Smoothing of structure in the fusion and quasielastic barrier distributions for the 20 Ne + 208 Pb system

We present simultaneously measured barrier distributions for the ${}^{20}$Ne $+$ ${}^{208}$Pb system derived from large-angle quasielastic scattering and fusion, in the latter case by means of the detection of fission fragments. Both distributions turned out to be smooth, in spectacular disagreement with the results of standard coupled-channels calculations. Namely, they do not posses the strong structure expected from coupled-channels calculations, even if apparently they take into account explicitly all relevant strong couplings. This points to the importance of weak channels, i.e., transfer reactions and scattering connected with noncollective excitations.