Y:BaF2

The Yb³⁺-doped crystals show very short decay time, but they have low LO due to thermal quenching. And 1 at% Y doping suppresses the slow scintillation component in BaF₂ crystals by a factor of 6, while the fast component remains unaffected.

Barium fluoride (BaF₂) crystal has a fast scintillation light peaked at 195 and 220 nm with a sub-ns decay time. This ultrafast scintillation promises a wide application in an area where extreme fast timing is important, such as future high-energy physics experiments, gigahertz hard X-ray imaging, and time-of-flight positron emission tomography. BaF₂ crystal, however, has also a slow scintillation component peaked at 310 nm with a decay time of about 600 ns, which causes pileup. the slow component in BaF₂ crystals can be suppressed by yttrium doping. BaF₂ provides a fast scintillation component with an ultrafast decay time of less than 0.6 ns and an ultrashort FWHM pulsewidth of less than nanoseconds, providing a solid foundation for an ultrafast scintillator. Its slow scintillation component with 600-ns decay time may be suppressed effectively by Y³⁺ doping. An imager consisting of bulk BaF2:Y crystals may serve as a total absorption detector concept for gigahertz hard X-ray imaging for the proposed MaRIE project.