New fast scintillators on the base of BaF2 crystals with increased light yield of 0.9Â ns luminescence for TOF PET

Presently a growing interest to time-of-flight PET is observed in a number of experimental works using LSO as scintillation crystals. We propose to use as scintillators BaF2 crystals and ceramics produced from identical material but with essentially more high light yield in the fast component of emission spectra. A light yield amplification of BaF2 single crystal fast component of 2 to 2.5 times is achieved in crystals annealed in CF4 and doped by scandium at concentration of 0.5 to 2.0 mol%. Ceramics from BaF2 doped by Sc have amplification factor order of 1.7 to 2.5. One can consider to produce scintillator of size 10×10×20 mm3with an improved light transmission of ceramics in the range (200-250) nm up to single crystal level and with a light yield of 0.9 ns component at the level of 3000 to 4000 ph/MeV. Another promising scintillator obtained in our collaboration is BaF2:Tm3+. In this case one can have a scintillator in UV range with a time decay 0.9 ns and a strongly decreased yield of BaF2 slow component.