Avalanche Photodiode Arrays Enable Large-Area Measurements of Medium-Energy Electrons

We demonstrate the performance of a large-area avalanche photodiode array as a medium-energy electron detector. This avalanche photodiode array is composed of eight pixels with 1.2 cm² of total active area. The energy resolution (DeltaE/E) is as low as 4.5% in full width at half maximum for 25-keV electrons, and the linearity is excellent. Monte Carlo modeling by Geant4 shows that the detection efficiency of this device is appropriate for the detection of electrons ranging from < 5 to > 200 keV. This new device can be coupled with magnetic deflectors, electrostatic analyzers, and other physics instruments requiring position-sensitive or large-area solutions for the detection of electrons in this energy range.