Time dependence of multifragmentation in light-ion-induced reactions

The evolution of multifragmentation reactions has been investigated via large-angle correlations of IMFs emitted in 4.8 GeV 3He bombardment of 197Au nuclei. Relative IMF-IMF velocity data agree well with fission kinetic energy systematics for IMFs with Z ≳ 8, but increasingly deviate above the fission prediction as the IMF charge decreases. This result depends only weakly on IMF multiplicity. The results suggest that IMF emission occurs from an evolving system in which lighter fragments are emitted preferentially from a hotter, more dense source prior to breakup of a dilute residue that also produces heavier fragments. The data are compared with both time-dependent (EES) and simultaneous (SMM) multifragmentation models.