Isospin Dynamics and Dipolar degrees of freedom in Heavy Ion collisions

In this contribution the connection between the Dipolar degree of freedom excited in Heavy Ion Collisions through pre-equilibrium dipolar modes and the Isospin-equilibration processes is discussed. The connection leads to the definition of a new observable the so called "dipolar signal", able to describe the equilibration process in the momentum space related to the final fragmentation produced by the HIC. Preliminary results on this observable measured on the system48Ca +27 Al at 40 MeV/nucleon and corresponding to different degrees of dissipation/centrality are presented. The beam was accelerated through the Superconductor Cyclotron at the Laboratori Nazionali del Sud di Catania (Italy) and fragments were detected and identified with the 4π multi-detector CHIMERA.