- Person
- Ilya Frank
- Lived
- 1908–1990
- Field
- Physics
- From
- Soviet
The story
Ilya Frank was born in St Petersburg in 1908; his father, the mathematician Mikhail Frank, came from a Jewish family. Trained in optics under Sergei Vavilov, Frank was working at the Lebedev Physical Institute in Moscow when Vavilov’s student Pavel Cherenkov found something strange. Liquids exposed to gamma rays from radium gave off a faint blue light that appeared even in pure water, was not dimmed by chemicals that quench ordinary luminescence, and shone mainly in one direction.
In 1937 Frank and the theorist Igor Tamm explained it. A charged particle, such as an electron knocked loose by a gamma ray, can move through water or glass faster than light travels in that material, because light slows down inside it. When that happens the particle leaves behind a cone of light, an optical counterpart of the sonic boom made by a supersonic jet. Frank and Tamm showed that the angle of the cone depends on the particle’s speed and calculated the energy it radiates, a result still called the Frank–Tamm formula.
That explanation turned a curiosity into one of the most useful signals in physics. Because the light reveals a particle’s speed, Cherenkov counters and ring-imaging detectors are used to identify particles at accelerators, including the ALICE experiment at CERN. Huge tanks of water or ice, such as Super-Kamiokande in Japan, the Sudbury Neutrino Observatory in Canada and IceCube at the South Pole, catch neutrinos by recording the Cherenkov flashes of the particles they produce. Telescopes such as VERITAS, H.E.S.S. and MAGIC detect very high energy gamma rays from space through the flashes they create in the atmosphere.
The effect is also the blue glow seen in the water around nuclear reactor cores, and inspectors use it to verify spent fuel for nuclear safeguards. Biologists use it to detect tiny amounts of radioactively labelled molecules, and medical researchers use it to image radioactive tracers in the body and to see, in real time, the shape of a radiotherapy beam on a patient’s skin. Frank shared the 1958 Nobel Prize in Physics with Cherenkov and Tamm, and went on to found the neutron physics laboratory at Dubna that now bears his name.
Why it matters
Cherenkov light, as Frank and Tamm explained it, lets scientists identify particles, detect neutrinos and cosmic gamma rays, check nuclear fuel and image radiation in medicine.
About Ilya Frank
Soviet physicist who, with Igor Tamm, explained the blue Cherenkov glow, now used to identify particles, catch neutrinos, watch for gamma rays from space and image radiation in medicine.
Sources
- Cherenkov radiation Wikipedia
- Il´ja M. Frank, Biographical NobelPrize.org
- I. M. Frank Frank Laboratory of Neutron Physics, JINR
- Ilya Frank Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.