Timing Performance of Cherenkov-Radiator-Integrated MCP-PMT

Coincidence time resolution (CTR) of 10 ps is an ultimate goal toward reconstruction-less positron emission tomography (PET). One of the ways to enhance the timing performance of the PET detector is to make use of Cherenkov photons which is promptly emitted on the order of picosecond. A Cherenkov detector composed of a Cherenkov radiator and a fast photo-detector, such as a microchannel plate photomultiplier tube (MCP-PMT) can reach the CTR better than 100 ps full width at half maximum (FWHM). Previously, we have developed the Cherenkov detector where the Cherenkov radiator is integrated with the MCP-PMT to enhance the timing performance, and the CTR of 41.9 ps FWHM was obtained. In this study, we performed two types of experiments; (1) increasing statistics roughly ten times larger than the previous study to precisely determine the timing performance of the detector, (2) stepping a
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Na point source and validating transitions of timing histograms according to the source positions. As a result, the CTR of 41.7 ps FWHM was obtained. Moreover, the CTR between the radiator and the MCP direct interaction was also investigated and approximately 55 ps FWHM was obtained. The transitions of the timing histograms according to the source positions were successfully observed. Finally, we show physical components affecting the CTR and potential capability toward the ultimate goal of 10 ps CTR is discussed.