A Study of Longitudinal Charged Pion Electroproduction on H , 2 H , 3 He

A series of measurements of single pion electroproduction on the proton, deuteron, and He was completed recently at Je erson Laboratory by the NucPi Collaboration. The data form the rst part of a study of longitudinal electroproduction in light nuclei. The goal is a determination of the longitudinal cross section in parallel kinematics by means of a Rosenbluth separation, and a search for target-mass dependent e ects. Longitudinal pion electroproduction should be sensitive to nuclear pion currents because of the dominance of the pion-pole process for charged-pion emission in the direction of the virtual photon. The mass dependence of the longitudinal cross section should provide insight into the absence of any enhancement of sea quark distributions in nuclei as measured in deep-inelastic scattering. Data have been obtained at Q = 0:4 GeV , forW = 1:15 andW = 1:6 GeV from H,H, and He, and for a range of values of Q on H and H at W = 1:95 GeV . Results from the analysis of these data are discussed, and a run plan of 400 hours of beam for completing this study is presented.