Competition between Quasi-molecular Resonances and Fusion-fission in Light Dinuclear Systems

The results presented in this paper clearly suggest that a coherent framework may exist which connects the topics of heavy-ion molecular resonances, hyperdeformation effects, and fission shape isomerism. New data on particleparticle-γ triple coincidences of the Si+Si reaction at a beam energy corresponding to the population of a conjectured J = 38 resonance in Ni are presented. The absence of alignment of the spins of the outgoing fragments with respect to the orbital angular momentum is found to be in contrast with the alignment as measured for the Mg+Mg resonances. A molecularmodel picture is presented to suggest a “butterfly” motion of two oblate Si nuclei interacting in a equator-to-equator molecular configuration. PACS numbers: 25.70.Jj, 25.70.Gh, 24.60.Dr ∗Presented at The International Conference “Nuclear Physics close to the Barrier”, Warsaw, Poland, June 30 July 4, 1998. to be published in Acta Physica Polonica B, fall 1998