Isobaric yield ratios in heavy-ion reactions, and symmetry energy of neutron-rich nuclei at intermediate energies

The isobaric yield ratios of the fragments produced in the neutron-rich Ca-48 and Ni-64 projectile fragmentation are analyzed in the framework of a modified Fisher model. The correlations between the isobaric yield ratios (R) and the energy coefficients in the Weiszacker-Beth semiclassical mass formula (the symmetry-energy term a(sym), the Coulomb-energy term a(c), and the pairing-energy term a(p)) and the difference between the chemical potentials of the neutron and proton (mu(n) - mu(p)) are investigated. Simple correlations between (mu(n) - mu(p))/T, a(c)/T, a(sym)/T, and a(p)/T (where T is the temperature), and ln R are obtained. It is suggested that (mu(n) - mu(p))/T, a(c)/T, a(sym)/T, and a(p)/T of neutron-rich nuclei can be extracted using isobaric yield ratios for heavy-ion collisions at intermediate energies.