Two characteristic volumes in thermal nuclear multifragmentation

The paper is devoted to the experimental determination of the space-time characteristics for the target multifragmentation in p(8.1GeV) + Au collisions. The experimental data on the fragment charge distribution and kinetic energy spectra are analyzed within the framework of the statistical multifragmentation model. It is found that the partition of hot nuclei is specified after expansion of the target spectator to a volume equal to Vt = (2.9 +- 0.2) Vo, with Vo as the volume at normal density. However, the freeze-out volume is found to be Vf = (11 +- 3) Vo. At freeze-out, all the fragments are well separated and only the Coulomb force should be taken into account. The results are in accordance with a scenario of spinodal disintegration of hot nuclei.