High spin states and a collective oblate band in Ce-137 - art. no. 044310

High spin states in the N=79 Ce-137 nucleus have been studied with the reac tion Sn-124(O-18, 5n)Ce-137 at beam energy 78 MeV. The level scheme has bee n expanded with spin up to 43/2 (h) over bar. At low spins, the yrast colle ctive structure built on the nu h(11/2)(-1) x 2(+) multiplet shows a transi tional shape with gamma = 30.8 degrees according to calculations of the tri axial rotor-plus-particle model. The configurations for several high spin s tates have been discussed from a systematical comparison with neighboring n uclei. A collective band built on I = 33/2 level has been observed for the first time. This band has an oblate shape with gamma = -60 degrees and most probably originates from the five-quasiparticle nu s(1/2) x [nu h(11/2)] x pi g(7/2) x pi h(11/2) configuration.