James Chadwick
CH FRS | |
---|---|
Born | Bollington, Cheshire, United Kingdom | 20 October 1891
Died | 24 July 1974 , United Kingdom | (aged 82)
Education | |
Known for | |
Awards |
|
Scientific career | |
Fields | Physics |
Institutions |
|
Doctoral advisor | Ernest Rutherford |
Doctoral students | |
Signature | |
Sir James Chadwick,
Chadwick graduated from the
After the war, Chadwick followed Rutherford to the Cavendish Laboratory at the University of Cambridge, where Chadwick earned his Doctor of Philosophy degree under Rutherford's supervision from Gonville and Caius College, Cambridge, in June 1921. He was Rutherford's assistant director of research at the Cavendish Laboratory for over a decade at a time when it was one of the world's foremost centres for the study of physics, attracting students like John Cockcroft, Norman Feather, and Mark Oliphant. Chadwick followed his discovery of the neutron by measuring its mass. He anticipated that neutrons would become a major weapon in the fight against cancer. Chadwick left the Cavendish Laboratory in 1935 to become a professor of physics at the University of Liverpool, where he overhauled an antiquated laboratory and, by installing a cyclotron, made it an important centre for the study of nuclear physics.
During the Second World War, Chadwick carried out research as part of the
Education and early life
James Chadwick was born in
Chadwick chose to attend
Having devised a means of measuring gamma radiation, Chadwick proceeded to measure the absorption of gamma rays by various gases and liquids. This time the resulting paper was published under his name alone. He was awarded his
Chadwick was still in Germany at the start of the
Rutherford gave Chadwick a part-time teaching position at Manchester, allowing him to continue research.
Researcher
Cambridge
Chadwick's Clerk-Maxwell studentship expired in 1923, and he was succeeded by the Russian physicist
In 1925, Chadwick met Aileen Stewart-Brown, the daughter of a Liverpool stockbroker. The two were married in August 1925,[22] with Kapitza as Best Man. The couple had twin daughters, Joanna and Judith, who were born in February 1927.[24]
In his research, Chadwick continued to probe the nucleus. In 1925, the concept of spin had allowed physicists to explain the Zeeman effect, but it also created unexplained anomalies. At the time it was believed that the nucleus consisted of protons and electrons, so nitrogen's nucleus, for example, with a mass number of 14, was assumed to contain 14 protons and 7 electrons. This gave it the right mass and charge, but the wrong spin.[25]
At a conference at Cambridge on beta particles and gamma rays in 1928, Chadwick met Geiger again. Geiger had brought with him a new model of his Geiger counter, which had been improved by his post-doctoral student Walther Müller. Chadwick had not used one since the war, and the new Geiger–Müller counter was potentially a major improvement over the scintillation techniques then in use at Cambridge, which relied on the human eye for observation. The major drawback with it was that it detected alpha, beta and gamma radiation, and radium, which the Cavendish laboratory normally used in its experiments, emitted all three, and was therefore unsuitable for what Chadwick had in mind. However, polonium is an alpha emitter, and Lise Meitner sent Chadwick about 2 millicuries (about 0.5 μg) from Germany.[26][27]
In Germany,
Chadwick dropped all his other responsibilities to concentrate on proving the existence of the neutron, assisted by Feather[29] and frequently working late at night. He devised a simple apparatus that consisted of a cylinder containing a polonium source and beryllium target. The resulting radiation could then be directed at a material such as paraffin wax. The displaced particles, which were protons, would go into a small ionisation chamber where they could be detected with an oscilloscope.[28] In February 1932, after only about two weeks of experimentation with neutrons,
The theoretical physicists
An accurate value for the mass of the neutron could be determined from this process. Chadwick and Goldhaber tried this and found that it worked.
For his discovery of the neutron, Chadwick was awarded the Hughes Medal by the Royal Society in 1932, the Nobel Prize in Physics in 1935, the Copley Medal in 1950 and the Franklin Medal in 1951.[6] His discovery of the neutron made it possible to produce elements heavier than uranium in the laboratory by the capture of slow neutrons followed by beta decay. Unlike the 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 enter the nuclei of even the heaviest elements such as uranium. This inspired Enrico Fermi to investigate the nuclear reactions brought about by collisions of nuclei with slow neutrons, work for which Fermi would receive the Nobel Prize in 1938.[45]
Liverpool
With the onset of the Great Depression in the United Kingdom, the government became more parsimonious with funding for science. At the same time, Lawrence's recent invention, the cyclotron, promised to revolutionise experimental nuclear physics, and Chadwick felt that the Cavendish laboratory would fall behind unless it also acquired one. He therefore chafed under Rutherford, who clung to the belief that good nuclear physics could still be done without large, expensive equipment, and turned down the request for a cyclotron.[53]
Chadwick was himself a critic of
In March 1935, Chadwick received an offer of the Lyon Jones Chair of physics at the University of Liverpool, in his wife's home town, to succeed Lionel Wilberforce. The laboratory was so antiquated that it still ran on direct current electricity, but Chadwick seized the opportunity, assuming the chair on 1 October 1935. The university's prestige was soon bolstered by Chadwick's Nobel Prize, which was announced in November 1935.[59] His medal was sold at auction in 2014 for $329,000.[60]
Chadwick set about acquiring a cyclotron for Liverpool. He started by spending £700 to refurbish the antiquated laboratories at Liverpool, so some components could be made in-house.[61] He was able to persuade the university to provide £2,000 and obtained a grant for another £2,000 from the Royal Society.[62] To build his cyclotron, Chadwick brought in two young experts, Bernard Kinsey and Harold Walke, who had worked with Lawrence at the University of California. A local cable manufacturer donated the copper conductor for the coils. The cyclotron's 50-ton magnet was manufactured in Trafford Park by Metropolitan-Vickers, which also made the vacuum chamber.[63] The cyclotron was completely installed and running in July 1939. The total cost of £5,184 was more than Chadwick had received from the university and the Royal Society, so Chadwick paid the rest from his 159,917 kr (£8,243) Nobel Prize money.[64]
At Liverpool the Medicine and Science faculties worked together closely. Chadwick was automatically a committee member of both faculties, and in 1938 he was appointed to a commission headed by Lord Derby to investigate the arrangements for cancer treatment in Liverpool. Chadwick anticipated that neutrons and radioactive isotopes produced with the 37-inch cyclotron could be used to study biochemical processes, and might become a weapon in the fight against cancer.[65][66]
Second World War
Tube Alloys and the MAUD Report
In Germany,
Chadwick did not believe that there was any likelihood of another war with Germany in 1939, and took his family for a holiday on a remote lake in northern Sweden. The news of the outbreak of the
In October 1939, Chadwick received a letter from Sir
A special subcommittee of the Committee for the Scientific Survey of Air Warfare (CSSAW), known as the
In July 1941, Chadwick was chosen to write the final draft of the MAUD Report, which, when presented by Vannevar Bush to President Franklin D. Roosevelt in October 1941, inspired the U.S. government to pour millions of dollars into the pursuit of an atom bomb.[81] When George B. Pegram and Harold Urey visited Britain to see how the project,[82] now known as Tube Alloys,[83] was going, Chadwick was able to tell them: "I wish I could tell you that the bomb is not going to work, but I am 90 per cent sure that it will."[82]
In a recent book about the Bomb project, Graham Farmelo wrote that "Chadwick did more than any other scientist to give Churchill the Bomb. ... Chadwick was tested almost to the breaking point."[84] So worried that he could not sleep, Chadwick resorted to sleeping pills, which he continued to take for most of his remaining years. Chadwick later said that he realised that "a nuclear bomb was not only possible—it was inevitable. Sooner or later these ideas could not be peculiar to us. Everybody would think about them before long, and some country would put them into action".[85] Sir Hermann Bondi suggested that it was fortunate that Chadwick, not Rutherford, was the doyen of UK physics at the time, as the latter's prestige might otherwise have overpowered Chadwick's interest in "looking forward" to the Bomb's prospects.[86]
Manhattan Project
Owing to the danger from aerial bombardment, the Chadwicks sent their twins to Canada as part of a government evacuation scheme.[87] Chadwick was reluctant to move Tube Alloys there, believing that the United Kingdom was a better location for the isotope separation plant.[88] The enormous scope of the effort became more apparent in 1942: even a pilot separation plant would cost over £1 million and strain Britain's resources, to say nothing of a full-scale plant, which was estimated to cost somewhere in the vicinity of £25 million. It would have to be built in America.[89] At the same time that the British became convinced that a joint project was necessary, the progress of the American Manhattan Project was such that British cooperation seemed less essential, although the Americans were still eager to use Chadwick's talents.[90]
The matter of cooperation had to be taken up at the highest level. In September 1943, the
Leaving Rotblat in charge in Liverpool, Chadwick began a tour of the Manhattan Project facilities in November 1943, except for the Hanford Site where plutonium was produced, which he was not allowed to see. He became the only man, apart from Groves and his second in command, to have access to all the American research and production facilities for the uranium bomb. Observing the work on the K-25 gaseous diffusion facility at Oak Ridge, Tennessee, Chadwick realised how wrong he had been about building the plant in wartime Britain. The enormous structure could never have been concealed from the Luftwaffe.[92] In early 1944, he moved to Los Alamos, New Mexico, with his wife and their twins, who now spoke with Canadian accents.[93] For security reasons, he was given the cover name of James Chaffee.[94]
Chadwick accepted that the Americans did not need British help, but that it could still be useful in bringing the project to an early and successful conclusion. Working closely with the director of the Manhattan Project,
Although he had more knowledge of the project than anyone else from Britain,
By early 1945, Chadwick was spending most of his time in Washington, D.C., and his family relocated from Los Alamos to a house on Washington's
Later life
Shortly after the war ended, Chadwick was appointed to the Advisory Committee on Atomic Energy (ACAE). He was also appointed as the British scientific advisor to the United Nations Atomic Energy Commission. He clashed with fellow ACAE member Patrick Blackett, who disagreed with Chadwick's conviction that Britain needed to acquire its own nuclear weapons; but it was Chadwick's position that was ultimately adopted. He returned to Britain in 1946, to find a country still beset by wartime rationing and shortages.[106]
At this time, Sir James Mountford, the Vice Chancellor of the University of Liverpool, wrote in his diary "he had never seen a man 'so physically, mentally and spiritually tired" as Chadwick, for he "had plumbed such depths of moral decision as more fortunate men are never called upon even to peer into ... [and suffered] ... almost insupportable agonies of responsibility arising from his scientific work'."[107]
In 1948, Chadwick accepted an offer to become the
By the 1970s Chadwick became more frail, and seldom left his flat, although he travelled to Liverpool for celebrations of his eightieth birthday. A lifelong atheist, he saw no reason to adopt religious faith in later life. He died in his sleep on 24 July 1974.[110]
Honours
- Elected a Fellow of the Royal Society in 1927.[111]
- Medal for Merit from the United States,
- Pour le Mérite from Germany.[110]
- Foreign member of the Royal Netherlands Academy of Arts and Sciences in 1946
- International member of the American Philosophical Society in 1948.[112]
- Member of the Order of the Companions of Honour in the New Year Honours on 1 January 1970 for "services to science",[113] and went to Buckingham Palacefor the investiture ceremony.
Legacy
- Chadwick's papers are held at the Churchill Archives Centre in Cambridge, and are accessible to the public.[114]
- The Chadwick Laboratory at the University of Liverpool.[115]
- Sir James Chadwick Chair of Experimental Physics, also at the University of Liverpool. Named in 1991 as part of celebrations of the centenary of his birth.[116]
- crater on the moon[117]
- James Chadwick Building, which houses part of the School of Chemical Engineering and Analytical Sciences, University of Manchester.[118]
- Chadwick was described by the United Kingdom Atomic Energy Authority official historian Lorna Arnold as "a physicist, a scientist-diplomat, and a good, wise, and humane man."[119]
Notes
- ^ a b c d "James Chadwick". academictree.org. Retrieved 21 July 2014.
- ^ "Ernest Rutherford". Figures in Radiation History. Michigan State University. Archived from the original on 29 June 2015. Retrieved 3 June 2014.
- ^ Falconer 2004.
- ^ Oliphant 1974.
- ^ Brown 1997, pp. 3–5.
- ^ The Nobel Foundation. Retrieved 21 April 2013.
- ^ Rutherford & Chadwick 1912.
- ^ Brown 1997, pp. 6–14.
- ^ Brown 1997, pp. 16–21.
- ^ Chadwick 1914.
- ^ Chadwick & Ellis 1922.
- ^ a b Weiner 1969.
- ^ Jensen 2000, pp. 88–90.
- ^ Brown 1997, pp. 24–26.
- ^ APS News. 16 (5): 2. 2007.
- ^ "Obituary: Sir James Chadwick". The Times. 25 July 1974. p. 20, column F.
- ^ "Obituary: Sir Charles Ellis". The Times. 15 January 1980. p. 14, column F.
- ^ a b Brown 1997, p. 39.
- ^ Brown 1997, pp. 43.
- ^ Brown 1997, pp. 43–50.
- ^ Brown 1997, p. 58.
- ^ a b Brown 1997, pp. 73–76.
- ^ "The History of the Cavendish". University of Cambridge. 13 August 2013. Retrieved 15 August 2014.
- ^ Brown 1997, p. 85.
- ^ Brown 1997, pp. 92–93.
- ^ a b Brown 1997, pp. 95–97.
- ^ Sublette 2006.
- ^ a b Brown 1997, pp. 103–104.
- ^ "Oral History interview transcript with Norman Feather, Session I". American Institute of Physics, Niels Bohr Library and Archives. 25 February 1971.
- ^ Chadwick 1932a.
- ^ Chadwick 1932b.
- ^ Chadwick 1933.
- ^ Whaling 2009, pp. 8–9.
- ^ Bacher & Condon 1932.
- ^ Heisenberg 1932a.
- ^ Heisenberg 1932b.
- ^ a b Heisenberg 1933.
- ^ a b c Bromberg 1971.
- ^ Brown 1997, pp. 115–116.
- ^ Heilbron & Seidel 1989, pp. 153–157.
- ^ Goldhaber 1934.
- ^ Chadwick & Goldhaber 1934.
- ^ a b Chadwick & Goldhaber 1935.
- ^ a b Brown 1997, pp. 122–125.
- ^ Brown 1997, pp. 125.
- ^ Brown 1997, pp. 119–120.
- ^ Close 2012, pp. 15–18.
- ^ Fermi 1968.
- ^ Close 2012, pp. 22–25.
- ^ Close 2012, pp. 26–28.
- S2CID 4001646.
- ^ Close 2012, pp. 37–41.
- ^ Brown 1997, pp. 129–132.
- ^ Herken 2002, p. 10.
- ^ Heilbron & Seidel 1989, pp. 165–167.
- ^ Oliphant & Rutherford 1933.
- ^ Oliphant, Kinsey & Rutherford 1933.
- ^ Oliphant, Harteck & Rutherford 1934.
- ^ Brown 1997, pp. 134–139.
- ^ Gannon, Megan (4 June 2014). "Sold! Nobel Prize for Neutron Discovery Auctioned for $329,000". Yahoo News. Retrieved 16 September 2014.
- ^ Brown 1997, p. 142.
- ^ Brown 1997, pp. 149–151.
- ^ Holt 1994.
- ^ Brown 1997, pp. 173–174.
- ^ King 1997.
- ^ Brown 1997, p. 150.
- ^ Brown 1997, p. 170.
- ^ Meitner & Frisch 1939.
- ^ Frisch 1939.
- ^ Hahn & Strassmann 1939.
- ^ von Halban, Joliot & Kowarski 1939.
- ^ Gowing 1964, pp. 24–27.
- ^ Bohr & Wheeler 1939.
- ^ Brown 1997, pp. 174–178.
- ^ Gowing 1964, pp. 38–39.
- ^ Gowing 1964, pp. 39–41.
- ^ Gowing 1964, p. 45.
- ^ Gowing 1964, p. 63.
- ^ Brown 1997, p. 206.
- ^ Brown 1997, p. 204.
- ^ Bundy 1988, pp. 48–49.
- ^ a b Gowing 1964, p. 85.
- ^ Gowing 1964, p. 109.
- ^ Farmelo 2013, p. 119.
- ^ Brown 1997, p. 205.
- ^ Bondi 1997.
- ^ Brown 1997, pp. 197–198.
- ^ Brown 1997, pp. 218–219.
- ^ Gowing 1964, pp. 141–142.
- ^ Gowing 1964, p. 152.
- ^ Gowing 1964, pp. 166–171.
- ^ Brown 1997, p. 253.
- ^ Brown 1997, pp. 250–261.
- ^ Hoddeson et al. 1993, p. 95.
- ^ Brown 1997, pp. 247–51.
- ^ Gowing 1964, pp. 241–244.
- ^ Szasz 1992, p. xvi.
- ^ Gowing 1964, p. 329.
- ^ Brown 1997, p. 317.
- ^ "No. 36866". The London Gazette (Supplement). 29 December 1944. p. 1. Knight Bachelor
- ^ a b Brown 1997, p. 279.
- ^ Brown 1997, p. 290.
- ^ Brown 1997, p. 292.
- ^ Brown 1997, p. 287.
- ^ Laurence 1946, p. 26.
- ^ Brown 1997, pp. 306, 316.
- ^ Brown 1997, p. 323.
- ^ a b Brown 1997, pp. 340–353.
- ^ Zhang 2010.
- ^ a b Brown 1997, pp. 360–363.
- ^ Massey & Feather 1976, p. 11.
- ^ "J. Chadwick (1891–1974)". Royal Netherlands Academy of Arts and Sciences. Retrieved 21 July 2015.
- ^ "No. 44999". The London Gazette (Supplement). 30 December 1969. p. 23. Companion of Honour
- ^ "The Papers of Sir James Chadwick". Churchill Archives Centre, ArchiveSearch. Retrieved 30 September 2021.
- ^ "Liverpool Science Places". Scienceplaces.org. Archived from the original on 15 August 2014. Retrieved 6 August 2014.
- ^ "University Chairs and their Holders Past and Present" (PDF). University of Liverpool. Retrieved 1 August 2014.[permanent dead link]
- ^ "Planetary Names: Crater, craters: Chadwick on Moon". United States Geological Survey. Archived from the original on 22 November 2017. Retrieved 12 August 2012.
- ^ "James Chadwick Building – directions". The University of Manchester. Retrieved 18 May 2016.
- ^ Arnold 1998.
References
- S2CID 161661986. Archived from the original(PDF) on 8 August 2014.
- doi:10.1103/PhysRev.41.683.2. Archived from the originalon 7 April 2023. Retrieved 17 July 2022.
- .
- Times Higher Education Supplement. Retrieved 20 July 2014.
- Bromberg, Joan (1971). "The Impact of the Neutron: Bohr and Heisenberg". S2CID 8516458.
- Brown, Andrew (1997). The Neutron and the Bomb: A Biography of Sir James Chadwick. ISBN 978-0-19-853992-6.
- ISBN 978-0-394-52278-4.
- Chadwick, James (1914). "Intensitätsverteilung im magnetischen Spektrum von β-Strahlen von Radium B+C". Verhandlungen der Deutschen Physikalischen Gesellschaft(in German). 16: 383–391.
- —; Ellis, Charles D. (1922). "A Preliminary Investigation of the Intensity Distribution in the β-Ray Spectra of Radium B and C". Proceedings of the Cambridge Philosophical Society. 21: 274–280.
- — (1932). "Possible Existence of a Neutron" (PDF). S2CID 4076465.
- — (1932). "The Existence of a Neutron". JSTOR 95816.
- — (1933). "Bakerian Lecture. The Neutron". JSTOR 96108.
- —; S2CID 4137231.
- —; JSTOR 96561.
- Close, Frank E. (2012). Neutrino. Oxford: Oxford University Press. OCLC 840096946.
- Falconer, Isobel (2004). "Chadwick, Sir James (1891–1974)". doi:10.1093/ref:odnb/30912. (Subscription or UK public library membershiprequired.)
- ISBN 978-0-465-02195-6.
- Fermi, E. (1968). "Fermi's Theory of Beta Decay (English translation by Fred L. Wilson, 1968)". . Retrieved 20 January 2013.
- S2CID 4076376.
- S2CID 4092342.
- OCLC 3195209.
- S2CID 5920336. Archived from the original(PDF) on 15 December 2014.
- S2CID 4089039.
- ISBN 978-0-520-06426-3.
- S2CID 186218053.
- — (1932). "Über den Bau der Atomkerne. II". S2CID 186221789.
- — (1933). "Über den Bau der Atomkerne. III". S2CID 126422047.
- Herken, Gregg (2002). Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller. ISBN 978-0-8050-6589-3.
- ISBN 978-0-521-44132-2.
- JSTOR 532169.
- Jensen, Carsten (2000). Controversy and Consensus: Nuclear Beta Decay 1911–1934. ISBN 978-3-7643-5313-1.
- King, Charles D. (1997). "Sir James Chadwick and his Medical Plans for the Liverpool 37-inch Cyclotron" (PDF). Medical Historian. 9: 43–55. Archived from the original (PDF) on 15 December 2014. Retrieved 7 August 2014.
- OCLC 4354887.
- JSTOR 769732.
- S2CID 4113262.
- JSTOR 96218.
- —; Kinsey, B. B.; JSTOR 96179.
- —; JSTOR 2935553.
- — (1974). "James Chadwick". .
- .
- Sublette, Carey (14 December 2006). "Polonium Poisoning". Nuclear Weapon Archive. Retrieved 1 August 2014.
- Szasz, Ferenc (1992). British Scientists and the Manhattan Project: The Los Alamos Years. ISBN 978-0-312-06167-8.
- Weiner, Charles (20 April 1969). "Interview with Sir James Chadwick". American Institute of Physics. Archived from the original on 16 July 2014. Retrieved 5 August 2014.
- Whaling, Ward (2009). Robert F. Bacher 1905–2004 (PDF). Biographical Memoirs of the National Academy of Sciences. National Academy of Sciences. Archived from the original (PDF) on 31 May 2014. Retrieved 22 March 2013.
- Zhang, Youshang (2010). "In memory of Professor Tianqin Cao (Tien-chin Tsao)". PMID 21246905. Archived from the originalon 10 August 2014.
Further reading
- "Sir James Chadwick, F.R.S." doi:10.1038/161964a0.
- "Sir James Chadwick, C.H., LL.D., F.R.S.: 80th birthday". .
- ISBN 978-1-108-00901-0.
External links
- Oral history interview transcript with James Chadwick on 15 April 1969, American Institute of Physics, Niels Bohr Library & Archives – Session I
- Oral history interview transcript with James Chadwick on 16 April 1969, American Institute of Physics, Niels Bohr Library & Archives – Session II
- Oral history interview transcript with James Chadwick on 17 April 1969, American Institute of Physics, Niels Bohr Library & Archives – Session III
- Oral history interview transcript with James Chadwick on 20 April 1969, American Institute of Physics, Niels Bohr Library & Archives – Session IV
- James Chadwick on Nobelprize.org