The Gas Photodiode as a Possible Large-Area Photon Detector

Testing extensively a dozen custom-manufactured gas photodiodes, we have observed stable and reproducible characteristics of the argon-filled devices at pressures around 1 Torr, with gains up to 30-40. Methane-filled diodes operate at even higher gains (60-70) at around the same pressure, and have a faster response; they show, however, long-term degradation at relatively low light fluxes. At higher pressures, while the argonfilled device is largely degraded, high quantum efficiency and a good collection plateau is observed in methane. When operated in the collection mode, the CH4 high-pressure device does not show any sign of degradation.