Cherenkov detector
{{Short description|Particle detector for Cherenkov radiation}}
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A Cherenkov detector (pronunciation: /tʃɛrɛnˈkɔv/; Russian: Черенко́в) is a type particle detector designed to detect and identify particles by the Cherenkov Radiation produced when a charged particle travels through the medium of the detector.
Fundamental
{{See also|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) = {{frac2|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 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 or by coherent emission, for 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.
Different levels of information can be used. 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 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 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.
Examples
Cherenkov detectors are primarily used in Particle Physics experiments:
=LHCb=
The LHCb experiment at CERN employs the RICH detector. As a charged particle travels through the medium of the detector (C4F10 for RICH-1 and CF4 for RICH-4) it emits Cherenkov radiation in a ring pattern. Photon detectors are then used to detect the Cherenkov photons and by measuring the angle at which the Cherenkov photons are produced the velocity of the particle is determined. This can then be used along with information obtained from other parts of the detector (e.g. momentum and charge of the particle) to identify the particle type.{{cite web |author= |title= RICH detectors |url= https://lhcb-outreach.web.cern.ch/detector/rich-detectors/
|website= CERN|location= |publisher= |access-date= June 5, 2025 |language = | date =}}
=Super-Kamiokande=
File:Superkamiokande electron muon discriminator.png while the ring on the right is much cleaner meaning it has been produced by a muon.]]
The Super-Kamiokande detector in Japan is Cherenkov detector used to detect neutrinos. It consists of 50,220 tonnes of ultrapure water which is used as the medium. As neutrinos pass through the water they have a small chance to interact with the electrons or nuclei in the water, producing either an electron or a muon. These are highly energetic and produce a cone of Cherenkov radiation as they travel through the water. The Cherenkov light is detected as a circular feature by the photomultiplier tubes placed around the detector and it is possible to distinguish between muons and electrons by the fuzziness of the rings. Muons are weakly interacting particles and can travel through the detector un-impeded, producing sharp rings, while electrons will scatter in the water producing rings that are much more fuzzy.{{cite journal
| last = M. Shiozawa (On behalf of Super-Kamiokande collaboration)| first = | author-link = | title = Reconstruction algorithms in the Super-Kamiokande large water Cherenkov detector| journal = Nuclear Instruments and Methods in Physics Research A| volume = 433| issue = 1-2| pages = 240-246| publisher = Elsevier| location = | date = August 21, 1999| language = | url = https://www.sciencedirect.com/science/article/abs/pii/S0168900299003599| doi = 10.1016/S0168-9002(99)00359-9| access-date = }}
See also
References
{{DEFAULTSORT:Cherenkov Detector}}
=Further reading=
{{refbegin}}
- {{cite web | url = https://lhcb.web.cern.ch/_archives/rich/richtdr/tdr.pdf | title = LHCb RICH Technical Design Report | website = CERN | access-date = 6 June 2025 | language = | quote =}}
- {{cite web | url = https://arxiv.org/pdf/1805.04163 | title = Hyper-Kamiokande Design Report | website = arXiv | access-date = 6 June 2025 | language = | quote =}}
{{Refend}}