NA50 final results on charmonia suppression

NA50; The last results from the NA50 experiment on charmonia production in Pb-Pb interactions at 158 GeV/c per nucleon are presented. A strong J/$\psi$ suppression is observed, which increases with the centrality of the collisions. The J/$\psi$ production is seen to be anomalously suppressed starting at mid-centralities, when compared to a reference taken from proton-induced collisions. The most recent developments on the determination of this normal absorption curve are explained. It is also shown that for sulphur-induced reactions there is full agreement with the extrapolated normal p-A behaviour. The suppression of $\psi'$ production in heavy ion collisions (Pb-Pb and S-U) is also presented. It is seen to increase with the centrality of the collisions, and to be significantly stronger than the one measured in proton-induced reactions.