Study of the 2n-evaporation channel in the 4,6He + 206,208Pb reactions

Excitation functions of the reaction products were measured for the reactions induced by 4,6He projectiles on 208,206Pb targets, leading to the same compound nucleus. This was accomplished by using the stacked-foil activation technique. The identification of the reaction products (accumulated in the Pb targets) was done by their radioactive α-decays. The excitation functions for the various products were obtained at energies including the sub-Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound 6He projectile.