A Mّller polarimeter for high energy electron beams

A single arm Møller polarimeter used to measure the longitudinal beam polarization of the 48 GeV electron beam for SLAC fixed target experiment E-154 is described. The polarimeter utilizes an array of silicon strip detectors and a dipole magnetic spectrometer to detect Møller scattered electrons from magnetized FeCo alloy target foils. The details of the foil polarization measurements and analysis technique are discussed. The high statistical precision of the Møller data and the stability of the SLAC polarized source made precise studies of the systematic errors in the analysis possible. An overall systematic error of 2.7% is assigned to the beam polarization determination.