Isomeric levels in92Rb and the structure of neutron-rich92,94Rb isotopes (original) (raw)

The medium-spin structure of the 92 Rb nucleus, populated in spontaneous fission of 248 Cm and 252 Cf has been studied using the EUROGAM2 and the GAMMASPHERE Ge arrays, respectively. Two isomers have been found in 92 Rb at 284.2 keV and 1958.2 keV with halflives of T 1/2 = 54(3) ns and T 1/2 = 7(2) ns, respectively. A measurement of neutron-induced fission of 235 U, at the PF1B cold-neutron beam facility of ILL Grenoble has been performed to confirm the assignment of the T 1/2 = 54(3) ns, 284.2-keV isomeric level to the 92 Rb nucleus. Excited levels in 92 Rb and 94 Rb nuclei have been calculated in a large-scale shell-model framework. Isomers observed in these two nuclei have been interpreted as proton-neutron configurations involving the high-j ν1h 11/2 and π1g 9/2 orbitals.