James Chadwick

Sir James Chadwick, CH, FRS (20 October 1891 – 24 July 1974) was a British physicist who was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932. In 1941, he wrote the final draft of the MAUD Report, which inspired the U.S. government to begin serious atomic bomb research efforts. He was the head of the British team that worked on the Manhattan Project during the Second World War. He was knighted in Britain in 1945 for his achievements in physics.

Chadwick graduated from the Victoria University of Manchester in 1911, where he studied under Ernest Rutherford (known as the "father of nuclear physics").[2] At Manchester, he continued to study under Rutherford until he was awarded his MSc in 1913. The same year, Chadwick was awarded an 1851 Research Fellowship from the Royal Commission for the Exhibition of 1851. He elected to study beta radiation under Hans Geiger in Berlin. Using Geiger's recently developed Geiger counter, Chadwick was able to demonstrate that beta radiation produced a continuous spectrum, and not discrete lines as had been thought. Still in Germany when the First World War broke out in Europe, he spent the next four years in the Ruhleben internment camp.

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 Tube Alloys project to build an atomic bomb, while his Manchester lab and environs were harassed by Luftwaffe bombing. When the Quebec Agreement merged his project with the American Manhattan Project, he became part of the British Mission, and worked at the Los Alamos Laboratory and in Washington, D.C. He surprised everyone by earning the almost-complete trust of project director Leslie R. Groves, Jr. For his efforts, Chadwick received a knighthood in the New Year Honours on 1 January 1945. In July 1945, he viewed the Trinity nuclear test. After this, he served as the British scientific advisor to the United Nations Atomic Energy Commission. Uncomfortable with the trend toward Big Science, Chadwick became the Master of Gonville and Caius College in 1948. He retired in 1959.

Sir James Chadwick
James Chadwick
Born20 October 1891
Died24 July 1974 (aged 82)
Cambridge, England
Alma mater
Known for
Scientific career
Doctoral advisorErnest Rutherford
Doctoral students

Education and early life

James Chadwick was born in Bollington, Cheshire, on 20 October 1891,[3][4] the first child of John Joseph Chadwick, a cotton spinner, and Anne Mary Knowles, a domestic servant. He was named James after his paternal grandfather. In 1895, his parents moved to Manchester, leaving him in the care of his maternal grandparents. He went to Bollington Cross Primary School, and was offered a scholarship to Manchester Grammar School, which his family had to turn down as they could not afford the small fees that still had to be paid. Instead he attended the Central Grammar School for Boys in Manchester, rejoining his parents there. He now had two younger brothers, Harry and Hubert; a sister had died in infancy. At the age of 16, he sat two examinations for university scholarships, and won both of them.[5][6]

Chadwick chose to attend Victoria University of Manchester, which he entered in 1908. He meant to study mathematics, but enrolled in physics by mistake. Like most students, he lived at home, walking the 4 miles (6.4 km) to the university and back each day. At the end of his first year, he was awarded a Heginbottom Scholarship to study physics. The physics department was headed by Ernest Rutherford, who assigned research projects to final-year students, and he instructed Chadwick to devise a means of comparing the amount of radioactive energy of two different sources. The idea was that they could be measured in terms of the activity of 1 gram (0.035 oz) of radium, a unit of measurement which would become known as the curie. Rutherford's suggested approach was unworkable—something Chadwick knew but was afraid to tell Rutherford—so Chadwick pressed on, and eventually devised the required method. The results became Chadwick's first paper, which, co-authored with Rutherford, was published in 1912.[7] He graduated with first class honours in 1911.[8]

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 Master of Science (MSc) degree in 1912, and was appointed a Beyer Fellow. The following year he was awarded an 1851 Exhibition Scholarship, which allowed him to study and research at a university in continental Europe. He elected to go to the Physikalisch-Technische Reichsanstalt in Berlin in 1913, to study beta radiation under Hans Geiger.[9] Using Geiger's recently developed Geiger counter, which provided more accuracy than the earlier photographic techniques, he was able to demonstrate that beta radiation did not produce discrete lines, as has been previously thought, but rather a continuous spectrum with peaks in certain regions.[10][11][12][13] On a visit to Geiger's laboratory, Albert Einstein told Chadwick that: "I can explain either of these things, but I can't explain them both at the same time."[12] The continuous spectrum would remain an unexplained phenomenon for many years.[14]

Chadwick was still in Germany at the start of the First World War, and was interned in the Ruhleben internment camp near Berlin, where he was allowed to set up a laboratory in the stables and conduct scientific experiments using improvised materials such as radioactive toothpaste.[15] With the help of Charles Drummond Ellis, he worked on the ionisation of phosphorus, and the photochemical reaction of carbon monoxide and chlorine.[16][17] He was released after the Armistice with Germany came into effect in November 1918, and returned to his parents' home in Manchester, where he wrote up his findings over the previous four years for the 1851 Exhibition commissioners.[18]

Rutherford gave Chadwick a part-time teaching position at Manchester, allowing him to continue research.[18] He looked at the nuclear charge of platinum, silver, and copper, and experimentally found that this was the same as the atomic number within an error of less than 1.5 per cent.[19] In April 1919, Rutherford became director of the Cavendish Laboratory at the University of Cambridge, and Chadwick joined him there a few months later. Chadwick was awarded a Clerk-Maxwell studentship in 1920, and enrolled as a Doctor of Philosophy (PhD) student at Gonville and Caius College, Cambridge. The first half of his thesis was his work with atomic numbers. In the second, he looked at the forces inside the nucleus. His degree was awarded in June 1921.[20] In November, he became a Fellow of Gonville and Caius College.[21]



Chadwick's Clerk-Maxwell studentship expired in 1923, and he was succeeded by the Russian physicist Pyotr Kapitza. The Chairman of the Advisory Council of the Department of Scientific and Industrial Research, Sir William McCormick arranged for Chadwick to become Rutherford's assistant director of research. In this role, Chadwick helped Rutherford select PhD students. Over the next few years these would include John Cockcroft, Norman Feather and Mark Oliphant, who would become firm friends with Chadwick. As many students had no idea what they wanted to research, Rutherford and Chadwick would suggest topics. Chadwick edited all the papers produced by the laboratory.[22]

The Cavendish Laboratory - geograph.org.uk - 631839
The Cavendish Laboratory was the home of some of the great discoveries in physics. It was founded in 1874 by the Duke of Devonshire (Cavendish was his family name), and its first professor was James Clerk Maxwell.[23]

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, Walther Bothe and his student Herbert Becker had used polonium to bombard beryllium with alpha particles, producing an unusual form of radiation. Chadwick had his Australian 1851 Exhibition scholar, Hugh Webster, duplicate their results. To Chadwick, this was evidence of something that he and Rutherford had been hypothesising for years: the neutron, a theoretical nuclear particle with no electric charge.[26] Then in January 1932, Feather drew Chadwick's attention to another surprising result. Frédéric and Irène Joliot-Curie had succeeded in knocking protons from paraffin wax using polonium and beryllium as a source for what they thought was gamma radiation. Rutherford and Chadwick disagreed; protons were too heavy for that. But neutrons would need only a small amount of energy to achieve the same effect. In Rome, Ettore Majorana came to the same conclusion: the Joliot-Curies had discovered the neutron but did not know it.[28]

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]

Sir Ernest Rutherfords laboratory, early 20th century. (9660575343)
Sir Ernest Rutherford's laboratory

In February 1932, after only about two weeks of experimentation with neutrons,[15] Chadwick sent a letter to Nature titled "Possible Existence of a Neutron".[30] He communicated his findings in detail in an article sent to Proceedings of the Royal Society A titled "The Existence of a Neutron" in May.[31][32] His discovery of the neutron was a milestone in understanding the nucleus. Reading Chadwick's paper, Robert Bacher and Edward Condon realised that anomalies in the then-current theory, like the spin of nitrogen, would be resolved if the neutron has a spin of 1/2 and that a nitrogen nucleus consisted of seven protons and seven neutrons.[33][34]

The theoretical physicists Niels Bohr and Werner Heisenberg considered whether the neutron could be a fundamental nuclear particle like the proton and electron, rather than a proton–electron pair.[35][36][37][38] Heisenberg showed that the neutron was best described as a new nuclear particle,[37][38] but its exact nature remained unclear. In his 1933 Bakerian Lecture, Chadwick estimated that a neutron had a mass of about 1.0067 u. Since a proton and an electron had a combined mass of 1.0078 u, this implied the neutron as a proton–electron composite had a binding energy of about MeV, which sounded reasonable,[39] although it was hard to understand how a particle with so little binding energy could be stable.[38] Estimating such a small mass difference required challenging precise measurements, however, and several conflicting results were obtained in 1933–4. By bombarding boron with alpha particles, Frédéric and Irène Joliot-Curie obtained a large value for the mass of a neutron, but Ernest Lawrence's team at the University of California produced a small one.[40] Then Maurice Goldhaber, a refugee from Nazi Germany and a graduate student at the Cavendish Laboratory, suggested to Chadwick that deuterons could be photodisintegrated by the 2.6 MeV gamma rays of 208Tl (then known as thorium C"):


→  1


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.[41][42][43] They measured the kinetic energy of the proton produced as 1.05 MeV, leaving the mass of the neutron as the unknown in the equation. Chadwick and Goldhaber calculated that it was either 1.0084 or 1.0090 atomic units, depending on the values used for the masses of the proton and deuteron.[44][43] (The modern accepted value for the mass of the neutron is 1.00866 u.) The mass of the neutron was too large to be a proton–electron pair.[44]

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]

Wolfgang Pauli proposed another kind of particle on 4 December 1930 in order to explain the continuous spectrum of beta radiation that Chadwick had reported in 1914. Since not all of the energy of beta radiation could be accounted for, the law of conservation of energy appeared to be violated, but Pauli argued that this could be redressed if another, undiscovered, particle was involved.[46] Pauli also called this particle a neutron, but it was clearly not the same particle as Chadwick's neutron. Fermi renamed it the neutrino, Italian for "little neutron".[47] In 1934, Fermi proposed his theory of beta decay which explained that the electrons emitted from the nucleus were created by the decay of a neutron into a proton, an electron, and a neutrino.[48][49] The neutrino could account for the missing energy, but a particle with little mass and no electric charge was difficult to observe. Rudolf Peierls and Hans Bethe calculated that neutrinos could easily pass through the Earth, so the chances of detecting them were slim.[50][51] Frederick Reines and Clyde Cowan would confirm the neutrino on 14 June 1956 by placing a detector within a large antineutrino flux from a nearby nuclear reactor.[52]


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 Big Science in general, and Lawrence in particular, whose approach he considered careless and focused on technology at the expense of science. When Lawrence postulated the existence of a new and hitherto unknown particle that he claimed was a possible source of limitless energy at the Solvay Conference in 1933, Chadwick responded that the results were more likely attributable to contamination of the equipment.[54] While Lawrence rechecked his results at Berkeley only to find that Chadwick was correct, Rutherford and Oliphant conducted an investigation at the Cavendish that found that deuterium fuses to form helium-3, thereby causing the effect that the Lawrence had observed. This was another major discovery, but the Oliphant-Rutherford particle accelerator was an expensive state-of-the-art piece of equipment.[55][56][57][58]

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, Otto Hahn and Fritz Strassmann bombarded uranium with neutrons, and noted that barium, a lighter element, was among the products produced. Hitherto, only the same or heavier elements had been produced by the process. In January 1939, Meitner and her nephew Otto Frisch astounded the physics community with a paper that explained this result.[67] They theorised that uranium atoms bombarded with neutrons can break into two roughly equal fragments, a process they called fission. They calculated that this would result in the release of about 200 MeV, implying an energy release orders of magnitude greater than chemical reactions,[68] and Frisch confirmed their theory experimentally.[69] It was soon noted by Hahn that if neutrons were released during fission, then a chain reaction was possible.[70] French scientists, Pierre Joliot, Hans von Halban and Lew Kowarski, soon verified that more than one neutron was indeed emitted per fission.[71] In a paper co-authored with the American physicist John Wheeler, Bohr theorised that fission was more likely to occur in the uranium-235 isotope, which made up only 0.7 percent of natural uranium.[72][73]

William Penney, Otto Frisch, Rudolf Peierls and John Cockroft
Key British physicists. Left to right: William Penney, Otto Frisch, Rudolf Peierls and John Cockcroft. They are wearing the Medal of Freedom.

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 Second World War therefore came as a shock. Determined not to spend another war in an internment camp, Chadwick made his way to Stockholm as fast as he could, but when he arrived there with his family, he found that all air traffic between Stockholm and London had been suspended. They made their way back to England on a tramp steamer. When he reached Liverpool, Chadwick found Joseph Rotblat, a Polish post-doctoral fellow who had come to work with the cyclotron, was now destitute, as he was cut off from funds from Poland. Chadwick promptly hired Rotblat as a lecturer, despite his poor grasp of English.[74]

In October 1939, Chadwick received a letter from Sir Edward Appleton, the Secretary of the Department of Scientific and Industrial Research, asking for his opinion on the feasibility of an atomic bomb. Chadwick responded cautiously. He did not dismiss the possibility, but carefully went over the many theoretical and practical difficulties involved. Chadwick decided to investigate the properties of uranium oxide further with Rotblat.[75] In March 1940, Otto Frisch and Rudolf Peierls at the University of Birmingham re-examined the theoretical issues involved in a paper that became known as the Frisch–Peierls memorandum. Instead of looking at uranium metal, they considered what would happen to a sphere of pure uranium-235, and found that not only could a chain reaction occur, but that it might require as little as 1 kilogram (2.2 lb) of uranium-235, and unleash the energy of tons of dynamite.[76]

Liverpool Blitz D 5984
Part of Liverpool devastated by the Blitz

A special subcommittee of the Committee for the Scientific Survey of Air Warfare (CSSAW), known as the MAUD Committee, was created to investigate the matter further. It was chaired by Sir George Thomson and its original membership included Chadwick, along with Mark Oliphant, John Cockcroft and Philip Moon.[77] While other teams investigated uranium enrichment techniques, Chadwick's team at Liverpool concentrated on determining the nuclear cross section of uranium-235.[78] By April 1941, it had been experimentally confirmed that the critical mass of uranium-235 might be 8 kilograms (18 lb) or less.[79] His research into such matters was complicated by all-but-incessant Luftwaffe bombings of the environs of his Liverpool lab; the windows were blown out so often that they were replaced by cardboard.[80]

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 atomic 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 utilise Chadwick's talents.[90]

The matter of cooperation had to be taken up at the highest level. In September 1943, the Prime Minister, Winston Churchill, and President Roosevelt negotiated the Quebec Agreement, which reinstated cooperation between Britain, the United States and Canada. Chadwick, Oliphant, Peierls and Simon were summoned to the United States by the director of Tube Alloys, Sir Wallace Akers, to work with the Manhattan Project. The Quebec Agreement established a new Combined Policy Committee to direct the joint project. The Americans disliked Akers, so Chadwick was appointed technical advisor to the Combined Policy Committee, and the head of the British Mission.[91]

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]

Groves and Chadwick 830308
Chadwick (left) with Major General Leslie R. Groves, Jr., the director of the Manhattan Project

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, Major General Leslie R. Groves, Jr., he attempted to do everything he could to support the effort.[95] He also endeavoured to place British scientists in as many parts of the project as possible in order to facilitate a post-war British nuclear weapons project to which Chadwick was committed. Requests from Groves via Chadwick for particular scientists tended to be met with an immediate rejection by the company, ministry or university currently employing them, only to be overcome by the overriding priority accorded to Tube Alloys.[96] As a result, the British team was critical to the Project's success.[97]

Although he had more knowledge of the project than anyone else from Britain,[98] Chadwick had no access to the Hanford site. Lord Portal was offered a tour of Hanford in 1946. "This was the only plant to which Chadwick had been denied access in wartime, and now he asked Groves if he could accompany Portal. Groves replied that he could, but if he did then 'Portal will not see very much'."[99] For his efforts, Chadwick received a knighthood in the New Year Honours on 1 January 1945.[100] He considered this to be a recognition of the work of the whole Tube Alloys project.[101]

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 Dupont Circle in April 1945.[101] He was present at the meeting of the Combined Policy Committee on 4 July when Field Marshal Sir Henry Maitland Wilson gave Britain's agreement to use the atomic bomb against Japan,[102] and at the Trinity nuclear test on 16 July, when the first atomic bomb was detonated.[103] Inside its pit was a polonium-beryllium modulated neutron initiator, a development of the technique that Chadwick had used to discover the neutron over a decade before.[104] William L. Laurence, the New York Times reporter attached to the Manhattan Project, wrote that "never before in history had any man lived to see his own discovery materialize itself with such telling effect on the destiny of man."[105]

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 Master of Gonville and Caius College. The job was prestigious but ill-defined; the Master was the titular head of the College, but authority actually resided in a council of 13 fellows, of whom one was the Master. As Master, Chadwick strove to improve the academic reputation of the college. He increased the number of research fellowships from 31 to 49, and sought to bring talent into the college.[108] This involved controversial decisions, such as hiring in 1951 the Chinese biochemist Tien-chin Tsao[109] and the Hungarian-born economist Peter Bauer. In what became known as the Peasants' Revolt, fellows led by Patrick Hadley voted an old friend of Chadwick's off the council and replaced him with Bauer. More friends of Chadwick's were removed over the following years, and he retired in November 1958. It was during his mastership that Francis Crick, a PhD student at Gonville and Caius College, and James Watson discovered the structure of DNA.[108]

Over the years, Chadwick received many honours, including the Medal for Merit from the United States, and the Pour le Mérite from Germany.[110] He was elected a Fellow of the Royal Society in 1927,[111] and in 1946 he became foreign member of the Royal Netherlands Academy of Arts and Sciences.[112] He was made a Companion of Honour in the New Year Honours on 1 January 1970 for "services to science",[113] and went to Buckingham Palace for the investiture ceremony. He 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]

His 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 is named after him,[115] as is its Sir James Chadwick Chair of Experimental Physics, which was named after him in 1991 as part of celebrations of the centenary of his birth.[116] A crater on the moon is also named after him.[117] The James Chadwick Building, which houses part of the School of Chemical Engineering and Analytical Sciences, University of Manchester is named in his honour.[118] He 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]


  1. ^ a b c d "James Chadwick". academictree.org. Retrieved 21 July 2014.
  2. ^ "Ernest Rutherford". Figures in Radiation History. Michigan State University. Archived from the original on 29 June 2015. Retrieved 3 June 2014.
  3. ^ Falconer 2004.
  4. ^ Oliphant 1974.
  5. ^ Brown 1997, pp. 3–5.
  6. ^ a b "James Chadwick – Biography". The Nobel Foundation. Retrieved 21 April 2013.
  7. ^ Rutherford & Chadwick 1912.
  8. ^ Brown 1997, pp. 6–14.
  9. ^ Brown 1997, pp. 16–21.
  10. ^ Chadwick 1914.
  11. ^ Chadwick & Ellis 1922.
  12. ^ a b Weiner 1969.
  13. ^ Jensen 2000, pp. 88–90.
  14. ^ Brown 1997, pp. 24–26.
  15. ^ a b "This Month in Physics History: May 1932: Chadwick reports the discovery of the neutron". APS News. 16 (5): 2. 2007.
  16. ^ "Obituary: Sir James Chadwick". The Times. 25 July 1974. p. 20, column F.
  17. ^ "Obituary: Sir Charles Ellis". The Times. 15 January 1980. p. 14, column F.
  18. ^ a b Brown 1997, p. 39.
  19. ^ Brown 1997, pp. 43.
  20. ^ Brown 1997, pp. 43–50.
  21. ^ Brown 1997, p. 58.
  22. ^ a b Brown 1997, pp. 73–76.
  23. ^ "The History of the Cavendish". University of Cambridge. Retrieved 15 August 2014.
  24. ^ Brown 1997, p. 85.
  25. ^ Brown 1997, pp. 92–93.
  26. ^ a b Brown 1997, pp. 95–97.
  27. ^ Sublette 2006.
  28. ^ a b Brown 1997, pp. 103–104.
  29. ^ "Oral History interview transcript with Norman Feather, Session I". American Institute of Physics, Niels Bohr Library and Archives. 25 February 1971.
  30. ^ Chadwick 1932a.
  31. ^ Chadwick 1932b.
  32. ^ Chadwick 1933.
  33. ^ Whaling 2009, pp. 8–9.
  34. ^ Bacher & Condon 1932.
  35. ^ Heisenberg 1932a.
  36. ^ Heisenberg 1932b.
  37. ^ a b Heisenberg 1933.
  38. ^ a b c Bromberg 1971.
  39. ^ Brown 1997, pp. 115–116.
  40. ^ Heilbron & Seidel 1989, pp. 153–157.
  41. ^ Goldhaber 1934.
  42. ^ Chadwick & Goldhaber 1934.
  43. ^ a b Chadwick & Goldhaber 1935.
  44. ^ a b Brown 1997, pp. 122–125.
  45. ^ Brown 1997, pp. 125.
  46. ^ Brown 1997, pp. 119–120.
  47. ^ Close 2012, pp. 15–18.
  48. ^ Fermi 1968.
  49. ^ Close 2012, pp. 22–25.
  50. ^ Close 2012, pp. 26–28.
  51. ^ Bethe, H; Peierls, R (7 April 1934). "The Neutrino". Nature. 133 (3362): 532. Bibcode:1934Natur.133..532B. doi:10.1038/133532a0. ISSN 0028-0836.
  52. ^ Close 2012, pp. 37–41.
  53. ^ Brown 1997, pp. 129–132.
  54. ^ Herken 2002, p. 10.
  55. ^ Heilbron & Seidel 1989, pp. 165–167.
  56. ^ Oliphant & Rutherford 1933.
  57. ^ Oliphant, Kinsey & Rutherford 1933.
  58. ^ Oliphant, Harteck & Rutherford 1934.
  59. ^ Brown 1997, pp. 134–139.
  60. ^ Gannon, Megan (4 June 2014). "Sold! Nobel Prize for Neutron Discovery Auctioned for $329,000". Yahoo News. Retrieved 16 September 2014.
  61. ^ Brown 1997, p. 142.
  62. ^ Brown 1997, pp. 149–151.
  63. ^ Holt 1994.
  64. ^ Brown 1997, pp. 173–174.
  65. ^ King 1997.
  66. ^ Brown 1997, p. 150.
  67. ^ Brown 1997, p. 170.
  68. ^ Meitner & Frisch 1939.
  69. ^ Frisch 1939.
  70. ^ Hahn & Strassmann 1939.
  71. ^ von Halban, Joliot & Kowarski 1939.
  72. ^ Gowing 1964, pp. 24–27.
  73. ^ Bohr & Wheeler 1939.
  74. ^ Brown 1997, pp. 174–178.
  75. ^ Gowing 1964, pp. 38–39.
  76. ^ Gowing 1964, pp. 39–41.
  77. ^ Gowing 1964, p. 45.
  78. ^ Gowing 1964, p. 63.
  79. ^ Brown 1997, p. 206.
  80. ^ Brown 1997, p. 204.
  81. ^ Bundy 1988, pp. 48–49.
  82. ^ a b Gowing 1964, p. 85.
  83. ^ Gowing 1964, p. 109.
  84. ^ Farmelo 2013, p. 119.
  85. ^ Brown 1997, p. 205.
  86. ^ Bondi 1997.
  87. ^ Brown 1997, pp. 197–198.
  88. ^ Brown 1997, pp. 218–219.
  89. ^ Gowing 1964, pp. 141–142.
  90. ^ Gowing 1964, p. 152.
  91. ^ Gowing 1964, pp. 166–171.
  92. ^ Brown 1997, p. 253.
  93. ^ Brown 1997, pp. 250–261.
  94. ^ Hoddeson et al. 1993, p. 95.
  95. ^ Brown 1997, pp. 247–51.
  96. ^ Gowing 1964, pp. 241–244.
  97. ^ Szasz 1992, p. xvi.
  98. ^ Gowing 1964, p. 329.
  99. ^ Brown 1997, p. 317.
  100. ^ "No. 36866". The London Gazette (Supplement). 29 December 1944. p. 1. Knight Bachelor
  101. ^ a b Brown 1997, p. 279.
  102. ^ Brown 1997, p. 290.
  103. ^ Brown 1997, p. 292.
  104. ^ Brown 1997, p. 287.
  105. ^ Laurence 1946, p. 26.
  106. ^ Brown 1997, pp. 306, 316.
  107. ^ Brown 1997, p. 323.
  108. ^ a b Brown 1997, pp. 340–353.
  109. ^ Zhang 2010.
  110. ^ a b Brown 1997, pp. 360–363.
  111. ^ Massey & Feather 1976, p. 11.
  112. ^ "J. Chadwick (1891–1974)". Royal Netherlands Academy of Arts and Sciences. Retrieved 21 July 2015.
  113. ^ "No. 44999". The London Gazette (Supplement). 30 December 1969. p. 23. Companion of Honour
  114. ^ "The Papers of Sir James Chadwick". Janus. Retrieved 26 April 2013.
  115. ^ "Liverpool Science Places". Scienceplaces.org. Archived from the original on 15 August 2014. Retrieved 6 August 2014.
  116. ^ "University Chairs and their Holders Past and Present" (PDF). University of Liverpool. Retrieved 1 August 2014.
  117. ^ "Planetary Names: Crater, craters: Chadwick on Moon". United States Geological Survey. Archived from the original on 22 November 2017. Retrieved 12 August 2012.
  118. ^ "James Chadwick Building - directions". The University of Manchester. Retrieved 18 May 2016.
  119. ^ Arnold 1998.


Further reading

Academic offices
Preceded by
John Forbes Cameron
Master of Gonville and Caius College
Succeeded by
Sir Nevill Francis Mott
Angels We Have Heard on High

"Angels We Have Heard on High" is a Christmas carol with the lyrics written by James Chadwick, Bishop of Hexham and Newcastle, to the music from a French song called Les Anges Dans Nos Campagnes. The music is the same as the original song, though Chadwick's lyrics albeit unique and original are clearly derived and inspired, and in parts a loose translation. The song's subject is the birth of Jesus Christ narrated in the Gospel of Luke, specifically the scene in which shepherds outside Bethlehem encounter a multitude of angels singing and praising the newborn child.


Chadwickryggen is a mountain on Spitsbergen in Svalbard, Norway. At 1,640 metres (5,380 ft) high, it is the fourth-largest peak on Svalbard. It is located west of Wijdefjorden between Smutsbreen and Tryggvebreen in Ny-Friesland. It is named for the English physicist James Chadwick (1891–1974).

Churchill Archives Centre

The Churchill Archives Centre (CAC) is one of the largest repositories in the United Kingdom for the preservation and study of modern personal papers. It is best known for housing the papers of Sir Winston Churchill, the private papers of Baroness Thatcher, and a wide range of political, diplomatic, military and scientific collections, including such well-known modern personalities as: Ernest Bevin, Enoch Powell, Lord Kinnock, Sir John Colville, Lord Hankey, Admiral Lord Fisher, Field Marshal Lord Slim, Sir John Cockcroft, Sir James Chadwick, Professor Lise Meitner, Dr Rosalind Franklin and Sir Frank Whittle.

The Centre is located in the grounds of Churchill College, Cambridge, England, itself the National and Commonwealth Memorial to Churchill. It has been awarded designated status by the Museums, Libraries and Archives Council. It is open to the public and welcomes enquiries about its collections. Its mission is to preserve the collections in its care for future generations and to make them as accessible as possible.

Electron neutrino

The electron neutrino (νe) is a subatomic lepton elementary particle which has zero net electric charge. Together with the electron it forms the first generation of leptons, hence the name electron neutrino. It was first hypothesized by Wolfgang Pauli in 1930, to account for missing momentum and missing energy in beta decay, and was discovered in 1956 by a team led by Clyde Cowan and Frederick Reines (see Cowan–Reines neutrino experiment).

Franklin Medal

The Franklin Medal was a science award presented from 1915 through 1997 by the Franklin Institute located in Philadelphia, Pennsylvania, U.S. It was founded in 1914 by Samuel Insull.

The Franklin Medal was the most prestigious of the various awards presented by the Franklin Institute. Together with other historical awards, it was merged into the Benjamin Franklin Medal, initiated in 1998.

Gonville and Caius College, Cambridge

Gonville & Caius College (often referred to simply as Caius KEEZ) is a constituent college of the University of Cambridge in Cambridge, England. The college is the fourth-oldest college at the University of Cambridge and one of the wealthiest. The college has been attended by many students who have gone on to significant accomplishment, including fourteen Nobel Prize winners, the second-most of any Oxbridge college (after Trinity College, Cambridge).The college has long historical associations with medical teaching, especially due to its alumni physicians: John Caius (who gave the college the caduceus in its insignia) and William Harvey. Other famous alumni in the sciences include Francis Crick (joint discoverer, along with James Watson, of the structure of DNA), James Chadwick (discoverer of the neutron) and Howard Florey (developer of penicillin). Stephen Hawking, previously Cambridge's Lucasian Chair of Mathematics Emeritus, was a fellow of the college until his death in 2018. The college also maintains reputable academic programmes in many other disciplines, including law, economics, English literature and history.

Several streets in the city, such as Harvey Road, Glisson Road and Gresham Road, are named after alumni of the College. The college and its masters have been influential in the development of the university, founding other colleges like Trinity Hall and Darwin College and providing land on the Sidgwick Site, e.g. for the Squire Law Library.

J. F. Cameron

John Forbes Cameron (July 1873 – 21 March 1952) was a Scottish mathematician, academic and academic administrator. He was Master of Gonville and Caius College, Cambridge from 1928 to 1948 and was Vice-Chancellor of the University of Cambridge from 1933 to 1935.

James Chadwick (bishop)

James Chadwick (24 April 1813 at Drogheda, Ireland – 14 May 1882 at Newcastle-upon-Tyne, and buried at Ushaw) was an Anglo-Irish Roman Catholic priest, and second Bishop of Hexham and Newcastle. He is famous for writing the lyrics of the song Angels We Have Heard on High.

James Chadwick Medal and Prize

The James Chadwick Medal and Prize is a biennial award presented by Institute of Physics (IOP) for distinguished research in particle physics. The medal is accompanied by a prize of £1000 and a certificate. It is named for Nobel Prize–winning physicist James Chadwick.

James Dunkerley

James Chadwick Dunkerley OBE is Professor of Politics at Queen Mary, University of London, and the former Director of the Institute for the Study of the Americas and the Institute of Latin American Studies of the University of London. He has written extensively on Bolivia, Central America, and elsewhere in Latin America.

Dunkerley was appointed Officer of the Order of the British Empire (OBE) in the 2010 Birthday Honours.

Jimmy Townley

James Chadwick Townley (2 May 1902 – 1983) was an English professional footballer who played Victoria Hamburg, FC St Gallen, Chelsea, Tottenham Hotspur, Brighton & Hove Albion and Clapton Orient.

John Dainton

John Bourke Dainton FRS is a British physicist, and Sir James Chadwick Professor of Physics, at University of Liverpool. Dainton was awarded the Max Born Prize in 1999.

His father was Frederick Dainton, Baron Dainton.

He was founding director of the Cockcroft Institute.He was elected a Fellow of the Royal Society in 2002 and in 2018 he became Editor of the Royal Society journal, Philosophical Transactions of the Royal Society A.

John McLachlan (bishop)

John McLachlan (1826–1893) was a Scottish Roman Catholic clergyman who served as the Bishop of Galloway from 1878 to 1893.Born in Glasgow, Scotland on 7 September 1826, he was ordained to the priesthood on 16 March 1850. He was appointed the Bishop of the Diocese of Galloway by the Holy See on 22 March 1878, and consecrated to the Episcopate on 23 May 1878. The principal consecrator was Archbishop Charles Petre Eyre of Glasgow, and the principal co-consecrators were Bishop James Chadwick of Hexham and Newcastle and Bishop John MacDonald of Aberdeen.He died in office on 16 January 1893, aged 66. His Pontifical Mass of Requiem was celebrated at St Andrew's Cathedral in Dumfries after which his coffin was borne to the vaults beneath the church.

List of Fellows of the Royal Society elected in 1696

This is a list of Fellows of the Royal Society elected in 1696.

Maurice Pryce

Maurice Henry Lecorney Pryce (24 January 1913 – 24 July 2003) was a British physicist.

Pryce was born in Croydon to an Anglo-Welsh father and French mother, and in his teens attended the Royal Grammar School, Guildford. After a few months in Heidelberg to add German to the French that had been his first language at home, he went up to Trinity College, Cambridge. In 1935 he went to Princeton University, supported by a Commonwealth Fund Fellowship (now Harkness Fellowship) where he worked with Wolfgang Pauli and John von Neumann, obtaining his Ph.D. with a thesis on The wave mechanics of the photon under the supervision of Max Born and Ralph Fowler. In 1937 he returned to England as a Fellow of Trinity, until in 1939 he was appointed Reader in Theoretical Physics at Liverpool University under James Chadwick. In 1941 he joined the Admiralty Signals Establishment (now part of the Admiralty Research Establishment) to work on radar. In 1944 he joined the British atomic energy team in Montreal designing nuclear reactors, but in 1945 returned to England, first to Cambridge and then in 1946 to Oxford, where he was appointed Wykeham Professor of Physics.

Among of his doctoral students were Anatole Abragam and John Clive Ward. In 1947, in collaboration with John Ward, he co-authored a paper that originated on the probability amplitude of two entangled quanta propagating in opposite directions.In 1950, when Klaus Fuchs, head of the theoretical physics group at AERE, Harwell, was arrested for supplying atomic secrets to the USSR, Maurice also served part-time as his replacement. In 1954 he moved to the University of Bristol as Head of the Physics Department. In 1964 he went back to North America, first to the University of Southern California and then in 1968 to the University of British Columbia. From 1968 to 1978 he served on the Technical Advisory Committee (for nuclear waste management) of Atomic Energy of Canada Limited.

Nuclear physics

Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions. Other forms of nuclear matter are also studied.

Nuclear physics should not be confused with atomic physics, which studies the atom as a whole, including its electrons.

Discoveries in nuclear physics have led to applications in many fields. This includes nuclear power, nuclear weapons, nuclear medicine and magnetic resonance imaging, industrial and agricultural isotopes, ion implantation in materials engineering, and radiocarbon dating in geology and archaeology. Such applications are studied in the field of nuclear engineering.

Particle physics evolved out of nuclear physics and the two fields are typically taught in close association. Nuclear astrophysics, the application of nuclear physics to astrophysics, is crucial in explaining the inner workings of stars and the origin of the chemical elements.

Science and engineering in Manchester

Manchester is one of the principal cities of the United Kingdom, gaining city status in 1853, thus becoming the first new city in over 300 years since Bristol in 1542. Often regarded as the first industrialised city, Manchester was a city built by the Industrial Revolution and had little pre-medieval history to speak of. Manchester had a population of 10,000 in 1717, but by 1911 it had burgeoned to 2.3 million.As its population and influence burgeoned, Manchester became a centre for new discoveries, scientific breakthroughs and technological developments in engineering. A famous but unattributed quote linked to Manchester is: "What Manchester does today, the rest of the world does tomorrow". Pioneering breakthroughs such as the first 'true' canal which spawned 'Canal Mania', the first intercity railway station which led to 'railway mania' and the first stored-program computer. The city has achieved great success in the field of physics, with the electron (J. J. Thomson, 1897), proton (Rutherford, 1917), neutron (James Chadwick, 1934) all being discovered by scientists educated (Chadwick and Rutherford) or born (Thomson) in Manchester.

Famous scientists to have studied in Manchester include John Dalton, James Prescott Joule, J. J. Thomson, Ernest Rutherford, James Chadwick and Alan Turing. A creative and often seen as a bohemian city, Manchester also had the highest number of patent applications per head of population in the United Kingdom in 2003. The city is served by the University of Manchester, previously UMIST and the Victoria University of Manchester pre-2004. The university has a total of 25 Nobel Laureates; only the Oxbridge universities have more Nobel laureates. The city is also served by the Museum of Science and Industry celebrating Mancunian, as well as national achievements in both fields.

Étienne Biéler

Étienne Samuel Biéler (3 February 1895 – 25 July 1929) was a Swiss-born Canadian physicist who made important advances in the study of the strong interaction that holds the atomic nucleus together.

A graduate of McGill University, he worked at the Cavendish Laboratory, where he studied the atomic nucleus under Sir Ernest Rutherford and James Chadwick. A 1921 paper with Chadwick has been hailed as "marking the birth of the strong interactions". In his doctoral thesis, Biéler explored the strong interaction, and showed that it varied with the fourth power of the distance.

Biéler returned to Canada, where he was appointed Assistant Professor of physics at McGill. He became interested in geophysics, and he attempted to develop electrical methods for detecting hidden bodies of ore. He was given two years' leave from McGill to participate in an Imperial Geophysical Experimental Survey to try out various methods of ore detection. While in Australia he became ill and died of pneumonia on 28 July 1929.

Recipients of the Copley Medal (1901–1950)
Gonville Hall
Gonville and Caius College
Related topics

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.