Multi-quasiparticle bands inCe137

High-spin structures in Xe132 and Xe133 and evidence for isomers along the NVogt1, Siciliano2, Birkenbach3 et al. 2017Phys. Rev. C122120View full textAdd to dashboardCite

“…However, the 2389-keV state in 135 Ba, which was assigned with spin J = (21/2) by both Che et al [72] and Cluff [70], later revised to spin J = (23/2) by Kumar et al [38], could be an isomer candidate. Higher-lying (first excited) 23/2 + states are known in 135 Ba and 137 Ce which do not fit the N = 79 systematics. Besides, the recent discovery of the 277(2)-ns J π = 23/2 + isomer in 139 Nd [30] results in a smooth onset of 23/2 + states along the isotone chain from the high-Z side.…”

“…Although more fragmented in 133 Xe, the structures of the negative-parity states above J π = 11/2 137 Ce, before emerging again in 139 Nd. However, the 2389-keV state in 135 Ba, which was assigned with spin J = (21/2) by both Che et al [72] and Cluff [70], later revised to spin J = (23/2) by Kumar et al [38], could be an isomer candidate.…”

“…Besides, the recent discovery of the 277(2)-ns J π = 23/2 + isomer in 139 Nd [30] results in a smooth onset of 23/2 + states along the isotone chain from the high-Z side. Therefore, the existence of a lower-lying first 23/2 + state, possibly isomeric, might be anticipated at approximately 2.6 MeV in 137 Ce.…”

“…Thus far, there are no experimentally observed states which populate the 23/2 + isomer in the hard-to-reach nucleus 131 Te. Although studies of 135 Ba and 137 Ce were performed up to highest spins and excitation energies, no isomer candidates below 3 MeV were found yet. The observation of a (23/2 + ) isomer in this work and the recent observation of a 277(2)-ns isomer in 139 Nd corroborate the existence of J π = 23/2 + isomers also in the aforementioned two nuclei.…”

“…The group finally achieved an unambiguous placement of the isomer in the level scheme as it is populated by the decay of three higher-lying (25/2 − ) states. In 137 Ce, a J = (31/2) state was observed to be isomeric with a half-life of 5 ns [37]. Up to now, no high-lying isomeric states have been reported for 133 Xe and 135 Ba.…”