Dependence of barrier distribution and fusion-fission process on entrance channel

Ikezoe, Hiroshi; Mitsuoka, Shinichi; Nishio, Katsuhisa   ; Watanabe, Yutaka*; Jeong, S. C.*; Otsuki, Tsutomu*; Hirose, Kentaro*

The Coulomb barrier distribution between heavy nuclei is important quantity to investigate the effect of quantum couplings of nuclear vibration and nucleon transfer to nucleus-nucleus interaction. We obtained the barrier distributions of lead-based fusion reactions of Ti, Cr, Fe, Ni, Zn, Ge, and Kr projectiles on Pb by means of the measurements of the quasi-elastic cross sections at backward scattering angles. The obtained positions and widths of the barrier distributions are compared with a calculation taking account of the channel couplings. The effect of the nuclear deformation on reaction process was also investigated by means of the measurements of product mass distributions for the systems of Si, S, Ar projectiles on U. We found that the collision at polar side gives rise to quasi-fission, where an asymmetric fission is dominant.