Design considerations for embedded real-time processing for 3D digital SiPMs with multiple TDCs

Abstract

The timing performance of digital silicon photomultipliers (dSiPMs) detectors have placed them as serious candidates for time-of-flight (TOF) measurement in positron emission tomography (PET). Contributors to timing uncertainty in current dSiPM scintillation detectors include: 1) routing skew and array non-uniformities, 2) SPAD dark counts and 3) scintillator statistics. A photodetector with a one-to-one coupling of timeto- digital converters (TDCs) and single photon avalanche diodes (SPADs) is under study as it opens new methods to minimize the impact these contributors. However, the number of TDCs required for this coupling scheme generates a tremendous amount of data. Acknowledging these design considerations, a real-time processing scheme is proposed to minimize the bandwidth while improving the timing resolution by 1) correcting routing skews and array non-uniformities, 2) filtering dark counts and 3) estimating the time of interaction from multiple photoelectron timestamps. Simulations were conducted to evaluate the impact of the contributors to timing uncertainty and the efficiency of the proposed architecture. With a simulated 1 x 1 x 10 mm3 LYSO scintillator, the coincidence timing resolution is improved from 161 ps to 115 ps with the simulated detector.