Scintillation characteristics of nonstoichiometric phases formed in MF2–GdF3–CeF3 systems Part III. Dense Gd1−x−yMxCeyF3−x tysonite-related crystals (M=Ca, Sr)

We evaluated the scintillation characteristics and the radiation hardness of Gd1−xCaxF3−x and Gd1−xSrxF3−x tysonite-type solid solutions (close to 6.6 g/cm3 in density) doped with Ce which were grown from the congruent melt. As the Ce concentration increased, the Ce3+ emission at 345 nm increased to a level comparable with the Gd3+ emission at 310 nm. Both emissions, however, were slow with the decay constant in the order of ms. The radiation hardness, which was roughly 104 rad, tends to degrade as the wavelength decreases and/or the Ce concentration increases. Both spontaneous recovery and UV annealing of the radiation damages were significant. The intensity of the γ-ray excited luminescence, integrated over time, was as large as 50% of that in BaF2 (12% of that in CdWO4). When the Ce concentration is nil or only small, the yellow–green luminescence for UV excitation was as intense as in CdWO4. Although the present crystals are not good for the applications in high-energy physics experiments, they may find applications in display devices, thermal neutron monitors, etc.