Critical-like behaviours in central and peripheral collisions: a comparative analysis

Abstract

Quasi-projectile events from peripheral $\text{35}\text{A}\text{MeV}$ Au+Au collisions are compared with $\text{25}\text{A}\text{MeV}$ Au+C, 25 and $\text{35}\text{A}\text{MeV}$ Au+Cu and $\text{35}\text{A}\text{MeV}$ Au+Au central events. By fitting the measured charge yields with the Fisher droplet model technique, all the different data sets coherently point to a value $\text{E}{}^{\mathrm{\ast }}{}_{\mathrm{c}}\text{≈4.5}\text{A}\text{MeV}$ as the excitation energy where size distribution are best fitted by a power law. The physical parameters extracted from the fit strongly depend on the detailed shape assumed for the scaling function with the exception of τ and σ which are consistent with the critical exponents of the liquid-gas phase transition. Possible implications concerning the observation of a phase transition in multifragmentation experiments are discussed.