Clustering and symmetry energy in a low density nuclear gas

Temperature and density dependent symmetry energy coefficients have been derived from isoscaling analyses of the yields of nuclei with A <= 4 in the reactions of 35AMeV Zn-64 projectiles with Mo-92 and Au-197 target nuclei. The symmetry energies at low density are larger than those obtained in mean field calculations, reflecting the clustering of low density nuclear matter. They are in quite good agreement with results of a recently proposed Virial Equation of State calculation.