Multi-Well Avalanche Selenium Detector for Time-of-Flight PET

For the first time, we propose using amorphous selenium (a-Se) as the photoconductive material for time-of-flight (TOF) PET detectors. One major drawback of a-Se is its poor timing jitter stemming from low carrier mobility due to shallow-traps, a problem that must be circumvented for TOF applications. Thus, we propose using a nanopattern multi-well selenium detector that enables both avalanche multiplication gain and ultrafast charge sensing in one device. We've previously shown the capabilities of our avalanche mode multi-well selenium detector, which has a large active area, impact ionization avalanche gain and timing jitter on the order of 100 ps. Using Cramér-Rao Lower Bound analysis in conjunction with experimental measurements, we calculate the lower bound on coincidence time resolution for our selenium photodetector and compare it with that of the current state-of-the-art TOF-PET photodetectors. Our results show that our multi-well selenium detector is a promising candidate to achieve 100 ps coincidence time resolution in TOF-PET using standard-sized scintillator crystals with a photodetector that is cost-effective and uniformly scalable to large area.