Inorganic scintillating materials

Seeing what cannot be seen is the main goal of a scintillating material, which converts the energy deposited by an X or γ -ray, but also from other ionizing particles such as electrons or neutrons, into visible light (or Ultra-Violet and Infrared). Each induced flash of light can be then detected using a traditional photodetector. The scintillator is thus a key element of ionizing radiation detectors. They are widely used in various societal sectors such as medical imaging, homeland security or oil drilling. A wide range of scintillator types exist. Some of them have reached technological maturity and are already on the market at a large scale, others are more exploratory and are only prepared and studied in labs. This wide choice of materials is due to the wide range of performance and parameters required for the various applications.

After defining scintillation and the various ways of using it, this review discusses the scope of the different applications and the related societal fields using these converting materials. It then aims to explain to the reader, as a potential end-user of scintillating materials, the role and impact of the various quality criteria. Depending on the target applications, these parameters are ranked in terms of importance. The various ionizing radiation interactions with matter are described since it plays a major role in material selection. In the second section, the theoretical bases of the energy relaxation processes are described. Being rather complex, this description is not essential for understanding the first part. Nevertheless, it becomes of interest for material scientists. Indeed, a tiny change in the material may lead to huge consequences for performance. The optimization of performance and the synthesis processes thus require a good overview of these mechanisms, which include energy transfers as well as luminescence. The conclusion gives an overview of current developments and research on this topic. A glossary as well as a table of the symbols is presented at the end of the article.