Observation of fast scintillation light in a PbF2:Gd crystal

A weak scintillation emission has been observed in a lead fluoride crystal doped with 0.15% gadolinium (PbF2:Gd). The scintillation is produced by two emission peaks, one at ∼278 nm, and another at ∼311 nm, which, when combined with the Cherenkov light produced in the crystal, results in a total light yield of 4--6 photoelectrons per MeV on a bialkali photocathode phototube. This is approximately 3--4 times the intensity of the pure Cherenkov light produced in an undoped lead fluoride crystal. The decay time for the observed light output was found to be ∼18 ns with no appreciable slow component. The total light yield of PbF2:Gd is comparable to that of lead tungstate, and, because of the lack of a slow component, could make it attractive for use in high energy electromagnetic calorimetry