Evaluation of a microchannel photomultiplier and small-size phototubes for cerenkov counters

A high-energy charged particle of velocity βc radiates cerenkov light in any transparent gas of refractive index n, if nβ > 1, but this light is not emitted at random but precisely at an angle e with the trajectory given by the relation cos θ = l/nβ. A focusing Cerenkov counter is an optical system designed to extract from the position of the impacts of the Cerenkov photons on a photodetector plane, the velocity and direction of a single particle.