James Chadwick was born in Cheshire, England, on 20 October, 1891. He attended Manchester High School prior to entering Manchester University in 1908; he graduated from the Honours School of Physics in 1911 and spent the next two years under Professor (later Lord) Rutherford in the Physical Laboratory in Manchester, where he worked on various radioactivity problems, gaining his M.Sc. degree in 1913.
After the World War I in 1919, he returned to England at and resume work under Rutherford. Chadwick joined Rutherford in accomplishing the transmutation of other light elements by bombardment with alpha particles, and in making studies of the properties and structure of atomic nuclei.
In 1932, Chadwick made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons—elementary particles devoid of any electrical charge. Chadwick in this way prepared the way towards the fission of uranium 235 and towards the creation of the atomic bomb. For this epoch-making discovery he was awarded the Hughes Medal of the Royal Society in 1932, and subsequently the Nobel Prize for Physics in 1935.
From 1943 to 1946 he worked in the United States as Head of the British Mission attached to the Manhattan Project for the development of the atomic bomb. He returned to England and, in 1948, retired from active physics. From 1957 to 1962 he was a part-time member of the United Kingdom Atomic Energy Authority.
Chadwick has had many papers published on the topic of radioactivity and connected problems and, with Lord Rutherford and C.D. Ellis, he is co-author of the book Radiations from Radioactive substances (1930).
Sir James was knighted in 1945. Apart from the Hughes Medal (Royal Society) mentioned above, he received the Copley Medal (1950) and the Franklin Medal of the Franklin Institute, Philadelphia (1951).
Sir James Chadwick died on July 24, 1974.
