High efficiency photocathodes for gaseous detectors of visible photons

Our latest results in the development of gaseous detectors for visible photons are presented in this paper. Quantum efficiencies of a few percent at 400 nm were routinely achieved. These detectors can operate at gas gains up to ∼1000. The main effort was focused on a study of the effect of different liquids and solid layers on the quantum efficiency of photocathodes. Some of these layers make the photocathodes more robust, while others increase the quantum efficiency. It was found, for example, that thin layers of solid and liquid Xe and Kr enhance the quantum efficiency by a factor ∼2. These solid layers can also protect the photocathodes against some impurities in the surrounding gas. some further development gaseous detectors for visible photons will probably find applications in crystal calorimetry, noble liquid scintillation detectors, Cherenkov counters, air shower detectors and the readout of scintillating fibers for preshower and max-shower detectors.