Ring-imaging Cherenkov detector

The ring-imaging Cherenkov, or RICH, detector is a device for identifying the type of an electrically charged subatomic particle of known momentum, that traverses a transparent refractive medium, by measurement of the presence and characteristics of the Cherenkov radiation emitted during that traversal. RICH detectors were first developed in the 1980s and are used in high energy elementary particle- , nuclear- and astro-physics experiments.

This article outlines the origins and principles of the RICH detector, with brief examples of its different forms in modern physics experiments.

The ring-imaging detection technique was first proposed by Jacques Séguinot and Tom Ypsilantis, working at CERN in 1977. Their research and development, of high precision single-photon detectors and related optics, lay the foundations for the design and construction of the first large-scale Particle Physics RICH detectors, at CERN's OMEGA facility and LEP (Large Electron–Positron Collider) DELPHI experiment.

A ring-imaging Cherenkov (RICH) detector allows the identification of electrically charged subatomic particle types through the detection of the Cherenkov radiation emitted (as photons) by the particle in traversing a medium with refractive index ${\displaystyle n}$ > 1. The identification is achieved by measurement of the angle of emission, ${\displaystyle \theta _{c}}$, of the Cherenkov radiation, which is related to the charged particle's velocity ${\displaystyle v}$ by

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