Space and Time pattern of mid-velocity IMF emission in peripheral heavy-ion collisions at Fermi energies

The emission pattern in the V perp − V par plane of Intermediate Mass Fragments with Z =3-7 (IMF) has been studied in the collision 116 Sn + 93 Nb at 29.5 A MeV as a function of the Total Kinetic Energy Loss of the reaction. This pattern shows that for peripheral reactions most of IMF’s are emitted at mid-velocity. Coulomb trajectory calculations demonstrate that these IMF’s are produced in the early stages of the reaction and shed light on geometrical details of these emissions, suggesting that the IMF’s originate both from the neck and the surface of the interacting nuclei.