CHARACTERIZATION OF VERY HIGHLY EXCITED COMPOSITE NUCLEI - TEMPERATURE, SPIN ZONE, RADIAL EXTENT, AND LIFETIME SCALE OF 10-22S

Particle-particle coincidence measurements have been made for the reactions 312- and 680-MeV Ar-40 + (nat)Ag. The large-angle correlation data indicate essentially complete energy thermalization even for 680-MeV Ar-40 + (nat)Ag. They also allow for an assignment of almost-equal-to 64h for the rms spin and almost-equal-to 4.3 MeV for the average initial temperature of the composite nuclei formed by incomplete fusion. The small-angle correlation data for H-1-H-1 and H-2-H-2 are consistent with phase-space, statistical-model predictions of the evaporation lifetimes. This result implies that energy mixing and evaporative particle-emission steps occur with intervals of almost-equal-to 10(-22) s, a time period comparable to the traversal time for a projectile velocity of 17 MeV/nucleon.