SPINODAL DECOMPOSITION OF LOW-DENSITY ASYMMETRIC NUCLEAR-MATTER

We investigate the dynamical properties of asymmetric nuclear matter a t low density. The occurrence of new instabilities, that lead the syst em to a dynamical fragment formation, is illustrated, discussing in pa rticular the charge symmetry dependence of the structure of the most i mportant unstable modes. We observe that instabilities are reduced by charge asymmetry, leading to larger size and time scales in the fragme ntation process, Configurations with less asymmetric fragments surroun ded by a more asymmetric gas are favoured. Interesting variances with respect to a pure thermodynamical prediction are revealed, that can be checked experimentally. All these features are deeply related to the structure of the symmetry term in the nuclear Equation of State (EOS) and could be used to extract information on the low density part of th e EOS, (C) 1998 Elsevier Science B.V.