Construction of Drift Chambers for Drell-Yan Measurement by SeaQuest at FNAL

d distributions in the proton. This experiment measures the cross sections of the Drell-Yan process in a proton-proton reaction and proton-deuteron reaction. The ratio between ¯ u and ¯ d distributions can be derived from the cross section ratio. The Drell-Yan process in proton-proton collisions is the reaction in which a quark in one proton and an antiquark in the other proton annihilate into a virtual photon and then it decays to a muon pair: q + ¯ q → ∗ → + + − . This process is suited to the study of antiquarks in the proton. The physics run will start in spring 2013. We are constructing drift chambers for this physics run. In this paper, the structure and performance of the SeaQuest spectrometer and the status of the new chamber construction is described.