The Physics behind Cherenkov Radiation

            As stated earlier, Cherenkov Radiation is caused by a charged particle passing through a medium (which must be dielectric, or electrically polarizable) faster than the speed of light in that medium. When this occurs the traveling particle disrupts the electromagnetic field in that medium, which then causes the molecules in that medium to become electrically polarized. In an insulator, photons are emitted when the molecules drop back to their ground state. Normally these photons experience destructive interference and are more difficult to detect, however when the charged particle disrupting the medium passes through faster than the speed of light in that medium, the photons begin to constructively interfere, and intensify the observed effects of the radiation.



This diagram shows the path of the charged particle (red arrow), resulting Cherenkov Radiation (blue arrows), and how they are deflected.

Sean Lemley Physics 212X F05.