Characterization of very highly excited composite nuclei: Temperature, spin zone, radial extent, and lifetime scale of 10^-22 s

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