MAUD Committee in the context of Atomic bomb

Sir James Chadwick (20 October 1891 – 24 July 1974) was a British experimental physicist who received the Nobel Prize in Physics in 1935 for his discovery of the neutron. In 1941, he wrote the final draft of the MAUD Report, which inspired the U.S. government to begin serious atomic bomb research efforts. He was the head of the British team that worked on the Manhattan Project during World War II. He was knighted in Britain in 1945 for his achievements in nuclear physics.

Chadwick graduated from the Victoria University of Manchester in 1911, where he studied under Ernest Rutherford (known as the "father of nuclear physics"). At Manchester, he continued to study under Rutherford until he was awarded his MSc in 1913. The same year, Chadwick was awarded an 1851 Research Fellowship from the Royal Commission for the Exhibition of 1851. He elected to study beta radiation under Hans Geiger in Berlin. Using Geiger's recently developed Geiger counter, Chadwick was able to demonstrate that beta radiation produced a continuous spectrum, and not discrete lines as had been thought. Still in Germany when World War I broke out in Europe, he spent the next four years in the Ruhleben internment camp.

Tube Alloys was the research and development programme authorised by the United Kingdom, with participation from Canada, to develop nuclear weapons during the Second World War. Starting before the Manhattan Project in the United States, the British efforts were kept classified, and as such had to be referred to by code even within the highest circles of government.

The possibility of nuclear weapons was acknowledged early in the war. At the University of Birmingham, Rudolf Peierls and Otto Robert Frisch co-wrote a memorandum explaining that a small mass of pure uranium-235 could be used to produce a chain reaction in a bomb with the power of thousands of tons of TNT. This led to the formation of the MAUD Committee, which called for an all-out effort to develop nuclear weapons. Wallace Akers, who oversaw the project, chose the deliberately misleading code name "Tube Alloys". His Tube Alloys Directorate was part of the Department of Scientific and Industrial Research.

Gaseous diffusion is a technology that was used to produce enriched uranium by forcing gaseous uranium hexafluoride (UF₆) through microporous membranes. This produces a slight separation (enrichment factor 1.0043) between the molecules containing uranium-235 (U) and uranium-238 (U). By use of a large cascade of many stages, high separations can be achieved. It was the first process to be developed that was capable of producing enriched uranium in industrially useful quantities, but is nowadays considered obsolete, having been superseded by the more-efficient gas centrifuge process (enrichment factor 1.05 to 1.2).

Gaseous diffusion was devised by Francis Simon and Nicholas Kurti at the Clarendon Laboratory in 1940, tasked by the MAUD Committee with finding a method for separating uranium-235 from uranium-238 in order to produce a bomb for the British Tube Alloys project. The prototype gaseous diffusion equipment itself was manufactured by Metropolitan-Vickers (MetroVick) at Trafford Park, Manchester, at a cost of £150,000 for four units (est. £10–11 million today), for the M. S. Factory, Valley. This work was later transferred to the United States when the Tube Alloys project became subsumed by the later Manhattan Project.