Fusion and direct reactions for the system He-6+Zn-64 at and below the Coulomb barrier
Scuderi, V × Di Pietro, A Figuera, P Fisichella, M Amorini, F Angulo, C Cardella, G Casarejos, E Lattuada, M Milin, M Musumarra, A Papa, M Pellegriti, M. G Raabe, Riccardo Rizzo, F Skukan, N Torresi, D Zadro, M #
Published for the American Physical Society by the American Institute of Physics
Fusion and transfer + breakup channels have been studied in the collision induced by the two-neutron-halo He-6 on a Zn-64 target at energies from below to above the Coulomb barrier. For comparison, the reaction induced by the stable isotope He-4 on the same target has been studied. The fusion cross section has been measured by using an activation technique, detecting off-line the delayed x-ray activity following the electron capture decay of the evaporation residues. New measurements of the He-4 + Zn-64 fusion cross section at sub-barrier energies have been performed in order to cover the same energy range of the He-6 + Zn-64 fusion cross section and to compare the excitation functions for the two systems down to the lowest energy data point measured for He-6. From the new comparison a sub-barrier fusion enhancement has been observed in the He-6 case with respect to the He-4 one whereas no effect on the He-6 fusion cross section has been seen at energies above the barrier. It has been concluded that such enhancement seems to be due to the diffuse halo structure properties of the He-6 nucleus. Moreover, the reactions induced by He-6 have shown a strong yield of alpha particles coming from direct processes.