Heavy-ion two-particle transfer reactions as a probe of pairing correlations

Two-particle transfer processes induced by light and heavy ions are known to be an ideal dynamical tool for extracting information on nuclear pairing correlations. The procedure is however not unique and different reaction mechanism models (ranging from microscopic correlated successive one-particle transfer to collective macroscopic models) can be introduced to establish a link with the structural aspects of initial and final states. In the case of reactions involving weakly-bound nuclei the low-density features characterizing the vicinity of the drip line and the suggested consequent enhancement of the pairing correlations should show up as clear signature in the two-particle transfer cross sections. From a theoretical point of view in the weakly-bound case the focus is centered on the specific role of continuum states, both at the nuclear structure level, to give properly correlated wave functions, and at the reaction level, for example to treat the unbound states in the intermediate A +/- 1 system.