Frisch–Peierls memorandum
The Frisch–Peierls memorandum was the first technical exposition of a practical nuclear weapon. It was written by expatriate German-Jewish physicists Otto Frisch and Rudolf Peierls in March 1940 while they were both working for Mark Oliphant at the University of Birmingham in Britain during World War II.
The memorandum contained the first calculations about the size of the critical mass of fissile material needed for an atomic bomb. It revealed that the amount required might be small enough to incorporate into a bomb that could be delivered by air. It also anticipated the strategic and moral implications of nuclear weapons.
It helped send both Britain and America down a path which led to the MAUD Committee, the Tube Alloys project, the Manhattan Project, and ultimately the atomic bombings of Hiroshima and Nagasaki.
Influence[edit]
The memorandum was given to Oliphant, who passed it on to Tizard in his capacity as the chairman of the Committee for the Scientific Survey of Air Warfare (CSSAW). He in turn passed it to Thomson, the chairman of the committee to which the CSSAW had delegated responsibility for uranium research.[48] Thomson's committee was about to disband. It had studied nuclear reactions in uranium, and the use of graphite as a neutron moderator in a nuclear reactor, but its results had been negative, and it had concluded that the rate of capture of neutrons by the graphite was too great to make such a reactor a practical proposition. The Frisch–Peierls memorandum caused Thomson to reconsider.[38] After discussions between Cockcroft, Oliphant and Thomson, CSSAW created the MAUD Committee to investigate further.[49] As enemy aliens, Peierls and Frisch were initially excluded from its deliberations, but they were later added to its technical subcommittee.[38]
The research from the MAUD committee was compiled in two reports, commonly known as the MAUD reports in July 1941. The first report, "Use of Uranium for a Bomb", discussed the feasibility of creating a super-bomb from uranium, which they now thought to be real. The second, "Use of Uranium as a Source of Power" discussed the idea of using uranium as a source of power, not just a bomb. The MAUD Committee and report helped bring about the British nuclear program, the Tube Alloys project. Not only did it help start a nuclear project in Britain but it helped jump-start the American project. Without the help of the MAUD Committee the American program, the Manhattan Project, would have started months behind. Instead they were able to begin thinking about how to create a bomb, not whether it was possible.[50][51] Historian Margaret Gowing noted that "events that change a time scale by only a few months can nevertheless change history."[52]
In August 1941, Oliphant was sent to the US to assist the Americans with microwave radar.[53] He took the initiative to enlighten the scientific community there of the ground-breaking discoveries of the MAUD Committee. He travelled to Berkeley to meet with his friend Ernest Lawrence, who soon caught his enthusiasm. Oliphant convinced the Americans to move forward with nuclear weapons, and his lobbying resulted in Vannevar Bush taking the report directly to the president.[54] Leo Szilard later wrote: "if Congress knew the true history of the atomic energy project, I have no doubt but that it would create a special medal to be given to meddling foreigners for distinguished services, and that Dr Oliphant would be the first to receive one."[55]