J/psi production and suppression at SPS energies

Abstract We present the set of measurements carried out by the NA50 experiment to study J/ψ production in proton- and ion-induced reactions. We also make use of results obtained previously under similar conditions by experiments NA51, NA38 and NA3. All these measurements were performed in fixed target experiments at the CERN SPS. Due to accelerator constraints, momentum was 450, 400 and 200 GeV/c for incident proton beams (corresponding to sqrt{s}=29.0, 27.4, 19.4,{rm GeV} respectively) whereas, for ion beams, incident momentum was 200 GeV/nucleon for oxygen and sulfur and 158 GeV/nucleon for Pb beams (sqrt{s}=19.4 and sqrt{s}=17.2,{rm GeV} respectively). The p–A data allow us to determine with high accuracy the absorption cross section of the (pre-)resonant {rm c}bar{rm c} state with nuclear matter. The J/ψ production cross section normally expected for ion-induced reactions can then be determined and compared to the results obtained from the data collected for oxy...