Armed Forces Special Weapons Project

"The Manhattan Project" redirects here. For the 1986 film of the same name, see The Manhattan Project (film).

Manhattan Engineer District (MED)
The Manhattan Project created the first nuclear bombs. The first human-engineered nuclear detonation, the Trinity test, is shown.
Active	1942–1945
Allegiance	United States, United Kingdom, Canada
Branch	U.S. Army Corps of Engineers
Nickname(s)	Manhattan Project
Commanders
Notable commanders	General Leslie Groves

The Manhattan Project was the codename for a project conducted during World War II to develop the first atomic bomb, before the Germans or the Japanese. The project was led by the United States, and included participation from the United Kingdom and Canada. Formally designated as the Manhattan Engineer District (MED) (sometimes referred to as the Manhattan District) it refers specifically to the period of the project from 1942–1946 under the control of the U.S. Army Corps of Engineers and General Leslie R. Groves. The scientific research was directed by American physicist J. Robert Oppenheimer.

The project's roots began in 1939 when at the urging of Leó Szilárd, Albert Einstein signed a letter to President Roosevelt expressing his concerns that Nazi Germany may be trying to develop nuclear weapons. The Manhattan Project, which began as a small research program that year, eventually employed more than 130,000 people and cost nearly US$2 billion ($31 billion in present day value). It resulted in the creation of several research and production sites whose construction and operations were secret.

Project research took place at more than 30 sites, including universities across the United States, Canada, and the United Kingdom. The three primary research and production sites of the project were the plutonium-production facility at what is now the Hanford Site in eastern Washington state; the uranium-enrichment facilities at Oak Ridge, Tennessee; and the weapons research and design laboratory now known as Los Alamos National Laboratory. The MED maintained control over U.S. atomic weapons production until the formation of the Atomic Energy Commission in January 1947.

Naming the Project

It is widely believed that the Manhattan Project's name was a code name. In fact, the project was named after Manhattan island of New York City, as that was the location where many of its early operations were conducted. According to historian Robert S. Norris, at least ten sites operated in Manhattan. The island was an ideal location because of its port facilities, the military presence, a large available work force, a population of expatriate European physicists, and Columbia University, a center of early nuclear research.

Uranium Committee (1939–1941)

In 1939, President Franklin Roosevelt called on Lyman Briggs of the National Bureau of Standards to head "The Uranium Committee" to undertake nuclear research, as a result of the Einstein–Szilárd letter. Even though Roosevelt had sanctioned the project, progress was slow and was not directed exclusively towards military applications.

[[:Image:Frisch-Peierls Memorandum - Opening Paragraph.png|frame|right|The opening paragraph of the Frisch–Peierls memorandum in which the amount of Uranium estimated to be needed to produce a bomb was revised downwards to that where a working device became practicable]]

Meanwhile, in the United Kingdom, Otto Frisch and Rudolf Peierls made a breakthrough by discovering the fissile properties of uranium-235. A British committee, the MAUD Committee, concluded that:

(i) The committee considers that the scheme for a uranium bomb is practicable and likely to lead to decisive results in the war
(ii) It recommends that this work continue on the highest priority and on the increasing scale necessary to obtain the weapon in the shortest possible time

(iii) That the present collaboration with America should be continued and extended especially in the region of experimental work

Their reports were sent to Briggs at the National Bureau of Standards, but he ignored them. One of the members of the MAUD Committee, Mark Oliphant, flew to the United States in late August 1941 to find out why the U.S. was ignoring the MAUD Committee's findings. He reported, "[T]his inarticulate and unimpressive man (Briggs) had put the reports in his safe and had not shown them to members of his committee." Oliphant then met with the whole Uranium Committee and other physicists to galvanize the USA into action. As a result, in December 1941 Vannevar Bush created the larger and more powerful Office of Scientific Research and Development and became its director. The office was empowered to engage in large engineering projects in addition to research.

Acceleration of the Project

A few months after he was put in charge of fast neutron research, Berkeley physicist J. Robert Oppenheimer convened a conference on the topic of nuclear weapon design.

With the bomb project under the OSRD, the project leaders began to accelerate the work. Arthur Compton organized the University of Chicago Metallurgical Laboratory in early 1942 to study plutonium and fission piles (primitive nuclear reactors). He asked theoretical physicist J. Robert Oppenheimer of the University of California, Berkeley to take over research on fast neutron calculations—key to calculations about critical mass and weapon detonation—from Gregory Breit, who had quit because of concerns over lax operational security. John Manley, a physicist at the Metallurgical Laboratory, was assigned to help Oppenheimer find answers by coordinating and contacting several experimental physics groups scattered across the country.

During 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). 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) quickly confirmed that a fission bomb was feasible.

There were still many unknown factors in the development of a nuclear bomb, however, although it was considered theoretically possible. The properties of pure uranium-235 were relatively unknown, as were the properties of plutonium, a new element which had only been discovered in February 1941 by Glenn Seaborg and his team. Plutonium was the product of uranium-238 absorbing a neutron which had been emitted from a fissioning uranium-235 atom, and was thus able to be created in a nuclear reactor. But at this point no reactor had yet been built, so while plutonium was being pursued as an additional fissile substance, it was not yet to be relied upon. Only microgram quantities of plutonium existed at the time (produced from neutrons derived from reaction started in a cyclotron).

A number of the different fission bomb assembly methods explored during the June 1942 conference, later reproduced as drawings in The Los Alamos Primer. In the end, only the "gun" method (at top) and a more complicated variation of the "implosion" design would be used. At the bottom are "autocatalytic method" designs.

The scientists at the Berkeley conference determined that there were many possible ways of arranging the fissile material into a critical mass. The simplest was shooting a "cylindrical plug" into a sphere of "active material" with a "tamper"—dense material that would focus neutrons inward and keep the reacting mass together to increase its efficiency (this model "avoids fancy shapes", Serber would later write). They also explored designs involving spheroids, a primitive form of "implosion" (suggested by Richard C. Tolman), and explored the possibility of "autocatalytic methods" which would increase the efficiency of the bomb as it exploded.

Considering the idea of the fission bomb theoretically settled—at least until more experimental data was available—the conference then turned in a different direction. Hungarian physicist Edward "Ede" Teller pushed for discussion on a more powerful bomb: the "Super", which would use the explosive force of a detonating fission bomb to ignite a fusion reaction in deuterium and tritium. Such a bomb, they calculated, would have an explosive yield of 10 megatons, hundreds of times more powerful than the atomic bomb. The concept was based on studies of energy production in stars made by Hans Bethe before the war. Enrico Fermi suggested it as a possibility to Teller not long before the conference. When the detonation wave from the fission bomb moved through the mixture of deuterium and tritium nuclei, these would fuse together to produce much more energy than fission could. But Bethe was skeptical. As Teller pushed hard for his "superbomb"—now usually referred to as a "hydrogen bomb"—proposing scheme after scheme, Bethe refused each one. The fusion idea was put aside to concentrate on producing fission bombs.

Teller also raised the speculative possibility that an atomic bomb might "ignite" the atmosphere because of a hypothetical fusion reaction of nitrogen nuclei. Bethe calculated that it could not happen. However, a report co-authored by Teller showed that ignition of the atmosphere was not impossible, just unlikely. In Serber's account, Oppenheimer 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 being "never laid to rest".

The conferences in June 1942 provided the detailed theoretical basis for the design of the atomic bomb. Oppenheimer was convinced of the benefits of having a single centralized laboratory to manage the research for the bomb project, rather than having specialists spread out at different sites across the United States.

Project sites

Though it involved over thirty different research and production sites, the Manhattan Project was largely carried out at four secret laboratories which the national governments established by power of eminent domain in four cities: Los Alamos, New Mexico; Oak Ridge, Tennessee; Richland, Washington; Chalk River, Ontario, Canada. The Tennessee site was chosen because of the vast quantities of cheap hydroelectric power already available (from the Tennessee Valley Authority) to power uranium enrichment processes. The Hanford Site near Richland, Washington, was chosen for its location near the Columbia River, which could supply sufficient water to cool the reactors which would produce the plutonium. The Canadian site was chosen for its proximity to the industrial manufacturing of Ontario and Quebec, and access to a rail head adjacent to a large military base, Camp Petawawa. Further, located on the Ottawa River it had access to abundant water. All the sites were suitably far from coastlines and therefore less vulnerable to possible enemy attack from Germany or Japan.

The Los Alamos National Laboratory was built on a mesa that previously hosted the Los Alamos Ranch School, a private school for teenage boys. The site was chosen primarily because it was remote and relatively unpopulated. Oppenheimer had known of it from his horse-riding near his ranch in New Mexico. He showed it as a possible site to the government representatives, who promptly bought it for $440,000. In addition to being the main "think-tank", Los Alamos was responsible for final assembly of the bombs, mainly from materials and components produced by other sites. Manufacturing at Los Alamos included casings, explosive lenses, and fabrication of fissile materials into bomb cores.

Oak Ridge facilities covered more than 60,000 acres (240 km²) of several former farm communities in the Tennessee Valley area. Some Tennessee families were given two weeks' notice to vacate family farms that had been their homes for generations. So secret was the site during World War II that the state governor was unaware that Oak Ridge (which was to become the fifth largest city in the state) was being built. At one point Oak Ridge plants were consuming 1/6th of the electrical power produced in the U.S., more than New York City. Oak Ridge mainly produced uranium-235.

The Chalk River site was established to house the allied effort that was going on at McGill University in Montreal. Since the site was 120 miles west of Ottawa, a new community was singe built at Deep River, Ontario to provide residences and facilities for the project team members. Both were established in 1944, with scientists, engineers, trades from Canada, the United Kingdom, New Zealand, Australia, France, Norway, etc. providing their contribution to the war effort.

The Hanford Site, which grew to almost 1,000 square miles (2,600 km²), took over irrigated farm land, fruit orchards, a railroad, and two farming communities, Hanford and White Bluffs. This was a relatively highly populated area where three cities converge. The Tri Cities are Kennewick, Pasco, and Richland, adjacent to the Columbia River. Hanford built nuclear reactors cooled by the river and was the plutonium production center.

The operations were kept secret until the announcement of the Hiroshima bombing and nuclear explosion. The locations of Los Alamos, Oak Ridge, Richland, and Chalk River were held secret until after the end of WWII.

The project originally was headquartered at 270 Broadway in Manhattan. Other offices were scattered throughout the city, including the New York Friars' Club building. The Broadway headquarters lasted little more than a year before it was moved in 1943, although many of the other offices in Manhattan remained.

A selection of U.S. sites important to the Manhattan Project.

Major Manhattan Project sites and subdivisions included:

• Site W (Hanford, Washington): a plutonium production facility (now Hanford Site)
• Site X (Oak Ridge, Tennessee): enriched uranium production and plutonium production research (now Oak Ridge National Laboratory) Site X also included:
  • X-10 Graphite Reactor: graphite reactor research pilot plant (on the site of what is now Oak Ridge National Laboratory)
  • Y-12: electromagnetic separation uranium enrichment plant
  • K-25: gaseous diffusion uranium enrichment plant
  • S-50: thermal diffusion uranium enrichment plant
• Site Y (Los Alamos, New Mexico): a bomb research laboratory (now Los Alamos National Laboratory)
• Metallurgical Laboratory (Chicago, Illinois): reactor development (now Argonne National Laboratory)
• Project Alberta (Wendover, Utah and Tinian): preparations for the combat delivery of the bombs
• Project Ames (Ames, Iowa): production of raw uranium metal (now Ames Laboratory)
• Dayton Project (Dayton, Ohio): research and development of polonium refinement and industrial production of polonium for atomic bomb triggers
• Project Camel (Inyokern, California): high explosives research and non-nuclear engineering for the Fat Man bomb
• Project Trinity (Alamogordo, New Mexico): preparations for the testing of the first atomic bomb
• Radiation Laboratory (Berkeley, California): electromagnetic separation enrichment research (now Lawrence Berkeley National Laboratory)
• Project '9' (Trail, British Columbia): heavy water (deuterium) production.
• Health Project (Rochester, NY): "to investigate heretofore unexplored fields in medical research on the effects of radiation and other problems related to the development and production of the atomic bomb."

Need for coordination

The measurements of the interactions of fast neutrons with the materials in a bomb were essential. The scientists needed to know the number of neutrons produced in the fission of uranium and plutonium. The substance surrounding the nuclear material needed the ability to reflect, or scatter, neutrons back into the chain reaction before it was blown apart, in order to increase the energy produced. Therefore, researchers had to measure the neutron scattering properties of materials to find the best reflectors.

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 1942. The need for better coordination was clear. By September 1942, the difficulties in conducting studies on nuclear weapons at universities scattered throughout the country indicated the need for a laboratory dedicated solely to that purpose. A greater need was the construction of industrial plants to produce uranium-235 and plutonium—the fissionable materials to be used in the weapons.

Vannevar Bush, the head of the civilian Office of Scientific Research and Development (OSRD), asked President Roosevelt to assign the operations connected with the 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.

Marshall and his deputy, Col. Kenneth Nichols, struggled to understand the proposed processes and the scientists with whom they had to work. Thrust 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, Tennessee, would be suitable for the first production plant, they did not know how large the site needed to be, and thus delayed its acquisition.

Because of its experimental nature, the nuclear weapons work could not compete for priority with the Army's more urgent tasks. The scientists' construction of the work and production plants were often delayed by Marshall's inability to obtain critical materials such as steel, which were needed in other military projects.

With the need for secrecy in the midst of war, selecting a name for the project was difficult. The title chosen by Gen. Brehon B. Somervell, "Development of Substitute Materials," was objectionable because it seemed to reveal too much.

Manhattan Engineer District

General Leslie Groves (left) was appointed the military head of the Manhattan Project, while Robert Oppenheimer (right) was the scientific director.

Vannevar Bush became dissatisfied with Col. James Marshall's failure to get the project moving forward expeditiously and told Secretary of War Stimson and Army Chief of Staff George Marshall. Marshall directed General Somervell to replace Col. Marshall with a more energetic officer as director. In the summer of 1942, Col. Leslie Groves was deputy to the chief of construction for the Army Corps of Engineers. He had directed the very rapid construction of the Pentagon, the world's largest office building. He was widely respected as an intelligent, hard driving, though brusque officer who got things done in a hurry.

Hoping for an overseas command, Groves vigorously objected when Somervell appointed him to the weapons project. His objections were overruled. Groves resigned himself to leading a project he thought had little chance of success. Groves appointed Oppenheimer as the project's scientific director, to the surprise of many. (Oppenheimer's radical political views were thought to pose security problems). However, Groves was convinced Oppenheimer was a genius who could talk about and understand nearly anything, and he was convinced such a man was needed for a project such as the one being proposed.

Groves renamed the project The Manhattan Engineer District. The name evolved from the Corps of Engineers practice of naming districts after its headquarters' city (Marshall's headquarters were at 270 Broadway in New York City). At that time, Groves was promoted to brigadier general, giving him the rank necessary to deal with senior people whose cooperation was required, or whose own projects were hampered by Groves' top-priority project. Within a week of his appointment, Groves had solved the Manhattan Project's most urgent problems. His forceful and effective manner was soon to become all too familiar to the atomic scientists.

The first major scientific hurdle of the project was solved on December 2, 1942, beneath the bleachers of Stagg Field at the University of Chicago, where a team led by Enrico Fermi, for whom Fermilab is named, initiated the first artificial self-sustaining nuclear chain reaction in an experimental nuclear reactor named Chicago Pile-1. Compton reported the success to Conant in Washington, DC by a coded call, saying, "The Italian navigator [referring to Fermi] has landed in the new world, the natives are friendly."

Uranium bomb

A gun-type nuclear bomb.

The Hiroshima bomb was made from uranium-235. It is a rare isotope of uranium that has to be physically separated from the more plentiful uranium-238 isotope, which is not suitable for use in an explosive device. Since U-235 makes up only 0.7% of raw uranium and is chemically identical to the 99.3% of U-238, various physical methods were considered for separation. Most of the uranium enrichment work was performed at Oak Ridge.

Operators at their calutron control panels at the Y-12 Plant in Oak Ridge, Tennessee.

One method of separating uranium 235 from raw uranium ore was devised by Franz Simon and Nicholas Kurti, at Oxford University. Their method using gaseous diffusion was scaled up in a large separation plant at Oak Ridge, using uranium hexafluoride (UF₆) gas as the process fluid. During the war this method was important primarily for producing partly enriched material to feed the electromagnetic separation process undertaken in calutrons (see below).

Another method—electromagnetic isotope separation—was developed by Ernest Lawrence at the University of California Radiation Laboratory at the University of California, Berkeley. This method was implemented in Oak Ridge at the Y-12 Plant, employing devices known as calutrons, which were effectively mass spectrometers. Copper was originally intended for electromagnet coils, but there was an insufficient amount available due to war shortages. The project engineers were forced to borrow silver from the U.S. Treasury. A total of 70,000,000 pounds of silver from the U.S. Treasury reserves was used for coils, and was returned after the project ended. Initially the method seemed promising for large scale production but was expensive and produced insufficient material and was later abandoned after the war.

Other techniques were also tried, such as thermal diffusion and the use of high-speed centrifuges. Thermal diffusion was not used to produce highly-enriched uranium, but was used during the war in the S-50 facility to begin enrichment of the uranium, and its product was passed as the feed into the other facilities.

The uranium bomb was a gun-type fission weapon. One mass of U-235, the "bullet," is fired down a more or less conventional gun barrel into another mass of U-235, rapidly creating the critical mass of U-235, resulting in an explosion. The method was so certain to work that no test was carried out before the bomb was dropped over Hiroshima, though extensive laboratory testing was undertaken to make sure the fundamental assumptions were correct. Also, the bomb that was dropped used all the existing extremely highly purified U-235 (and even most of the less highly purified material) so there was no U-235 available for such a test anyway. The bomb's design was known to be inefficient and prone to accidental discharge.

Plutonium bomb

The basic concept of an implosion-style nuclear weapon. Actual pictures and details of the bomb's inner workings remain classified.

The bombs used in the first test at Trinity Site on July 16, 1945, in New Mexico (the gadget of the Trinity test), and in the Nagasaki bomb, Fat Man, were made primarily of plutonium-239, a synthetic element.

Although uranium-238 is useless as a fissile isotope for an atomic bomb, it is key in producing plutonium. The fission of U-235 releases neutrons, which are absorbed by U-238, which creates uranium-239. U-239 rapidly decays to neptunium-239 (U-239 has a half-life of 23.45 minutes). Neptunium-239 (with a half-life of 2.35 days) then decays into plutonium-239. The production and purification of plutonium used techniques developed in part by Glenn Seaborg while working at Berkeley and Chicago. Beginning in 1943, huge plants were built to produce plutonium at the Hanford Site.

A mock-up of the plutonium bomb, Fat Man

In 1943–1944, development efforts were directed to a gun-type fission weapon with plutonium, called "Thin Man". Once this was achieved, the scientists thought the uranium version, "Little Boy," would require a relatively simple adaptation.

Initial research on the properties of plutonium was done using cyclotron-generated plutonium-239, which was extremely pure, but could only be created in very small amounts. On April 5, 1944, Emilio Segrè at Los Alamos received the first sample of Hanford-produced plutonium. Within ten days, he discovered a problem: reactor-bred plutonium was far less isotopically pure than cyclotron-produced plutonium. A higher concentration of Pu-240, formed from Pu-239 by capture of an additional neutron, gave it a much higher spontaneous fission rate than U-235. Pu-240 was even harder to separate from Pu-239 than U-235 was to separate from U-238, so no purification was attempted. This made the Hanford plutonium unsuitable for use in a gun-type weapon.

The gun-type bomb worked by mechanically assembling the critical mass from two subcritical masses: a "bullet" and a target. The chain reaction resulting from collision of the "bullet" with the target released tremendous energy, producing an explosion, but also blew apart the critical mass and ended the chain reaction. The configuration of the critical mass determined how much of the fissile material reacted in the interval between assembly and dispersal, and therefore the explosive yield of the bomb. Even a 1% fission of the material would result in a workable bomb, equal to thousands of tons of high explosive. A poor configuration, or slow assembly, would release enough energy to disperse the critical mass quickly, and the yield would be greatly reduced, equivalent to only a few tons of high explosive.

The chain reaction of U-235 was slow enough that gun-type assembly would work, but in a gun-type bomb made with the Hanford plutonium, "early" neutrons from spontaneously fissioning Pu-240 would start the chain reaction more quickly during detonation. This would release enough energy to disperse the critical mass with only a minimal amount of plutonium reacted, reducing the resulting yield of the weapon.

In July 1944, based on the measurements of spontaneous fission for Hanford plutonium, the decision was made to cease work on a gun-type assembly for plutonium. There would be no "Thin Man."

Ideas for alternative detonation schemes had existed for some time at Los Alamos. One of the more innovative was the idea of "implosion". Using chemical explosives, a sub-critical sphere of fissile material could be squeezed into a smaller and denser form. When the fissile atoms were packed closer together, the rate of neutron capture would increase, and the mass would become a critical mass. The metal needed to travel only very short distances, so the critical mass would be assembled in much less time than it would take to assemble a mass by a bullet impacting a target. Initially, implosion had been entertained as a possible, though unlikely, method.

The gun method was further developed for uranium only, while most efforts were then directed towards rapidly developing an implosion system. Oppenheimer chose to pursue a design based on the April 1944 suggestion by James L. Tuck to use explosive lenses to create spherical, converging implosion waves.

In July 1944 the Los Alamos laboratory abandoned the plutonium gun-type bomb ("Thin Man", shown above) and focused almost entirely on the problem of implosion. (The Fat Man casing is also visible in the photo background.)

By the end of July 1944, the entire Manhattan Project had been reorganized around building the implosion-type bomb.

The required implosion was achieved by using shaped charges with many explosive lenses to produce the perfectly spherical explosive wave which compressed the plutonium sphere.

Because of the complexity of an implosion-style weapon, it was decided that, despite the waste of fissile material, an initial test would be required. The first nuclear test took place on July 16, 1945, near Alamogordo, New Mexico, under the supervision of Groves's deputy Brig. Gen. Thomas Farrell. Oppenheimer gave the test the code name "Trinity".

Cost of Manhattan Project

The project expenditure to 1 October 1945 was $1.845 billion, and was $2.191 billion when the AEC assumed control on 1 January 1947. Total allocation was $2.4 billion, an amount equal to $32.7 billion in current value. Over 90% of the cost was for building plants and producing the fissionable materials, and less than 10% for development and production of the weapons. The first allocation in June 1942 for fiscal 1943, as recommended in a 13 June report by Bush and Conant and approved by FDR on 17 June, was for only $90 million. This was a small start compared to the scale of a single TNT plant built in Pennsylvania which cost $128 million.

The Atomic Energy Commission (AEC) was set up by the Atomic Energy Act in 1946 to take over the functions and assets of the Manhattan Project. It established civilian control over atomic development, and separated the development, production and control of atomic weapons from the military.

Similar efforts

See also: German nuclear energy project

See also: Tube Alloys

See also: Soviet atomic bomb project

See also: Kahuta Project

A similar effort was undertaken in the USSR in September 1941 headed by Igor Kurchatov (with some of Kurchatov's World War II knowledge coming secondhand from Manhattan Project countries, thanks to spies, including at least two on the scientific team at Los Alamos, Klaus Fuchs and Theodore Hall, unknown to each other).

After the MAUD Committee's report, the British and Americans exchanged nuclear information but initially did not pool their efforts. A British project, code-named Tube Alloys, was started but did not have United States resources. Consequently the British bargaining position worsened, and their motives were mistrusted by the Americans. Collaboration therefore lessened markedly until the Quebec Agreement of August 1943, when a large team of British, Canadian and Australian scientists joined the Manhattan Project at McGill University in Montreal and at a new project site located at Chalk River, Ontario, with living facilities for those working in the newly created community of Deep River, Ontario.

The German experimental nuclear pile at Haigerloch

The question of Axis efforts on the bomb has been a contentious issue for historians. It is believed that efforts undertaken in Germany, headed by Werner Heisenberg, and in Japan, were also undertaken during the war with little progress. It was initially feared that Hitler was very close to developing his own bomb. Many German scientists in fact expressed surprise to their Allied captors when the bombs were detonated in Japan. They were convinced that talk of atomic weapons was merely propaganda. However, Werner Heisenberg (by then imprisoned in Britain at Farm Hall with several other nuclear project physicists) almost immediately figured out what the Allies had done, explaining it to his fellow scientists (and hidden microphones) within days. The Nazi reactor effort had been severely handicapped by Heisenberg's belief that heavy water was necessary as a neutron moderator (slowing preparation material) for such a device. The Germans were short of heavy water throughout the war because of Allied efforts such as Operation Gunnerside to prevent Germany from obtaining it, and the Germans never did stumble on the secret of purified graphite for making nuclear reactors from natural uranium.

Niels Bohr, Werner Heisenberg and Enrico Fermi were all colleagues who were key figures in developing the quantum theory together with Wolfgang Pauli, prior to the war. They had known each other well in Europe and were friends. Niels Bohr and Heisenberg even discussed the possibility of the atomic bomb prior to and during the war, before the United States became involved. Bohr recalled that Heisenberg was unaware that the supercritical mass could be achieved with U-235, and both men gave differing accounts of their conversations at this sensitive time. Bohr at the time did not trust Heisenberg, and never quite forgave him for his decision not to flee Germany before the war when given the chance. Heisenberg, for his part, seems to have thought he was proposing to Bohr a mutual agreement between the two sides not to pursue nuclear technology for destructive purposes. If so, Heisenberg's message did not get through. Heisenberg, to the end of his life, maintained that the partly-built German heavy-water nuclear reactor found after the war's end in his lab was for research purposes only, and a full bomb project had not been contemplated (there is no evidence to contradict this, but by this time late in the war, Germany was far from having the resources for a Hanford-style plutonium bomb, even if its scientists had decided to pursue one and had known how to do it).

Controversy

Main article: Human experimentation in the United States

Harold Hodge was chosen to head the United States Atomic Energy Commission's (AEC) Division of Pharmacology and Toxicology for the Manhattan Project, where he studied on the effects of the inhalation of uranium and beryllium through the "Rochester Chamber". This project and others similar led to civilian oversight after World War II.

Details of this Division came out in Eileen Welsome's book The Plutonium Files, for which she won a Pulitzer Prize. It documented human experiments in which the subjects did not know they were being tested to find the safety limits of uranium and plutonium. Hodge attended a meeting where the experiments were planned in 1945, and an AEC memo thanks Hodge for his planning and suggestions in the experiment. The US government settled with the victims' families, paying $400,000 per family. Seven victims were injected with material smuggled into a hospital secretly through a tunnel. One unmarried, white 24-year old woman was injected with 584 micrograms of uranium; another 61-year old man was injected with 71 micrograms of uranium per kilogram body mass. Hodge also arranged for Dr. Sweet to inject 11 terminally-ill patients with uranium for their brain tumors; however, these subjects may have known they were being tested.

See also

• Timeline of the Manhattan Project
• Human experimentation in the United States
• Alsos Digital Library for Nuclear Issues
• Quebec Agreement
• August 1945
  • Atomic bombings of Hiroshima and Nagasaki
  • Smyth Report
• Related locations
  • Hanford Site (plutonium production)
    • B Reactor
  • Ames Laboratory (uranium production from ores)
  • Los Alamos National Laboratory (secret weapons lab)
  • Lawrence Livermore National Laboratory (second weapons lab, created in 1950s)
  • Metallurgical Laboratory (first controlled nuclear chain reaction)
  • Oak Ridge, Tennessee
    • Oak Ridge National Laboratory (site of graphite reactor and pilot facilities for plutonium production)
    • Y-12 National Security Complex (uranium enrichment)
    • K-25 (uranium enrichment)
  • Trinity site (first nuclear test)
  • Trail, British Columbia (Project 9, heavy water plant)
• Nuclear weapons
  • History of nuclear weapons
  • Nuclear arms race
  • Nuclear weapon
  • Nuclear weapon design
  • Isotope separation (necessary for uranium enrichment)
  • List of countries with nuclear weapons
  • The United States and nuclear weapons
• People
  • Category:Manhattan Project people (lists articles about people involved in the project)
  • List of Cornell Manhattan Project people, a large number of Cornell University physicists were associated with the project
  • Lise Meitner and Otto Hahn, discoverers of fission
  • David Bohm, did work that was immediately classified, that he then wasn't allowed to read
• Other projects
  • Operation Downfall, the planned Allied invasion of the Japanese homeland; cancelled due to the success of the Manhattan Project.
  • German nuclear energy project
  • Japanese atomic program
  • Operation Alsos, post-war assessment of the German nuclear project
  • Soviet atomic bomb project
  • The Plutonium Files
  • Tube Alloys (British WWII atomic program)
  • Project-706
• Movies (in chronological order)
  • Above and Beyond (1952), a film related to the project, centered on Col Paul Tibbets, pilot of the plane which dropped the Hiroshima bomb
  • The Day After Trinity (1981), a documentary about the project
  • The Manhattan Project (film) (1986), a-bomb as a science fair project
  • Day One (1989), a film about the project in a political perspective
  • Fat Man and Little Boy (1989), Hollywood drama based on the project starring Paul Newman
  • White Light/Black Rain: The Destruction of Hiroshima and Nagasaki (2007)

References

Overall, administrative, and diplomatic histories of the Manhattan Project

• DeGroot, Gerard, The Bomb: A History of Hell on Earth, London: Pimlico, 2005. ISBN 0-7126-7748-8
• Feynman, Richard P. "Surely You're Joking, Mr. Feynman!". W. W. Norton & Company, 1997. ISBN 978-0393316049.
• Groves, Leslie. Now it Can be Told: The Story of the Manhattan Project. New York: Harper, 1962. ISBN 0-306-70738-1.
• Herken, Gregg. Brotherhood of the Bomb : The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller. New York: Henry Holt and Co., 2002. ISBN 0-8050-6588-1.
• Hewlett, Richard G., and Oscar E. Anderson. The New World, 1939–1946. University Park: Pennsylvania State University Press, 1962.
• Howes, Ruth H. and Herzenberg, Caroline L. Their Day in the Sun: Women of the Manhattan Project. Philadelphia: Temple University Press, 1999. ISBN 1-56639-719-7.
• Jungk, Robert. Brighter Than a Thousand Suns: A Personal History of the Atomic Scientists. New York: Harcourt, Brace, 1956, 1958.
• Nichols, Kenneth The Road to Trinity. New York: Morrow, 1987 ISBN 068806910X
• Norris, Robert S., Racing for the Bomb: General Leslie R. Groves, The Manhattan Project's Indispensable Man. Vermont: Steerforth Press, First Paperback edition, 2002. ISBN 1-58642-067-4.
• Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon & Schuster, 1986. ISBN 0-671-44133-7.
• Rhodes, Richard. Dark Sun: The Making of the Hydrogen Bomb. New York: Simon & Schuster, 1995. ISBN 0-684-80400-X.
• Kelly, Cynthia. Remembering the Manhattan Project: Perspectives on the Making of the Atomic Bomb and Its Legacy New Jersey: World Scientific, 2005. ISBN 978-981-256-040-7.
• Kelly, Cynthia. Oppenheimer and the Manhattan Project: Insights into J Robert Oppenheimer, “Father of the Atomic Bomb” New Jersey: World Scientific, 2005. ISBN 978-981-256-418-4.

Technical histories

• Groueff, Stephane. Manhattan Project: The Untold Story of the Making of the Atomic Bomb. Boston: Little, Brown & Co, 1967.
• Hoddeson, Lillian, Paul W. Henriksen, Roger A. Meade, and Catherine L. Westfall. Critical Assembly: A Technical History of Los Alamos During the Oppenheimer Years, 1943–1945. New York: Cambridge University Press, 1993. ISBN 0-521-44132-3.
• David Hawkins, Edith C. Truslow, and Ralph C. Smith. "Project Y: The Los Alamos Story. Part I: Toward Trinity. Part II: Beyond Trinity. (History of Modern Physics, 1800-1950, V. 2)." American Inst. of Physics; 1st edition (September 1, 2000).
• Serber, Robert. The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb. Berkeley: University of California Press, 1992. ISBN 0-520-07576-5—Original 1943, Los Alamos Report "LA-1", declassified in 1965. (Available on Wikimedia Commons).
• Sherwin, Martin J. A World Destroyed: The Atomic Bomb and the Grand Alliance. New York: Alfred A. Knopf, 1975. ISBN 0-394-49794-5.
• Smyth, Henry DeWolf. Atomic Energy for Military Purposes; the Official Report on the Development of the Atomic Bomb under the Auspices of the United States Government, 1940–1945. Princeton: Princeton University Press, 1945. See Smyth Report.
• Yenne, William. "The Manhattan Project", Secret Weapons of World War II: The Techno-Military Breakthroughs That Changed History. New York: Berkley Books, 2003, p. 2–7.

Participant accounts

• Badash, Lawrence, Joseph O. Hirschfelder, Herbert P. Broida, eds. Reminiscences of Los Alamos, 1943–1945. Dordrecht, Boston: D. Reidel, 1980. ISBN 90-277-1097-X.
• Bethe, Hans A. The Road from Los Alamos. New York: Simon and Schuster, 1991. ISBN 0-671-74012-1.
• Nichols, Kenneth David. The Road to Trinity: A Personal Account of How America's Nuclear Policies Were Made. New York: William Morrow and Company Inc, 1987. ISBN 0-688-06910-X.
• Serber, Robert. Peace and War: Reminiscences of a Life on the Frontiers of Science. New York: Columbia University Press, 1998. ISBN 0-231-10546-0.
• Ulam, Stanisław. Adventures of a Mathematician. New York: Charles Scribner's Sons, 1983. ISBN 0-520-07154-9.

External links

• Template:Dmoz
• Why They Called It the Manhattan Project
• Development of the Atomic Bomb
• Annotated bibliography for the Manhattan Project from the Alsos Digital Library for Nuclear Issues.
• Nuclear Files.org Information on the history of the Manhattan Project
• Interview with Joseph Rotblat who worked on the Manhattan Project and left to work for Pugwash. The Nobel Peace Prize was awarded to both Rotblat and Pugwash. Freeview video provided by the Vega Science Trust.
• Works by United States Army—Corps of Engineers (Manhattan District) at Project Gutenberg
• The Cold War International History Project (CWIHP) for Alexander Vassiliev's Notebooks containing evidence on Soviet atomic espionage
• Historic photos of Oak Ridge, TN during the Manhattan Project