Symmetry energy extracted from fragments in relativistic energy heavy-ion collisions induced by 124,136Xe

In the framework of a modified Fisher model, the ratio of the symmetry-energy coefficient to temperature (a sym /T) is extracted from the fragment produced in the 124, 136Xe induced reactions using the isobaric yield ratio methods based on different approximations. It is found that for nuclei with the same neutron excess (I ≡ N − Z) increases when the mass of the fragment increases, while for isobar a sym /T decreases when I increases. It is also found that the extracted a sym /T of the nucleus has very little dependence on the n/p ratio of the projectile, target, and the incident energies in the reaction.