K Kwiatkowski, L Woo, V Viola, W Friedman, E Pollacco, C Volant, S Yennello
Multifragment emission data from the 3He + Ag reaction at 3.6 GeV (Ref. 1) have been examined in the framework of a hybrid model that treats the reaction dynamics in terms of an intranuclear cascade cal~ulation,~ followed by decay from an expanding, emitting source. The INC calculations demonstrate that the average excitation of the excited residues formed in central collisions increases rapidly with bombarding energy; for more peripheral collisions this increase is much more gradual. The
more » ... ant role of the A resonance in producing highly excited residues is illustrated by the calculations. This mechanism provides a rapid, efficient means of energy dissipation that would appear to be essential in forming the highly excited species required for multifragmentation in light-ion-induced reactions. The results suggest that mult ifragment ation studies, when complement ed by pion emission probabilities, may provide valuable insight into the question of pion reabsorption in the nuclear m e d i ~ m. ~ The INC calculations also show that pll and p l are comparable for excitation energies above about 500 MeV; these calculated values are in good agreement with source velocities derived from a rapidity analysis of the spectra for high multiplicity events in the 3 ~ e + Ag system. Fits to the 3.6-GeV 3He + Ag multiplicity data with the combined INC/EES model require a relatively soft equation of state (K = 144). This value also described the charge distribution data best. Calculations with stiffer equations of state or without A excitations in the cascade severely underpredict the high mulitplicity data; in fact, the calculations are quite sensitive to all parameters. In order to describe the data with a stiffer equation of state, the probability for A excitation and/or pion absorption in the INC code would need to be increased significantly in order to enhance the probability for high excitation