Multifragment events in the 238U+197Au reaction at 15 MeV/nucleon.

The {sup 238}U+{sup 197}Au reaction has been studied at 15 MeV/nucleon bombarding energy. Correlations between two to seven final fragments with {ital Z}{ge}8 have been measured using CR-39 nuclear track detectors. An event-by-event kinematic analysis was carried out for three-body exit channel reactions which exhaust about half of the final fragment 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 quasielastic or dissipative collision followed by the sequential binary fission of the excited quasi-{ital U} (or to a lesser extent of the excited target remnant). We observe also a net drift of nucleons from the target to the projectile prior to its decay.