The Manhattan Project
The Beginning
It was assumed that Nazi Germany already begun creating atomic weaponry, so leading physicists Enrico Fermi, Albert Einstein, and Leó Szilárd recommended that the United States work on atomic technology. It was assumed that whoever succeeded to create an atomic weapon first would win the war. Ironically, Germany never had the resources to create such atomic weapons.
Formally known as the Manhattan Engineering District, the Manhattan Project was formed in August 1942. It was a secret wartime effort to create the first atomic weapons. In September 1942, the project was put under Army Brigadier General Leslie Richard Groves. He made the decision to appoint J. Robert Oppenheimer as the director of the project.
Formally known as the Manhattan Engineering District, the Manhattan Project was formed in August 1942. It was a secret wartime effort to create the first atomic weapons. In September 1942, the project was put under Army Brigadier General Leslie Richard Groves. He made the decision to appoint J. Robert Oppenheimer as the director of the project.
J. Robert Oppenheimer, director of the Manhattan Project
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The unofficial emblem of the Manhattan Project.
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Leslie Richard Groves, head of the Manhattan Project.
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Together, Groves and Oppenheimer picked a location to create a new laboratory for the project, they settled for a school they purchased for $440,000 in Los Alamos, New Mexico. Suggested by Oppenheimer which attended the school during a summer camp as a young boy, he remembered the area. The owners of the school were pleased to sell the buildings and property, since it was difficult to find teachers to apply because of the war.
Two other major locations were also chosen for secret laboratories for other tasks of the project. In Hanford, Washington three reactors were built, eventually they would be used to produce plutonium. A nuclear reactor and a plant was built in Oak Ridge, Tennessee. The plant was for producing and purifying large quantities of uranium. Originally, a site near Knoxville, Tennessee was chosen, but Groves disapproved, because they would be risking the major population of the area if any nuclear accident were to happen, such as damage to health and loss of life.
Two other major locations were also chosen for secret laboratories for other tasks of the project. In Hanford, Washington three reactors were built, eventually they would be used to produce plutonium. A nuclear reactor and a plant was built in Oak Ridge, Tennessee. The plant was for producing and purifying large quantities of uranium. Originally, a site near Knoxville, Tennessee was chosen, but Groves disapproved, because they would be risking the major population of the area if any nuclear accident were to happen, such as damage to health and loss of life.
A map of site locations used during the Manhattan Project.
Small self-contained communities were built around the project sites. They had houses, bus systems, grocery stores, everything that anyone working on the project would need. Isolating people involved with the project, to not let any information leak out, was a key to keeping the project a secret. Any families that resided near major sites were forced to relocate. This was a sacrifice believed to be necessary to maintain security of the project.
Fuel Production
By 1943, all three sites were ready for use, the scientists decided to deal with the first task of obtaining enough amounts of the isotope uranium-235. Uranium-238 was much more abundant than uranium-235, but it can't be used for fission.
Uranium-238 is not capable of fission because it cannot sustain the chain reaction like uranium-235. Scientist needed a way of separating the two isotopes, uranium-235 and uranium-238.
The first method used to separate the two isotopes was the cyclotron. The cyclotron was invented by Ernest Lawrence. in the 1930s. The cyclotron separated the two particles by spinning them in a machine at high speeds and a magnet that would attract the lighter uranium-235 as it passed closer to the magnet, while the uranium-238's atoms would spin further away.
The method of the cyclotron was decided to not be efficient, as it would attract dirt, so it would need to be cleaned frequently and would delay production, so the use of the cyclotron would be replaced by a second method called gaseous diffusion. The method seems simple in theory, a membrane would be a diffusion barrier allowing the lighter uranium-235 molecules to pass through quickly, leaving the heavier and slower moving uranium-238 behind.
Although uranium was still a primary focus as a fuel source for an atomic weapon, plutonium was discovered. Plutonium had similar characteristics to uranium, it had an unstable isotope, plutonium-239 which was capable of sustaining the fission chain reaction. Glenn Seaborg, a physicist working at the University of California, Berkeley who discovered plutonium, had also discovered that uranium-238 could be transformed into plutonium-239. To go through the transformation, the only step to initiate the process is to put uranium-238 into a nuclear reactor. Once in the reactor, the uranium isotope would attract extra neutrons.
Uranium-238 is not capable of fission because it cannot sustain the chain reaction like uranium-235. Scientist needed a way of separating the two isotopes, uranium-235 and uranium-238.
The first method used to separate the two isotopes was the cyclotron. The cyclotron was invented by Ernest Lawrence. in the 1930s. The cyclotron separated the two particles by spinning them in a machine at high speeds and a magnet that would attract the lighter uranium-235 as it passed closer to the magnet, while the uranium-238's atoms would spin further away.
The method of the cyclotron was decided to not be efficient, as it would attract dirt, so it would need to be cleaned frequently and would delay production, so the use of the cyclotron would be replaced by a second method called gaseous diffusion. The method seems simple in theory, a membrane would be a diffusion barrier allowing the lighter uranium-235 molecules to pass through quickly, leaving the heavier and slower moving uranium-238 behind.
Although uranium was still a primary focus as a fuel source for an atomic weapon, plutonium was discovered. Plutonium had similar characteristics to uranium, it had an unstable isotope, plutonium-239 which was capable of sustaining the fission chain reaction. Glenn Seaborg, a physicist working at the University of California, Berkeley who discovered plutonium, had also discovered that uranium-238 could be transformed into plutonium-239. To go through the transformation, the only step to initiate the process is to put uranium-238 into a nuclear reactor. Once in the reactor, the uranium isotope would attract extra neutrons.
Ernest Lawrence, inventor of the cyclotron.
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Glenn Seaborg, discovered plutonium and that uranium-238 could be transformed into plutonium-239.
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"Fat Man" & "Little Boy"
Since the Manhattan Project was developing two fuel sources, two different bomb designs were created. The reason for two designs was the different chemical properties of uranium and plutonium. The uranium bomb was nicknamed "Little Boy". The fissionable material of uranium needed to be squeezed together, so a wad of uranium-235 was propelled through a modified gun barrel into another clump of uranium-235. When the two substances combined, a critical mass was created, which then started a fission chain reaction that set off an atomic explosion.
The second bomb, named after British Prime Minister Winston Churchill, called "Fat Man" used plutonium instead of uranium. "Fat Man" had a different method of starting an atomic explosion, plutonium was surrounded by a ring of explosives. When the explosives are detonated, the plutonium would implode resulting in an atomic explosion.
Enough uranium and plutonium was produced by early 1945 for scientists to test a device at Los Alamos, New Mexico. On July 13, 1945 a plutonium bomb was assembled and brought to a test site in New Mexico on the Alamagordo Bombing Range. The test would be code named "Trinity". Bad weather would delay the test for three days.
The predawn of July 16,1945, the bomb was ready to be set off. Exactly 5:29:45 AM, July 16,1945 the bomb was detonated. The explosion produced a flash visible from over 250 miles away and released heat four times hotter than the sun's interior, it also produced a deafening sound that broke windows 120 miles away. The explosion itself was measured to be equivalent to around 19,000 tons of TNT, four times stronger than scientists anticipated. The bombs would be used on Hiroshima and Nagasaki.
The second bomb, named after British Prime Minister Winston Churchill, called "Fat Man" used plutonium instead of uranium. "Fat Man" had a different method of starting an atomic explosion, plutonium was surrounded by a ring of explosives. When the explosives are detonated, the plutonium would implode resulting in an atomic explosion.
Enough uranium and plutonium was produced by early 1945 for scientists to test a device at Los Alamos, New Mexico. On July 13, 1945 a plutonium bomb was assembled and brought to a test site in New Mexico on the Alamagordo Bombing Range. The test would be code named "Trinity". Bad weather would delay the test for three days.
The predawn of July 16,1945, the bomb was ready to be set off. Exactly 5:29:45 AM, July 16,1945 the bomb was detonated. The explosion produced a flash visible from over 250 miles away and released heat four times hotter than the sun's interior, it also produced a deafening sound that broke windows 120 miles away. The explosion itself was measured to be equivalent to around 19,000 tons of TNT, four times stronger than scientists anticipated. The bombs would be used on Hiroshima and Nagasaki.
The bomb "Fat Man"
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Explosion from the Trinity test.
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The bomb "Little Boy"
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