Leipunskii, Aleksandr Il’ich

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LEIPUNSKII, ALEKSANDR IL’ICH

(b. Dragli, Grodnenskaia guberniia, Russia [now Poland], 7 December 1903; d. Obninsk, Kaluzhskaia Oblast, U.S.S.R., 14 August 1972)

physics.

Leipunskii’s father, Il’ia Isaakovich Leipunskii, was a construction and road technician: his mother, Sophia Naumovna, was a housewife.

Leipunskii started working in 1918; before he entered the Petrograd Polytechnical Institute (1921) he had served as an unskilled laborer and as a foreman’s assistant at a chemical factory in Rybinsk (now Andropoy). He graduated from the Faculty of Physics and Mechanics at the Petrograd Polytechnical Institute (PTI) in 1926. When he was still a student, he started work at the PTI in the laboratory of N. N. Semenov (1924–1928). After a year of preparation, Leipunskii moved to the Ukrainian PTI in Kharkov, where he worked from 1929 to 1941 (with two interruptions when he was at the Cavendish Laboratory, Cambridge [1934–1935], and in Leningrad as head of a department at the Radium Institute). At the Ukrainian PTI, Leipunskii advanced from senior physicist to director. From 1941 to 1952 he was head of the department of physics, deputy director, and director of the Institute of Physics of the Ukrainian Academy of Sciences (Kiev). In 1952 he moved to the Institute of Energy Physics in Obninsk and from 1959 to 1972 was its scientific head.

At the Leningrad PTI, Leipunskii was involved with chemical physics and electronic chemistry. The main results are concerned with the experimental investigation of nonelastic collisions when the excited atoms (molecules) transfer their energy to slow electrons by the radiation-free mechanism; this reaction is inverse to that of excitation of atoms by electrons due to elastic collisions. With G. D. Latishev, Leipunskii conducted a classical experiment that demonstrated the existence of such processes for excited atoms of mercury. He also investigated dissociation and recombination of halogen molecules and the formation of the negative ions.

After moving to Kharkov, Leipunskii shifted his attention to nuclear physics and worked on the design of linear (and in the late 1930’s cyclic) accelerators. With his colleagues he carried out an experiment on splitting the nuclei of lithium by artificially accelerated protons (this experiment, the first of its kind in the Soviet Union, was a modification of a classical experiment by J. D. Cockroft and E. T. S. Walton). In a series of experiments on absorption of neutrons within a wide temperature range (20–463 K), Leipunskii was the first to discover the resonance effects on light nuclei during neutron scattering.

While at the Cavendish Laboratory in Cambridge (1934–1935), directed by Rutherford, Leipunskii carried out important research on β-decay and on the physics of the neutrino. He developed the experimental technique for demonstrating the existence of the neutrino that was based on the investigation of energy distribution of recoil nuclei of the C 11 isotope released in the course of β-decay associated with the “flight” of a neutrino. This experiment (realized in part) may be thought of as a prototype of the research carried out in 1938 at A. I. Alikhanov’s laboratory at the Leningrad PTI and of the decisive result achieved by James Allen in 1942 in his investigation of an energy spectrum of recoil nuclei arising from the decay of Be 7.

Leipunskii devoted the last twenty-five years of his life to the development of reactor engineering. In 1947, during his study of nuclear processes involving fast neutrons, Leipunskii developed the idea of breeding the nuclear fuel in fast-neutron reactors following the formation of plutonium from U 238. In 1949 he started working on the practical realization of this idea. At the Institute of Energy Physics in Obninsk, he developed the procedure of designing breeder fast-neutron reactors, having solved many problems associated not only with the nuclear processes but also with some purely engineering problems, particularly the choice of a heat-transfer fluid, for which he suggested using liquid metals (sodium).

As a result of these efforts, the first fast-neutron reactor in the Soviet Union started operating in 1955. By the end of the 1950’s, the possibility of breeding the nuclear fuel and the reliability of the reactors’ design had been demonstrated by experiments on their laboratory prototypes, built by Leipunskii’s group. In 1959 the 5,000-kw fast-neutron reactor went into operation, and work had started on design and construction of an industrial power station with fast-neutron reactors, its electrical power being equal to 350,000 kw. The station and reactor, located at Shevchenko, on the coast of the Caspian Sea, would solve three problems at once: production of nuclear fuel, production of electric energy, and distillation of water (the last saving power). The importance of this plant increased with time because the fast-neutron breeders solved the problem of supply of a nuclear fuel.

Leipunskii’s achievements are not limited to those already mentioned. He was chief editor of the journal Physikalische Zeitschrift der Sowjetunion, which was published in the Soviet Union from 1932 to 1937 and received international recognition. He also was among the founders of the Moscow Institute of Engineering Physics, where he taught and served as head of a department.

In 1924 Leipunskii was elected a full member of the Ukrainian Academy of Sciences. In 1960 he and his colleagues O. D. Kasachkovskii, I. I. Bondarenko, and L. N. Usachev were awarded the Lenin Prize for their work on fast-neutron reactor physics. In 1963 Leipunskii was awarded the title of Hero of Socialist Labor.

BIBLIOGRAPHY

I. Original Works. “Stösse zweiter Art zwischen Elektronen und angeregten Molekülen,” in Zeitschrift für physik, 58 (1929), 104–128, written with E. Strauff: “Dissoziation durch Stoss positiver lonen,” ibid., 59 (1929), 857–863, written with A. Schechter: “The Disintegration of Lithium by High Velocity Protons,” in PhysikalischeZeitschrift der Sowjetunion, 2 , no. 3 (1932), 285 written with G. D. Latyshev. K. D. Sinelnikov, and A. K. Walter: “Slowing Down of Neutrons in Liquid Hydrogen.” ibid., 9 , no. 6 (1936), 696–698, written with V. Fomin, F. G. Houtermans, and L. V. Schubnikov; “Determination of the Energy Distribution of Recoil Atoms During β Decay and the Existence of the Neutrino,” in Proceedings of the Cambridge Philosophical Society, 32 (1936), 301–302; “Issledovanie po fizike reaktorov na bystrykh neitronakh” (Investigation of physics of fast-neutron reactors), in Atomnaia energiia, 5 , no. 3 (1959), 277–293; “Budushchee bystrykh reactorov” (The future of fast reactors), ibid., 11 , no. 4 (1961), 370–378, written with O. D. Kasachkovskii and M. S. Pinkhasik;“Bystrye reactory BN-350 I BOR” (Fast reactors BN-350 and BOR), ibid., 21 , no. 1 (1966), 450–462, written with 17 co-authors; “Razvitie iadernoi energetiki v SSSR s reaktoramai na bystrykh neitronakh” (Development in the U.S.S.R. of reactor energetics with fast-neutron reactors). ibid25 , no. 5 (1968), 380–387; and “Opit pusko–naladochnikh rabot i energo–pusk rektora BN-350” (Experience of starting and adjustment, and the beginning of energy supply of reactor BN-350), ibid., 36 , no. 2 (1974), 91–97, written with 21 coauthors.

II. Secondary Literature. A. P. Alexandrov, I. K. Kikoin, and Iu. B. Chariton, “Pamiati Aleksandra Il’icha Leipunskogo” (In memory of Aleksandr ll’ich Leipunskii) in Atomnaia energiia, 35 , no. 4 (1973), paste–in page; and O. D. Kasachkovskii, “A. I. Leipunskii i razvitie atomnoi nauki i tekhniki v SSSR” (A. I. Leipunskii and the development of atomic science and technology in the U.S.S.R.), in Ukrainskii fizicheskii zhurnal, 24 , no. 3 (1979), 420–422.

V. J. Frenkel