Dynamics of dissipative binary collisions

In this paper we discuss the reaction mechanisms that occur in the overlap zone for semiperipheral heavy ion collisions at intermediate energies. In particular we focus on the development of neck instabilities, which could determine a possible increase of dynamical fluctuations. As observed in recent experimental data, at beam energies just above 10 MeV/nucleon the most relevant expected consequence is the possibility to obtain large variances in the projectilelike and targetlike observables. With increasing beam energy we pass to a midrapidity fragment production. In this way we predict a smooth transition from a deep-inelastic to a fragmentation reaction mechanism.