Pavel Alekseevich Cherenkov

28.07.1904 – 06.01.1990

Scientific biography

The 28th of July 2004 is the centennial anniversary of the birth of an outstanding experimental physicist Academician Pavel Alekseevich Cherenkov.

Pavel Alekseevich was born in the village of Novaya Chigla, Bobrovsk district of the Voronezh province (now the Talowskii district of the Voronezh region). He got his primary and secondary education in that village. In 1928, he graduated from the Department of Physics and Mathematics of the Voronezh State University.

P.A. Cherenkov's scientific activity began in the year of 1932 when he was a post-graduate student in the Physics and Mathematics Institute of the Academy of Sciences of the USSR. Initiated by his supervisor, S.I. Vavilov, he started to investigate the luminescence of uranil salt solutions under action of gamma-rays. In 1934, the Institute was split into Mathematical and Physical Institutes. Since then, Pavel Alekseevich became a post-graduate student and, later on, a permanent employee in the P.N. Lebedev Physical Institute (LPI) of the Academy of Sciences of the USSR.

Making his PhD research, Pavel Alekseevich discovered a new, surprisingly beautiful physical phenomenon. He found that a weak visible radiation emerges from clean optically-transparent liquids under the action of gamma-ray emitted by radium: a kind of radiation which is clearly different from the usual luminescence. In a series of simple (from the modern point of view), though labour-consuming, experiments based on the threshold-of-vision method (this method was developed by S.I. Vavilov and E.M. Brumberg), Pavel Alekseevich revealed and investigated fundamental properties of the newly discovered radiation. Carrying out these experiments, Pavel Alekseevich vividly demonstrated the best features of his character - the enthusiasm, extraordinary persistence, ability to find out simple solutions to arising problems, the care of fine experimental details.

Already in the first experiments, a number of properties of the radiation has been reliably established: polarisation, insensitivity to quenching factors, rising intensity of the radiation spectrum with the descrease of the wave length. These findings enabled S.I. Vavilov to conclude in 1934 that this new kind of radiation is somehow connected with electrons produced in transparent liquids in the process of Compton scattering of gamma-rays.

In a new series of experiments the influence of the magnetic field on the radiation properties (such as polarisation) was examined. Pavel Alekseevich has proved that the radiation is indeed caused by the secondary Compton electrons rather than by primordial gamma rays. Also discovered in this series of experiments was the most important property of the new radiation - the fact that it is emitted in the direction of the Compton electrons.

The latter property turned out to be the key point for understanding the nature of the new phenomenon. The theory that successfully and completely explained all the observed regularities was developed in 1937 by I.M. Frank and I.E. Tamm on the basis of the classical electrodynamics. They have shown that the radiation observed by P.A. Cherenkov is caused by charged particles passing through a transparent medium with a constant speed greater than the speed of light in that medium.

A series of additional experiments carried out by P.A. Cherenkov in 1936-1937 confirmed the Frank-Tamm theory at a precise quantitative level. The characteristic property, the radiation opening angle was measured in these new experiments, and the connection between the opening angle and the refraction index of the medium was established. Later on, the shape of the radiation energy spectrum and the absolute radiation intensity was measured with good accuracy.

By a figuratively colloquialism of Academician G.S. Landsberg, the classical P.A.Cherenkov's researches are "an ornament of physics in the USSR". Further development of the theory of Cherenkov radiation is connected with names of I.E. Tamm, I.M. Frank and some other physicists. In particular, V.L. Ginzburg has developed the quantum theory of this radiation. (Many russian physicists call this effect the Vavilov-Cherenkov radiation).

Detailed quantitative investigations of properties of the radiation and understanding of its nature have allowed to Pavel Alekseevich to put forward in 1937 an idea of possible application of the new effect for determination of charge particle velocities. This idea became a basis for future creation of RICH (Ring Imaging Cherenkov) counters and spectrometers. It is now not possible to think of experimental high-energy physics without such devices. Application of Cherenkov detectors in the science has achieved such a scale that one can state being not afraid of making a mistake that P.A. Cherenkov is now one of the most quoted physicists in the world. In 1946, S.I. Vavilov, P.A. Cherenkov, I.M. Frank and I.E. Tamm have been awarded with the USSR First-Degree State Prize for discovery, investigation and explanation of a new kind of radiation. Later, in 1958, the Nobel Prize in physics has been awarded to Pavel Alekseevich Cherenkov, Ilya Mihajlovich Frank and Igor Evgenjevich Tamm "for discovery and interpretation of the Cherenkov effect".

During the Great Patriotic War (1941-45) Pavel Alekseevich was engaged into development of a defensive device based on using nuclear physics methods.

Next years, P.A. Cherenkov's scientific interests have been connected with a research of cosmic rays. One of results of that research was a discovery of multicharged ions in the secondary component cosmic radiation.

Since 1946, Pavel Alekseevich participated in the development and construction of first synchrotrons in the V.I. Veksler laboratory.

Together with a group of collaborators, Pavel Alekseevich has been awarded with the USSR Second-Degree State Prize for participation in the creation of the 250 MeV electron synchrotron of Lebedev Physical Institute. In the following, P.A. Cherenkov has headed works connected with improvements of main nodes of the synchrotron. As a result, a modern experimental base has been created in the Soviet Union for experimental investigations of electromagnetic interactions at medium energies.

Since 1959 Pavel Alekseevich was a director of the LPI laboratory of photomesonic processes. Investigations of electromagnetic interactions of elementary particles became the main scientific direction of the laboratory. A number of fundamental researches of the photon-nucleon interaction has been fulfilled. Also, photodisintegration of lightest nuclei at energies up to 250 MeV was also studied in detail.

Aspiring to upgrade experimental base of the laboratory, Pavel Alekseevich has headed works on design and creation a new scientific complex of LPI including a more powerful synchrotron of the energy 1.2 GeV in Troitsk, near Moscow.

The first physical results have been obtained at this synchrotron at the end of 70th. In particular, the ondulator radiation from an orbit of a cyclic electron accelerator has been experimentally investigated for the first time.

The Cherenkov laboratory carried out researches on electromagneti processes at the accelerators of FNAL, CERN, DESY, IHEP, JINR. An important step in carrying out the researches was, in particular, a creation of the electronic beam at the Serpukhov proton accelerator in collaboration with IHEP and Yerevan Physics Institute in 1970.

For Pavel Alekseevich, as well as for the majority of great scientists, it was typical the aspiration to maintain a constant creative dialogue with scientific youth. In 1948-1977, he was a professor in the Moscow Energy Institute and Moscow Physics and Engineering Institute. The group headed by P.A.Cherenkov is well known in the world scientific community.

The Nobel Prize winner Academician Pavel Alekseevich Cherenkov was a member of the US National Academy of Sciences. He participated in Pugwash Conferences on Science and World Affairs. He had the honorary rank of the Hero of Socialist Work of the USSR, the Order of Honour. He has been awarded with three Orders of Lenin, two Orders of the Red Banner, Medals of the USSR. P.A. Cherenkov's high merits have been awarded by foreign countries too.

Pavel Alekseevich Cherenkov died on January 6, 1990. He rests on the Novodevichie cemetery of Moscow.