I don't understand how is the energy measured in a cherenkov detector. How is the number of photons radiated related to the energy of the particle or the measure of energy has nothing to do with the light yield ?
closed as unclear what you're asking by John Rennie, Kyle Kanos, Jon Custer, glS, Cosmas Zachos Jan 15 '18 at 22:16
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Cerenkov detectors measure velocity (either above/below threshold for simple detectors or via the opening angle for ring-imaging devices).
Energy depends on both velocity and mass, so if you have a reliable particle ID, then the velocity measurement from a Cerenkov device can be used to establish the energy to moderate precision.
Similarly if you know the momentum (say, from a spectrometer) and the velocity then you can deduce the energy.
With neither PID nor velocity a Cerenkov device does not measure energy.