A Cherenkov detector (pronunciation: /tʃɛrɛnˈkɔv/; Russian: Черенко́в) is a

particle detector In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify ionizing particles, such as those produced by nuc ...

using the speed threshold for light production, the speed-dependent light output or the speed-dependent light direction of Cherenkov radiation.

Fundamental

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 A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to t ...

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 θ_c about the direction in which the particle is moving, with cos(θ_c) = (c = the vacuum

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit ...

, n = the

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

of the medium, and v is the speed of the particle). The angle of the cone θ_c thus is a direct measure of the particle's speed. The

Frank–Tamm formula The Frank–Tamm formula yields the amount of Cherenkov radiation emitted on a given frequency as a charged particle moves through a medium at superluminal velocity. It is named for Russian physicists Ilya Frank and Igor Tamm who developed the theo ...

= sin²θ_c gives the number of photons produced.

Aspects

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 In particle physics, a shower is a cascade of secondary particles produced as the result of a high-energy particle interacting with dense matter. The incoming particle interacts, producing multiple new particles with lesser energy; each of these t ...

or by coherent emission, example

Askaryan effect The Askaryan radiation also known as Askaryan effect is the phenomenon whereby a particle traveling faster than the phase velocity of light in a dense dielectric (such as salt, ice or the lunar regolith) produces a shower of secondary charged par ...

. 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. Different levels of information can be used. A binary information can be based on the absence or presence of detected Cherenkov radiation. The amount or the direction of Cherenkov light can be used. In contrast to a

scintillation counter A scintillation counter is an instrument for detecting and measuring ionizing radiation by using the excitation effect of incident radiation on a scintillating material, and detecting the resultant light pulses. It consists of a scintillator w ...

the light production is instantaneous.

Detector types

In the simple case of a threshold detector the mass-dependent threshold energy allows the discrimination between a lighter particle (which does radiate) and a heavier particle (which does not radiate) of the same energy or momentum. Several threshold stages can be combined to extend the covered energy range. Cherenkov threshold detectors have been used for fast timing and

time of flight Time of flight (ToF) is the measurement of the time taken by an object, particle or wave (be it acoustic, electromagnetic, etc.) to travel a distance through a medium. This information can then be used to measure velocity or path length, or as a w ...

measurements in particle detectors. More elaborate designs use the amount of light produced. Recording light from both primary and secondary particles, for a Cherenkov calorimeter the total light yield is proportional to the incident particle energy. Using the light direction are differential Cherenkov detectors. Recording individual Cherenkov photon locations on a position-sensitive sensor area,

RICH Rich may refer to: Common uses * Rich, an entity possessing wealth * Rich, an intense flavor, color, sound, texture, or feeling ** Rich (wine), a descriptor in wine tasting Places United States * Rich, Mississippi, an unincorporated commun ...

detectors then reconstruct Cherenkov angles from the recorded patterns. As RICH detectors hence provide information on the particle velocity, if the momentum of the particle is also known (from magnetic bending), combining these two informations enables the particle mass to be deduced so that the particle type can be identified.

Fundamental

Aspects

Detector types

See also