A systematic study on the strip-line readout method for SiPM-based TOF PET

Signal multiplexing for SiPM-based TOF PET to achieve high multiplexing ratio and keep the fast timing performance is a challenging issue. We have developed a multiplexing method using a strip-line; multiple SiPMs are connected to a single micro-strip transmission line, and the position of hit SiPM is determined by the signal arrival time difference on the strip-line. The strip-line method is scalable; high multiplexing ratio can be easily achieved by increasing the number of SiPMs connected on a strip-line. To test the scalable feature of the strip-line readout systematically, we have implemented several strip-lines with different trace lengths and varied the number of SiPMs (Hamamatsu S13361-3050NE) on the strip-lines up to 32. Experimental tests have been conducted to assess the influences of the strip-lines on detector performance: position, energy, and coincidence time resolution. Preliminary results from the study are presented, and our ongoing efforts on strip-line readout for TOF PET are discussed.