Igor Tamm and Ilya Frank explained the coherent radiation emitted when a charged particle outruns the phase velocity of light in a material. The Cherenkov radiation condition is for refractive index , without requiring a particle to exceed the vacuum speed of light. Their theory connected the observed optical emission with a definite speed threshold, making it useful for identifying fast particles.[ref]
Ilya Mikhailovich Frank: first FLNP JINR director, laureate of Nobel Prize by Joint Institute for Nuclear Research. 1937 joint theoretical explanation of the observed Vavilov–Cherenkov effect; modern threshold notation
A physicist.[ref]
https://www.nobelprize.org/prizes/physics/1958/tamm/biographical/. Independent professional profile
Portrait of Igor Tamm
. CBS press photograph, identifier ner18397; individual photographer unidentified; existing Commons crop. Commons PD-US-no-notice claim: US publication during 1931–1977 without notice. Other jurisdictions may retain protection., via Wikimedia Commons. Source. Articles by others on the same topic
Igor Tamm (1895–1971) was a notable Russian and Soviet physicist, best known for his work in the field of plasma physics and controlled thermonuclear fusion. He played a significant role in the development of magnetic confinement fusion devices, including the tokamak, which is a device designed to confine plasma using magnetic fields in order to achieve nuclear fusion. Tamm's contributions to science and technology helped lay the groundwork for future advancements in nuclear physics and energy generation.