Word: cherenkov
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Died. Igor Tamm, 75, physicist and a leading libertarian within Soviet science; in Moscow. A critic of Kremlin attempts to police the scientific community, Tamm never joined the Communist Party. In 1958 he shared the Nobel Prize with two Soviet colleagues for discovering and explaining the "Cherenkov effect," the bluish glow that occurs when high-energy electrons pass through a transparent substance. Tamm's prominence among Russian theoretical physicists was based largely on his work blending quantum mechanics and Einstein's theory of relativity...
...research that led to the award began in 1934, when Cherenkov. then 30, noticed a bluish glow where gamma rays from radium were striking through water in a flask. The glow was exceedingly faint, and a less curious man might have put it aside as ordinary fluorescence, which is given off by many materials when struck by gamma rays. But Cherenkov's mysterious light proved to be strongly polarized, had a continuous (rainbow-like) spectrum, and was given off predominantly in the direction of the gamma rays...
...Cherenkov radiation remained a tantalizing mystery until three years later. Two other Soviet physicists, Ilya M. Frank and his senior, Igor Tamm (who studied at Edinburgh and speaks English with a Scottish burr), became interested, worked out a strange but correct theory. When gamma rays pass through water, they hit electrons, and the impact bumps the electrons up to high velocities. The electrons do not move faster than light in a vacuum (186,000 m.p.sec., the Einsteinian speed limit of the universe), but they do move faster than light in water, 140,000 m.p.sec. For exceeding the local speed limit...
This led to the development of an extremely important modern instrument: the Cherenkov counter. It is made of some transparent substance such as Lucite. When a proton, electron or other charged particle enters it at a speed that is greater than the speed of light in the material, Cherenkov radiation is given off. Its angle (like the angle of a ship's bow wave) depends on the speed of the particle. When the angle is measured by a photomultiplier tube, the speed of the particles can be determined...
...Cherenkov counters are now among the leading tools of physics. They fly high in rockets and Sputniks to measure the energy of cosmic rays. They keep watch in cyclotron laboratories. The Russians are now building a monster Cherenkov counter two stories high...