ABSTRACT
References .....................................................................................................................................311
4.3 Scintillators The fluorescence caused by incident radiations such as α, β, and γ-rays is called scintillation. Scintillators are mainly used in detection and measurement of energy, position, and time of the incident radiation. Although scintillation can occur for all materials, efficient scintillators have to satisfy the following requirements: (1) fast deexcitation; (2) high efficiency of emitting UV or visible light; and (3) transparency of the material to its own emission. A sketch of a typical scintillation counter is given in Figure 15(a). The photosensor as a readout device is usually a photomultiplier tube (PMT) or a Si PIN photodiode (PD) or an avalanche photodiode (APD). It should be noted that the light output in practical detectors depends on the spectral match between the emission and the photosensors. Light outputs are compared between PMTs and PDs for typical scintillators by Sakai1. There is a wide variety of inorganic (crystals, ceramics, glasses, gases, liquids) and organic (crystals, liquids, plastics) scintillators, depending on the application. Characteristics of typical scintillators are given in Table 3. Inorganic crystals and plastic scintillators are most widely used. Emphasis is made on inorganic crystals, followed by a brief description of ceramic, glass, and organic scintillators.
