Efficient energy spectrometer for charged particle detection in surface studies

Abstract

We have recently built a spectrometer that efficiently collects the energy spectrum of charged particles that emerge from targets bombarded by low‐flux (10⁻¹⁵ A) incident beams. The spectrometer is used to detect positron‐induced secondary electrons and low‐energy positron‐stimulated Auger electron emission. Slow positrons and positron‐induced secondary electrons are generated from a cold neon positron moderator deposited onto an encapsulated ²²Na source. The moderated beam is magnetically transported to the target with two sets of E×B plates. The particles emerging from the target are energy dispersed by a third set of plates and are detected with a one‐dimensional position‐sensitive detector. The data‐collection rate for the energy‐distribution spectrum is ∼10–100 times faster for this experiment relative to the more common method of sweeping grids or the plates.