  The experimental ratio of $\psi'$ to $J/\psi$ is approximately a constant in
$pA$ collisions, but decreases as the transverse energy increases in
nucleus-nucleus collisions. These peculiar features can be explained as arising
from approximately the same $c \bar c$-baryon absorption cross section for
$\psi'$ and $J/\psi$ but greater disruption probabilities for $\psi'$ than for
$J/\psi$ due to the interaction of the $c\bar c$ system with soft particles
produced in baryon-baryon collisions.
