Cherenkov radiation

Cherenkov radiation is electromagnetic radiation emitted when a charged particle moves through a material faster than light’s phase velocity in that material. It forms a characteristic cone whose angle depends on the particle’s speed and the material’s refractive index.

Cherenkov angle: The angle between a particle’s direction and the wavefront of its Cherenkov radiation. Its value encodes particle speed and the material’s refractive index.
Ring-imaging Cherenkov detector: A particle-identification detector that measures the ring formed by Cherenkov photons. The ring radius estimates particle velocity for distinguishing particle species.
Pavel Cherenkov: A Soviet physicist who experimentally studied the blue light emitted by liquids exposed to radiation. His observations established the phenomenon that bears his name.
Bremsstrahlung: Electromagnetic radiation emitted when a charged particle is accelerated, often by deflection in a field. It comes from particle acceleration, unlike Cherenkov radiation’s passage through a medium above threshold.
Phase velocity: The speed at which a fixed phase of a wave propagates through space. Cherenkov radiation requires the particle to exceed this speed in the medium.
Frank–Tamm formula: A formula for the spectral energy emitted as Cherenkov radiation by a charged particle. It predicts how emission varies with wavelength, charge, speed, and refractive index.
Super-Kamiokande: A large underground water Cherenkov detector in Japan used to study neutrinos and cosmic rays. Charged particles from neutrino interactions produce detectable light in its water.
Sergei Vavilov: A Soviet physicist who directed the research in which Cherenkov radiation was identified. He recognized the light as a distinct physical effect and guided its investigation.
Synchrotron radiation: Radiation emitted by relativistic charged particles accelerated along curved paths by magnetic fields. It requires curved motion rather than superluminal motion relative to a material’s light phase velocity.
Charged particle: A particle with a nonzero electric charge that interacts electromagnetically. Its electric field polarizes the material and enables radiation when the threshold is crossed.

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