a Pulsed Polarized Electron Source for Atomic Physics Experiments

Recently, a pulsed photoelectron source has been set up to satisfy the beam specifications required for atomic collision studies using so-called "reaction microscopes". The gun is in operation and delivers short electron pulses (~500ps) using GaAs/AlGaAs heterostructure crystals. Illuminating the photocathode with light from a pulsed laser diode an average electron current of 60 μA has been obtained. A quantum efficiency of 3% and a cathode lifetime of one week have been achieved.

Planned future atomic collision measurements require a cold beam of transversely polarized electrons. First design changes have been made to produce short pulses of monochromatic and spin-polarized electrons in the future.