High-spin states beyond the proton drip-line: Quasiparticle alignments in 113Cs

Excited states have been studied in the deformed proton emitter 113Cs. Gamma-ray transitions have been unambiguously assigned to 113Cs by correlation with its characteristic proton decay, using the method of recoil-decay tagging. Two previously identified rotational bands have been observed and extended to tentative spins of 45/2 and 51/2ħ, with excitation energies over 8 MeV above the lowest state. These are the highest angular momenta and excitation energies observed to date in any nucleus beyond the proton drip-line. Transitions in the bands have been rearranged compared to previous work. A study of aligned angular momenta, in comparison to the predictions of Woods–Saxon cranking calculations, is consistent with the most intense band being based on the πg7/2[422]3/2+ configuration, which would contradict the earlier πh11/2 assignment, and with the second band being based on the πd5/2[420]1/2+ configuration. The data suggest that the band based upon the πh11/2 configuration is not observed. Keywords: Proton decay, Recoil-decay tagging, Gamma-ray spectroscopy, High-spin states, Quasiparticle alignments