Barium fluoride (BaF2) crystal has a fast scintillation light peaked at 195 and 220 nm with a 0.8 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

CaF2(Eu) crystal refers to a crystal composed of calcium fluoride (CaF2) doped with europium (Eu) ions. The europium doping introduces luminescent properties to the CaF2 crystal, making it capable of emitting light when excited by certain stimuli.