Observation of a collective oblate band in Ce-137

High spin states in Ce-137 have been studied by using the heavy-ion induced reaction Sn-124(O-18, 5n) carried out at China Institute of Atomic Energy. Partial level scheme with spin up to (43/2(-)), including a high spin coll ective rotational band observed for the first time, has been established. T he collective band shows the properties similar to those oblate hands with gamma similar to - 60 degrees in neighboring nuclei and probably originates from the five quasi-particle configuration vs(1/2) circle times [vh(11/2)] (2) circle times pi g(7/2)circle times pi h(11/2). The characteristics of t his oblate band have been discussed.