On the way from thermal multifragmentation to dynamical disintegration

Multiple emission of intermediate-mass fragments has been studied for the collisions of p, 4He and “C on Au with the 47r setup FASA. In the case of “C(22.4 GeV)+Au and 4He(14.6 GeV)+Au collisions, the deviations from a pure thermal break-up are seen in the energy spectra of the emitted fragments, which are harder than those both from model calculations and from measured p-induced collisions. This difference is attributed to a collective flow with an expansion velocity at the surface about 0.1 c (for “C+Au collisions).