Inorganic Scintillators—A Never Ending Story

Abstract

For decades, scintillation detectors based on inorganic materials have become one of the most widely applied instrumentation techniques in physics—in particular in the fields of nuclear and high-energy physics. Their discovery and development are strongly correlated with the experimental needs in basic research and technology in physics. Visual counting of the discovered X-rays or natural radioactivity became possible with CaWO4 or ZnS at the end of the 19th century. The first construction of scintillation detectors, made possible by the development of the photomultiplier tube, started with the discovery of activated and pure alkali halide crystals. NaI(Tl) and CsI(Tl), introduced by Hofstadter [1, 2], have provided for 60 years efficient photon and particle detection. The continuous increase of the energy range of the probes to be detected directed crystal development toward faster response, shorter decay times, and higher compactness implementing high-Z ions. In particular, the discovery of the fast core-valence luminescence in BaF2 [3, 4], the allowed electric dipole transitions in Ce3+, and the short radiation lengths of BGO [5] or PbWO4 [6] set important milestones in the last decades of the 20th century to find or even engineer the ideal scintillator.