IMF isotopic properties in semi-peripheral collisions at Fermi energies

We study the neutron and proton dynamical behavior along the fragmentation path in semi-peripheral collisions: 58Fe + 58Fe (charge asymmetric, N/Z=1.23) and 58Ni + 58Ni (charge symmetric, N/Z=1.07), at 47A MeV. We observe that isospin dynamics processes take place also in the charge-symmetric system 58Ni + 58Ni, that may produce more asymmetric fragments. A neutron enrichment of the neck fragments is observed, resulting from the interplay between pre-equilibrium emission and the phenomenon of isospin-migration. Both effects depend on the EoS (equation of state) symmetry term. This point is illustrated by comparing the results obtained with two different choices of the symmetry energy density dependence. New correlation observables are suggested, to study the reaction mechanism and the isospin dynamics.