Decay-out of 151Tb yrast superdeformed band and shape coexistence

Linking transitions between the superdeformed (SD) and the normal deformed (ND) wells have been searched in Tb-151 nucleus. Two experiments of 5 and 17 days have been performed with EUROBALL IV. Transitions of 2818 keV and 3748 keV with intensities of about 1 % relative to the yrast SD band have been observed. Their decay-out properties are discussed in the text. In addition the eight known SD bands have been extended towards higher rotational frequencies where orbital crossings are observed. For the first time, weakly populated collective ND structures, likely triaxial, similar to the ones recently identified in Dy-152, Ho-153 and Er-155 nuclei have been observed in Tb-151. The SD and ND structures are interpreted in the frame of Woods-Saxon theoretical calculations

Extended investigation of superdeformed bands in 151,152Tb nuclei

A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV \u3b3-ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new \u3b3-ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the 152Tb and the two others to the 151Tb nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations