DEEXCITATION OF SUPERDEFORMED BANDS IN THE NUCLEUS TB-151

The aim of this work is to get more informations about the decay-out o f superdeformed bands. One of the best candidates in the mass A simila r or equal to 150 region for that kind of research is the nucleus Tb-1 51. From previous works, it has been established that the first excite d band goes lower in frequency than the band SD(1) [2], and it is the only known case in that mass region. One way to investigate these diff erent behaviours, is to perform measurements of the average entry spin . The nucleus Tb-151 has been populated via the fusion-evaporation rea ction Te-130(Al-27,6n)Tb-151 at a beam energy of 155 MeV. This experim ent has been performed at the Vivitron facility accelerator in Strasbo urg using the Eurogam II spectrometer, consisting of 54 Germa nium det ectors. It came out of this study, that the band SD(2) and band SD(3) feed the normal deformed well 9HBAR lower than the band SD(1). For the moment, it is not possible to explain the observed shell structure ef fects and to conclude about the statistical decay-out. The analysis is still under progress.