A Cherenkov (Čerenkov) detector is a particle detector utilizing the mass-dependent threshold energy of Čherenkov radiation. This allows a discrimination between a lighter particle (which does radiate) and a heavier particle (which does not radiate).
It is a more advanced form of scintillation counter. A particle passing through a material at a velocity greater than that at which light can travel through the material emits light. This is similar to the production of a sonic boom when an aeroplane is traveling through the air greater than sound waves can move through the air. This light is emitted in a cone about the direction in which the particle is moving. The angle of the cone is a direct measure of the particle's given angle can reach a detector, so that the Čerenkov chamber becomes a device for selecting certain velocities of particle. Alternatively, if the momentum of the particle is known (from magnetic bending) the Čerenkov's information on the particle's velocity enables the mass to be deduced so that the particle can be identified.