d/p and t/p ratios in nucleon-nucleus and heavy ion reactions: Can entropy be determined?

The relative yields of high energy deuterons and tritons as compared to protons have been measured in p+Kr, O-16+Kr and Ne-20+Ar reactions with a continuously varying beam energy up to 500A (400A) MeV. Statistical (expanding) evaporation models are not able to reproduce these d/p or t/p ratios, which for high particle energy (>30 MeV) increase smoothly with beam energy. Models that contain nucleon-nucleon scattering, Like cascade or nuclear molecular dynamics models, can only reproduce the ratios if a final-state interaction is introduced via the coalescence prescription. The coalescence radius that best fit the data is rather constant over wide beam energy intervals. Entropy can, however, not be directly determined from these ratios. [S0556-2813(99)05607-1].