Nuclear Dependence of J/ψ and ψ Production

FNAL E866/NuSea has made a number of measurements of J/ψ and ψprime production by 800 GeV protons on fixed targets of Be, Fe and W. Preliminary results are presented and discussed in the context of nuclear effects such as energy loss and multiple scattering of the partons, absorption of the produced cbar c pairs, and shadowing. Production mechanisms involving color-singlet or color-octet states for the cbar c pair which eventually forms a J/ψ or ψprime have implications on the strength of absorption in the nucleus. These nuclear dependence studies arc critical in furthering the authors understanding of these processes towards future measurements at RHIC and the LHC, where J/ψ suppression is predicted to be an important signature of the creation of quark-gluon plasma in heavy-ion collisions