Probing nucleon-nucleon correlations in heavy-ion transfer reactions

Pair correlations have been investigated in heavy-ion collisions via studies of the transfers of different nucleon pairs. In particular, excitation functions of one- and two-neutron transfer channels have been measured for the closed shell Ca-40 + Zr-96 and superfluid Ni-60 + Sn-116 systems from the Coulomb barrier energy to energies far below. By using the unique performance of the magnetic spectrometer PRISMA, in terms of resolution and efficiency, measurements at very low bombarding energies have been performed. The experimental transfer probabilities have been compared with semiclassical microscopic calculations that incorporate nucleon-nucleon correlations, together with known structure information of entrance and exit channels nuclei and reaction dynamics. These calculations well reproduce, in the whole energy range, one- and two-neutron transfer channels in shape and magnitude.