Manhattan Project

[[Image:Calutrons at Oak Ridge.jpg|thumb|right|300px|Control panels and operators for calutrons at the Y-12 National Security Complex|Y-12 Plant in Oak Ridge National Laboratory|Oak Ridge, Tennessee.

History

In the years between World War I and World War II, the United States had caught up in nuclear physics and rose to pre-eminence at the beginning of World War II, driven by the work of recent immigrants and local physicists. These scientists had developed the basic tools of nuclear research ? cyclotrons and other particle accelerators ? and had used these new tools to discover many new substances, including radioisotopes like Carbon-14.

Related Topics:
World War I - World War II - Nuclear physics - Cyclotron - Radioisotope - Carbon-14

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Early ideas on nuclear energy

Enrico Fermi recalled the beginning of the project in a speech given in 1954 when he retired as President of the APS.

Related Topics:
Enrico Fermi - APS

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I remember very vividly the first month, January 1939, that I started working at the Pupin Laboratories because things began happening very fast. In that period, Niels Bohr was on a lecture engagement in Princeton and I remember one afternoon Willis Lamb came back very excited and said that Bohr had leaked out great news. The great news that had leaked out was the discovery of fission and at least the outline of its interpretation. Then, somewhat later that same month, there was a meeting in Washington where the possible importance of the newly discovered phenomenon of fission was first discussed in semi-jocular earnest as a possible source of nuclear power.

Related Topics:
1939 - Niels Bohr - Princeton - Willis Lamb - Fission - Nuclear power

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Nuclear scientists Leó Szilárd, Edward Teller and Eugene Wigner (all Hungarian Jewish refugees from Hitler's Europe) believed that the energy released in nuclear fission might be used in bombs by the Germans. They persuaded Albert Einstein, one of the world's most famous physicists and a Jewish refugee himself, to warn President Franklin D. Roosevelt of this danger in an August 2, 1939 letter which Szilárd drafted http://www.pbs.org/wgbh/amex/truman/psources/ps_einstein.html. In response to the warning, Roosevelt encouraged further research into the national security implications of nuclear fission. After the bombing of Hiroshima, Einstein later commented "I could burn my fingers that I wrote that first letter to Roosevelt." The Navy awarded the first atomic energy funding of $6,000 for graphite for experiments, which grew into the Manhattan Project under scientific leadership of J. Robert Oppenheimer and the Italian-born nuclear physicist Fermi.

Related Topics:
Leó Szilárd - Edward Teller - Eugene Wigner - Hungarian - Jew - Albert Einstein - Franklin D. Roosevelt - August 2 - 1939 - J. Robert Oppenheimer

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Roosevelt created an ad hoc Uranium Committee under the chairmanship of National Bureau of Standards chief Lyman Briggs. It began small research programs in 1939 at the Naval Research Laboratory in Washington, where physicist Philip Abelson explored uranium isotope separation. At Columbia University Fermi built prototype nuclear reactors using various configurations of graphite and uranium. On October 9, 1941 Roosevelt authorized atomic weapon development.

Related Topics:
Ad hoc - National Bureau of Standards - Lyman Briggs - 1939 - Naval Research Laboratory - Philip Abelson - Uranium - Isotope separation - Columbia University - Nuclear reactor

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Vannevar Bush, director of the Carnegie Institution of Washington, organized the National Defense Research Committee (NDRC) in 1940 to mobilize the United States' scientific resources in support of the war effort.

Related Topics:
Vannevar Bush - National Defense Research Committee - 1940

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New laboratories were created, including the Radiation Laboratory at the Massachusetts Institute of Technology, which aided the development of radar, and the Underwater Sound Laboratory at San Diego, which developed sonar.

Related Topics:
Radiation Laboratory at the Massachusetts Institute of Technology - Radar - Underwater Sound Laboratory - San Diego - Sonar

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The NDRC also took over the uranium project, as Briggs' program in nuclear physics was called. In 1940, Bush and Roosevelt created the Office of Scientific Research and Development to expand these efforts.

Related Topics:
1940 - Office of Scientific Research and Development

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The uranium project had not made much progress by the spring of 1941, when word came from Britain of calculations by Otto Frisch and Rudolf Peierls. The report was based on the March 1940 Frisch-Peierls memorandum, and prepared by the MAUD Committee, itself a sub-committee of the Committee for the Scientific Survey of Air Warfare under G.P. Thomson, professor of physics at Imperial College, London. Critically it showed that the assumption that a uranium bomb would need to house many tons of uranium was wrong - it could be produced using "about 1lb" of the fissionable isotope of uranium, U-235. From this would come an explosion equivalent to that of several thousand tons of TNT.

Related Topics:
1941 - Otto Frisch - Rudolf Peierls - Frisch-Peierls memorandum - MAUD Committee - Imperial College - Isotope - TNT

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The National Academy of Sciences proposed an all-out effort to build nuclear weapons. Bush created a special committee, the S-1 Committee, to guide the effort. This happened to be on the day before the Japanese attack on Pearl Harbor, which was on December 7th, 1941, and meant the start of the war for the United States.

Related Topics:
National Academy of Sciences - Attack on Pearl Harbor - December 7 - 1941

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Scientists at the University of Chicago Metallurgical Laboratory, the University of California Radiation Laboratory and Columbia University's physics department, accelerated their efforts to prepare the nuclear materials for a weapon. They needed to learn how to separate Uranium 235 from raw uranium ore (mostly made of Uranium 238), and they needed to learn how to create plutonium, a very rare element, by bombarding natural Uranium (U-238) in a reactor with neutrons generated by Uranium 235. Beginning in 1942, huge plants were built to produce Uranium 235 at Oak Ridge (Site X) in Tennessee and to produce plutonium at Hanford (Site W) outside of Richland, Washington.

Related Topics:
University of Chicago Metallurgical Laboratory - University of California Radiation Laboratory - Columbia University - 1942 - Oak Ridge (Site X) - Tennessee - Hanford (Site W) - Richland, Washington

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When the United States entered World War II in December 1941, several projects were under way to investigate the separation of fissionable uranium 235 from uranium 238, the manufacture of plutonium, and the feasibility of nuclear piles and explosions.

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Physicist and Nobel laureate Arthur Holly Compton organized the Metallurgical Laboratory at the University of Chicago in early 1942 to study plutonium and fission piles. Compton asked theoretical physicist Dr. J. Robert Oppenheimer of the University of California to take over research on fast neutron calculations, essential to the feasibility of a nuclear weapon. John Manley, a physicist at the University of Chicago Metallurgical Laboratory, was assigned to help Dr. Oppenheimer find answers by coordinating and contacting several experimental physics groups scattered across the country.

Related Topics:
Arthur Holly Compton - 1942 - Plutonium - University of California - Nuclear weapon - John Manley - University of Chicago Metallurgical Laboratory

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In the spring of 1942, Oppenheimer and Robert Serber of the University of Illinois, worked on the problems of neutron diffusion (how neutrons moved in the chain reaction) and hydrodynamics (how the explosion produced by the chain reaction might behave).

Related Topics:
Robert Serber - University of Illinois - Neutron - Chain reaction - Hydrodynamics

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To review this work and the general theory of fission reactions, Oppenheimer convened a summer study at the University of California, Berkeley in June 1942. Theorists Hans Bethe, John Van Vleck, Edward Teller, Felix Bloch, Emil Konopinski, Robert Serber, Stanley S. Frankel, and Eldred C. Nelson (the latter three all former students of Oppenheimer) concluded that a fission bomb was feasible. The scientists suggested that such a reaction could be initiated by assembling a critical mass - an amount of nuclear explosive adequate to sustain it - either by firing two subcritical masses of plutonium or uranium 235 together or by imploding (crushing) a hollow sphere made of these materials with a blanket of high explosives. (Serber credits an early idea of implosion to Tolman). Until the numbers were better known, this was all that could be done.

Related Topics:
University of California, Berkeley - June 1942 - Hans Bethe - John Van Vleck - Felix Bloch - Emil Konopinski - Stanley S. Frankel - Eldred C. Nelson - Critical mass

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Teller saw another possibility: By surrounding a fission bomb with deuterium and tritium, a much more powerful "superbomb" (which he called simply, the "Super") might be constructed. This concept was based on studies of energy production in stars made by Bethe before the war. When the detonation wave from the fission bomb moved through the mixture of deuterium and tritium nuclei, they would fuse together to produce much more energy than fission could, in the process of nuclear fusion, just as elements fused in the sun produce light and heat.

Related Topics:
Deuterium - Tritium - Nuclear fusion

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Bethe was skeptical, and as Teller pushed hard for his "superbomb", and proposed scheme after scheme, Bethe refuted each one. The idea had to be put aside while the fission bombs, and the war, were completed. (The "super", or thermonuclear device, was produced after the war and tested in 1952, after an acrimonious political fight pitting Teller against Oppenheimer, leading to loss of Oppenheimer's official status, and using methods different than Teller's specific ideas, which Bethe was correct in refuting.)

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Teller also raised the speculative possibility that an atomic bomb might "ignite" the atmosphere, due to a hypothetical fusion reaction of nitrogen nuclei. Bethe showed, according to Serber, theoretically that it couldn't happen; in his book The Road from Los Alamos, Bethe says a refutation was written by Konopinski, C. Marvin, and Teller as report LA-602 (declassified Feb. 1973 online), showing that it was impossible, not just unlikely. In Serber's account, Oppenheimer unfortunately mentioned it to Arthur Compton, who "didn't have enough sense to shut up about it. It somehow got into a document that went to Washington" which led to the question "never laid to rest". In Bethe's account, this ultimate catastrophe came up again in 1975 when it appeared in a magazine article by H. C. Dudley, who got the idea from a report by Pearl Buck of an interview she had with Arthur Compton in 1959, where she completely misunderstood Compton! The worry was not entirely extinguished in some people's minds until the Trinity test; though if Bethe had been wrong, we would never know.

Related Topics:
Arthur Compton - Pearl Buck - Trinity

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The summer conferences, the results of which were later summarized by Serber in "The Los Alamos Primer" (LA-1 online), provided the original theoretical basis for the design of the atomic bomb, which was to become the principal task at Los Alamos during the war, and the idea of the H-bomb, which was to haunt the Laboratory in the postwar era.

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The measurements of the interactions of fast neutrons with the materials in a bomb were essential because the number of neutrons produced in the fission of uranium and plutonium must be known, and because the substance surrounding the nuclear material must have the ability to reflect, or scatter, neutrons back into the chain reaction before it is blown apart in order to increase the energy produced. Therefore, the neutron scattering properties of materials had to be measured to find the best reflectors.

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Estimating the explosive power required knowledge of many other nuclear properties, including the cross section (a measure of the probability of an encounter between particles that result in a specified effect) for nuclear processes of neutrons in uranium and other elements. Fast neutrons could only be produced in particle accelerators, which were still relatively uncommon instruments in physics departments in 1942.

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The need for better coordination was clear. By September 1942, the difficulties involved with conducting preliminary studies on nuclear weapons at universities scattered throughout the country indicated the need for a laboratory dedicated solely to that purpose. The need for it, however, was overshadowed by the demand for plants to produce uranium-235 and plutonium - the fissionable materials that would provide the nuclear explosives.

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Vannevar Bush, the head of the civilian Office of Scientific Research and Development (OSRD), asked President Roosevelt to assign the large-scale operations connected with the quickly growing nuclear weapons project to the military. Roosevelt chose the Army to work with the OSRD in building production plants. The Army Corps of Engineers selected Col. James Marshall to oversee the construction of factories to separate uranium isotopes and manufacture plutonium for the bomb.

Related Topics:
Vannevar Bush - Office of Scientific Research and Development - Army Corps of Engineers

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OSRD scientists had explored several methods to produce plutonium and separate uranium-235 from uranium, but none of the processes was ready for production - only microscopic amounts had been prepared.

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Only one method - electromagnetic separation, which had been developed by Ernest Lawrence at the University of California Radiation Laboratory at the University of California, Berkeley - seemed promising at the time for large-scale production. But scientists could not stop studying other potential methods of producing fissionable materials, because it was so expensive and because it was unlikely that it alone could produce enough material before the war was over.

Related Topics:
Ernest Lawrence - University of California Radiation Laboratory - University of California, Berkeley

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Marshall and his deputy, Col. Kenneth Nichols, had to struggle to understand both the processes and the scientists with whom they had to work. Thrust suddenly into the new field of nuclear physics, they felt unable to distinguish between technical and personal preferences. Although they decided that a site near Knoxville would be suitable for the first production plant, they didn't know how large the site had to be and so put off its acquisition. There were other problems, too.

Related Topics:
Kenneth Nichols - Knoxville

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Because of its experimental nature, the nuclear weapons work could not compete with the Army's more-urgent tasks for top-priority ratings. The selection of scientists' work and production-plant construction often were delayed by Marshall's inability to get the critical materials, such as steel, that also were needed in other military productions.

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Even selecting a name for the new Army project was difficult. The title chosen by Gen. Brehon Somervell, "Development of Substitute Materials," was objectionable because it seemed to reveal too much.

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