Cherenkov detector

The general term Cherenkov detector is among those used to indicate an instrument or set of instruments to detect relativistic particles (such as energetic cosmic rays) through the Cherenkov radiation they produce, in some cases, doing this as a means of detecting high-energy photons (e.g., a Cherenkov gamma-ray telescope) that produce such relativistic particles through interactions such as pair production.

Such a detector used for astronomical purposes may be specifically termed a Cherenkov telescope implying imaging ability, e.g., an IACT for imaging atmospheric Cherenkov telescope, specifically using Earth's atmosphere to generate the Cherenkov radiation. Generation of particles from photons and photons from particles can happen repeatedly through a downward cone-shaped volume of the medium, each time with lower energies, the whole process termed an air shower when it occurs in the atmosphere. Detectors on the ground that can sense either photons or particles or both can pick up enough information to work out something about the originating photon or particle. The ground detectors may be somewhat-ordinary telescopes for some spectral band.

Cherenkov detectors can also consist of a tank or tanks of some fluid chosen for its practical ability to produce detectable Cherenkov radiation (in some cases, water), surrounded by sensors such as photomultiplier tubes. Natural bodies of water have also been used.

From the theory of Cherenkov radiation production, data from a number of such sensors, including timing, yields information regarding characteristics of the photon or particle that triggered it. Examples of Cherenkov telescopes:

• High-altitude Water Cherenkov Observatory (HAWC).
• High Energy Stereoscopic System (HESS).
• FACT (for First G-APD Cherenkov Telescope, at the Roque de los Muchachos Observatory (ORM)).
• MAGIC (for Major Atmospheric Gamma Imaging Cherenkov Telescopes, at the ORM).
• VERITAS (for Very Energetic Radiation Imaging Telescope Array System, at Fred Lawrence Whipple Observatory (FLWO)).
• Cherenkov Telescope Array (CTA) (under construction).
• Milagro (past).

Also using Cherenkov radiation are detectors of other particles, such as the neutrino detector, IceCube, which detects the radiation produced in a large volume of ice.