  The bare NN-potential, parametrized so as to reproduce the nuclear phase
shifts leads to a sizable Cooper pair binding energy in nuclei along the
stability valley. It is a much debated matter whether this value accounts for
the "empirical" value of the pairing gap or whether a similarly important
contribution arises from the exchange of collective vibrations between Cooper
pair partners. In keeping with the fact that two-particle transfer reactions
are the specific probe of pairing in nuclei, and that exotic halo nuclei like
11Li are extremely polarizable, we find that the recent studied reaction,
namely 11Li+p -> 9Li+t, provides direct evidence of phonon mediated pairing in
nuclei.
