J PSI SUPPRESSION AS EVIDENCE FOR HIGH-DENSITIES IN NUCLEAR COLLISIONS/

We determine the hadron density necessary to account for J/psi suppres sion in nuclear collisions by absorption, including the effects of nuc lear stopping and J/psi formation time. The suppression measured in ce ntral 200 GeV/A O-U and S-U collisions cannot be obtained from interac tions of the J/psi with the primary nucleons alone. Absorption on prim ary and secondary hadrons can describe these data, however, provided t he density of the secondaries is at least 0.8 fm-3 i.e., five times st andard nuclear density.