Large acceptance magnetic spectrometers for polarized deep inelastic electron scattering

The design of two magnetic spectrometers for the measurement of the spin-dependent structure function g/sub 1//sup n/ of the neutron and a test of the Bjorken sum rule are described. The measurement consists of scattering 23-GeV polarized electrons off a polarized /sup 3/He target and detecting scattered electrons of 7 to 18 GeV at 4.5 degrees and 7 degrees . Each spectrometer is based on two large aperture dipole magnets bending in opposite directions. Proper choice of the deflection angles and the distance between the two dipoles in each spectrometer allows a tolerable background. Each spectrometer is equipped with a pair of Cerenkov detectors, a pair of scintillation hodoscopes, and a lead-glass shower calorimeter providing electron and pion identification with angular and momentum resolutions sufficient for the experimental measurement. >