Design and testing of apparatus for 180° electron scattering at low momentum-transfer

Abstract We report the design, installation, and performance history of a system for electron scattering measurements at 180°. The initial planning for this system is described, with reference to earlier 180° systems, and including the rationale behind various crucial design choices. Magnet optics, sliding vacuum seals, beam monitoring, focal plane corrections, and background suppression measures are discussed. Sample data from representative scattering experiments are presented.