Heavy-ion resonance and multi-cluster structure of nuclei

New kind of heavy-ion resonances recently discovered in nuclear collisions of C-12+C-12 and O-16+O-16 systems leading to various multi-cluster exit ch annels, such as C-12+C-12 -->3 alpha+C-12, 3 alpha +3 alpha, 2 alpha+O-16 a nd O-16+O-16 --> (alpha+C-12)+O-16, (alpha+C-12)+(alpha+C-12), are studied theoretically by the coupled-channel (CC) and coupled-channel Born approxim ation (CCBA) calculations using microscopic cluster-model wave functions of the colliding nuclei, C-12 and O-16, and the nucleus-nucleus interactions based on the realistic G-matrix interaction. These resonance states corresp ond to highly excited states of the compound systems, Mg-24 and S-32 nuclei , at excitation energies more than 40 similar to 55 MeV, having the associa ted multi-cluster structures and large decay widths to these reaction chann els. In this talk, we show that characteristic features of these newly-foun d resonances as well as those of the classical resonances of di-nucleus mol ecular nature are well reproduced by the microscopic CC and CCBA calculatio ns. The reaction mechanism leading to the formation of these exotic resonan ces is also discussed in some detail for the O-16+O-16 --> (alpha+C-12)+O-1 6, (alpha+C-12)+(alpha+C-12) and C-12+C-12 --> Be-8+O-16 reactions.