  Ratios of the Psi' over the J/psi production cross sections in the dilepton
channel for C, Ti and W targets have been measured in 920 GeV proton-nucleus
interactions with the HERA-B detector at the HERA storage ring. The Psi' and
J/psi states were reconstructed in both the mu+mu- and the e+e- decay modes.
The measurements covered the kinematic range -0.35 < x_F < 0.1 with transverse
momentum p_T < 4.5 GeV/c. The Psi' to J/psi production ratio is almost constant
in the covered x_F range and shows a slow increase with p_T. The angular
dependence of the ratio has been used to measure the difference of the Psi' and
J/psi polarization. All results for the muon and electron decay channels are in
good agreement: their ratio, averaged over all events, is
R_psi'(mu)/R_psi'(e)=1.00+-0.08+-0.04. This result constitutes a new, direct
experimental constraint on the double ratio of branching fractions,
(B'(mu)*B(e))/(B(mu)*B'(e)), of Psi' and J/psi in the two channels.
