Year: 2026
Type: preprint
Abstract: Existing scintillation-detector models typically treat scintillation kinetics, optical transport, silicon photomultiplier (SiPM) response, and timing statistics separately, limiting end-to-end prediction of waveform formation and detector performance. We present a unified analytical framework for lutetium-yttrium oxyorthosilicate (LYSO)-SiPM scintillation detectors that links these processes within a single forward model. The framework incorporates finite thermalization, depth-dependent optical transit-time spread, and microcell occupancy dynamics to provide a physics-based description of macroscopic pulse formation. It yields closed-form exponentially modified Gaussian pulses in the linear regime, state-dependent integral solutions in saturation, and recovers the conventional bi-exponential pulse model---ubiquitously used yet hitherto only empirically justified in scintillation pulse fitting and sparse-sampling reconstruction---as a controlled reduction of the full optoelectronic cascade. Experimental validation on 10,000 directly digitized Na-22 pulses shows that the dynamic saturation model captures amplitude-dependent waveform distortion and is favored by the Akaike information criterion (AIC) over a matched bi-exponential baseline in 100/100 high-amplitude pulses and 98/100 medium-amplitude pulses. By coupling the dynamic triggering rate to compound Poisson statistics, the framework also predicts current-variance envelopes and Fisher-information-based timing limits, including an intrinsic coincidence timing resolution lower bound of about 100 ps full width at half maximum (FWHM) for a reference 511-keV LYSO-SiPM configuration. These results deepen the physical understanding of scintillation-detector waveform formation and timing limits by clarifying how scintillation kinetics, optical transport, and SiPM microcell dynamics jointly shape the observed response.
Source: arXiv (Cornell University)
Authors: Qiu, Ao, Xie, Qingguo
Institution: Huazhong University of Science and Technology
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G4522648408, G4760252565, G8053059139
OpenAlex ID: W7201863552
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