For central collisions of 1360 MeV ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ + Ag we report correlations in relative momentum and in velocity difference for ${}_{}{}^{1,2,3}{}_{}{}^{}\mathrm{H}$ ejectiles at 32° and 68°. Comparison to trajectory calculations gives a measure of the mean emission times, and, for unlike pairs, the average emission orders. There is a strong variation of the average emission times as a function of ejectile energy that is very similar for each H isotope; they change from ≳1000 fm/c for ∼10 MeV in the c.m. to ≲50 fm/c for ≳30 MeV. This indicates a broad spectrum of emission sources and associated characteristics. The longer times suggest evaporative emission from thermalized systems for ${}_{}{}^{1,2,3}{}_{}{}^{}\mathrm{H}$ of energies ∼10 MeV (i.e., those near the emission barrier). The shorter times, along with the observed energy spectra, suggest extensive prethermalization or direct emission from the central collision zone for ${}_{}{}^{1,2,3}{}_{}{}^{}\mathrm{H}$ ejectiles of much higher energy.

• Received 30 March 1995

DOI:https://doi.org/10.1103/PhysRevC.52.R2834