Charmonium production and absorption in heavy ion collisions is studied with the ultrarelativisitic quantum molecular dynamics model. We compare the scenario of universal and time-independent color-octet dissociation cross sections with one of distinct color-singlet $J/\psi ,$ ${\psi }^{\prime }$, and ${\chi }_c$ states, evolving from small, color transparent configurations to their asymptotic sizes. Both purely hadronic scenarios are compared with the $\mathrm{pA}$ and $\mathrm{AB}$ data at SPS energies. The predicted rapidity dependence of $J/\psi$ suppression can be used to discriminate between the two scenarios experimentally. The importance of interactions with secondary hadrons and the applicability of thermal reaction kinetics to $J/\psi$ absorption are investigated. We discuss the effect of nuclear stopping and the role of leading hadrons. The dependence of the ${\psi }^{\prime }/J/\psi$ ratio on the model assumptions and the possible influence of refeeding processes are also studied.

• Received 16 February 1999

DOI:https://doi.org/10.1103/PhysRevC.60.054901