Fast and efficient detection of 511 keV photons using Cherenkov light in PbF2 crystal, coupled to a MCP-PMT and SAMPIC digitization module

We study the possibility to use the Cherenkov light for the efficient detection of 511 keV photons with the goal to use it in TOF-PET. We designed and tested two detection modules consisting of PbF2 crystals attached to PlanaconMCP-PMT XP85012. AmplifiedPMTsignals are digitized by the SAMPIC module with high readout rate, up to 10(5) events/s, and a negligible contribution to the time resolution, below 20 ps (FWHM). We developed a fast 2D scanning system to calibrate the PMT time response and studied in details the timing characteristics of the Planacon PMT. Using a radioactive Na-22 source we measured a detection efficiency of 24% for 511 keV photons in a 10 mm thick crystal and a coincidence resolving time of 280 ps. We analyzed the main factors limiting the time resolution of the large-surface detection module and proposed solutions to improve it, which will be tested in our future project.