British contribution to the Manhattan Project
Britain initiated the first research project to design an atomic bomb in 1941. Building on this work, Britain prompted the United States to recognise how important this type of research was, helped the U.S. to start the Manhattan Project in 1942, and supplied crucial expertise and materials that contributed to the project's successful completion in time to influence the end of the Second World War.
Following the discovery of nuclear fission in uranium, scientists Rudolf Peierls and Otto Frisch at the University of Birmingham calculated, in March 1940, that the critical mass of a metallic sphere of pure uranium-235 was as little as 1 to 10 kilograms (2.2 to 22.0 lb), and would explode with the power of thousands of tons of dynamite. The Frisch–Peierls memorandum prompted Britain to create an atomic bomb project, known as Tube Alloys. Mark Oliphant, an Australian physicist working in Britain, was instrumental in making the results of the British MAUD Report known in the United States in 1941 by a visit in person. Initially the British project was larger and more advanced, but after the United States entered the war, the American project soon outstripped and dwarfed its British counterpart. The British government then decided to shelve its own nuclear ambitions, and participate in the American project.
In August 1943, the Prime Minister of the United Kingdom, Winston Churchill, and the President of the United States, Franklin D. Roosevelt, signed the Quebec Agreement, which provided for cooperation between the two countries. The Quebec Agreement established the Combined Policy Committee and the Combined Development Trust to coordinate the efforts of the United States, the United Kingdom and Canada. The subsequent Hyde Park Agreement in September 1944 extended this cooperation to the postwar period. A British Mission led by Wallace Akers assisted in the development of gaseous diffusion technology in New York. Britain also produced the powdered nickel required by the gaseous diffusion process. Another mission, led by Oliphant who acted as deputy director at the Berkeley Radiation Laboratory, assisted with the electromagnetic separation process. As head of the British Mission to the Los Alamos Laboratory, James Chadwick led a multinational team of distinguished scientists that included Sir Geoffrey Taylor, James Tuck, Niels Bohr, Peierls, Frisch, and Klaus Fuchs, who was later revealed to be a Soviet atomic spy. Four members of the British Mission became group leaders at Los Alamos. William Penney observed the bombing of Nagasaki and participated in the Operation Crossroads nuclear tests in 1946.
Cooperation ended with the Atomic Energy Act of 1946, known as the McMahon Act, and Ernest Titterton, the last British government employee, left Los Alamos on 12 April 1947. Britain then proceeded with High Explosive Research, its own nuclear weapons programme, and became the third country to test an independently developed nuclear weapon in October 1952.
Contribution[edit]
Early Anglo-American cooperation[edit]
In July 1940, Britain had offered to give the United States access to its scientific research,[14] and the Tizard Mission's John Cockcroft briefed American scientists on British developments. He discovered that the American project was smaller than the British, and not as far advanced.[11] As part of the scientific exchange, the Maud Committee's findings were conveyed to the United States. Oliphant, one of the Maud Committee's members, flew to the United States in late August 1941, and discovered that vital information had not reached key American physicists. He met the Uranium Committee, and visited Berkeley, California, where he spoke persuasively to Ernest O. Lawrence, who was sufficiently impressed to commence his own research into uranium at the Berkeley Radiation Laboratory. Lawrence in turn spoke to James B. Conant, Arthur H. Compton and George B. Pegram. Oliphant's mission was a success; key American physicists became aware of the potential power of an atomic bomb.[15][16] Armed with British data, Vannevar Bush, the director of the Office of Scientific Research and Development (OSRD), briefed Roosevelt and Vice President Henry A. Wallace in a meeting at the White House on 9 October 1941.[17]