SIGNATURES OF ABSORPTION MECHANISMS FOR J PSI AND PSI' PRODUCTION IN HIGH-ENERGY HEAVY-ION COLLISIONS/

J/psi and psi' produced in high-energy heavy-ion collisions are absorb ed by their collisions with nucleons and produced soft particles, lead ing to two distinct absorption mechanisms. The signature of absorption by produced soft particles, as revealed by psi' production data, cons ists of a gap and a change of the slope in going from the pA line to t he nucleus-nucleus line when we make a semi-log plot of the survival p robability as a function of the path length. Using this signature, we find from the J/psi production data in pA, O-Cu, O-U, and S-U collisio ns that the degree of J/psi absorption by produced soft particles is s mall and cannot account for the J/psi data in Pb-Pb collisions. The an omalous suppression of J/psi production in Pb-Pb collisions can be exp lained as due to the occurrence of a new phase of strong J/psi, absorp tion, which sets in when the local energy density exceeds about 3.4 Ge V/fm(3). To probe the chemical content of the new phase, we propose to study the abundance of open-charm mesons and charm hyperons which dep ends sensitively on the quark chemical potential.