SYSTEM OF DIPOLE MAGNETS FOR 180-DEGREES ELECTRON-SCATTERING

The design and performance of a four-magnet system for the measurement of 180° scattering of electrons with energies up to 450 MeV is described. Two of the magnets are moved perpendicular to the incident beam direction during an experiment. The post-target beam is directed along the same line as the incident beam, and a constant solid angle for backscattering is maintained regardless of the inelasticity of the collision suffered by the electron. The system is used in conjunction with a dispersion-matching transport system and a large spectrometer set at a fixed angle of 160°. Measured resolutions of less than 3 × 10-4 have been obtained. © 1979.