VERNOV, SERGEI NIKOLAEVICH

(b. Sestroretsk, Russia, 11 July 1910; d. Moscow. U.S.S.R., 26 September 1982)

physics.

Vernov’s father, Nikolai Stepanovich, was a postal clerk, and his mother, Antonina Mikhailovna, taught mathematics at a secondary school.

In 1931 Vernov graduated from the Faculty of Physics and Mechanics of Leningrad Polytechnic Institute. He then began a fellowship at the Radium Institute in Leningrad; at the same time he was working in the Physico-Technical Institute. In 1936 Vernov defended his master’s thesis and began a doctoral fellowship at the P. N. Lebedev Physics Institute in Moscow. In 1939 he defended his doctoral dissertation and in 1944 he became a professor at Moscow University. In 1946 Vernov moved to the Scientific Research Institute of Nuclear Physics of Moscow University, where, from 1960 until his death, he served as a director (a position that was previously occupied by D. V. Skobeltsyn, one of his teachers).

Vernov’s first paper on cosmic rays appeared in 1934. It was followed by more than three hundred published papers, most of them written in collaboration with his pupils and colleagues, and all of them devoted to cosmic rays. He began his research at the aerological observatory in Pavlovsk (near Leningrad). In order to reduce the influence of atmosphere on the observations of cosmic rays, Vernov, following A. L. Wegener and others, suggested conducting investigations beyond the atmosphere: he used radiosondes (earlier used by P. A. Molchanov for meteorological measurements) for his research in the stratosphere. In the spring of 1935 Vernov carried out his first experiments with spherical sondes filled with hydrogen, which carried the measuring equipment over eight miles (thirteen kilometers) high; the measurements were transmitted and received throughout the flight.

In later investigations in Armenia, an altitude of almost fourteen miles (twenty-two kilometers) was reached. In the late 1930’s, somewhat later than similar work by R. A. Millikan and A. H. Compton, Vernov investigated the dependence of the flux of cosmic rays in the stratosphere on the latitude. His experiments with radiosondes launched at various latitudes showed that about 90 percent of the initial component of cosmic radiation consists of the charged particles whose energy spectrum Vernov had been measuring. Vernov (and, independently, Marcel Schein) suggested that these particles are protons.

During World War II, Vernov was involved in defense research and did not publish any work. Immediately after the war, however, his research work on cosmic rays was renewed. With the aid of complex equipment, Vernov examined the eastwest asymmetry of cosmic ray flux and confirmed that the primary component consists of protons. In the late 1940’s Vernov and his colleagues carried out important experiments on geophysical rockets, and in the 1950’s they started investigations on space rockets. In 1958 Vernov, together with A. E. Chudakov, N. V. Pushkov, and S. Sh. Dolginov, discovered the earth’s outer radiation belt at the altitude of about 12,500–37,500 miles (about 20,000–60,000 kilometers) from the center of the earth. (The inner radiation belt at an altitude of about 625 miles [ 1,000 kilometers] was discovered by Van Allen in the same year.) The measurements were made on the Electron and Cosmos satellites, and the results were confirmed by American investigators. Vernov suggested that the earth’s magnetic trap captures the electrons generated in the course of neutron decay during nuclear reactions caused by cosmic rays in the atmosphere; he and his colleagues investigated the energy spectrum of these electrons.

In the late 1950’s Vernov and his collaborators built apparatus for investigation of cosmic-ray particles of ultrahigh energy (up to 10¹⁷ eV); a break in the spectrum was discovered at energies of 10¹⁵ eV on their spectral intensity graph. According to Vernov this point is associated with the transition from the cosmic particles originating in our galaxy to the most energetic particles coming from the metagalaxy. On Vernov’s initiative a group of observatories was created in the Soviet Union to continuously register cosmic radiation. He also established a correlation between the intensity of cosmic radiation and the eleven and twenty-two-year cycles of solar activity.

In 1970 Vernov and his colleagues built a detector (20 sq km in area) to investigate extended atmospheric showers; they also examined particles whose energies reached 10²⁰ eV.

Vernov initiated research on radiation safety during manned space flights. He also planned and carried out the first experiments on cosmic material technology in space.

Vernov was active in the U.S.S.R. Academy of Sciences, which elected him a corresponding member in 1953 and a full member in 1968. He served as a deputy secretary of the Division of Nuclear Physics of the Academy of Sciences and head of the council on cosmic rays. In 1949 he was awarded the State Prize and in 1960, the Lenin Prize. He also received the title Hero of Socialist Labor.

BIBLIOGRAPHY

I. Original Works. “On the Study of Cosmic Rays at Great Altitudes,” in Physical Review, 46 (1934), 822; “Radio-transmission of Cosmic Ray Data from the Stratosphere”, in Nature, 135 (1935), 1072–1073; “Analysis of the Latitude Effect of Cosmic Rays in the Stratosphere,” in Doklady Akademii nauk SSSR, n.s. 23 (1939), 140–142; “Opredeteniye znaka zaryada pervichnikh chastic kosmicheskikh luchei po izmereniyam azimutalnoi assimetrii v stratosphere v raiyone ekvatora” (Determination of the cosmic ray particles), ibid., n.s. 68 (1949), 253–255, written with N. A. Dobrotin el al.; “The Study of Primary Cosmic Radiation with the Aid of Satellites,” in “Proceedings of the Eighth International Astronautical Congress, Barcelona,” 1957 (1958), written with V. L. Ginzburg et al.; “Investigations of Cosmic Radiation and of the Terrestrial Corpuscular Radiation by Means of Rockets and Satellites,” in Soviet Physics Uspekhi, 3 (1960), 230–250, written with A. E. Chudakov; “Earth’s Radiation Belt,” in Proceedings of the Ninth International Conference on Cosmic Rays, London, 1965, I (London, 1966), 40–49, written with E. V. Gortchakov et at.; Radiycionniye poaysa zemli i kosmicheskiye luchi (Earth’s radiation belts and cosmic rays; Moscow, 1970), written with N. V. Vakulov et al.

II. Secondary Literature. N. L. Grigorov et al, “Sergei Nikolaevich Vernov (on His Seventieth Birthday),” in Soviet Physics Uspekhi, 23 (1980), 426–428; Spisok pechatnikh rabot akad. S. N. Vernova (List of S. N. Vernov’s papers; Moscow, 1980).

V. J. Frenkel