γ-ray spectroscopy of the odd-odd N=Z+2 deformed proton emitter 112Cs

Gamma-ray transitions have been observed in the proton-emitting N=Z+2 (Tz=1) isotope 112Cs. The transitions have been unambiguously assigned to 112Cs by correlation with the characteristic proton decay, using the method of recoil-decay tagging with mass selection. The measured proton-decay energy and half-life are Ep=810(5) keV and T1/2=470(50) μs, respectively, which are consistent with previous measurements. Five γ-ray transitions have been observed which appear to form a rotational sequence. The energy differences between excited states in the sequence are consistent with an assignment as the favored signature of the ν(h 11/2) π(h11/2) structure. Tentative evidence for fine structure in the 112Cs proton decay is also observed

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

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 51/2 h¯, 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 π g7/2[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.peerReviewe

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 alignment

Probing the maximally deformed light rare-earth region around the drip-line nucleus 130Sm

International audienceThe neutron deficient rare-earth nuclei of the A~130 region are of particular interest since highly deformed prolate ground states are expected. Indeed these nuclei are predicted to show maximal ground-state deformations of β2 ~ 0.40 (axis ratio of 3:2), comparable to the deformation deduced for superdeformed cerium isotopes at high spin. A fusion–evaporation experiment was performed with radioactive ion beams at GANIL in October 2004 which had the goal to reach very proton-rich exotic nuclei located near the proton drip-line. A radioactive 76Kr beam, delivered by the SPIRAL facility, was used to bombard a thin 58Ni target. Emitted γ-rays were detected by the EXOGAM γ-ray spectrometer which was, for the first time, coupled with both the DIAMANT charged-particle array and the VAMOS spectrometer