Digitizer-Based Single Photoelectron Detection Approach for Light Yield Measurement of Inorganic Scintillators

Background: Absolute light yield measurement based on single photoelectron (SPE) approach remain susceptible to random coincidences between pulsed excitation trigger and the photomultiplier tube (PMT) response.Few studies have reported a quantitative comparison of SPE-based light-yield estimation before and after random-coincidence suppression.To address this, we developed a simplified digitizer-based setup to quantify the light yield using a predefined time window to suppress random-coincidence events.Materials and Methods: SPE spectra were measured by stimulating a PMT with a dim light emitting diode, and the anode signals were recorded using a high-speed digitizer.Event timestamps were used to select correlated signals within the time window.A 11 CsI(Tl) scintillator was sequentially coupled to R2228 and R1924A PMTs under identical configurations to verify the consistency of the measured light yield across the two PMTs.Results and Discussion: Suppressing random coincidences eliminated bias in SPE estimation, which otherwise led to an ~11% overestimation in light yield.The CsI(Tl) light yield was determined as 50,0002,000 photons/MeV and 51,0002,000 photons/MeV for R2228 and R1924A PMT, respectively.This digitizer-based SPE approach provides a reliable and reproducible method for light yield measurement. Conclusion:We demonstrated a simplified digitizer-based SPE measurement method, applying a time-window filter to reject random coincidence events.This approach enables accurate estimation of the SPE charge and, consequently, a reliable and reproducible light yield evaluation, which have been confirmed with consistent results obtained by the two PMTs.