γ-ray spectroscopy of neutron-deficient 123Ce

Excited states have been identified in the very neutron-deficient Z=58 nucleus 123Ce. This is the most neutron-deficient odd-A cerium isotope in which excited states have been identified. The states have been unambiguously assigned to 123Ce by detecting de-excitation γ rays in coincidence with evaporated charged particles and neutrons. Three rotational bands, each consisting of at least eight E2 transitions, have been observed. The bands have tentatively been assigned to be based on neutrons in g 7/2 and h 11/2 orbitals. Two of the bands have been assigned to be signature partners, although no interband transitions have been observed. The aligned angular momenta of the bands have been studied in comparison with neighboring nuclei and with the results of Woods-Saxon cranking calculations. Observation of the deformation-dependent π (h11 /2 )2 quasiparticle alignment at 0.36MeV/ in each of the bands suggests a quadrupole deformation of β 2 0.3, in good agreement with theoretical predictions for the suggested possible configuration assignments. © 2012 American Physical Society.