Level structure above the ${17}^{+}$ isomeric state in $_{69}^{152}\mathrm{Tm}_{83}$

Level structure above the $17^{+}$ isomeric state in ${}_{69}^{152}{Tm}_{83}$

B. S. Nara Singh et al.

Phys. Rev. C 98, 024319 – Published 28 August 2018

Abstract

Excited states above the $17^{+}$ isomeric state in the proton-rich nucleus ${}^{152}{Tm}$ were established by employing the recoil-isomer tagging technique. Data were collected using the JUROGAM gamma-ray array and the GREAT spectrometer together with the recoil ion transport unit (RITU) gas-filled recoil separator and analyzed to identify the prompt and delayed $γ$ decays from the levels in ${}^{152}{Tm}$ . Shell-model calculations, either in a large valence space or in a reduced model space with five protons in the $π 0 h_{11 / 2}$ orbital and one neutron in the $ν 1 f_{7 / 2}$ orbital, agree with the observed energies of the yrast levels up to angular momentum $J = 21$ . The observation of near degeneracies in the energy spectrum can be attributed to specific components of the proton-neutron interaction. The isomeric decay of the $17^{+}$ level is not reproduced in the shell-model calculations as it arises from a delicate balance between hindrance due to seniority selection rules and enhancement due to configuration mixing.