The MAUD Committee was a British scientific working group formed during the Second World War. It was established to perform the research required to determine if an atomic bomb was feasible. The name MAUD came from a strange line in a telegram from Danish physicist Niels Bohr referring to his housekeeper, Maud Ray.
The MAUD Committee was founded in response to the Frisch–Peierls memorandum, which was written in March 1940 by Rudolf Peierls and Otto Frisch, two physicists who were refugees from Nazi Germany working at the University of Birmingham under the direction of Mark Oliphant. The memorandum argued that a small sphere of pure uranium-235 could have the explosive power of thousands of tons of TNT.
The chairman of the MAUD Committee was George Thomson. Research was split among four different universities: the University of Birmingham, University of Liverpool, University of Cambridge and the University of Oxford, each having a separate programme director. Various means of uranium enrichment were examined, as was nuclear reactor design, the properties of uranium-235, the use of the then-hypothetical element plutonium, and theoretical aspects of nuclear weapon design.
After fifteen months of work, the research culminated in two reports, "Use of Uranium for a Bomb" and "Use of Uranium as a Source of Power", known collectively as the MAUD Report. The report discussed the feasibility and necessity of an atomic bomb for the war effort. In response, the British created a nuclear weapons project, code named Tube Alloys. The MAUD Report was made available to the United States, where it energised the American effort, which eventually became the Manhattan Project. The report was also revealed to the Soviet Union by its atomic spies, and helped start the Soviet atomic bomb project.
Origins The discovery of nuclear fission
The neutron was discovered by James Chadwick at the Cavendish Laboratory at the University of Cambridge in February 1932. Two months later, his Cavendish colleagues John Cockcroft and Ernest Walton split lithium atoms with accelerated protons. In December 1938, Otto Hahn and Fritz Strassmann at Hahn's laboratory in Berlin-Dahlem bombarded uranium with slow neutrons, and discovered that barium had been produced. Hahn wrote to his colleague Lise Meitner, who, with her nephew Otto Frisch, proved that the uranium nucleus had been split. They published their finding in Nature in 1939. This phenomenon was a new type of nuclear disintegration, and was more powerful than any seen before. Frisch and Meitner calculated that the energy released by each disintegration was approximately . By analogy with the division of biological cells, they named the process "fission".
Niels Bohr and John A. Wheeler applied the liquid drop model developed by Bohr and Fritz Kalckar to explain the mechanism of nuclear fission. Bohr had an epiphany that the fission at low energies was principally due to the uranium-235 isotope, while at high energies it was mainly due to the more abundant uranium-238 isotope. The former makes up just 0.7% of natural uranium, while the latter accounts for 99.3%. Frédéric Joliot-Curie and his Paris colleagues Hans von Halban and Lew Kowarski raised the possibility of a nuclear chain reaction in a paper published in Nature in April 1939. It was apparent to many scientists that, in theory at least, an extremely powerful explosive could be created, although most still considered an atomic bomb an impossibility. The term was already familiar to the British public through the writings of H. G. Wells, in his 1913 novel The World Set Free.
British response In Britain, a number of scientists considered whether an atomic bomb was practical. At the University of Liverpool, Chadwick and the Polish refugee scientist Joseph Rotblat tackled the problem, but their calculations were inconclusive. At Cambridge, Nobel Prize in Physics laureates George Paget Thomson and William Lawrence Bragg wanted the government to take urgent action to acquire uranium ore. The main source of this was the Belgian Congo, and they were worried that it could fall into German hands. Unsure as to how to go about this, they spoke to Sir William Spens, the master of Corpus Christi College, Cambridge. In April 1939, he approached Sir Kenneth Pickthorn, the local Member of Parliament, who took their concerns to the Secretary of the Committee of Imperial Defence, Major General Hastings Ismay. Ismay in turn asked Sir Henry Tizard for an opinion. Like many scientists, Tizard was sceptical of the likelihood of an atomic bomb being developed, reckoning the odds of success at 100,000 to 1.
Even at such long odds, the danger was sufficiently great to be taken seriously. Lord Chatfield, the Minister for Coordination of Defence, checked with the Treasury and Foreign Office, and found that the Belgian Congo uranium was owned by the Union Minière du Haut Katanga company. Its British vice-president, Lord Stonehaven, arranged a meeting with the Belgian president of the company, Edgar Sengier. Since Union Minière management were friendly towards Britain, it was not considered necessary to immediately acquire the uranium, but Tizard's Committee for the Scientific Survey of Air Warfare (CSSAW) was directed to continue the research into the feasibility of atomic bombs. Thomson, at Imperial College London, and Mark Oliphant, an Australian physicist at the University of Birmingham, were each tasked with carrying out a series of experiments on uranium. By February 1940, Thomson's team had failed to create a chain reaction in natural uranium, and he had decided that it was not worth pursuing.
Frisch–Peierls memorandum
At Birmingham, Oliphant's team had reached a different conclusion. Oliphant had delegated the task to Frisch and Rudolf Peierls, two German refugee scientists who could not work on Oliphant's radar project because they were enemy aliens, and therefore lacked the requisite security clearance. Francis Perrin had defined a critical mass of uranium to be the smallest amount that could sustain a chain reaction, and had calculated it to be about . He reckoned that if a neutron reflector were placed around it, this might be reduced to . In a theoretical paper written in 1939, Peierls attempted to simplify the problem by using the fast neutrons produced by fission, thus omitting consideration of a neutron moderator. He too believed the critical mass of a sphere of uranium to be "of the order of tons".
However, Bohr had contended that the uranium-235 isotope was far more likely to capture neutrons and fission even from neutrons with the low energies produced by fission. Frisch began experimenting with uranium enrichment through thermal diffusion. Progress was slow; the required equipment was not available, and the radar project had first call on the available resources. He wondered what would happen if he was able to produce a sphere of pure uranium-235. When he used Peierls' formula to calculate its critical mass, he received a startling answer: less than a kilogram would be required. Frisch and Peierls produced the Frisch–Peierls memorandum in March 1940. In it they reported that a five kilogram bomb would be the equivalent to several thousand tons of dynamite, and even a one kilogram bomb would be impressive. Because of the potential radioactive fallout, they thought that the British might find it morally unacceptable.
Oliphant took the Frisch–Peierls memorandum to Tizard in March 1940. He passed it on to Thomson, who discussed it with Cockcroft and Oliphant. They also heard from Jacques Allier of the French Deuxième Bureau, who had been involved in the removal of the entire stock of heavy water from Norway. He told them of the interest the Germans had shown in the heavy water, and in the activity of the French researchers in Paris. Immediate action was taken: the Ministry of Economic Warfare was asked to secure stocks of uranium oxide in danger of being captured by the Germans; British intelligence agencies were asked to investigate the activities of German nuclear scientists; and A. V. Hill, the British Scientific Attaché in Washington, was asked to find out what the Americans were up to. Hill reported that the Americans had scientists investigating the matter, but they did not think that any military applications would be found.
Organisation A committee was created as a response to the Frisch–Peierls memorandum. It held its first meeting on 10 April 1940, in the ground-floor main committee room of the Royal Society in Burlington House in London. Its meetings were invariably held there. The original members were Thomson, Chadwick, Cockcroft, Oliphant and Philip Moon; Patrick Blackett, Charles Ellis and Norman Haworth were subsequently added, along with a representative of the Director of Scientific Research at the Ministry of Aircraft Production (MAP). The MAUD Committee held its first two meetings in April 1940 before it was formally constituted by CSSAW. CSSAW was abolished in June 1940, and the MAUD Committee then came directly under the MAP. Thomson chaired the committee, and initially acted as its secretary as well, writing up the minutes in longhand on foolscap, until the MAP provided a secretary.
At first the new committee was named the Thomson Committee after its chairman, but this was soon exchanged for a more unassuming name, the MAUD Committee. MAUD was assumed by many to be an acronym, but it is not. The name MAUD came to be in an unusual way. On 9 April 1940, the day Germany invaded Denmark, Niels Bohr had sent a telegram to Frisch. The telegram ended with a strange line "Tell Cockcroft and Maud Ray Kent". At first it was thought to be code regarding radium or other vital atomic-weapons-related information, hidden in an anagram. One suggestion was to replace the "y" with an "i", producing 'radium taken'. When Bohr returned to England in 1943, it was discovered that the message was addressed to John Cockcroft and Bohr's housekeeper Maud Ray, who was from Kent. Thus the committee was named the MAUD Committee. Although the initials stood for nothing, it was officially the MAUD Committee, not the Maud Committee.
Because of the top secret aspect of the project, only British-born scientists were considered. Even despite their early contributions, Peierls and Frisch were not allowed to participate in the MAUD Committee because, at a time of war, it was considered a security threat to have enemy aliens in charge of a sensitive project. In September 1940, the Technical Sub-Committee was formed, with Peierls and Frisch as members. However, Halban did not take his exclusion from the MAUD Committee in as good grace as Frisch and Peierls. In response, two new committees were created in March 1941 to replace the MAUD Committee and the Technical Sub-Committee, called the MAUD Policy Committee and the MAUD Technical Committee. Unlike the original two committees, they had written terms of reference. The terms of reference of the MAUD Policy Committee were: To supervise on behalf of the Director of Scientific Research, MAP, an investigation into the possibilities of uranium as contributing to the war effort; and To consider the recommendations of the MAUD Technical Committee and to advise the Director of Scientific Research accordingly. Those of the MAUD Technical Committee were: To consider the problems arising in the uranium investigation; To recommend to the MAUD Policy Committee the experimental work necessary to establish the technical possibilities; and To ensure co-operation between the various groups of investigators.