  To understand the reliability of the charmonia suppression as a signature of
the Quark-Gluon Plasma formation in nucleus-nucleus collisions it is important
first to understand the details of the production of J/psi and psi' in pA
interactions and the difference in the suppression of these two states. This
report presents the results of the study by the NA50 collaboration of the J/psi
and psi' production in pA interactions at 450 GeV beam energy and its
dependence on rapidity. It is shown that the psi' suffers more suppression than
the J/psi, which is consistent with a similar observation made at 800 GeV beam
energy by the E866/NuSea collaboration.
