  The mean transverse kinetic energies of the fragments formed in the
interaction of 1 A GeV Au+C have been determined. An energy balance argument
indicates the presence of a collective energy which increases in magnitude with
increasing multiplicity and accounts for nearly half of the measured mean
transverse kinetic energy. The radial flow velocity associated with the
collective energy yields estimates for the time required to expand to the
freeze-out volume. Isentropic trajectories in the temperature-density plane are
shown for the expansion and indicate that the system goes through the critical
region at the same multiplicities as deduced from a statistical analysis. Here,
the expansion time is approximately 70 fm/c.
