Symmetry energy of fragments produced in multifragmentation

Isospin properties of fragments measured in multifragmentation of $^{136}$Xe and $^{124}$Xe projectiles in mid-peripheral collisions with a lead target at 1 A GeV were studied within the statistical approach describing the liquid-gas nuclear phase transition. By analyzing the isoscaling phenomenon and the mean N-over-Z ratio of the fragments with Z=10-13 we have concluded that the symmetry energy of hot fragments produced at subnuclear densities at high temperatures decreases in comparison with cold nuclei