Correlations between nucleon transfer and fusion at near-barrier energies for the systems32S +100,101Ru and33S +90,91,92Zr

Transfer reactions at two near-barrier energies for the systems32S +100,101Ru have been studied. Differential cross sections have been extracted for a large variety of channels, with a set-up yielding good mass, nuclear charge and energy resolutions. A steeper decrease of the measured angular distributions at backward angles with respect to the prediction of a semiclassical theory is interpreted as a loss of transfer flux feeding more complex channels and/or fusion. Coupled channels calculations, which use the transfer form factors derived from the experiment, reproduce the fusion cross sections at sub-barrier energies. Multi-nucleon transfer seems to play an essential role for the fusion process, as evidenced by the found strong correlations. A systematic comparison is made with the systems33S +90,91,92Zr, which have been the object of a previous experimental study with the same set-up.