Development of an efficient multiplexing scheme for multichannel detection systems based on organic scintillators and silicon photomultipliers

Radiation detection applications requiring a large number of detectors, such as attempting to use an array of silicon photomultipliers as a multi-channel light sensor, can often be infeasible because of prohibitive hardware costs to readout many channels. Therefore, it is beneficial to efficiently multiplex many detectors into a single data-readout channel to dramatically decrease the equipment cost, while only marginally affecting the system performance. This work demonstrates a multiplexing method based on mixing silicon photomultiplier pulses with sinusoids of varying and well-defined frequency. It is shown that the presented multiplexing method can efficiently preserve the information on the signal origin (detector number), and that characteristics such as pulse shape discrimination with organic scintillators and time resolution are only minimally affected. The effects of varying the frequency and amplitude of the sinusoids on the aforementioned properties were characterized to find the ideal signal configuration. Finally, a prototype with four SiPM channels has been developed to demonstrate that effective performance remains when scaling to larger numbers of silicon photomultiplier channels. This relatively simple multiplexing approach, requiring only diodes and a sinusoid producing circuit, can effectively multiplex many silicon photomultiplier channels together, and it provides major hardware-cost improvements at the expense of only marginal pulse shape discrimination and timing performance losses.