Using Thin Films to Screen Possible Scintillator Materials

The discovery and optimization of new scintillators has traditionally been a rather slow process due to the difficulties of single crystal growth. This paper discusses the production of polycrystalline scintillator thin films which were tested in order to determine what characterizations could be made concerning a material's ultimate potential as a scintillator prior to pursuing crystal growth. Thin films of a few microns thickness of CaF
₂
(Eu), CeF
₃
, and CeCl
₃
, all known scintillators, were produced by vapor deposition. The hygroscopic CeCl
₃
was coated with multiple polymer-aluminum oxide bi-layers. Emission wavelengths and decay times agreed with values from single crystals. The films were too thin to measure gamma photopeaks, but using alpha energy deposition peaks, one could compare the relative photon yield/MeV between materials. The values obtained appear to give a relevant indication of a material's light yield potential. The technique may also be useful for quickly indicating the proper dopant amount for a given material.