High-Resolution Room Temperature Spectroscopy with Lanthanum Halides

The most desirable features in a spectroscopic material are high sensitivity and high resolution. Cerium-activated crystals of lanthanum bromide (LaBr₃:Ce) have higher sensitivity and better spectroscopic resolution than sodium/cesium iodide (NaI/CsI) crystals because of higher density (5.29 g/cm³), faster decay time (35 ns), minimal afterglow, and larger (63 000 photons/MeV) and more linear light output (6% nonlinearity over the energy range between 60 and 1332 keV). Of all the recent scintillator materials manufactured to date, LaBr₃, with cerium activators, is one of the most promising for high-resolution, fast timing techniques as applied to medical image reconstructions or associated particle imaging.