Timing performance enhancement in SiPM array-coupled plastic scintillator detectors via fast output and a dedicated compensation network

In recent years, plastic scintillators with pulse shape discrimination (PSD) capability have been widely used in neutron detection when coupled with silicon photomultipliers (SiPMs). The China Spallation Neutron Source (CSNS) offers a valuable experimental platform for response matrix measurements of plastic scintillators over a broad neutron energy range, facilitating their application to high-energy neutron detection. Since the response matrix at CSNS is derived using time-of-flight (TOF) techniques, high timing precision is required to accurately resolve neutron energies. In addition, the pulsed neutron beam at CSNS exhibits high instantaneous flux, which demands that the detector produce sufficiently narrow output pulses to reduce pulse pile-up and ensure stable operation at high count rates. Although the fast output of SiPMs provides superior timing performance and significantly narrower pulse widths than the standard output, the pronounced undershoot following the main pulse limits its applicability in high-count-rate environments. Building upon our previous design of a compensation network (CN), this study systematically evaluates the effects of CN parameter tuning and SiPM bias voltage on the timing characteristics of a plastic scintillator detector. Under an overvoltage of 4.1 V, the optimized CN circuit achieved a coincidence timing resolution with a standard deviation of 0.306 ns, demonstrating good repeatability. Further increasing the overvoltage to 4.9 V resulted in the best timing performance, yielding a coincidence timing resolution of 0.287 ns with similarly good repeatability. These findings provide technical support for high-resolution neutron response measurements at CSNS.