Fitch (Fitch), Val AL( American physicist, Nobel Prize in Physics, 1980)
Comments for Fitch (Fitch), Val AL
Biography Fitch (Fitch), Val AL
genus. March 10, 1923
American physicist Val Logsdon Fitch, the youngest of three children, Francis M. (Logsdon), Fitch and Fred B. Fitch, was born on the cattle ranch in Cherry County (Nebraska), near the border in South Dakota. When F. was still a child, his father, rode a horse, was badly damaged and the family had to move to the neighboring g. Gordon, where the head of the family engaged in insurance.
After completing secondary school F. was mobilized into the army and in 1943. was sent as part of a special engineering unit at Los Alamos (New Mexico) for the work under the Manhattan Project, the secret program of building an atomic bomb. The designated laboratory in the group, led by the British physicist Ernest Titterton of the British mission to Los Alamos, F. acquainted with such eminent physicists like Enrico Fermi, Isaac Rabi, Robert Oppenheimer, Niels Bohr, James Chadwick and R.CH. Tolman. Their professional and personal qualities made him an indelible impression. Subsequently F. remembered that this was when he learned to 'not be used for measurements of an existing device, and surrender to the free flow of ideas and try to invent a way to solve the problem in a new way'. F. witnessed the first atomic explosion in the desert of New Mexico, where his team paved the cable, which was referred to the signal of a bomb blast.
F. discharged in 1946, and in 1948. received a bachelor of science degree in electrical engineering from McGill University (Montreal) and enrolled in graduate school at Columbia University in New York under the leadership of James Rainwater F. prepared a dissertation on the mesic atoms. Theme dissertation prompted him Aage Bohr, who was then a neighbor of James Rainwater in the cabinet. In mesic atoms instead of the normal electrons in orbits are mu-mesons - particles, initially discovered in cosmic rays. Mu-mesons in all electrons are identical, except that they are about 200 times heavier than their. As calculations show, the excess weight increases the differences between closely spaced energy levels and thereby influence the spectrum of radiation emitted by the atom. Learning from last year in graduate school, F. began teaching physics at the same university. Doctoral dissertation he defended in 1954. Then F. worked as a teacher of physics at Princeton University, where in 1960. became a full professor and in 1976. was appointed dean of the faculty.
In 1963, Mr.. F. and James I. Cronin, along with James Christenson (student Cronin) and a physicist at the French Center for Nuclear Research, RenцL Thurloe performed an experiment at Brookhaven National Laboratory on Long Island (New York) for the study of neutral K-mesons (kaons),
. Kaons are known for their strange properties - unstable particle with mass equal to about half the mass of the proton - are formed in the collisions of nuclei with high energy. Previously, they were described in the work of Lee and Yang Tszundao Chzhenina (1956) as an unusual particle in the so-called 'weak' reactions, which can break down one of the three fundamental symmetries and conservation laws. These symmetries have special designations C, P and T. Preservation of C (charge conjugation) means that the reaction should occur equally, if the particles are replaced by antiparticles (particles-twins, but with opposite electric charge), such as protons, electrons and positrons, antiprotons. Save P (parity) means that the reaction should occur the same, if geometrical characteristics of the particles change their mirror images, such as left-right, clockwise rotation - counterclockwise rotation. Preservation of T (symmetry under time reversal) indicates that the direct reaction proceeds as the reverse.
. Lee and Yang proposed an experiment to test their theoretical assumptions, . By a Tszinsyan and her staff of Columbia University found, . that parity is conserved in beta decay (electron emission) of radioactive nuclei are not strictly, . but only approximately nucleus emits predominantly 'left-' electrons,
. Other experiments showed that C remains too inaccurate some of the reaction between the particles are more likely than the reaction between antiparticles. Theoretical difficulties have been overcome after, . as it was suggested that, . that must be preserved combined parity CP; violation of charge conjugation C must be compensated by a simultaneous violation of parity P, . Just as in algebra the product of two positive numbers is positive, . If both factors simultaneously to negative,
. Since the full symmetry of CPT conservation is supported by general principles, and the parity of CP at the time was considered invariant, should be preserved and the symmetry under time reversal T. Violation of the symmetry of T could not be offset by a very unlikely symmetry breaking Wed
In 1955, Mr.. Murray Gell-Mann and Abraham Pais suggested, . the beam of kaons consist of combinations of particle antiparticle, . manifested in the experimental observations of how two different electrically neutral kaon KS0 (S short-lived) and KL0 (L-lived),
. Lifetime KL0 is only about one ten millionth of a second, but this value is approximately 500 times greater than the lifetime of the kaon KS0. Save the combined symmetry Wed allows kaon decay KS0 two pi-meson (pion) one - the other positively charged, negatively charged (pions associated with strong interaction, ensuring the integrity of the nucleus). However, this decay is forbidden for kaon KL0, which can only decay into three pions positively charged, negatively charged and neutral. The theoretical position was confirmed in 1956, when it was experimentally proved KL0 kaon decay into three pions. Two types of kaons could be divided, . because in a typical experimental situation, short-lived particles have time to fly to the collapse of only a few centimeters, . whereas long-lived particles flying tens of meters, . that would only watch KL0.,
. F., Cronin and their staff began their research, using advanced equipment, such as a spark chamber, allowing to accurately determine the specific tracks the decay products and select the response for observation
. For kaons, the experimenters bombarded a beryllium target with protons accelerated to high energies at the Brookhaven synchrotron with a strong focus (accelerator, capable to disperse the particles to energies of several billion. electron-volts). Its detectors experimenters placed at 17 m from the target, where kaons were born, at a distance large enough to have time to pass the kaon decay KS0 stayed beam, consisting of mere kaon KL0. But one of the features in the behavior of kaons, discovered in the course of the experiment, was that after passing through a block of absorbent material KL0, the beam again, the kaons KS0. This phenomenon is called regeneration. Investigating it, the researchers used a block of tungsten, copper, carbon and liquid hydrogen, and found confirmation of the theoretical assumptions in the complete absence of anomalies. The data allowed the participants to the experiment argue that regeneration is a slight effect on the results of their tests later, when the kaon decay region KL0 was introduced vessel filled with helium. The results of the experiment, which was met first with disbelief, showed that in 45 out of 23 thousand. photographed events in the spark chamber kaon KL0 split into two pions, instead of in accordance with the theory of decay into three. Given the importance of the results, the experimenters confirmed his retest, and over half a year unsuccessfully tried to find alternative explanations before they decided to publish the details of the violation of the combined symmetry Wed
. Violation of CP symmetry means that, in effect maintaining CPT-symmetry is broken and the symmetry under time reversal T, and therefore can be concluded that nature is indifferent to the direction in which time flows, forward or backward
. This symmetry breaking has enabled scientists to make certain assumptions to explain why matter and antimatter that emerged in the theory of 'big bang', the birth of the universe, not completely annihilated. If the matter has even a slightly longer period of decay, . than antimatter, . it leads, . that the Universe is the residue, . which survived after the mutual annihilation of matter and antimatter, and the final disappearance of antimatter, because of its more rapid decay,
. In this case it is the source of the annihilation of most of the cosmic electromagnetic radiation.
F. and Cronin was awarded the Nobel Prize in Physics 1980. 'for the discovery of violations of fundamental principles in the decay of neutral K-mesons'. Introducing the winners at the awards ceremony Gest Ekspong of the Royal Swedish Academy of Sciences described the three basic symmetry as a 'guiding rules that allow us to discover the mathematical laws of nature'. Referring to the work of Gell-Mann of neutral K-mesons and the opening of Lee and Yang, he noted that Cronin and F. 'interpret the results of their experiments as a weak, but clear-cut violation of symmetry', and stressed that "nobody, absolutely nobody, not expecting anything like this'.
. Violation SL symmetry can be explained by new theories claiming the existence of fundamental particles - quarks, which are composed of other subatomic particles
. The existence of quarks was first postulated by Gell-Mann. There are 6 quarks: u-quark (top), d-quark (bottom), s-quark (strange), c-quark (charmed), b-quark (bottom), t-quark (upper or true).
In 1949, Mr.. F. married Eliza Cunningham. They had two sons. Four years after the death of his first wife F. in 1973. married Daisy Harker, who had three children from a previous marriage. From childhood, EF. was an ardent fan of outdoor recreation: hiking, trekking with overnights in tents, etc.. He loves listening to classical music and in his spare time cultivating dwarf trees.
F. is a member of the American Physical Society. American Academy of Arts and Sciences and National Academy of Sciences. From 1970 to 1973. He was a member of the American Association for the Advancement of Science and was a member of the Advisory Committee on Science at the U.S. president. Among them received awards and distinctions Prize for Science Research Corporation of America (1968), . Prize in physics, Ernest Orlando Lawrence Atomic Energy Commission, the United States of America (1968) and Medal of John Price Uezerilla Franklinovskogo Institute (1976).,