Photodetectors

Abstract

The chapter covers photodetectors for photons in the optical and near UV range (about 200 nm to 700 nm). Important for particle and astroparticle experiments are photodetectors which detect light generated in scintillation or Cherenkov detectors, for example. The detection of photons always starts with the generation of an electron by photoeffect at a photocathode. The photoelectron can then be either multiplied in a photomultiplier tube by secondary electron emission or the cathode could be the surface of a semiconductor detector; both techniques can also be combined in hybrid photodetectors. A relatively new semiconductor detector is the silicon photomultiplier using an avalanche operation mode to obtain sufficiently large signals. In the last section the different photodetectors are compared and are assigned to typical applications according to their properties.