SEARCH FOR EXTREMELY DEFORMED FISSION FRAGMENT IN Si+Si WITH EUROGAM PHASE II

A high-resolution study of fragment-fragment-γ triple coincident measurements of the symmetric-mass fission exit-channel from the Si+Si reaction has been performed at the VIVITRON Tandem facility by using the EUROGAM Phase II γ-ray spectrometer. The bombarding energy Elab( Si) = 111.6 MeV has been chosen to populate a well known quasi-molecular resonance in Ni. Evidence is presented for a selective population of states in Si fragments arising from the symmetric-fission of the Ni compound nucleus. In the resonant region the enhanced population of the K = 3−1 band of the Si nucleus, indicative of an oblate deformed shape, appears to play a significant role in the collision processes. The resonant behavior in the elastic and inelatic Si+Si exit-channels is found to be correlated to strong disalignment features of the di-nuclear oblate-oblate system with an equator-equator stable configuration.