Isospin Equilibration in Reactions of 40Ca, 40Ar with 58Fe, 58Ni At E/A = 33, 45 MeV

In the field of heavy-ion reactions there is much discussion occurring about the nature of dissassembly of excited nuclear matter e.g.[1]. At one extreme the system is modeled as a simultaneous break up. While at the other extreme the system is portrayed as disassembling through a series of virtualy independent binary breakups. Additionally there are discussion of spinodal decompositions, expanision — either before or after breakup, and liquid gas phase transitions[2]. Many of the above decay models only treat the disassembly of nuclear matter — decoupled from any effects of how the system was formed. In all of these discussions of disassembly we must be careful that the fragmentation timescale does not become so short that the underlying assumption of statistical equilibrium independent of entrance channel is violated.