Statistical model of nuclear multifragmentation

Abstract

We present a statistical approach to the problem of multifragmentation in heavy-ion collisions. We begin with a generalized Sakur-Tetrode expression for the entropy. Through it we find expressions for the configuration weight functions. Fluctuations in the configurations are shown to be Poisson-like. Fragmentation yields are calculated by minimizing the total information subject to conservation of energy and baryon number. We work within the framework of a liquid-gas phase transition, and include a study of the effects of the nuclear surface (including a surface curvature correction), the Coulomb energy, and the internal excited states of the drop. Coulomb effects are investigated using both a simple $A^{5/3}$ dependence (as in the liquid-drop model) and a more complete expression which includes the presence of the surrounding vapor. We adopt a virial expansion for the equation of state and have found an analytic solution for the coexistence curve in infinite, uncharged matter. The case of charged, finite matter is also discussed. By identifying the clusters with the nuclei which are detected experimentally we can calculate fragment yields over a range of temperatures. We do so for a representative case and discuss the results.