High resolution electron scattering facility at the Darmstadt linear accelerator (DALINAC): II. Beam transport system and spectrometer (energy-loss system)

Abstract

Design and installation of a high resolution energy-loss electron scattering system at the Darmstadt linear accelerator are described. The apparatus consists of a beam transport system with two 70°-dipole bending magnets, eleven quadrupole focussing magnets, a five quadrupole magnet set as rotating element, and a magic angle (169.7°) spectrometer for analyzing the scattered electrons. For a primary momentum spread Δp/ p 0 = 3 × 10 −3, a spectrometer acceptance solid angle Ω = 5 msr, and a 10 mg/cm 2 thick Be target, the resolution was measured to be δp/ p 0 = 4 × 10 −4, equivalent to 25 keV for 60 MeV electrons.