John Cockcroft

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Sir John Cockcroft
Born (1897-05-27)27 May 1897
Todmorden, England
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Cambridge, England
Nationality United Kingdom
Fields Physics
Institutions Atomic Energy Research Establishment
Alma mater Victoria University of Manchester
Manchester College of Technology
St. John's College, Cambridge
Academic advisors Ernest Rutherford
Notable students Ishfaq Ahmad
Known for Splitting the atom
Influences Horace Lamb
Notable awards Hughes Medal (1938)
Nobel Prize in Physics (1951)
Royal Medal (1954)
Faraday Medal (1955)
Atoms for Peace Award (1961)
Wilhelm Exner Medal (1961)

Sir John Douglas Cockcroft OM KCB CBE FRS (27 May 1897 – 18 September 1967)[1][2] was a British physicist. He shared the Nobel Prize in Physics for splitting the atomic nucleus with Ernest Walton, and was instrumental in the development of nuclear power. He was the first Master of Churchill College and is buried at the Parish of the Ascension Burial Ground in Cambridge, together with his wife Elizabeth and son John, known as Timothy, who had died at the age of two in 1929.

Early years

Cockcroft was born in Todmorden, West Yorkshire, England, the eldest son of a mill owner. He was educated at Todmorden Secondary School (1909–1914) (where his physics teacher, Luke Sutcliffe, would later tutor another future Nobel Prize-winner, Geoffrey Wilkinson) and studied mathematics at the Victoria University of Manchester (1914–1915). He was a signaller in the Royal Artillery from 1915 to 1918. After the war ended, he studied electrotechnical engineering at UMIST from 1919 until 1920. He undertook an apprenticeship with Metropolitan Vickers Electrical Company whilst in receipt of an 1851 Exhibition Scholarship from the Royal Commission for the Exhibition of 1851.[3] He then went to St. John's College, Cambridge, from where he received a mathematics degree in 1924, and began research work under Ernest Rutherford. In 1929 he was elected a Fellow of St. John's College; in 1939, he became Jacksonian Professor of Philosophy.

Nuclear research

In 1928, he began to work on the acceleration of protons with Ernest Walton. In 1932, they bombarded lithium with high energy neutrons, electrons and protons and succeeded in transmuting it into helium and other chemical elements. This was one of the earliest experiments to change the atomic nucleus of one element to a different nucleus by artificial means. This feat was popularly known as splitting the atom.

At the outbreak of the Second World War, he took up the post of Assistant Director of Scientific Research in the Ministry of Supply, working on radar. In 1944, he took charge of the Canadian Atomic Energy project and became Director of the Montreal Laboratory and Chalk River Laboratories, replacing Hans von Halban, who was considered a security risk. In 1946, he returned to Britain to set up the Atomic Energy Research Establishment (AERE) at Harwell, charged with developing Britain's atomic power programme. He became the first director of AERE. Even when leaving the post, he continued to be involved with Harwell. He was made a Commander of the Order of the British Empire in 1944, knighted in 1948, and created Knight Commander of the Order of the Bath in 1953.

In post-war years, AERE under his direction took part in frontier fusion research, including the ZETA program.

Cockcroft's folly

As director of the AERE, he famously insisted that the coolant discharge chimney stacks of the Windscale plutonium production reactors be fitted, at great expense, with high performance filters. Since this was decided after the stacks had been designed, they produced iconic lumps in the shape of the structures. The reactors were designed to remain clean and uncorroded during use, thus it was not considered that there would be any particulate present for the filters to catch. These filters were therefore known as Cockcroft's Folly until the core of one of the two reactors famously caught fire in the Windscale fire of 1957, and the filters prevented the disaster from becoming a catastrophe.[4] Terence Price, future scientific advisor at the Ministry of Defence in the 1960s, pointed out "the word folly did not seem appropriate after the accident".[5]

Personal life

Cockcroft married Eunice Elizabeth Crabtree (born 26 October 1898, died 4 October 1989) in 1925 and had six children: John Haslam, known as Timothy, born 29 January 1927, died 11 October 1929; Joan Dorothea, known as Thea, born 5 October 1932; Jocelyn, born 1 September 1934; Elisabeth Fielden, born 23 February 1936; Catherine Helena, born 17 October 1939; and Christopher Hugh John, born 14 January 1942. He died at Churchill College, Cambridge, 18 September 1967; he is buried at the Parish of the Ascension Burial Ground in Cambridge, in the same grave as his wife and son John, known as Timothy.[6] John R. Cockcroft is his great nephew, notable in the field of cardiology and arterial stiffness.


In 1951, Cockcroft, along with Walton, was awarded the Nobel Prize in Physics for his work in the use of accelerated particles to study the atomic nucleus. In 1959, he became the first Master of Churchill College, Cambridge. He was president of the Institute of Physics, the Physics Society, and the British Association for the Advancement of Science. Cockcroft served as chancellor of the Australian National University from 1961 to 1965. He received the American Atoms for Peace Award in 1961. He delivered the Rutherford Memorial Lecture in 1944.

Today, six buildings in the United Kingdom are named after him: the Cockcroft building at the New Museums Site of the University of Cambridge, comprising a lecture theatre and several hardware laboratories; the Cockcroft Institute at Daresbury Laboratory in Cheshire; the Cockcroft Hall lecture theatre at the Harwell Science and Innovation Centre; the Cockcroft building of the University of Brighton; and the Cockcroft building of the University of Salford, in the town of Todmorden, where he was born, there is a housing block (Cockroft House) named after him which is next to Wilkinson House which is named after Todmorden's other Nobel Prize winner Geoffrey Wilkinson. The oldest building at the Research School of Physical Sciences and Engineering, Australian National University, the Cockcroft building, is named after him. In Ontario Canada, a short distance from the Chalk River Laboratories, a road in Deep River is named Cockcroft Crescent in recognition of his work at Chalk River.

In the 1950s, the AERE commissioned a number of homes to be built in the nearby town of Didcot for the many Harwell workers who lived there. The "focal" road of this development in the south of the town (the one with the shops, school and public house) is named Cockcroft Road.


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  3. 1851 Royal Commission Archives
  4. BBC News: Windscale Piles: Cockcroft's Follies avoided nuclear disaster
  5. BBC News: Windscale Piles: Cockcroft's Follies avoided nuclear disaster
  6. A Guide to Churchill College, Cambridge: text by Dr. Mark Goldie, pages 62 and 63 (2009)

Further reading

External links

Academic offices
New title Master of
Churchill College, Cambridge

Succeeded by
William Hawthorne
Preceded by Chancellor of the Australian National University
1961 – 1965
Succeeded by
Baron Florey