Nonequilibrium features of the nuclear liquid-gas phase transition

Energy spectra of protons emitted by the target residue in Au + Au collisio ns at 1 GeV/u were measured for different excitation energy bins. They reve al two components with different slopes attributed to preequilibrium and eq uilibrium emission. The relative contribution of the latter decreases rapid ly with excitation energy, so that its presence becomes not apparent for th e highest energy bins. It is argued therefore, that equilibrium may not be reached on the gas branch of the caloric curve.