MULTIFRAGMENT EVENTS IN THE U-238-197 REACTION AT 15 MEV(AU)NUCLEON/

The U-238+Au-197 reaction has been studied at 15 MeV/nucleon bombardin g energy. Correlations between two to seven final fragments with Z gre ater than or equal to 8 have been measured using CR-39 nuclear track d etectors. An event-by-event kinematic analysis was carried out for thr ee-body exit channel reactions which exhaust about half of the final f ragment production cross section. Most of these ternary processes can be associated with intermediate and peripheral impact parameters. The dominant reaction mechanism is shown to be that of a first binary quas ielastic or dissipative collision followed by the sequential binary fi ssion of the excited quasi-U (or to a lesser extent of the excited tar get remnant). We observe also a net drift of nucleons from the target to the projectile prior to its decay.