Examining the caloric curve in argon+scandium and krypton+niobium systems.

摘要

Excited state populations and isotope temperatures have been measured as a function of the energy of the outgoing particle for central Kr+Nb and Ar+Sc collisions at E/A = 100 MeV. Temperatures are extracted from these measurements that increase significantly with energy of the outgoing particle. These results indicate the presence of important cooling mechanisms that operate on the time scale of the collective expansion of the system. They raise questions about the widespread interpretation of multi-fragmentation data in terms of equilibrium statistical models and indicate the necessity of using models that take such cooling mechanisms directly into account.