Cherenkov detector
A Cherenkov (Черенко́в) detector is a particle detector using the speed threshold for light production, the speed-dependent light output or the velocity-dependent light direction of Cherenkov radiation.
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 airplane is traveling through the air faster than sound waves can move through the air. The direction this light is emitted is on a cone with angle θc about the direction in which the particle is moving, with cos(θc) = c/nv (c = the vacuum speed of light, n = the refractive index of the medium, and v is the speed of the particle). The angle of the cone θc thus is a direct measure of the particle's speed. The Frank–Tamm formula d2N/dωdx = z2α/csub2θc gives the number of photons produced.
Most Cherenkov detectors aim at recording the Cherenkov light produced by a primary charged particle. Some sensor technologies explicitly aim at Cherenkov light produced (also) by secondary particles, be it incoherent emission as occurring in an electromagnetic particle shower or by coherent emission, example Askaryan effect.
Cherenkov radiation is not only present in the range of visible light or UV light but also in any frequency range where the emission condition can be met i.e. in the radiofrequency range.
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