Design and implementation of simple electron detectors for accelerator diagnostics

We have constructed a compact, planar retarding field analyzer (RFA) for the diagnostics of low-energy, background electrons in a high-energy particle accelerator. Bench measurements of the analyzer have been made to characterize it, and the results are reasonable in light of models of this type of analyzer. We have recently implemented an upgraded detector, based on a "Bessel Box" design. This detector has the advantage of superior energy dispersion, but has lower signal levels. Here we present bench measurements and initial data from the Advanced Photon Source.