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THE MAUD REPORT
(1941)
Events
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Early Government Support, 1939-1942
The most influential study of the feasibility of the
atomic bomb originated on the other side of the Atlantic.
In July 1941, just days after finding the second National
Academy of Sciences report so disappointing,
Vannevar Bush received a copy of a draft
report forwarded from the
National Defense Research Committee
liaison office in London. The report, prepared by a
group codenamed the MAUD Committee and set up by the
British in spring 1940 to study the possibility of
developing a nuclear weapon, maintained that a
sufficiently purified critical mass of
uranium-235 could fission even with fast neutrons.
Building upon theoretical work on atomic bombs performed
by refugee physicists Rudolf Peierls and Otto Frisch in
1940 and 1941, the MAUD report estimated that a critical
mass of ten kilograms would be large enough to produce an
enormous explosion. A bomb this size could be
loaded on existing aircraft and be ready in approximately
two years.
(The name "MAUD" is strange enough to merit
explanation. Although many people assume MAUD is an
acronym of some sort, it actually stems from a simple
misunderstanding. Early in the war, while Niels Bohr
(right) was still trapped in German-occupied Denmark, he
sent a telegram to his old colleague Frisch. Bohr
ended the telegram with instructions to pass his words
along to "Cockroft and Maud Ray Kent." "Maud,"
mistakenly thought to be a cryptic reference for something
atomic, was chosen as a codename for the committee.
Not until after the war was Maud Ray Kent identified as
the former governess of Bohr's children who subsequently
moved to England.)
Americans had been in touch with the MAUD Committee since
fall 1940, but it was the July 1941 MAUD report that
helped the American bomb effort turn the corner.
(Internal British discussions of the MAUD Report also
probably first alerted
Soviet intelligence to the atomic bomb program.)
The MAUD Report was influential because it
contained plans for producing a bomb drawn up by a
distinguished group of scientists with high credibility in
the United States, not only with Bush and
James Conant but with
President Roosevelt. The MAUD
report dismissed plutonium production,
thermal diffusion, the
electromagnetic method, and the
centrifuge and called for
gaseous diffusion of uranium-235 on a
massive scale. The British believed that uranium
research could lead to the production of a bomb in time to
affect the outcome of the war. While the MAUD report
provided encouragement to Americans advocating a more
extensive uranium research program, it also served as a
sobering reminder that
fission had been discovered in Nazi Germany almost three years earlier
and that since spring 1940 a large part of the Kaiser
Wilhelm Institute in Berlin had been set aside for uranium
research.
Bush and Conant (right) immediately went to work.
After strengthening the
S-1 (Uranium) Committee, particularly
with the addition of Enrico Fermi as head
of theoretical studies and Harold C. Urey as head of
isotope separation and heavy water
research (heavy water was highly regarded as a moderator
for piles (reactors)), Bush asked yet
another reconstituted National Academy of Sciences
committee to evaluate the uranium program. This time
he gave Arthur Compton
specific instructions to address technical questions of
critical mass and destructive capability, partially to
verify the MAUD results.
With the MAUD Report and its influence on developments in
the United States, the prospects for a wartime atomic bomb
had brightened considerably.
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Sources and notes for this page.
The text for this page was adapted from, and portions
were taken directly from the
Office of History and Heritage Resources
publication:
F. G. Gosling,
The Manhattan Project: Making the Atomic Bomb
(DOE/MA-0001; Washington: History Division, Department
of Energy, January 1999), 9. On the credibility the MAUD Committee
members had in Washington, see McGeorge Bundy,
Danger and Survival: Choices About the Bomb in the
First Fifty Years
(New York: Random House, 1988), 48-49. For the
origin of the word "MAUD," see the footnote in
Dennis C. Fakley, "The British Mission,"
Los Alamos Science (Winter/Spring 1983), 186. In addition to the internet version, which
is at
http://www.nuclearfiles.org/menu/key-issues/nuclear-weapons/history/pre-cold-war/manhattan-project/maud-report.htm, the MAUD Report is available on
the National Archives
microfilm collection M1392,
Bush-Conant File Relating to the Development of the
Atomic Bomb, 1940-1945
(Washington: National Archives and Records
Administration, 1990), reel #1/14. The photograph
of Niels Bohr is courtesy the
Fermi National Accelerator Laboratory. Click
here for information on the photograph of Vannevar
Bush and James Conant.
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