Cherenkov radiation (pronunciation: /tʃɛrɛnˈkɔv/) is an electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium at a speed greater than the phase velocity of light in that medium. It is also known as the Vavilov–Cherenkov radiation (VCR) (named after Sergey Vavilov and Pavel Cherenkov). It is named after the Soviet scientist Pavel Cherenkov, the 1958 Nobel Prize winner who was the first to detect it experimentally. A theory of this effect was later developed within the framework of Einstein's special relativity theory by Igor Tamm and Ilya Frank, who also shared the Nobel Prize. Cherenkov radiation had been theoretically predicted by the English polymath Oliver Heaviside in papers published in 1888–89.
The characteristic blue glow of an underwater nuclear reactor is due to Cherenkov radiation.
