Time based readout of a silicon photomultiplier (SiPM) for time of flight positron emission tomography (TOF-PET)

Time of flight (TOF) measurements in positron emission tomography (PET) are very challenging in terms of timing performance, and should achieve ideally less than 100 ps FWHM precision. We present a time-based differential technique to read out SiPMs that has less than 25 ps rms electronic jitter. The novel readout is a fast front end circuit (NINO) based on a first stage differential current mode amplifier with 20 ¿ input resistance. Therefore the amplifier inputs are connected differentially to the SiPM's anode and cathode ports. The leading edge of the output signal provides the time information, while the trailing edge provides the energy information. Based on a Monte Carlo photon-generation model, SPICE simulations were run with a 3 × 3 mm
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SiPM-model, read out with a differential current amplifier. The results of these simulations are presented here and compared with experimental data obtained with a 3 × 3 × 15 mm
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LSO crystal coupled to a SiPM. The measured time coincidence precision is interpreted by the combined Monte Carlo/SPICE simulation, as well as by Poisson statistics.