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... of more than 90 %. " (Grolier 5) This Uranium was then transported to "the Los Alamos, N. Mex. , laboratory headed by J. Robert Oppenheimer. " (Grolier 5) "Oppenheimer was the major force behind the Manhattan Project. He literally ran the show and saw to it that all of the great minds working on this project made their brainstorms work. He oversaw the entire project from its conception to its completion. " (Outlaw 3) Once the purified Uranium reached New Mexico, it was made into the components of a gun-type atomic weapon. "Two pieces of U- 235, individually not large enough to sustain a chain reaction, were brought together rapidly in a gun barrel to form a supercritical mass that exploded instantaneously. " (Grolier 5) "It was originally nicknamed 'Thin Man' (after Roosevelt, but later renamed 'Little Boy' (for nobody) when technical changes shortened the proposed gun barrel. " (Szasz 25) The scientists were so confident that the gun-type atomic bomb would work "no test was conducted, and it was first employed in military action over Hiroshima, Japan, on Aug. 6, 1945. " (Grolier 5) Before the Uranium- 235 "Little Boy" bomb had been developed to the "point of seeming assured of success, " (Grolier 5) another bomb was proposed.
The Uranium- 238 that had been earlier ruled out as an option was being looked at. It could capture a free neutron without fission ing and become Uranium- 239. "But the Uranium- 239 thus produced is unstable (radioactive) and decays first to neptunium- 239 and then to plutonium- 239. " (Grolier 5) This proved to be useful because the newly created plutonium- 239 is fissionable and it can "be separated from uranium by chemical techniques, " (6) which would be far simpler than the physical processes to separate the Uranium- 235 from the Uranium- 238. Once again the University of Chicago, under Enrico Fermi's direction built the first reactor. "This led to the construction of five large reactors at Hanford, Wash. , where U- 238 was irradiated with neutrons and transmuted into plutonium. " (6) The plutonium was sent to Los Alamos. The problem to overcome in the development of the plutonium bomb was an isotope of plutonium. The scientists feared this isotope would cause premature detonation and most of the plutonium would blow apart before it could all fission. "To overcome this so-called 'defect of nature, ' the plutonium had to be brought into a supercritical mass far faster than conventional ballistics could achieve. " (Grolier 6) Physicist Seth Neddermeyer and mathematician John von Neumann devised the theory of "implosion. " A subcritical sphere of plutonium was surrounded by chemical high-explosives.
The 5, 300 pounds of explosives were all "carefully shaped as 'lenses. ' When these were detonated, they focused the blast wave so as to compress the plutonium instantly into a supercritical mass. " (Szasz 25) This was much more complex, and many people doubted that it would work. There was a debate at Los Alamos about whether to test the new plutonium 'implosion' bomb before it was actually dropped. "Harvard explosives expert George B. Kistiakowsky and Oppenheimer both argued for such a test, but initially Groves was opposed. He was afraid that if the test failed, the precious plutonium would be scattered all across the countryside. " (Szasz 26) Brigadier General Leslie R. Groves, the man the army placed in charge, was eventually persuaded.
Hanford's plutonium production was increasing fast enough so that a test would cause little delay in time. They feared that if they dropped the untested plutonium bomb and it failed to work, "the enemy would find themselves owners of a 'gift' atomic weapon. " (Szasz 26) The final agreement for the test was that the bomb would be placed in "a gigantic, 214 -ton, cylinder-shaped tank (called 'Jumbo'). " (Szasz 26) If the plutonium correctly fashioned, the tank would be vaporized. If it did not work correctly, the conventional explosives would be contained in the tank and the plutonium would stay in the tank. After further development of the implosion design and fears that "Jumbo" would dramatically distort all "their complicated instrumentation-the raison d'tre for the test, " (Szasz 36) the world's largest pressure tank was not used. On Monday, July 16, 1945, at 5: 29: 45 A. M. , Mountain War Time, the plutonium bomb ignited at the Trinity site, a remote site in the New Mexico desert. "The explosion created s brilliant flash that was seen in three states. " (Szasz 83) There were many reports from civilians from all over that described the experience.
People who saw it said it looked like the sun had risen for a few minutes and then went back down. Others thought they had seen a large plane or meteor crash. A sheep herder who was laying sleeping on a cot fifteen miles away was blown off. "The Smithsonian Observatory on Burro Mountain confirmed a shock but noted that the vibrations were unlike any earthquake ever recorded. " (Szasz 84) An eight year-old boy was awakened and ran for his Methodist parents, and they considered if this might be the end of the world. The most powerful statement that has been cited in practically every coverage of the atomic bomb is Georgia Green's experience. She was being driven to Albuquerque. "What was that?" she asked her brother-in-law, who was driving. This was very unusual because Georgia Green was blind.
Brigadier General Farrell wrote a letter for the Secretary of War. "'No man-made phenomenon of such tremendous power had ever occurred before... Thirty seconds after the explosion came, first, the air blast pressing hard against people and things, to be followed almost immediately by the strong, sustained, awesome roar which warned of doomsday and made us feel that we puny things were blasphemous to dare tamper with forces heretofore reserved to the Almighty. Words are inadequate tools for the job of acquainting those not present with the physical, mental and psychological effects. " (Groueff 355) Upon witnessing the explosion, reactions among the bomb's creators were mixed. Their mission had been successfully accomplished, however, they questioned whether "the equilibrium in nature had been upset -- as if humankind had become a threat to the world it inhabited. " (Outlaw 3) Oppenheimer was ecstatic about the success of the bomb, but quoted a fragment from Bhagavad Gita. "I am become Death, the destroyer of worlds. " Many people who were involved in the creation of the atomic bomb signed petitions against dropping the bomb. The atomic bomb has been used twice in warfare. The Uranium bomb nicknamed "Little Boy, " which weighed over 4. 5 tons, was dropped over Hiroshima on August 6, 1945.
At 0815 hours the bomb was dropped from the Enola Gay. It missed Ground Zero at 1, 980 feet by only 600 feet. "At 0816 hours, in the flash of an instant, 66, 000 people were killed and 69, 000 people were injured by a 10 kiloton atomic explosion. " (Outlaw 4) [See blast ranges diagram] Nagasaki fell to the same treatment as Hiroshima on August 9, 1945. The plutonium bomb, "Fat Man, " was dropped on the city. It missed its intended target by over one and a half miles. "Nagasaki's population dropped in one split-second from 422, 000 to 383, 000. 39, 000 were killed, over 25, 000 were injured. That blast was less than 10 kilotons as well. Physicists who have studied the atomic explosions conclude that the bombs utilized "only 0. 1 % of their respective explosive capabilities. " (Outlaw 4) Controversy still exists about dropping the two atomic bombs on Japan.
Arguments defending the Japanese claim "the atomic bomb did not win the war in the Pacific; at best, it hastened Japanese acceptance of a defeat that was viewed as inevitable. " (Grolier 8) Other arguments state that the United States should have warned the Japanese, or that we should have invited them to a public demonstration. "In retrospect that U. S. use of the atomic bomb may have been the first act of the cold war. " (Grolier 8) On the other side, advocates claimed that the invasion of the Japanese islands could and would result in over one million military casualties plus the civilian losses based on previous invasions of Japanese occupied islands. On the morning of August 6, 1945, a B- 29 bomber named Enola Gay flew over the industrial city of Hiroshima, Japan and dropped the first atomic bomb ever.
The city went up in flames caused by the immense power equal to about 20, 000 tons of TNT. The project was a success. They were an unprecedented assemblage of civilian, and military scientific brain power brilliant, intense, and young, the people that helped develop the bomb. Unknowingly they came to an isolated mountain setting, known as Los Alamos, New Mexico, to design and build the bomb that would end World War 2, but begin serious controversies concerning its sheer power and destruction.
I became interested in this topic because of my interest in science and history. It seemed an appropriate topic because I am presently studying World War 2 in my Social Studies Class. The Hiroshima and Nagasaki bombings were always taught to me with some opinion, and I always wanted to know the bomb itself and the unbiased effects that it had. This I-search was a great opportunity for me to actually fulfill The Manhattan Project was the code name for the US effort during World War II to produce the atomic bomb. It was appropriately named for the Manhattan Engineer District of the US Army Corps of Engineers, because much of the early research was done in New York City (Badash 238). Sparked by refugee physicists in the United States, the program was slowly organized after nuclear fission was discovered by German scientists in 1938, and many US scientists expressed the fear that Hitler would attempt to build a fission bomb.
Frustrated with the idea that Germany might produce an atomic bomb first, Leo Szilard and other scientists asked Albert Einstein, a famous scientist during that time, to use his influence and write a letter to president FDR, pleading for support to further research the power of nuclear fission (Badash 237). His letters were a success, and President Roosevelt established the Manhattan Project. Physicists from 1939 onward conducted much research to find answers to such questions as how many neutrons were emitted in each fission, which elements would not capture the neutrons but would moderate or reduce their velocity, and whether only the lighter and scarcer isotope of uranium (U- 235) fashioned or the common isotope (U- 238) could be used. They learned that each fission releases a few neutrons. A chain reaction, therefore, was theoretically possible, if not too many neutrons escaped from the mass or were captured by impurities. To create this chain reaction and turn it into a usable weapon was the ultimate goal of the Manhattan Project.
In 1942 General Leslie Groves was chosen to lead the project, and he immediately purchased a site at Oak Ridge, Tenn. , for facilities to separate the necessary uranium- 235 from the much more common uranium- 238. Uranium 235 was an optimal choice for the bomb because of its unusually unstable composition. Thus, the race to separate the two began. During that time, the work to perfect the firing mechanism and structure of the bomb was also swiftly underway. General Groves initial task had been to select a scientific director for the bomb project.
His first two choices, Ernest O. Lawrence, director of the electromagnetic separation project, and Arthur H. Compton, director of Chicago Metallurgical Laboratory, were not available. Groves had some doubts regarding the next best candidate, J.
Robert Oppenheimer (Wood 2). Finally, Groves gambled on Oppenheimer, a theoretical mathematician, as director of the weapons laboratory, built on an isolated mesa (flat land area) at Los Alamos, New Mexico. After much difficulty, an absorbent barrier suitable for separating isotopes of uranium was developed and installed in the Oak Ridge gaseous diffusion plant. Finally, in 1945, uranium- 235 of bomb purity was shipped to Los Alamos, where it was fashioned into a gun-type weapon. In a barrel, one piece of uranium was fired at another, together forming a supercritical, explosive mass. To achieve chain-reaction fission, a certain amount of fissile material, called critical mass, is necessary.
The fissile material used in the Hiroshima model was uranium 235. In the bomb, the uranium was divided into two parts, both of which were below critical mass. The bomb was designed so that one part would be slammed into the other by an explosive device to achieve critical mass instantaneously (Badash 238). When critical mass is achieved, continuous fission (a chain reaction) takes place in an extremely short period of time, and far more energy is released than in the case of a gun-powder explosion (Badash 238).
On December 2, 1942, the first self-sustaining chain reaction with cadmium took place, overseen by Enrico Fermi, in the University of Chicago squash fields (Asimov 783). Another type of atomic bomb was also constructed using the synthetic element plutonium. Fermi built a reactor at Chicago in late 1942, the prototype of five production reactors erected at Hanford, Wash. These reactors manufactured plutonium by bombarding uranium- 238 with neutrons. At Los Alamos the plutonium was surrounded with high explosives to compress it into a super dense, super critical mass far faster than could be done in a gun barrel.
The result was tested at Alamogordo, New Mexico, on July 16, 1945, and was the first explosion of an atomic bomb code-named Trinity (Beyer 55). However, all was not that easy coming up to this milestone point. Security restrictions bound both workers and townspeople. Everybody had the same address where all mail was censored (Wood 4). Everybody was restricted to a 200 mile radius, and residents of Los Alamos were prohibited from telling friends and relatives where they lived (Wood 4).
There were serious issues of security of documents, due to failure to lock up (Wood 4). The one serious incident was the hiring of Klaus Fuchs. He was later found, and convicted of obtaining secret documents and sending them to the Soviet Union. A competent and hardworking scientist himself, Fuchs enabled the Soviet Union to create their own atomic bomb (Beyer 45). Names were not allowed to be mentioned outside of the laboratory. Everybody was a "sir" or "mister" instead of their own name (Wood 4).
Unless they worked at the lab themselves, wives knew nothing of their husbands research (Wood 4). Decisions to drop the atomic bomb went through several personalities, yet ultimately rested upon president Truman. The man whose decisions created the Manhattan Project, never lived to see the results of his labor. FDR died on April 12, three months before the first successful Trinity test (Beyer 56). The responsibilities were soon placed upon Truman, the next president. Truman knew nothing about the bomb and its effects yet hastily decided that the bomb be used on Japan, considering Germany was no longer a target with the war in Europe over.
Initiated by Szilard, a petition was made to offer the opinion that the bomb should be used only if Japan refused to surrender, even after being informed of the bombs destructive capabilities (Beyer 65). Nevertheless, the decision was made that the bombs would be used until Japan surrendered. The Hiroshima model is known as a gun-barrel-type atomic bomb. Due to its long and narrow shape, the Hiroshima model was called "Thin Man" at first, but during the manufacturing process the original plans were modified, shortening the length and giving rise to the name "Little Boy. " (Beyer 48). The energy released from the Hiroshima A-bomb was originally thought to be equivalent to the destructive power of 20, 000 tons of TNT.
Later estimates, however, put the energy equivalent to approximately 15, 000 tons of TNT, based on damage done to buildings and research on the bomb's composition. Despite the release of such enormous energy, it is believed that less than one kilogram of the 10 to 30 kilograms of uranium 235 housed in the bomb achieved fission. The fissionable material used in the Nagasaki bomb was plutonium 239. The plutonium 239 was divided into below-critical-mass units and packed into a spherical case. At the time of detonation, the units were compressed to the center with a gun-powder explosion to achieve fission. The Nagasaki model is known as an implosion-type atomic bomb.
Compared to the Hiroshima A-bomb, the one used in Nagasaki was larger in diameter and round so it was called "Fat Man. " Only slightly more than one kilogram of the plutonium 239 is thought to have achieved fusion, but the energy released is estimated to be equivalent to the destructive power of about 20, 000 tons of TNT Little boy killed about 100, 000 people outright, wounded another 100, 000, and destroyed about 90 percent of Hiroshima (Hewlett 216). Yet, while the first atomic bomb was a roaring success, it raised many ethical and controversial issues. Most of the people in the United States of America supported the use of the atomic bomb, even President Truman called it, "the greatest thing in history" (Beyer 75). Many people, including the scientists that developed the bomb, opposed the bombings and felt that it was immoral to kill that many innocent people just to get an influence in the war.
The Manhattan Project was one of the most important parts of American History. It was the first effort to create an atomic bomb, that helped end the war in the Pacific. I enjoyed researching the topic and learned a lot from my readings. Now I understand the atomic bomb better and also understand the motives behind it. Researching helped me understand the sheer strength and power of what a small element can do. All of our lives have changed through the development and bombing of the atomic bomb.
The cold war, nuclear restrictions, nuclear energy, are all results of the first nuclear breakthrough. However, the controversial issues will still rage on. Nuclear testing, nuclear power, and nuclear waste are still being debated for over 50 years, and the United States, the only country to actually use the bomb, is the leader. Bibliography:
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Research essay sample on Type Atomic Bomb J Robert Oppenheimer
