Effects of scintillation light collection on the time resolution of a time-of-flight detector for annihilation quanta

Monte Carlo methods were used to simulate the production and collection of scintillation light in a BaF/sub 2/ crystal. The calculated results were compared to measured values for detectors with different heights. Based on this simulation, a TOF (time-of-flight) detector consisting of two conical BaF/sub 2/ crystals (base radius 18 mm, top radius 15 mm, height 25 mm) was assembled. The total time resolution of this system was (210+or-5) ps FWHM (full width at half maximum) for 511-keV annihilation quanta and was found to be independent of the source position between the detectors. Since the time resolution of the TOF detector system consisting of two conical BaF/sub 2/ crystals is sufficiently constant in the volume of interest and does not change during operation, this detector meets the requirements for application in a clinical routine.>