Performance evaluation of novel LaBr3(Ce) scintillator geometries for fast-timing applications

Energy resolution and efficiency were measured using standard calibration sources. Timing measurements were performed at 60Co and 22Na γ-energies against a fast BaF2 reference detector. The time resolution was optimized by the choice of the photomultiplier bias voltage and the fine tuning of the constant fraction discriminator parameters. Monte Carlo simulations using the Geant4 toolkit were performed in order to achieve a better understanding of how the new geometries affect the light transport and thus the performance of the crystals. It is found that the conical-shaped LaBr3(Ce) crystals are optimal for fast-timing applications and for the construction of arrays such as FATIMA.