Optimizing the timing resolution of SiPM sensors for use in TOF-PET detectors

We have investigated the timing performance of Hamamatsu Multi-Pixel Photon Counter (MPPC) photosensors in light of their use in time-of-flight (TOF) positron emission tomography detectors. Measurements using picosecond laser pulses show a single photo-electron root-mean-square (RMS) timing resolution down to about 100 ps. In coincidences of 511 keV photons detected with an LYSO crystal coupled to a MPPC and a BaF2 detector, an optimum FWHM timing resolution of 600 ps was obtained with leading edge time pickoff at the 1–1.5 photo-electron level. By optimizing the LYSO/MPPC coupling, this can be improved by a factor of 2. We further conclude that the use of stored digitized pulses allows great flexibility and efficiency in developing data analysis algorithms.