High-Speed Detection of X-ray Pulses Using a Digital Counter Coupled with Perovskite Composite Scintillators

Accurate pulse-resolved detection of ionizing radiation at megahertz frequencies is essential for applications such as quality assurance in ultrahigh-dose-rate radiotherapy and low-dose X-ray monitoring. Conventional scintillator-based detectors employ bulky single crystals, such as lutetium-yttrium oxyorthosilicate (LYSO), which limit their flexibility and integrability. Furthermore, many perovskite scintillators exhibit afterglow, which leads to signal pile-up under high-flux conditions. To address these challenges, we developed thin polymer composite scintillator films comprising LYSO and (PEA)₂PbBr₄. These films retained the materials' intrinsic decay times (∼37 and ∼6 ns, respectively) while enhancing signal output through the optical scattering of scintillation photons within the inhomogeneous polymer matrix. When coupled with silicon photomultipliers and a field-programmable gate array (FPGA)-based digital counter, these films enabled rapid real-time detection across a broad frequency range. Specifically, the LYSO/PMMA composite detected intense signals up to 2 MHz (500 ns spacing), whereas the (PEA)₂PbBr₄/PMMA composite, with an amplification stage, enabled accurate pulse counting up to 5 MHz (200 ns spacing). With a dead time of ∼20 ns, the system resolved nanosecond-spaced pulses without pile-up, enabling reliable pulse-by-pulse readout from a few counts per second to multimegahertz bursts. These results demonstrate that inhomogeneous composite scintillator films, when integrated with FPGA-based digital processing, provide a compact and scalable pulse counter for high-frequency radiation detection, effectively addressing the limitations of conventional bulky crystal detectors.