Electronics design for a muon imaging system using triangular plastic scintillators with WLS fiber readouts

Abstract

Muon imaging technology has developed rapidly over the past decades with extensive applications. In many cases, plastic scintillator detectors are preferred because of their high cost performance, ease of processing and robustness in harsh environments. To reduce imaging time and improve imaging quality, detectors tend to have large areas and high position resolutions. The challenge to the electronics for such detectors is to maintain the scale of electronics acceptable while improving the high position resolution of the detector. In this paper, the basic detector unit is a triangular strip of plastic scintillator, each embedded with two wavelength-shifting (WLS) fibers read out by the silicon photomultipliers (SiPMs). Since the hit position of muon on the detector is determined by the splitting ratio of the scintillation light on two adjacent scintillator strips, it is necessary the readout electronics has high linearity and low noise. The possibility of the electronics channel multiplexing on the same detector plane is fully explored so that four WLS fibers can be read out by one SiPM realizing 2:1 readout channel compression. Furthermore, since multiple electronics modules are connected by a daisy chain structure, the electronics system is very scalable with its data acquisition system (DAQ) independent of detector size. In addition to detailing the position encoding readout scheme, the design of electronics module and the DAQ system, the electronics system has been implemented and applied to a prototype detector for performance evaluation. Using scintillator strips with 11 mm pitch size, the position resolution of the detector reaches 1.49 mm, which demonstrates that the designed electronics is suitable for the new detector structure, and the combination of the two has a good application prospect in muon imaging.