Fragment formation in collisions of fast heavy nuclei in molecular-dynamical model

Mass distributions energies and emission angles of fragments formed in Ca+Ca reactions at E/A=400, 800 MeV, in Nb+Nb reactions at E/A=150, 400, 650 and 800 MeV, and in La+La reactions at E/A=800 MeV are analyzed in the framework of the molecular-dynamical model. The mass spectra of fragments with masses 2 <or approx. A <or approx. 20 are predicted to vary in a power law, the exponent being 2.6-3.2 and weakly depending on the energy and size of the initial nuclei. The universality of the mass distributions is mainly due to some specific features of disintegration of the spectator pieces