cherenkov radiation, also known as vavilov–cherenkov radiation (; russian: черенков) is a type of electromagnetic radiation produced by charged particles when they pass through an optically transparent medium at a speed which is greater than the speed of light in that medium. (it doesn't violate special relativity because the refractive index slows down the speed of light in a medium. so, the particle doesn't have to travel at the speed of light in a vacuum.) it is named after pavel alekseyevich čerenkov, who discovered this phenomenon in 1934 under the supervision of sergey vavilov. igor tamm and ilya frank developed a theory on this effect in 1937. pavel čerenkov, igor tamm and ilya frank shared the 1958 nobel prize in physics because of their contribution in cherenkov radiation.