Heavy Quark Production in 920 GEV Proton-Nucleus Collisions

HERA-B is a fixed-target muti-particle spectrometer experiment at the 920 GeV HERA proton beam at DESY. The collected data sample from the 2002/2003 HERA run includes 200 million interactions recorded with a minimum bias trigger and about 300,000 J/Ψ decays recorded with a dilepton trigger. These data samples are being analyzed to extract production cross sections for J/Ψ, Υ, and charmed mesons as well as the total b-quark production cross section. Additionally, aspects of charmonium production including the χ_c to J/Ψ cross section ratio, the Ψ(2S) / J/Ψ cross section ratio, and the .x_F , transverse momentum and atomic number dependence of the J/Ψ cross section in the target hemisphere are under investigation. Preliminary results on these topics are presented.