J/Psi, Psi' and DY production in proton nucleus collisions at 450 GeV incident energy at the NA50 experiment

Drell-Yan, $J/\psi$ and $\psi'$ production in proton-induced collisions on Be, Al, Cu, Ag and W targets has been studied by the NA50 collaboration at the CERN SPS. The results are needed to fully understand nuclear suppression of the charmonia states and to provide a solid and accurate reference for the study of the anomalous $J/\psi$ suppression, observed by NA50 in Pb-Pb collisions. We show that $J/\psi$ suppression in proton-nucleus and in Sulfur-Uranium collisions can be understood in terms of nuclear absorption and there is no indication of an additional mechanism in S-U compared to p-A collisions.