Current status of studies on parton energy loss in cold nuclear matter at SeaQuest.

Parton energy loss in cold nuclear matter is integral to the understanding of interaction of partons with the nuclear medium. By measuring the nuclear modification, $R_{pA}$, Drell-Yan serves as a clean probe into initial state energy loss due initial state quark-medium interactions and color singlet final state. E906/SeaQuest, a is fixed target Drell-Yan experiment, uses the 120 GeV ($\sqrt{s_{NN}}=15$ GeV) Main Injector Beam at Fermilab to study the interaction of protons impinging on LH$_2$, LD$_2$, C, Fe, and W targets. SeaQuest is uniquely suited to measure this energy loss as the spectrometer acceptance is optimized in the high $x_2$ range, which minimizes other potential nuclear effects such as nuclear shadowing, and the lower beam energy increases the relative Drell-Yan yield to the charmonium backgrounds. We present recent progress toward this measurement.