Characterisation of silicon photomultipliers for time-of-flight PET

The recently developed Silicon Photo Multiplier (SiPM) is a solid state photon detector operating in the Geiger mode. Due to the avalanche nature of its operation, it has a fast response time, potentially useful in Time-Of-Flight (TOF) applications. This work is aimed at the application of TOF to Positron Emission Tomography (PET). We have characterised SiPMs from two manufacturers in terms of breakdown voltages, dark count rates and the rise times of the signal in response to pulsed light sources. SiPM timing performances were studied with a Na-22 source, using two-channel systems in which the SiPMs were coupled to scintillator crystals. The best timing resolutions measured were given by Hamamatsu 3×3 mm2 area 50 μm pixel size SiPMs. These devices gave timing resolutions of 176 ps (σ) and 227 ps (σ), when coupled to 30 mm-long LaBr3(Ce) and 5 mm-long LYSO crystals, respectively.