Cockcroft (Cockcroft), John( English physicist, Nobel Prize in Physics, 1951)
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Biography Cockcroft (Cockcroft), John
May 27, 1897, Mr.. - September 18, 1967
English physicist John Douglas Cockcroft was born in Todmordene, Yorkshire. He was the eldest of five sons, John Arthur Cockcroft and Maude (FIELD) Cockcroft. His father owned a small cotton mill, and three of his brothers went to his father's footsteps, because their family was engaged in this business for five generations. But John, a brilliant student and athlete, received in 1914. scholarship to the University of Manchester.
In Manchester By. began to study mathematics and physics to attend lectures Ernest Rutherford. Rutherford, received recognition for their work on radioactivity and atomic structure, was able to prove that alpha particles are the nuclei of helium atoms. Moreover, he showed that atoms consist of positively charged nucleus, around which revolve in their orbits negatively charged electrons. It was a time when the mathematicians and physicists rose many serious problems. Radioactivity was discovered by Henri Becquerel less than 20 years ago, in 1896, the theory of relativity, Albert Einstein, published in 1905, only beginning to make sense of the scientists. But the outbreak of the First World War, and in 1915, after a year of study at the university, K. joined volunteer units YMCA. On military service he was drafted in the same year. Prior to its release into the reserve in 1918. He fought on the Western Front, and moved the service from the signalman to an officer of the Royal Field Artillery.
Returning to Manchester, to. began to study electrical engineering, and for this work received a master's degree in 1922. Being in the future scholarship in mathematics College St.. John in Cambridge, he obtained a bachelor's degree with honors in 1924. and enrolled in the Cambridge Cavendish Laboratory younger assistant-researcher. Four years later, he received his doctorate. Cambridge K. lectured on physics and studied mathematics, and technology development. Together with the Russian physicist Pyotr Kapitsa, he developed a transformer winding to produce intense magnetic fields. He also investigated the surface films obtained by atomic beams.
. Rutherford was director of the Cavendish Laboratory in 1919, when he came here a famous scientist who proved that the nucleus can be destroyed by bombarding its subatomic particles
. The splitting of the nucleus, which Rutherford performed using the natural emission of alpha particles (helium nuclei) and transformed with the nitrogen atoms to oxygen atoms, has opened a new field of experimental research. Next primary goal was to learn how to implement the transmutation of atoms in a much larger scale than it could be done using the methods of Rutherford. Some researchers believe that this could be achieved by accelerating atomic particles in large quantities. Since the positively charged particles experience strong repulsion from the atomic nuclei, which are also positively charged, is required to obtain extremely high speed.
. Many scientists in Europe and the United States to race seeking greater acceleration of particles, using two different approaches
. In the so-called direct method of energy is produced using a single high voltage electrical pulse. In another method, particles are accelerated, passing cyclically through low-voltage field several times. Of the two methods of cyclic most researchers seem more promising: although it required more sophisticated equipment, . but is used quite affordable Voltage, . whereas the direct method requires the high voltage was difficult to get on the equipment at that time.,
. Inspired by the theories of physicist of Russian origin, George Gamow, K
. decided to develop a direct method. Gamow using quantum mechanics calculated that, since subatomic particles have wave properties, they are occasionally able to penetrate the nuclear barrier, even when their energy is not enough to overcome it. Equations Gamow explained how alpha particles could leave the nuclei of radioactive elements, but to. realized that the same principles allow other particles to penetrate into the nucleus with energy significantly lower than previously thought.
With Ernest Walton, his counterpart at the Cavendish Laboratory, K. developed based on the direct method of installation to provide power only at 600 kilovolts to the tube containing hydrogen. (To overcome the nuclear barrier would require several million. volts.) With this setup to. and Walton in April 1932. bombarded lithium hydrogen nuclei, or protons. 'Almost immediately, - later recalled K. - at an energy of 125 kilovolts Dr. Walton saw a nuclear scintillation, which is characteristic for alpha-particles'. They turned lithium and hydrogen into helium, thus becoming the first scientists who managed to artificially split the atom. Their achievement also served as experimental confirmation of the theory of Gamow and showed that the amount of energy released during the conversion of atoms, corresponds exactly to the basic equation of Einstein's theory of relativity: E = mc2.
In 30-ies. K. continued his experiments, using different bombarding particles and atomic nuclei, such as boron and fluorine. After the discovery of artificial radioactive elements Frederic Joliot and Irene Joliot-Curie to. and Walton have shown that they can also obtain such elements, irradiating the boron and carbon nuclei of hydrogen. In 1934, Mr.. K., able administrator, was appointed director of the Royal Society Mond Laboratory in Cambridge. A year later, he and Rutherford took up the refurbishment of the Cavendish Laboratory, in particular setting where the cyclotron - an accelerator, invented by Ernest O. Lawrence. Cyclic accelerators were soon improved and have now become generally accepted, although the generator Cockcroft - Walton continues to be used as a source of protons in a number of powerful systems.
In 1939, Mr.. World War II began, and K. again took part in the military development of Great Britain. He was entrusted with primary responsibility for development and deployment of radars, a crucial factor in the success of Britain in the air war against Germany. In 1940. he was sent to the U.S. as vice-president Tizardovskoy Commission, which negotiated the exchange of technical military information with American scientists before entering the United States in the war. After returning from the U.S. to. headed the research department of the RAF. In 1944, Mr.. He went to Canada to head the Department of Atomic Energy, subordinate to the National Research Council of Canada, this group took part in the Manhattan Project to develop and produce the first atomic bomb.
To. returned to England in 1946 to head the new agency for research in the field of atomic energy, the result of which was the creation of the world's first nuclear power plant at Calder Hall, the North of England. Leading active in many areas, he was a member of the British Department of Atomic Energy and CERN (European Organization for Nuclear Research in Geneva, Switzerland). He founded what is now known as the Rutherford High Energy Laboratory, first-class equipment which is open for use throughout the scientific community of British universities.
To. and Walton split in 1951. Nobel Prize in Physics "for his work on the transmutation of atomic nuclei by artificially accelerated atomic particles'. In his speech, Ivar Waller of the Royal Swedish Academy of Sciences said: 'To Work. and Walton confirmed the validity of Einstein's law concerning the equivalence of mass and energy. When lithium transmutation of energy is released, since the total kinetic energy is derived helium nuclei exceeds the energy source of nuclei. According to Einstein's law - continued Waller - is the increase in energy due to the corresponding mass loss of atomic nuclei. "
In 1959, Mr.. K. headed by Churchill College, Cambridge. By the time of his death in 1967. K. was president of the Pugwash Conference, and was one of the leaders of the Liberal Party.
To. married in 1925. at Eunice Elizabeth Krebtri, they had four daughters and a son.
In addition to the Nobel Prize, K. received the Royal Medal of the Royal Society (1954), an international gold medal of Niels Bohr Danish Society of Civil Engineers, electricians and mechanics (1958) and the prize 'for the peaceful atom', established by the Ford Foundation (1961). He was a member of the Royal Society, as well as an honorary member of the American Academy of Arts and Sciences and the Royal Swedish Academy of Sciences. In 1948, Mr.. K. was ennobled. He was the holder of honorary degrees from Oxford University, London University, University of Toronto and the University of Glasgow.