Outstanding Timing Resolution of Pure CsBr Scintillators for Coincidence Measurements of Positron Annihilation Radiation

An outstanding timing resolution of 75 ps at full width at half maximum (FWHM) has been achieved in coincidence measurement of positron annihilation radiation. Pure CsBr crystals characterized by an ultrafast response of less than 70 ps and a considerably low light output of 20 photons/MeV are utilized as ultrafast scintillators by coupling them with microchannel-plate photomultiplier tubes (MCP-PMTs) and a fast digitizer. The achieved timing resolution corresponds to a time-of-flight (TOF) localization of 11 mm in positron emission tomography (PET). The results can serve as a new standard in the development of scintillator materials to achieve a timing resolution better than 100 ps.