Performance evaluation of SensL SiPM arrays for high-resolution PET

Silicon photomultipliers (SiPMs) have high gain, excellent timing performance, and are well suited to PET/MRI applications due, in part, to their MR-compatibility and small form factor. Within the constraints of a resistor-based multiplexing circuit, it is useful to evaluate the four generations of SiPM arrays manufactured by SensL: the SPMArray4, ArraySL-4, ArraySM-4, and ArraySB-4. Breakdown voltage and dark current were measured as a function of temperature in two each of the four generations of SensL SiPM arrays. Flood histograms were created with a ⁶⁸Ge-irradiated 9×9 LYSO crystal array at temperatures of 5 °C to 45 °C in 5 °C increments and overvoltages of 2 to 4 V in 0.5 V increments. Measurements of dark current vs. bias voltage increased as temperature increased, with a corresponding increase in the breakdown voltage, V_b. The temperature dependence of V_b is similar between all four generations of SiPM arrays with slopes ranging from 17.0 to 23.8 mV/°C. Notably, the ArraySB-4 has lower values for the breakdown voltage, with V_b = 24 V at 0 °C. Mean energy resolution for individual LYSO crystals showed improvements in each successive generation. The average energy resolution of the ArraySB-4 was 11.9% after correcting for non-linearity in the SiPM pixels. The linearity of the SensL SiPM arrays as a function of temperature and breakdown voltage makes them a suitable choice for a high-resolution, small animal PET/MRI system. Based on its improved resolvability and energy resolution, lower sensitivity to temperature and higher PDE, the ArraySB-4 will be used in our PET system.