Fundamental time-scale limits in high-rate x-ray detection

High-rate x-ray detection is universally accompanied by spectral distortion and loss of information, yet prevailing explanations rely primarily on detector-specific dead-time or pile-up models. Here, we identify a detector-independent physical limit arising from the mismatch between the intrinsic relaxation time of the detection medium and the mean photon inter-arrival time. Treating signal formation as a dissipative relaxation process, we show that recoverable spectral information is governed by a single dimensionless time-scale ratio. When excitation rates approach or exceed intrinsic relaxation rates, overlapping responses lead to irreversible information loss prior to electronic readout, independent of bandwidth or post-processing. Representative normalized trends from publicly available high-count-rate detector studies illustrate the universal nature of this scaling. The results establish fundamental time-scale limits applicable to a broad class of x-ray and radiation detection systems.