Multifragmentation of the remnant produced in the reaction of 1A GeV gold with carbon

A high-statistics exclusive study of the multifragmentation of 1A GeV gold on carbon has been performed. Particles with Z less than or equal to 2 show evidence of emission in a first prompt stage as well as in a second equilibrium stage whereas fragments with Z greater than or equal to 3 appear to be emitted essentially only in the second stage. Two methods for the separation of the Z less than or equal to 2 particles into the two stages are given and they are ill agreement. The yields for each stage are determined as a function of the event charged particle multiplicity m. The mass, nuclear charge, excitation energy per nucleon, and temperature of the remnant left after the first stage and their fluctuations have been determined as a function of m. The expansion of the remnant to fragment freeze-out is examined. The freeze-out temperature is determined from double isotope ratios as a function of,li and isentropic trajectories are obtained in the temperature-density plane. The caloric curve shows a monotonic increase with excitation energy. Some of the energy is in the form of radial flow. Overall, the results are consistent with a previous statistical analysis of the data which suggests that, over a certain range of excitation energies, multifragmentation involves a continuous phase transition.