Nuclear Physics A447 (1985)67c-94~ North-Holland,Amsterdam 6lC STATISTICAL BREAK-UP OF HIGHLY EXCITED NUCLEI I.N. MISHUSTIN I.V. Kurchatov Institute of Atomic Energy, Moscow, USSR The statistical multifragmentation model is presented and its applications to the description of the disassembly of highly excited finite nuclear systems are demonstrated. The Monte Carlo method for simulating the nuclear multifragmentation process is introduced. The "cracking" phase transition as well as the liquid-gas phase transition are particularly discussed. zyxwvuts 1. INTRODUCTION At low incident energies, near the Coulomb barrier, nuclei be- have more or less like charged liquid drops. As a result of an interaction the state of nuclear matter changes only slightly, i.e. nuclei remain in the liquid phase. The acquired excitation energy is considerably less than the binding energy of nuclei. On the contrary, in heavy-ion collisions at relativistic energies the ex- citation energy in the overlap region considerably exceeds the binding energy of nuclear matter. Therefore, hot gas of partici- pant nucleons accompanied by moderately heated spectators is formed. Properties of liquid and gaseous phases of nuclear (had- ronic) matter are investigated fairly well both theoretically and experimentally. At the same time the properties of nuclear matter at intermedi- ate excitation energies comparable with nuclear binding energies are little-studied at present though this region is of great inter- est. At such excitation energies the system is composed of nu- cleans and nuclear fragments of various masses. This state is of the same nature as a liquid-gas mixture state at the liquid-gas phase transition. The reason for its arisal is that due to the presence of the attractive forces between the particles a homogene- ous distribution of dispersed matter turns out to be less advan- tageous than that at which a part of the particles join to form clusters (drops of the liquid phase) and the rest of the particles are homogeneously distributed over the whole zyxwvutsrqponmlkjihgfedcbaZ volume (the gaseous phase). Numerous calculations (see, for example, refs 1 - 8) actually 0375-9474/86/$03.50 OElsevier Science Publishers B.V. (North-Holland Physics Publishing Division)