the band based on the 8 − isomer is interpreted as being the coupling of a h̃ 9 2 proton strongly coupled to the nuclear symmetry axis and a rotation-aligned ▪ 12 2 quasi-neutron. A diagonalization of the particle-rotation coupling Hamiltonian within the \\ ̃ gph 9 2 ⊗ ▪ i 13 2 configuration space lends support to this description.