Precise metrology of SiPM: Measurement and reconstruction of time distributions of single photon detections and correlated events

Abstract

Recent advances in developments of fast scintillators and fast silicon photomultipliers (SiPM) resulted in significant improvements in a time resolution of TOF PET and similar applications. A coincidence time resolution of 10 ps is considered as an ultimate goal of these improvements. Approaching to fundamental timing limits in TOF applications, all essential SiPM parameters responsible for true and false detection events initiated by photons and dark carriers, and accompanied by crosstalk and afterpulsing correlated events, should be measured, reconstructed and identified in their timing dependencies with a high precision. This study is based on a probabilistic consideration of key SiPM parameters as temporal distributions of corresponding events. A single photon (true) detection is represented either by a probability density function (PDF) which width relates to a single photon time resolution (SPTR) and the area defines a photon detection efficiency (PDE) or by incomplete cumulative distribution function (CDF) approaching to the PDE at long times. A false detection is a probabilistic event combined from dark counts and correlated events, which can be specified and separated by corresponding CDFs. Proper extraction of pure photon detection and correlated event distributions is especially valuable in case of large area SiPMs with a high dark noise affecting quality and precision of standard measurement techniques. Representative examples of measurements of the time distributions as well as analytical models and reconstruction algorithms are presented and discussed.