Continuum-discretized coupled-channels calculations for Li 6 fusion reactions with closed channels

Fusion reactions induced by the weakly bound nucleus Li6 with targets Si28, Ni64, Sm144, and Bi209 at energies around the Coulomb barrier are investigated within a three-body model where Li6 is described with an α+d cluster model. The total fusion (TF) cross sections are calculated with the continuum-discretized coupled-channels (CDCC) method and the complete fusion (CF) cross sections are extracted through the sum-rule model. The calculations demonstrate that (i) for the TF cross-section calculations, the continuum states up to 40 MeV are found to be necessary, which corresponds to the inclusion of closed channels for light and medium mass targets, such as Si28, Co59, and Sm144; (ii) the converged CDCC results for TF cross section at energies above the Coulomb barrier are almost the same as single-channel results in which the continuum coupling effect is neglected; and (iii) the continuum coupling strongly influences partial-wave fusion cross sections and the closed channels play a significant role in the improvement of the description of the CF cross sections at energies below the Coulomb barrier for the Li6+Si28, Co59, and Sm144 systems.