Frank, Ilia

Born Oct. 10 (23), 1908, in St. Petersburg. Soviet physicist. Academician of the Academy of Sciences of the USSR (1968; corresponding member, 1946).

In 1930, Frank graduated from Moscow State University. From 1930 to 1934 he worked at the State Optics Institute, and from 1934 to 1970, at the Institute of Physics of the Academy of Sciences of the USSR. He became a professor at Moscow State University in 1940. He founded the neutron physics laboratory at the Joint Institute for Nuclear Research and was the laboratory’s director from 1957. At the same time, beginning in 1971, he worked at the Institute for Nuclear Research.

Frank’s major works deal with physical optics and nuclear physics. While still a student, he investigated, under the direction of S. I. Vavilov, processes of the quenching of luminescence in liquids. He then turned to the study of photochemical reactions by optical methods. In 1937, with I. E. Tamm, he provided an explanation for Cherenkov-Vavilov radiation; for this work, he shared a Nobel Prize in 1958. With V. L. Ginzburg, Frank was the first to observe transient radiation. He developed the theory of the complex and anomalous Doppler effect in a refracting medium. With L. V. Groshev, he experimentally studied the generation of electron-positron pairs by gamma rays. Frank studied the propagation of neutrons in heterogeneous uranium-graphite systems. He devoted a series of studies to reactions on light nuclei, in which neutrons are emitted, and to the interactions of fast neutrons with nuclei. He also proposed and developed the pulse method for the study of neutron propagation and discovered the diffusion cooling of neutrons.

Frank received the State Prize of the USSR in 1946, 1954, and 1971. He has been awarded three Orders of Lenin, three other orders, and several medals.