Excitation energy sharing in binary peripheral heavy ion reactions at Fermi energies

Evidence for the dependence of excitation energy sharing between two heavy remnants on the difference in the lost mass in two-body peripheral heavy ion reactions at Fermi energy is presented, based on experimental results for the reactions {sup 93}Nb+{sup 116}Sn, {sup 116}Sn+{sup 93}Nb, and {sup 93}Nb+{sup 93}Nb at 38A MeV. An observable based on the experimental velocities of the heavy residues is used to select reactions with equal preevaporative masses of projectile-like fragments and target-like fragments. The excitation energy, evaluated by means of a complete average calorimetry, is found to be larger for the nucleus that finally retains a larger part of the hot interaction region.