Scintillator

A scintillator is a material that emits light when it is exposed to ionizing radiation. The light is produced by the de-excitation of excited states created by the interaction of radiation with the material’s atoms or ions. Emission is typically in the visible or near‑ultraviolet region, and the emitted photons are detected by photosensors to measure the energy or intensity of the radiation.

There are inorganic scintillators, typically crystals or dense ceramics, such as sodium iodide doped with thallium (NaI(Tl)), cesium iodide doped with thallium (CsI(Tl)), bismuth germanate (BGO), and lutetium-based materials (LSO, LYSO). Organic scintillators include plastic scintillators (polystyrene or polyvinyltoluene) and liquid scintillators. Doping and composition tailor light yield and emission spectrum to suit specific detectors and energy ranges.

Key properties include light yield (photons per MeV of deposited energy), emission wavelength, decay time (from a few nanoseconds to microseconds), density and effective atomic number, attenuation length, and temperature dependence. Some scintillators exhibit afterglow or radiation-induced damage with prolonged exposure. Neutron-sensitive variants use materials that capture neutrons and produce scintillation signals.

Applications span gamma-ray spectroscopy, radiation dosimetry, positron emission tomography (PET), high-energy physics calorimetry, and security screening. In most systems the scintillator is coupled to a photosensor such as a photomultiplier tube or a silicon photomultiplier, which converts the light into an electrical signal for timing, energy measurement, and imaging or analysis.