James Chadwick: Wikis

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James Chadwick

Born 20 October 1891(1891-10-20)
Bollington, Cheshire, England
Died 24 July 1974 (aged 82)
Cambridge, England
Citizenship United Kingdom
Fields Physics
Institutions Technical University of Berlin
Liverpool University
Gonville and Caius College
Cambridge University
Manhattan Project
Alma mater University of Manchester
University of Cambridge.
Academic advisors Ernest Rutherford
Hans Geiger
Doctoral students Maurice Goldhaber
Ernest C. Pollard
Charles Drummond Ellis
Dai Chuanzeng
Known for Discovery of the neutron
Notable awards Nobel Prize in Physics (1935)

Sir James Chadwick, CH, FRS (20 October 1891 – 24 July 1974) was an English Nobel laureate in physics awarded for his discovery of the neutron.

Contents

Biography

Chadwick was born in Bollington, Cheshire to John Joseph Chadwick and Anne Mary Knowles. He went to Bollington Cross C of E Primary School, attended the Central Grammar School for Boys in Manchester,[1] and then studied at the Universities of Manchester and Cambridge.

In 1913 Chadwick went and worked with Hans Geiger at the Technical University of Berlin. He also worked with Ernest Rutherford. He was in Germany at the start of World War I and was interned in Ruhleben P.O.W. Camp just outside Berlin. While he was interned, he had the freedom to set up a laboratory in the stables. With the help of Charles Ellis he worked on the ionization of phosphorus and also on the photo-chemical reaction of carbon monoxide and chlorine.[2] He spent most of the war years in Ruhleben until Geiger's laboratory interceded for his release.

Career

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Research at Cambridge

In 1932, Chadwick discovered a previously unknown particle in the atomic nucleus.[3] This particle became known as the neutron because of its lack of electric charge. Chadwick's discovery was crucial for the fission of uranium 235. Unlike positively charged alpha particles, which are repelled by the electrical forces present in the nuclei of other atoms, neutrons do not need to overcome any Coulomb barrier and can therefore penetrate and split the nuclei of even the heaviest elements. For this discovery he was awarded the Hughes Medal of the Royal Society in 1932 and the Nobel Prize for Physics in 1935.[4]

Chadwick’s discovery made it possible to create elements heavier than uranium in the laboratory. His discovery particularly inspired Enrico Fermi, Italian physicist and Nobel laureate, to discover nuclear reactions brought by slowed neutrons, and led Otto Hahn and Fritz Strassmann, German radiochemists in Berlin, to the revolutionary discovery of “nuclear fission”.

Liverpool

Chadwick became professor of physics at Liverpool University in 1935. As a result of the Frisch-Peierls memorandum in 1940 on the feasibility of an atomic bomb, he was appointed to the MAUD Committee that investigated the matter further. He visited North America as part of the Tizard Mission in 1940 to collaborate with the Americans and Canadians on nuclear research. Returning to England in November 1940, he concluded that nothing would emerge from this research until after the war. In December 1940 Franz Simon, who had been commissioned by MAUD, reported that it was possible to separate the isotope uranium-235. Simon's report included cost estimates and technical specifications for a large uranium enrichment plant. James Chadwick later wrote that it was at that time that he "realised that a nuclear bomb was not only possible, it was inevitable. I had to then take sleeping pills. It was the only remedy."

He shortly afterward joined the Manhattan Project in the United States, which developed the atomic bombs dropped on Hiroshima and Nagasaki. Chadwick was knighted in 1945.

In 1940, Chadwick forwarded to the Royal Society the work of two French scientists, Hans Von Halban and Lew Kowarski, who worked in Cambridge. He asked that the papers be held as they were not appropriate for publication during the war. In 2007, the Society discovered the documents during an audit of their archives.[5]

References

  1. ^ Falconer, Isobel. ‘Chadwick, Sir James (1891–1974)’, Oxford Dictionary of National Biography, Oxford University Press, Sept 2004; online edn, Jan 2009 accessed 26 June 2009
  2. ^ Obituary: "Sir James Chadwick," The Times (of London, England), 25 July 1974, page 20, column F. (Available in part on-line at: http://ruhleben.tripod.com/id5.html .) See also: Obituary: "Sir Charles Ellis," The Times (of London, England), 15 January 1980, page 14, column F. (Available in part on-line at: http://ruhleben.tripod.com/id6.html .)
  3. ^ Chadwick announced his initial findings in: James Chadwick (27 Feb. 1932) "Letters to the editor: Possible existence of a neutron," Nature, vol. 129, page 312. (Available on-line at: http://web.mit.edu/22.54/resources/Chadwick.pdf .) Subsequently he communicated his findings in more detail in: (1) Chadwick, J. (1932) "The existence of a neutron," Proceedings of the Royal Society, Series A, vol. 136, pages 692-708 (Available on-line at: http://www.chemteam.info/Chem-History/Chadwick-1932/Chadwick-neutron.html .); and (2) Chadwick, J. (1933) "The Bakerian Lecture: The neutron," Proceedings of the Royal Society, Series A, vol. 142, pages 1-25.
  4. ^ James Chadwick - Biography
  5. ^ Staff writers (1 June 2007). "Nuclear Reactor Secrets Revealed". BBC News. http://news.bbc.co.uk/2/hi/science/nature/6709855.stm. Retrieved 2009-02-12. 

Further reading

  • Brown, Andrew (1997). The Neutron and the Bomb: A Biography of Sir James Chadwick. Oxford ; New York: Oxford University Press. ISBN 0-19-853992-4. 

External links


Simple English

[[File:|right|thumb|James Chadwick]]

Sir James Chadwick, (born 20 October 1891; died 24 July 1974) was an English physicist and Nobel Prize winner who is best known for discovering the neutron.

Contents

Biography

James Chadwick was born in Bollington, Cheshire, England. He went to Manchester High School, and studied at the Universities of Manchester and Cambridge. In 1913, Chadwick went to Berlin in Germany to work with the scientist Hans Geiger. He also worked with Ernest Rutherford. He was still in Germany when World War I broke out and he was interned in Ruhleben P.O.W. Camp just outside Berlin. The camp, which had more than 5,000 detainees (prisoners of war) had been a horse race course. There were stables, each with 27 horse boxes. The detainees lived in these boxes. The detainees were allowed to do things to keep themselves busy. Chadwick worked with a young scientist called Charles Ellis. Together they set up a laboratory in the stables where they worked on the ionisation of phosphorus and also on the photo-chemical reaction of carbon monoxide and chlorine.

Career

Research at Cambridge

After the war, Chadwick returned to Cambridge where he worked with Ernest Rutherford, studying the emission of gamma rays from radioactive materials. They also studied the transmutation of elements by bombarding them with alpha particles, and investigated the nature of the atomic nucleus.

In 1932 Chadwick made a very important discovery: he discovered the particle in the nucleus of an atom that became known as the neutron because it has no electric charge. In contrast with the helium nuclei (alpha particles) which are positively charged, and therefore repelled by the strong electrical forces in the nuclei of heavy atoms, this new tool in atomic disintegration need not overcome any electric barrier and is capable of penetrating and splitting the nuclei of even the heaviest elements. In this way, Chadwick prepared the way towards the fission of uranium 235 and towards the creation of the atomic bomb. For this important discovery he was awarded the Hughes Medal of the Royal Society in 1932, and later the Nobel Prize for Physics in 1935. He was also nicknamed "Jimmy Neutron" because of his discovery of the neutron.

Liverpool

Chadwick became professor of physics at Liverpool University in 1935. He worked on the possibility of an atomic bomb. Later he realized that the nuclear bomb really was going to be made. He found it very frightening that the science he had been working on could lead to such a terrible weapon. He started to take sleeping pills.

He joined the Manhattan Project in the United States, which developed the atomic bombs dropped on Hiroshima and Nagasaki. Chadwick was knighted in 1945.

Return to Cambridge

After the war, Chadwick moved to Cambridge University as master of Gonville and Caius College.

He died in Cambridge on 24 July 1974.


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