$\mathrm{J}/\psi$ Suppression in Heavy Ion Collisions at the CERN SPS

We reexamine the production of J/ψ and other charmonium states for a variety of target-projectile choices at the SPS, in particular for the interesting comparison between S+U at 200 GeV/c and Pb+Pb at 158 GeV/c as observed in the experiments NA38 and NA50 respectively. The result is a description of the NA38 and NA50 data in terms of a conventional, quasi-hadronic picture. The apparently anomalous suppression found in the most massive Pb+Pb system arises in the present simulation from three sources: destruction in the initial nucleon-nucleon cascade phase, use of coupled channels to exploit the larger breakup in the less bound xi and ψ′ states, and comover interaction in the final low energy phase.