ALTERNATIVES FOR UNDERSTANDING QUALITATIVE FEATURES THAT DOMINATE PARTICLE-PARTICLE CORRELATIONS IN HEAVY-ION REACTIONS OF APPROXIMATE-TO 50 MEV/NUCLEON

We use trajectory calculations to analyze small-angle particle-particle correlations for three typical situations: Ar-40 + Au-197 (E/A = 60 MeV) --> H-2-H-2 pairs and H-1-H-1 pairs, Ne-20 + Cu-59 (E/A = 30 MeV) --> n-n pairs. For the H-2-H-2 pairs our analysis of the gentle featureless anticorrelations suggests that the major driving force is Coulomb repulsion after a range of average time delays from almost-equal-to 5 x 10(-21) s for the H-2 pairs of lower energy to almost-equal-to 10(-22) s for the H-2 pairs of higher energy. Simulations are used to illustrate the separate dominance of source size and lifetime in the space-time extent of the emitter. For lifetimes less-than-or-equal-to 10(-22) s the emitter size dominates; for longer lifetimes the time delays become predominant. The peaks at almost-equal-to 20 MeV/c in the correlation functions for H-1-H-1 pairs can be accounted for by diproton ejection which decays into protons with a Q value of almost-equal-to 0.35 MeV and a decay width of almost-equal-to 1 MeV (or a meanlife of 6 x 10(-22) s). The positive correlations between neutron pairs can be accounted for by dineutron ejection which decays into neutrons with a near zero Q value and a decay width of almost-equal-to 0.25 MeV (or a meanlife of almost-equal-to 2 x 10(-21) s). If these diproton and dineutron clusters do indeed have a metastable existence, then one should reexamine the notion that their associated small-angle correlations reflect the space-time extent of the emission source.