Statistical decay of very hot nuclei-the production of large clusters

Heavy ion collisions are the only tools that enable us to reach compressions of nuclear matter up to a factor of about three. Theories of the collision dynamics that are necessary in order to extract the equation of state for nuclear matter are discussed. The main part of the review is devoted to the statistical decay of equilibrised very hot nuclei. A new mathematical method, microcanonical Metropolis sampling, which allows the explicit calculation of microcanonical observables directly out of the microcanonical partition sum with high statistics, is presented. Thermodynamics of finite nuclei can thus be established from the first principles. This is important as nuclei subjected to long-range Coulomb forces do not allow extrapolation to the thermodynamic limit. This peculiarity has interesting consequences for the phase transitions and the critical behaviour of nuclei. It is also related to the property of nuclei to break into large clusters at high excitation.