60-MSPS Coherent-State Measurement of Cherenkov Photon Responses with Contravariance Diagnostics for Astronomical Neutrino Detection

Multi-channel Cherenkov readouts can lose or censor waveform segments through deadtime, clipping, and channel unavailability. Because unobserved samples are not physical zeros, a multi-channel coherence score can move in the opposite direction from the underlying waveform structure. We formulate an observation model that separates valid, clipped, and unavailable samples, and define two distinct diagnostics: a reference-conditioned paired-inversion indicator and a single-event threshold-discordance indicator. Here "coherent state" means correlated multi-channel waveform structure, not a quantum-optical coherent state. The diagnostics are evaluated on a representative 16-channel, 60-MSPS, 12-bit synthetic readout using 1800 waveform-retaining pseudo-events and a separately parameterized 2.0 × 107-trial event-level surrogate across six readout-stress configurations. In the surrogate, the threshold-discordance fraction ranges from below 10−3% in the mildest configuration to 99.5% in a deliberately severe one. Null controls show that this inversion is built into the score definitions: removing the explicit reconstruction penalty lowers the severe-case fraction to 0.2%, and removing both the penalty and the coupling of live fraction to modulation eliminates paired inversion in every configuration. At the waveform level, bounded pairwise correlations are attenuated but never inverted by the simulated mask, while contiguous-block loss of exactly the same number of samples, which preferentially removes the prompt pulse, drives the mean correlation near zero and reverses its sign in up to 38% of severe-case events. The loss mechanism, not the live fraction alone, therefore sets the risk. The study does not establish an inversion effect in a detector, and its numbers are not detector performance, trigger efficiency, or source rates.