Szilard, Leo

Szilard, Leo (1898-1964) American (Hrmgarian-born) physicist who played an important roie in the development of nuclear fission. In collaboration with Fermi, he constructed the first nuciear reactor, terminal carbon atoms In an organic moiecule, terminal carbon atoms are those located at the end of a carbon chain. 

Fermi and another European refugee, Leo Szilard, discussed the impact nuclear fission would have on physics and on the veiy unstable state of the world... 

Working first with Polanyi, Weissenberg, and Brill, and later as the leader of the Textile Chemistry Section, Mark successively published papers on the crystal structures of hexamethylenetetramine, pentaerythritol, zinc salts, tin, urea, tin salts, triphenylmethane, bismuth, graphite, sulfur, oxalic acid, acetaldehyde, ammonia, ethane, diborane, carbon dioxide, and some aluminum silicates. Each paper showed his and the laboratory s increasing sophistication in the technique of X-ray diffraction. Their work over the period broadened to include contributions to the theories of atomic and molecular structure and X-ray scattering theory. A number of his papers were particularly notable including his work with Polanyi on the structure of white tin ( 3, 4 ), E. Wigner on the structure of rhombic sulfur (5), and E. Pohland on the low temperature crystal structure of ammonia and carbon dioxide (6, 7). The Mark-Szilard effect, a classical component of X-ray physics, was a result of his collaboration with Leo Szilard (8). And his work with E. A. Hauser (9, 10, 11) on rubber and J. R. 

Work on the structure of crystals and fibers was not the only way in which Mark made use of x-rays. With several collaborators, he reported the results of a number of significant investigations of the physics of x-rays in 1926 and 1927. With Ehrenberg he reported studies of the index of refraction of x-rays, and with Leo Szilard studies verifying the linear polarization of x-rays scattered from electrons at 90. An investigation of the width of x-ray lines was carried out by Mark and Ehrenberg, and Mark and Kallmann reported work on the properties of Compton-scattered x-radiation and on the theory of the dispersion and scattering of x-rays. 

In 1934 the Hungarian physicist Leo Szilard filed a patent with the British Patent Office. It was based on an idea, nothing more - an idea about how to harness nuclear energy. The Joliot-Curies had shown that bombarding nuclei with particles can induce radioactive decay artificially. And the work of Bothe and Chadwick had demonstrated that some radioactive nuclei emit neutrons. So what would happen if neutrons induced nuclear decay that led to more neutrons The result might be a chain reaction a self-sustaining release of nuclear energy. 

Sep. 29, 1901, Rome, Italy - Nov. 28, 1954, Chicago, USA) Fermi studied at the University of Pisa, receiving his Ph.D. in 1922. Later he worked with - Max Born in Gottingen, Germany (1923) and Paul Ehrenfest in Leyden, Holland. In 1924 he returned to Italy occupying the position of lecturer in mathematical physics and mechanics at the University of Florence. He became professor of theoretical physics at the University of Rome in 1927 and professor of physics at Columbia University, USA (1939-1942). During the Second World War he participated in the Manhattan project. In 1939, Fermi and Leo Szilard (1898-1964) invented the nuclear reactor at Columbia University. They assembled the first full-scale pile , as Fermi dubbed it, and executed the first... 

Such flashes, inspirations if you like, do not happen while one is thinking in one s study or talking with a student. They turn up like a photograph in the mind at some odd time later (Leo Szilard, for example, got some of his best ideas while soaking in the bathtub). But they don t turn up at all unless one has thought a great deal about the matter. 

Lanouette, William, with Bela Szilard. Genius in the Shadows A Biography of Leo Szilard, the Man Behind the Bomb. New York Charles Scribner s Sons, 1992. 

Leo Szilard, Atomic Bombs and the Postwar Position of the United States in the World, memorandum for President Franklin D. Roosevelt, March 1945 reprinted in M. Grodzins and E. Rabinowitch, eds., The Atomic Age Scientists in National and World Affairs, Articles from the Bulletin of the Atomic Scientists 1945-1962 (Basic Books New York. 1963), pp. 13-14. 

Leo Szilard determined that the formation of neutrons occurs during the fission of uranium. This is crucial to sustaining a chain reaction necessary to build an atomic bomb, the first of which he helped to construct in 1942. Shortly thereafter, realizing the destructive power of the atom bomb, Szilard argued for an end to nuclear weapons research. 

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