Isovector fluctuations and symmetry energy in fragmentation dynamics

Within a dynamical description of nuclear fragmentation, based on the spinodal decomposition scenario, we explore the relation between isovector density fluctuations and nuclear symmetry energy. We show that, inside the fragmenting system, isovector fluctuations follow the evolution of the local density and approach an equilibrium value connected to the local symmetry energy. Higher density domains are characterized by smaller average asymmetry and narrower isotopic distributions. This analysis indicates that fragment isotopic properties and isoscaling can probe the symmetry energy in the density regime corresponding to fragment formatio