Statistical fragmentation of Au projectiles at<i>E</i>/<i>A</i>=600 MeV

Abstract

The mean multiplicity of intermediate mass fragments (IMF) 〈${\mathit{M}}_{\mathrm{IMF}}$〉 produced by fragmentation of Au projectiles interacting with targets of C, Al, Cu, and Pb at an incident energy of E/A=600 MeV is compared to predictions of statistical multifragmentation and sequential evaporation models. The initial conditions for the calculations were provided by Boltzmann-Uehling-Uhlenbeck simulations. In the high excitation energy regime where the IMF multiplicity reaches its maximum the observed universal correlation between 〈${\mathit{M}}_{\mathrm{IMF}}$〉 and the total charge ${\mathit{Z}}_{\mathrm{bound}}$ of projectile fragments with charges Z\ensuremath{\ge}2 cannot be reproduced by a sequential evaporation code. In this regime the data are better described by statistical decay calculations which assume the formation of an expanded nuclear system and a rather fast breakup.