Optimization of Target-Dump Separation at Fermilab Seaquest Experiment

SeaQuest (E906) is a fixed-target Drell-Yan experiment at Fermilab designed to measure the flavor asymmetry of the light sea quarks of the nucleon. Collisions of the 120 GeV proton beam from Fermilab's Main Injector with hydrogen, deuterium, and nuclear targets result in the production of muon pairs; however, muon pairs are also produced in the iron beam dump. Spatial cuts on reconstructed tracks must be used to separate background events originating in the dump from signal events produced by the target. The analysis to optimize the efficiency and purity of target events, based on both simulated and real data, will be presented.