Charmonium suppression in lead-lead collisions: Is there a break in the J/psi cross section?

In the framework of a model based an nuclear absorption plus comover intera ction, we compute the E-T distribution of the J/psi in PbPb collisions at S PS and compare it with available NA50 data. Our analysis suggests that the existence of new physics (deconfinement phase transition) in the region E(T )less than or similar to 100 GeV is unlikely and that signals of new physic s should rather be searched in the region E(T)greater than or similar to 10 0 GeV. The E-T dependence of the J/psi transverse momentum has been compute d, At large E-T it turns out to be much flatter in the comover approach tha n in a phase transition framework. Estimates of the J/psi suppression at RH IC and LHC energies are also given. [S0556-2813(99)010011-8].