Charmonium Production in gamma-A, p-A and A-A

The data for the production of the $\psi'$ meson in pA collisions at 450 GeV at CERN-SPS (of the NA50-collaboration) yields $\sigma(\psi' N)\approx 8$ mb under the assumption that the $\psi'$ is produced as a result of the space-time evolution of a point-like $c\bar c$ pair which expands with time to the full size of the charmonium state. However, much higher values of $\sigma(\psi' N)$ are not ruled out by the data. We show that recent CERN data confirm the suggestion that color fluctuations are the major source of suppression of the $J/\psi$ yield as observed at CERN in both pA and AA collisions.