Non-yrast states of 132Ce populated in β-decay

Non-yrast low spin states of the nucleus Ce-132 were studied by means of gamma-spectroscopy following the beta-decay of the ground and medium spin isomeric states of Pr-132. The activity was produced with the reaction Sn-117(F-19, 4n) Pr-132 at the Cologne FN TANDEM accelerator. The gamma gamma coincidences and singles spectra were measured with the OSIRIS cube spectrometer. The beta-decay of Pr-132 populates states with spins up to 6 (H) over bar and excitation energies up to 4.4 MeV in Ce-132. Besides ground and quasi-gamma bands, an excited band based on the 0(2)(+) state and many other low-lying states were observed. The gamma gamma angular correlations were analyzed to assign spins and parities to the excited states, and to determine the multipolarities of the gamma-transitions, We found dominant E2 transitions in the quasi-gamma band and from the quasi-gamma band to the ground band. The experimental data are compared with calculations using the Interacting Boson Model (IBM). Good agreement is reached in the vicinity of the O(6) limit. O 1998 Elsevier Science B.V.