  Invariant transverse-velocity spectra of intermediate-mass fragments were
measured with the 4-pi multi-detector system INDRA for collisions of Au on Au
at incident energies between 40 and 150 MeV per nucleon. Their scaling
properties as a function of incident energy and atomic number Z are used to
distinguish and characterize the emissions in (i) peripheral collisions at the
projectile and target rapidities, and in (ii) central and (iii) peripheral
collisions near mid-rapidity. The importance of dynamical effects is evident in
all three cases and their origin is discussed.
