THE ROLE OF SHELL GAPS AND DEFORMATION-DRIVING ORBITALS IN SUPERDEFORMED CE-130

Four superdeformed bands have been assigned to Ce-130 following a high -statistics gamma-ray study using the EUROGAM 11 spectrometer. The ban ds are interpreted in terms of upsilon 6(1) circle times [411]1/2(+) a nd upsilon 6(1) circle times [523]7/2(-) signature-partner neutron con figurations. One of the bands exhibits a sharp backbend when the upsil on 6(1) orbital crosses the alpha = +1/2 [411]1/2(+) orbital at omega approximate to 0.55 MeV/ h. Below this crossing, the band is predicted to remain superdeformed despite the absence of N = 6 neutron intruder s. This suggests that these intruders are not a necessary ingredient o f superdeformation in this mass region but that the underlying shell g aps at Z = 58 and N = 72 are important.