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.