How it began
Pavel Cherenkov joined the Lebedev Physical Institute as a senior researcher in 1930. In 1934, while working under S. I. Vavilov, he observed blue light coming from a bottle of water subjected to radioactive bombardment. The Nobel organization describes the observation as a bluish light around a radioactive preparation placed in water. In 1937 Igor Tamm and Ilya Frank explained the phenomenon.
How it works
In certain media the speed of light is lower than in a vacuum, so particles can travel faster than light does there. A charged particle passing through the medium disturbs electrons along its path, and when these return to their positions they emit light. Normally nothing observable results, but when the particle moves faster than light in the medium a kind of backwash of light appears, comparable to the sonic boom of faster-than-sound motion. Most of the light falls in the blue, violet and ultraviolet range.
What changed first
The discovery was recognized first in the Soviet Union, where Cherenkov shared a Stalin Prize in 1946 with Vavilov, Frank and Tamm. In 1958 Cherenkov, Frank and Tamm shared the Nobel Prize in Physics for the discovery and interpretation of the effect. Cherenkov's Nobel lecture was devoted to radiation from particles moving faster than light and its possible uses in experimental physics.
What lasted
The Cherenkov detector, named for the effect, became a standard piece of equipment in particle physics research for observing the existence and velocity of high-speed particles. The blue glow is also the familiar light seen in water around reactor cores and stored nuclear fuel.
Where it stands today
Inspectors of the International Atomic Energy Agency use Cherenkov viewing devices to capture the light given off in ponds where spent reactor fuel is stored. By measuring it they can check whether the amount of spent fuel a state has declared is accurate and detect whether nuclear material has been diverted from peaceful use.
