Scintillation Detectors

This chapter focuses on the properties of scintillation detectors, in particular the most commonly used scintillation material, the sodium iodide crystal. A discussion of how the crystal converts gamma or X‐ray photon energy into light photon energy is followed by a discussion of other components of the detector that convert and amplify this light photon output into a detectable electric current. In a typical detector arrangement, photomultiplier tubes are optically coupled to the scintillation crystals to detect these light photons. The photomultiplier tube is a vacuum tube with a photocathode on the end adjacent to the crystal. The chapter reviews some of the general features of the sodium iodide detector energy spectrum, and examines the components of the spectrum of a sodium iodide crystal, the most commonly used crystal. Photopeaks in the spectrum correspond to the principal energies of gamma rays from the radioactive source. The chapter describes some commonly used scintillation‐based detectors.