Observation of signature inversion in the πh9/2Äνi13/2 oblate band

Abstract

High-spin states in 190Tl have been studied via the 160Gd(35Cl, 5nγ) reaction. The level scheme, consisting of the πh9/2⊗vi13/2 oblate band and a cascade with character of single particle excitations, has been established. Spin values have been firmly assigned to the oblate band in 190Tl, resulting in low-spin signature inversion in the πh9/2⊗vi13/2 oblate band for the first time. Based on the similarity of the level structure in doubly odd Tl nuclei, spin values for the oblate bands in 192–200Tl should be re-assigned, and a consistent low-spin signature inversion has occurred in these oblate deformed nuclei. The low-spin signature inversion phenomena can be interpreted qualitatively by using the 2-quasiparticle plus rotor model including p-n residual interactions.