Role of transfer channels in heavy ion reactions

Grazing reactions will be analyzed in a semi-classical framework in order to identify the degrees of freedom governing the evolution of the reaction in particular we will concentrate on the one responsible for the exchange of mass and charge between the two reactants. Any model aiming at the understanding of the reaction has to include these degrees of freedom if it want to describe the different aspects that the collision display at energies close to the Coulomb barrier. In this talk particular relevance will be given to the calculations of quasi-elastic excitation functions and of the corresponding barrier distributions. Comparison with fusion reaction will also be discussed.(author)