Change of collective-flow mechanism indicated by scaling analysis of transverse flow

Abstract

Transverse-momentum measurements of collective flow are analyzed in terms of scale-invariant quantities. Deviation from the fluid-dynamical scaling behavior, at energies below ${E}_{\mathrm{lab}=200}$ MeV/nucleon, indicates a drastic change in the reaction mechanism. This might be due to a liquid-gas phase transition and nuclear mean-field effects.