LABORATORI NAZIONALI DI LEGNARO
Heavy ion transfer reactions are an ideal tool to study the pair correlations. New experimental data [1,2] show that the probability to transfer a pair of neutrons is enhanced compared to the expected value in the uncorrelated limit or pure sequential transfer [3]. In order to understand this enhancement, the Time-dependent Hartree-Fock (TDHF) with BCS pairing is used. The transfer probabilities are determined using a double projection method with the use of the Pfaffian technique. This approach show that the pairing correlation enhanced the pair transfer [4]. Nevertheless, the TDHF+BCS underestimate the two-neutron transfer probability compare to the experimental results. As a complementary method, the coupled-channels formalism is used. A phenomenological approach is used consisting in fitting the transfer coupling to reproduce the experimental data for the 40Ca+96Zr and 60Ni+116Snsystems. We investigate two different mechanisms for the pair transfer: a pure sequential transfer hypothesis and a sequential plus direct pair transfer hypothesis. We discuss the validity of the perturbative approach and highlight the effect of high-order terms. In this simple model, it is find that the direct pair transfer give a better reproduction of the experimental data at energies close to the coulomb barrier. Finally, we use the coupled-channels approach to achieve a simultaneous description of the fusion cross sections and the transfer probabilities for the 40Ca+96Zr reaction.

DATA: 17-05-2016