James Chadwick

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James Chadwick was a renowned physicist, most famous for solving the puzzle of the weight of an atom by discovering the neutron.

Chadwick was born in 1891 in Bollington, Cheshire and was brought up by his grandparents in his childhood before he moved in with his parents in Manchester when he started Grammar School. From 1908 he started attending the Victoria University of Manchester and at the end of his first year he won a scholarship to study physics. Chadwick was the student of Ernest Rutherford, widely regarded as the father of nuclear physics, who headed the physics department. Chadwick co-authored his first scientific paper with Rutherford and graduated with honours in 1911. In 1912, he was awarded a master’s degree for his work on measuring the absorption of gamma rays by various gases and liquids. Chadwick won the prestigious 1851 Exhibition Scholarship and went to Berlin to study beta radiation under Hans Geiger. Using the Geiger counter, Chadwick demonstrated that beta radiation did not produce discrete lines but a continuous electromagnetic spectrum.

As the World War 1 started, Chadwick was imprisoned in the Ruhleben internment camp but he was allowed to set up a laboratory in the stables and carry on his experiments. At the end of the war, he was released and he returned to Manchester, published his findings and started teaching. In 1919, Rutherford became the director of the Cavendish Laboratory at the University of Cambridge and Chadwick soon joined him there. He enrolled as a PhD student and worked on atomic numbers and studies forces within the nucleus of an atom. He received his doctorate degree in 1921. From 1923, he helped Rutherford as the Assistant Director of the Department of Scientific and Industrial Research.

In 1832, after experimenting with neutrons he published his findings in detail in ‘The Existence of a Neutron’. Chadwick also determined the mass of the neutron and found that it was greater than that of the proton. 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. The discovery of the electron made it possible to produce heavier elements than uranium in the laboratory.

From 1935, Chadwick had started teaching physics at the University of Liverpool. He spent his award money refurbishing the laboratories at Liverpool and also installed a cyclotron. In 1939, after the discovery of nuclear fission, and as the World War II was starting, Chadwick, under the instigation of the Department of Scientific and Industrial Research started experimenting with the possibility of an atomic bomb. In 1941, he wrote the final draft of the MAUD report, which marked the beginning of the British atomic bomb project before the U.S. government also joined forces thereby starting the Manhattan Project. Chadwick became the head of the British Mission and worked at the Los Alamos Laboratory in Washington DC. For his contributions to the atomic bomb project, Chadwick was knighted in 1945. After the war ended, he served as the British scientific advisor to the United Nations Atomic Energy Commission. Chadwick was convinced that Britain should acquire its own nuclear weapons.

In 1946, Chadwick returned to Britain and from 1948 he became the Master of Gonville and Caius College, Cambridge and spent his years improving the academic reputation of the college until his retirement in 1959.