Quasifission reactions as a probe of nuclear viscosity

Abstract

Fission fragment mass and angular distributions were measured from the ${}^{64}\mathrm{Ni}{+}^{197}\mathrm{Au}$ reaction at 418 MeV and 383 MeV incident energy. A detailed data analysis was performed, using the one-body dissipation theory implemented in the code HICOL. The effect of the window and the wall friction on the experimental observables was investigated. Friction stronger than one body was also considered. The mass and angular distributions were consistent with one-body dissipation. An evaporation code DIFHEAT coupled to HICOL was developed in order to predict reaction time scales required to describe available data on prescission neutron multiplicities. The multiplicity data were again consistent with one-body dissipation. The cross sections for touch, capture and quasifission were also obtained.