Barrier distributions derived from quasielastic backscattering of Ti, Cr, Fe, Ni, and Zn projectiles on a Pb target

Mitsuoka, Shinichi; Ikezoe, Hiroshi; Nishio, Katsuhisa   ; Tsuruta, Kaoru*; Jeong, S.-C.*; Watanabe, Yutaka*

In order to study the nucleus-nucleus interaction in Pb-based cold fusion, we have measured excitation functions for quasi-elastic scattering of Ti, Cr, Fe, Ni and Zn projectiles on Pb target at backward angles of nearly 180. Coulomb barrier distributions were extracted from the first derivative of measured quasi-elastic scattering cross sections relative to the Rutherford scattering cross section. The mean values of the barrier distributions always shift toward the low energy side about 4-6 MeV compared with the Bass barrier height. The shape of the barrier distributions are well reproduced by the results of a coupled-channels calculation taking account of the coupling effects of two phonon excitations of the quadrupole vibration for the projectiles and three phonon excitations of the octupole vibration for the Pb target.