ABSTRACT
This chapter examines the mechanisms of detection in photon detectors and discusses the spectroscopic characteristics of the different types of x-ray and γ-ray detectors. Photons are detected by means of the electrons they produce when they interact in the material of which the detector is made. The fraction of counts recorded outside the full-energy peak depends on the energy of the gamma and on the size of the detector. There are four types of efficiency reported in the literature: total detector efficiency, full-energy peak efficiency, double-escape peak efficiency and a single-escape peak efficiency. Reduction of background in any measurement is very important. It becomes absolutely necessary in cases when the sample to be counted is a very weak radiation source and its activity barely exceeds that of the background. For certain measurements, like coincidence–anticoincidence counting or experiments involving accelerators, the time resolution of the signal is also important, in addition to energy resolution.
