Optimization of dual mode readout of Sensl SiPM for TOF PET detectors

A novel silicon photomultipliers (SiPM) has been developed with both a standard and a fast output, aiming at providing good energy and timing performance simultaneously for time of flight (TOF) PET application. Optimal readout method of this SiPM is investigated in this study. The standard output can be taken from either anode terminal or cathode terminal and different dual readout mode has different impact on timing resolution of fast output. Three dual mode readout methods were evaluated and we found the optimized way was to readout the standard output on the cathode side with a small capacitance in parallel. This readout method can preserve good timing performance using relatively few electronic components. We developed a detector module by directly coupling a 16×16 LYSO crystal block to an 8×8 Sensl FC30035 SiPM array. Through multiplexing and summing scheme and charge division resistor network, 64 channels of fast output and 64 channels of standard output are reduced to one fast timing signal and four energy signals, making the detector highly compact and scalable. The performance of the detector module was evaluated. 16×16 LYSO crystals were well resolved in the flood image and the average energy resolution were 12.4% ± 0.8% at 511 KeV. The average coincidence resolving timing (CRT) of the block against a single LYSO crystal coupled to a FC30035 pixel were 286 ± 13 ps. The average block-to-block CRT were estimated to be 311 ps. The proposed dual readout design has demonstrated excellent timing performance for TOF PET detectors.