FLUCTUATIONS AND DYNAMICAL INSTABILITIES IN HEAVY-ION REACTIONS

We present a new method to implement fluctuations in the mean-field dy namics. Assuming local thermal equilibrium, we calculate the fluctuati on amplitude according to the statistical value and we determine the a ssociated density variance. The method can be applied to study the rol e of fluctuations in both stable and unstable dynamics. While in stabl e cases fluctuations are only responsible for the width of the distrib utions around mean values, their role become crucial in unstable situa tions, where bifurcations occur and different reaction exit channels a re possible. We illustrate this point by describing the break-up of di -nuclear systems exhibiting neck instabilities. (C) 1998 Elsevier Scie nce B.V.