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

Abstract

Non-yrast low spin states of the nucleus 132Ce were studied by means of γ-spectroscopy following the β-decay of the ground and medium spin isomeric states of 132Pr. The activity was produced with the reaction 117Sn( 19F,4n) 132Pr at the Cologne FN TANDEM accelerator. The γγ coincidences and singles spectra were measured with the OSIRIS cube spectrometer. The β-decay of 132Pr populates states with spins up to 6ħ and excitation energies up to 4.4 MeV in 132Ce. Besides ground and quasi-gamma bands, an excited band based on the 0 2 + state and many other low-lying states were observed. The γγ angular correlations were analyzed to assign spins and parities to the excited states, and to determine the multipolarities of the γ-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.