  Using the QGP motivated threshold model, where all the $J/\psi$'s are
suppressed above a threshold density, we have analyzed the preliminary PHENIX
data on the centrality dependence of nuclear modification factor for $J/\psi$'s
in Cu+Cu and in Au+Au collisions, at RHIC energy, $\sqrt{s}_{NN}$=200 GeV.
Centrality dependence of $J/\psi$ suppression in Au+Au collisions are well
explained in the model for threshold densities in ranges of 3.6-3.7 $fm^{-2}$.
$J/\psi$ suppression in Cu+Cu collisions on the other hand are not explained in
the model.
