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 mm² 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 mm³ 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.