Scintillation properties of GSO

The timing properties of Gd₂SiO₅:Ce (GSO) single-crystal scintillators have previously been evaluated for positron emission tomography applications. The measured time resolution, however, was worse than expected from calculations based on photoelectron yield and a 60-ns exponential decay constant, leading the authors to further investigate GSO´s basic properties. With a time-correlated-single-photon technique, they found two decay components, one of 56 ns and one of 600 ns, the latter containing 10-15% of the total scintillation output. This may explain the difference between the experimental and theoretical time resolutions and confirms a previous hypothesis of a long decay component. In addition, it was found that the decay constant of each component strongly depends on the cerium concentration. The primary component varies from ~20 ns to ~190 ns and the secondary component varies from ~70 ns to ~1200 ns as the cerium concentration is varied from 5.0 mol.% to 0.1 mol.%