Self-calibrated deadtime correction using poisson-tail invariance in event-driven electron detectors

High-flux electron counting with event-driven detectors is fundamentally limited by pixel-level deadtime, resulting in nonlinear count loss, variance suppression, and distortion of spatial intensity profiles. We introduce a monitor-free, self-calibrated deadtime correction method based on the invariance of the long-time Poisson tail of inter-arrival time distributions. Under stationary Poisson illumination, the long-time inter-arrival tail provides an internal statistical estimate of the incident arrival rate, independent of external flux measurements. The approach is demonstrated using high-flux transmission electron microscopy beam-profile measurements, where spatial Fano-factor analysis confirms operation in the deadtime-limited regime. By calibrating an effective extended-deadtime model with the tail-derived rate, the corrected peak count rate increases from approximately 78 kHz to 131 kHz, corresponding to a 67% increase relative to the raw peak. These results establish a self-referenced framework for deadtime correction and dynamic-range extension in event-driven electron detectors, subject to the validity of the stationary-arrival and tail-invariance assumptions.