Chicago Pile-1 - Knowledge

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pieces of uranium metal and uranium oxide. The graphite arrived from the manufacturers in 4.25-by-4.25-inch (10.8 by 10.8 cm) bars of various lengths. They were cut into standard lengths of 16.5 inches (42 cm), each weighing 19 pounds (8.6 kg). A lathe was used to drill 3.25-inch (8.3 cm) holes in the blocks for the control rods and the uranium. A hydraulic press was used to shape the uranium oxide into "pseudospheres", cylinders with rounded ends. Drill bits had to be sharpened after each 60 holes, which worked out to be about once an hour. Graphite dust soon filled the air and made the floor slippery.

859:, Compton became convinced that a plutonium bomb was also feasible. In December, Compton was placed in charge of the plutonium project. Its objectives were to produce reactors to convert uranium to plutonium, to find ways to chemically separate the plutonium from the uranium, and to design and build an atomic bomb. It fell to Compton to decide which of the different types of reactor designs the scientists should pursue, even though a successful reactor had not yet been built. He proposed a schedule to achieve a controlled nuclear chain reaction by January 1943, and to have an atomic bomb by January 1945. 263: 1447:

to Fermi's new calculations, the countdown would reach 1 between the 56th and 57th layers. The resulting pile was therefore flatter on the top than on the bottom. Anderson called a halt after the 57th layer was placed. When completed, the wooden frame supported an elliptical-shaped structure, 20 feet (6.1 m) high, 6 feet (1.8 m) wide at the ends and 25 feet (7.6 m) across the middle. It contained 6 short tons (5.4 t) of uranium metal, 50 short tons (45 t) of uranium oxide and 400 short tons (360 t) of graphite, at an estimated cost of $ 2.7 million.

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use for graphite at that time. Because of his work studying the spectroscopy of the carbon arc, MacPherson knew that the major relevant contaminant was boron, both because of its concentration and its affinity for absorbing neutrons, confirming a suspicion of Szilard's. More importantly, MacPherson and Hamister believed that techniques for producing graphite of a sufficient purity could be developed. Had Fermi and Szilard not consulted MacPherson and Hamister, they might have concluded, incorrectly, as the Germans did, that graphite was unsuitable for use as a neutron moderator.

1124:, the University of Chicago and the University of California was creating too much duplication and not enough collaboration, and he resolved to concentrate the work in one location. Nobody wanted to move, and everybody argued in favor of their own location. In January 1942, soon after the United States entered World War II, Compton decided on his own location, the University of Chicago, where he knew he had the unstinting support of university administration. Chicago also had a central location, and scientists, technicians and facilities were more readily available in the 6853: 6841: 6829: 748: 1456: 1415: 1347: 1266: 1145: 1092: 668:, which would not absorb neutrons like ordinary hydrogen, and was a better neutron moderator than carbon; but heavy water was expensive and difficult to produce, and several tons of it might be needed. Fermi estimated that a fissioning uranium nucleus produced 1.73 neutrons on average. It was enough, but a careful design was called for to minimize losses. (Today the average number of neutrons emitted per fissioning uranium-235 nucleus is known to be about 2.4). 5782: 1606: 31: 1262:

reactor—at a more remote site. A building at Argonne to house Fermi's experimental pile was commenced, with its completion scheduled for 20 October. Due to industrial disputes, construction fell behind schedule, and it became clear the materials for Fermi's new pile would be on hand before the new structure was completed. In early November, Fermi came to Compton with a proposal to build the experimental pile under the stands at Stagg Field.

868: 6865: 270: 1483:, which he was to throw over the pile in the event of an emergency. The startup began at 09:54. Walter Zinn removed the zip, the emergency control rod, and secured it. Norman Hilberry stood ready with an axe to cut the scram line, which would allow the zip to fall under the influence of gravity. While Leona Woods called out the count from the boron trifluoride detector in a loud voice, 1423:

as the pile approached criticality. At the 15th layer, it was 390; at the 19th it was 320; at the 25th it was 270 and by the 36th it was only 149. The original design was for a spherical pile, but as work proceeded, it became clear that this would not be necessary. The new graphite was purer, and 6 short tons (5.4 t) of very pure metallic uranium began to arrive from the

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electric current from the boron trifluoride detector. He wanted to test the control circuits, but after 28 minutes, the alarm bells went off to notify everyone that the neutron flux had passed the preset safety level, and he ordered Zinn to release the zip. The reaction rapidly halted. The pile had run for about 4.5 minutes at about 0.5 watts. Wigner opened a bottle of

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morning of 16 November 1942. The first layer placed was made up entirely of graphite blocks, with no uranium. Layers without uranium were alternated with two layers containing uranium, so the uranium was enclosed in graphite. Unlike later reactors, it had no radiation shielding or cooling system, as it was only intended to be operated at very low power.

1540:, with overhead protection from 6 inches (15 cm) of lead and 50 inches (130 cm) of wood. More uranium was used, so it contained 52 short tons (47 t) of uranium and 472 short tons (428 t) of graphite. No cooling system was provided as it only ran at a few kilowatts. CP-2 became operational in March 1943, with a 1706:, stands in a small quadrangle outside the Regenstein Library on the former site of the west viewing stands' rackets court. It was dedicated on 2 December 1967, to commemorate the 25th anniversary of CP-1 going critical. The commemorative plaques from 1952, 1965 and 1967 are nearby. A graphite block from CP-1 can be seen at the 422:. Although the project's civilian and military leaders had misgivings about the possibility of a disastrous runaway reaction, they trusted Fermi's safety calculations and decided they could carry out the experiment in a densely populated area. Fermi described the reactor as "a crude pile of black bricks and wooden timbers". 1536:. There the original materials were used to build Chicago Pile-2 (CP-2). Instead of being spherical, the new reactor was built in a cube-like shape, about 25 feet (7.6 m) tall with a base approximately 30 feet (9.1 m) square. It was surrounded by concrete walls 5 feet (1.5 m) thick that acted as a 1446:

The 2.25-inch (5.7 cm) metallic uranium cylinders, known as "Spedding's eggs", were dropped in the holes in the graphite in lieu of the uranium oxide pseudospheres. The process of filling the balloon with carbon dioxide would not be necessary, and twenty layers could be dispensed with. According

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About two layers were laid per shift. Woods' boron trifluoride neutron counter was inserted at the 15th layer. Thereafter, readings were taken at the end of each shift. Fermi divided the square of the radius of the pile by the intensity of the radioactivity to obtain a metric that counted down to one

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in August, but by September it was apparent that the proposed facilities would be too extensive for the site, and it was decided to build the pilot plant elsewhere. The subcritical piles posed little danger, but Groves felt that it would be prudent to locate a critical pile—a fully functional nuclear

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factor was larger than originally thought. This removed the objections to the use of air or water as a coolant rather than expensive helium. It also meant that there was greater latitude in the choice of materials for coolant pipes and control mechanisms. Wigner now pressed ahead with his design for

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played squash there in 1940. Since it was intended for strenuous exercise, the area was unheated, and very cold in the winter. The nearby North Stands had a pair of ice skating rinks on the ground floor, which although they were unrefrigerated, seldom melted in winter. Allison used the rackets court

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Before leaving for Chicago, Fermi's team made one last attempt to build a working pile at Columbia. Since the cans had absorbed neutrons, they were dispensed with. Instead, the uranium oxide, heated to 250 °C (480 °F) to dry it out, was pressed into cylindrical holes 3 inches (7.6 cm)

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Another grant, this time of $ 40,000, was obtained from the S-1 Uranium Committee to purchase more materials, and in August 1941 Fermi began to plan the building of a sub-critical assembly to test with a smaller structure whether a larger one would work. The so-called exponential pile he proposed to

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to discuss the possible existence of impurities in graphite, and the procurement of graphite of a purity that had never been produced commercially. National Carbon, a chemical company, had taken the then unusual step of hiring MacPherson, a physicist, to research carbon arc lamps, a major commercial

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from the fission reactions. Since the rate of release of these neutrons depends on fission events taking place some time earlier, there is a delay between any power spikes and the later criticality event. This time gives the operators leeway; if a spike in the prompt neutron flux is seen, they have

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We went to Dean Pegram, who was then the man who could carry out magic around the University, and we explained to him that we needed a big room. He scouted around the campus and we went with him to dark corridors and under various heating pipes and so on, to visit possible sites for this experiment

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impurities in the graphite samples on which they ran their test of its usability as a moderator, while Leo Szilard and Enrico Fermi had asked suppliers about the most common contaminations of graphite after a first failed test. They consequently ensured that the next test would be run with graphite

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On 12 December 1942, CP-1's power output was increased to 200 W, enough to power a light bulb. Lacking shielding of any kind, it was a radiation hazard for everyone in the vicinity, and further testing was continued at 0.5 W. Operation was terminated on 28 February 1943, and the pile was

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The work was carried out in twelve-hour shifts, with a day shift under Zinn and a night shift under Anderson. For a work force they hired thirty high school dropouts who were eager to earn a bit of money before being drafted into the military. They machined 45,000 graphite blocks enclosing 19,000

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had a substantial scientific lead. The success of Chicago Pile-1 in producing the chain reaction provided the first vivid demonstration of the feasibility of the military use of nuclear energy by the Allies, as well as the reality of the danger that Nazi Germany could succeed in producing nuclear

1563:. Wartime experiments included measuring the neutron absorption cross-section of elements and compounds. Albert Wattenberg recalled that about 10 elements were studied each month, and 75 over the course of a year. An accident involving radium and beryllium powder caused a dangerous drop in his 1494:

The experiment resumed at 14:00. Weil worked the final control rod while Fermi carefully monitored the neutron activity. Fermi announced that the pile had gone critical (reached a self-sustaining reaction) at 15:25. Fermi switched the scale on the recorder to accommodate the rapidly increasing

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was used to haul it into place, with the top secured to the ceiling and three sides to the walls. The remaining side, the one facing the balcony from which Fermi directed the operation, was furled like an awning. A circle was drawn on the floor, and the stacking of graphite blocks began on the

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was present, at Compton's invitation. Other dignitaries present included Szilard, Wigner and Spedding. Fermi, Compton, Anderson and Zinn gathered around the controls on the balcony, which was originally intended as a viewing platform. Samuel Allison stood ready with a bucket of concentrated

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iron cans of uranium oxide. The cans were 8-by-8-by-8-inch (20 by 20 by 20 cm) cubes. When filled with uranium oxide, each weighed about 60 pounds (27 kg). There were 288 cans in all, and each was surrounded by graphite blocks so the whole would form a cubic lattice structure. A

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became director of the Manhattan Project on 23 September 1942. He visited the Metallurgical Laboratory for the first time on 5 October. Between 15 September and 15 November 1942, groups under Herbert Anderson and Walter Zinn constructed 16 experimental piles under the Stagg Field stands.

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capture cross section of uranium-235. At the time only such minute quantities of plutonium-239 had been produced, in cyclotrons, and it was not possible to produce a sufficiently large quantity that way. Compton discussed with Wigner how plutonium might be produced in a

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weapons. Previously, estimates of critical masses had been crude calculations, leading to order-of-magnitude uncertainties about the size of a hypothetical bomb. The successful use of graphite as a moderator paved the way for progress in the Allied effort, whereas

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and the Argonne National Laboratory yielded to public pressure and earmarked $ 24.7 million and $ 3.4 million respectively to rehabilitate the site. As part of the cleanup, 500 cubic yards (380 m) of radioactive waste was removed and sent to the

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is achieved when the rate of neutron production is equal to the rate of neutron losses, including both neutron absorption and neutron leakage. When a uranium-235 atom undergoes fission, it releases an average of 2.4 neutrons. In the simplest case of an

1281:. When a fuel atom undergoes fission, it releases neutrons that strike other fuel atoms in a chain reaction. The time between absorbing the neutron and undergoing fission is measured in nanoseconds. Szilard had noted that this reaction leaves behind 517:, a wartime research facility near Chicago, where it was reconfigured to become Chicago Pile-2 (CP-2). There, it was operated for research until 1954, when it was dismantled and buried. The stands at Stagg Field were demolished in August 1957 and a 1285:

that may also release neutrons, but do so over much longer periods, from microseconds to as long as minutes. In a slow reaction like the one in a pile where the fission products build up, these neutrons account for about three percent of the total

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to conduct the first nuclear fission experiment in the United States on 25 January 1939. Subsequent work confirmed that fast neutrons were indeed produced by fission. Szilard obtained permission from the head of the Physics Department at Columbia,

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was positioned near the bottom. The uranium oxide was heated to remove moisture, and packed into the cans while still hot on a shaking table. The cans were then soldered shut. For a workforce, Pegram secured the services of Columbia's

565:, which then caused further nuclear reactions, the process might be self-perpetuating. Szilard proposed using mixtures of lighter known isotopes which produced neutrons in copious amounts, and also entertained the possibility of using 1132:

long and 3 inches (7.6 cm) in diameter drilled into the graphite. The entire pile was then canned by soldering sheet metal around it, and the contents heated above the boiling point of water to remove moisture. The result was a

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that when cut would drop a control rod into the pile and stop the reaction. Richard Fox, who made the control-rod mechanism for the pile, remarked that the manual speed control that the operator had over the rods was simply a

744:. Its first meeting on 21 October 1939 was attended by Szilard, Teller, and Wigner. The scientists persuaded the Army and Navy to provide $ 6,000 for Szilard to purchase supplies for experiments—in particular, more graphite. 683:

Over the next two years, MacPherson, Hamister and Lauchlin M. Currie developed thermal purification techniques for the large scale production of low boron content graphite. The resulting product was designated AGOT graphite

700:. By November 1942 National Carbon had shipped 255 short tons (231 t) of AGOT graphite to the University of Chicago, where it became the primary source of graphite to be used in the construction of Chicago Pile-1. 1646:

a water-cooled production reactor. There remained concerns about the ability of a graphite-moderated reactor being able to produce plutonium on industrial scale, and for this reason the Manhattan Project continued the

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The process was abruptly halted by the automatic control rod reinserting itself, due to its trip level being set too low. At 11:25, Fermi ordered the control rods reinserted. He then announced that it was lunch time.

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was in no position to make an independent judgment of the hazards involved. Based on considerations of the University's welfare, the only answer he could have given would have been—no. And this answer would have been

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for a situation in which two molecules react to form not just the final reaction products, but also some unstable molecules that can further react with the original substances to cause more to react. The concept of a

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Brasch, A.; Lange, F.; Waly, A.; Banks, T. E.; Chalmers, T. A.; Szilard, Leo; Hopwood, F. L. (8 December 1934). "Liberation of Neutrons from Beryllium by X-Rays: Radioactivity Induced by Means of Electron Tubes".

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count that lasted for three years. As the dangers of things such as inhaling uranium oxide became more apparent, experiments were conducted on the effects of radioactive substances on laboratory test animals.

1128:, where war work had not yet taken them away. In contrast, Columbia University was engaged in uranium enrichment efforts under Harold Urey and John Dunning, and was hesitant to add a third secret project. 1333:

Compton informed Groves of his decision at the 14 November meeting of the S-1 Executive Committee. Although Groves "had serious misgivings about the wisdom of Compton's suggestion", he did not interfere.

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at Columbia, using a radium-beryllium source to bombard uranium with neutrons. They discovered significant neutron multiplication in natural uranium, proving that a chain reaction might be possible.

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sample, which, after being mailed to Dunning at Columbia, was confirmed to be the isolated fissile material. When he was working in Rome, Fermi had discovered that collisions between neutrons and

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Leo Szilard (right) and Norman Hilberry under the plaque commemorating Chicago Pile-1 on the West Stands of Old Stagg Field. While the stands were later demolished, the plaque is now located at

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court. Stagg Field had been largely unused since the University of Chicago had given up playing American football in 1939, but the rackets courts under West Stands were still used for playing

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team. It was the custom at the time for football players to perform odd jobs around the university. They were able to manipulate the heavy cans with ease. The final result was a disappointing

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blanketing one of the United States' major urban areas in radioactive fission products. But the physics of the system suggested that the pile could be safely shut down even in the event of a

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As a responsible officer of the University of Chicago, according to every rule of organizational protocol, I should have taken the matter to my superior. But this would have been unfair.

4761: 1297:, and by carefully controlling the reaction rates as the power is ramped up, a pile can reach criticality at fission rates slightly below that of a chain reaction relying solely on the 5816: 1616:

By the 1970s there was increased public concern about the levels of radioactivity at the site, which was used for recreation by local residents. Surveys conducted in the 1980s found

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had found a suitable location 60 feet (18 m) long, 30 feet (9.1 m) wide and 26 feet (7.9 m) high, sunk slightly below ground level, in a space under the stands at

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in St Louis, which was now producing 30 short tons (27 t) a month. Metallic uranium also began arriving in larger quantities, the product of newly developed techniques.

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build was 8 feet (2.4 m) long, 8 feet (2.4 m) wide and 11 feet (3.4 m) high. This was too large to fit in the Pupin Physics Laboratories. Fermi recalled that:

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The next day, 2 December 1942, everybody assembled for the experiment. There were 49 scientists present. Although most of the S-1 Executive Committee was in Chicago, only

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can slow the neutrons down, and thereby make them more likely to be captured by uranium nuclei, causing the uranium to fission. Szilard suggested to Fermi that they use

5032: 6155: 1362:. A 25-foot (7.6 m) cube-shaped balloon was somewhat unusual, but the Manhattan Project's AAA priority rating ensured prompt delivery with no questions asked. A 1226:

as soon as she completed her doctoral thesis. She also helped Anderson locate the required large number of 4-by-6-inch (10 by 15 cm) timbers at lumber yards in

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Szilard estimated he would need about 50 short tons (45 t) of graphite and 5 short tons (4.5 t) of uranium. In December 1940, Fermi and Szilard met with

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One of at least 29 experimental piles that were constructed in 1942 under the West Stands of Stagg Field. Each tested elements incorporated into the final design.

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to denote his own great invention of a source of electrical energy. I was disillusioned by Fermi himself, who told me that he simply used the common English word

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of 1.055. During the war Walter Zinn allowed CP-2 to be run around the clock, and its design was suitable for conducting experiments. CP-2 was joined by

1338:, the chairman of the NDRC, was reported to have turned white. But because of the urgency and their confidence in Fermi's calculations, no one objected. 2786: 2002:"Improvements in or relating to the transmutation of chemical elements, British patent number: GB630726 (filed: 28 June 1934; published: 30 March 1936)" 1665:

A commemorative plaque was unveiled at Stagg Field on 2 December 1952, the occasion of the tenth anniversary of CP-1 going critical. It read as follows:

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The risk of building an operational reactor running at criticality in a populated area was a significant issue, as there was a danger of a catastrophic

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After a series of attempts, the successful reactor was assembled in November 1942 by a team of about 30 that, in addition to Fermi, included scientists

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Video of west stands of Stagg Field, Institute for the Study of Metals (Metallurgical Laboratory), Enrico Fermi, and an active experiment using CP-1

716:, explaining the possibility of nuclear weapons, and encouraging the development of a program that could result in their creation. With the help of 6114: 1571:

Though the design was held secret for a decade, Szilard and Fermi jointly patented it, with an initial filing date of 19 December 1944 as the

481:. Unlike most subsequent nuclear reactors, it had no radiation shielding or cooling system as it operated at very low power – about one-half watt. 2438: 1590:, and the CP-2 and CP-3 reactors were dismantled in 1955 and 1956. Some of the graphite blocks from CP-1/CP-2 were reused in the reflector of the 6915: 6792: 6175: 5951: 3513: 1620:

in the soil at Plot M, trace amounts of tritium in nearby wells, and plutonium, technetium, caesium, and uranium in the area. In 1994, the

288: 457:. The reactor used natural uranium. This required a very large amount of material in order to reach criticality, along with graphite used as a 1669:

On December 2, 1942 man achieved here the first self-sustaining chain reaction and thereby initiated the controlled release of nuclear energy.

6925: 6616: 5672: 1246: 6426: 4179: 262: 6857: 6371: 5237: 5099: 3447: 789:. In October he wrote another report on the practicality of an atomic bomb. For this report, he worked with Fermi on calculations of the 1317:. Compton felt this delay was enough to provide a critical margin of safety, and allowed Fermi to build Chicago Pile-1 at Stagg Field. 6965: 6910: 6416: 6160: 5564: 3725: 6945: 6752: 6376: 6016: 4631: 1715: 939: 871:

On the fourth anniversary of the team's success, 2 December 1946, members of the CP-1 team gathered at the University of Chicago.

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In order for a chain reaction to occur, fissioning uranium atoms had to emit additional neutrons to keep the reaction going. At

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Amaldi, Ugo (2001). "Nuclear Physics from the Nineteen Thirties to the Present Day". In Bernardini, C.; Bonolis, Luisa (eds.).

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The final draft of Compton's November 1941 report made no mention of plutonium, but after discussing the latest research with

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about how that plutonium might be separated from uranium. His report, submitted in November, stated that a bomb was feasible.

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to separate uranium isotopes for determination of the fissile component, and, on 29 February 1940, Nier separated the first

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in restoring a research-graphite pile, similar in design to Chicago Pile-1, ceremonially inserted the final uranium slugs.

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in Oak Ridge as part of a plutonium semiworks, followed by larger water-cooled production reactors at the Hanford Site in

589:, opened up the possibility of creating a nuclear chain reaction with uranium, but initial experiments were unsuccessful. 6667: 6498: 6009: 762: 6955: 6930: 6213: 5048: 4281: 2570: 1621: 836: 6747: 6626: 6391: 6140: 5117: 1201: 6960: 6406: 6396: 6270: 6109: 4534:. Oak Ridge, Tennessee: United States Atomic Energy Commission, Division of Technical Information. pp. 22–26. 1899: 1359: 4347:. Oak Ridge, Tennessee: United States Atomic Energy Commission, Division of Technical Information. pp. 1–21. 3425: 6692: 6596: 6483: 6316: 6091: 5092: 1774:, William H. Hinch, Robert E. Johnson, W.R. Kanne, August C. Knuth, Phillip Grant Koontz, Herbert E. Kubitschek, 773:, to report on the uranium program. Compton's report, submitted in May 1941, foresaw the prospects of developing 2043:

On the detection and characteristics of the alkaline earth metals formed by irradiation of uranium with neutrons

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Salvetti, Carlo (2001). "The Birth of Nuclear Energy: Fermi's Pile". In Bernardini, C.; Bonolis, Luisa (eds.).

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Manhattan District History, Book IV – Pile Project X-10, Volume 2 – Research, Part 1 – Metallurgical Laboratory

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The plaque was saved when the West Stands were demolished in August 1957. The site of CP-1 was designated as a

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The reactors were used to undertake research related to weapons, such as investigations of the properties of

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as a fuel. He filed a patent for his idea of a simple nuclear reactor the following year. The discovery of

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The successful test of CP-1 not only proved that a nuclear reactor was feasible, it demonstrated that the

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to help celebrate the first self-sustaining, controlled chain reaction. It was signed by the participants.

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The pile was built in September 1941 from 4-by-4-by-12-inch (10 by 10 by 30 cm) graphite blocks and

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Another group, under Volney C. Wilson, was responsible for instrumentation. They also fabricated the

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I thought for a while that this term was used to refer to a source of nuclear energy in analogy with

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Bonolis, Luisa (2001). "Enrico Fermi's Scientific Work". In Bernardini, C.; Bonolis, Luisa (eds.).

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area to construct a 7-foot (2.1 m) experimental pile before Fermi's group arrived in 1942.

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in August 1939, and convinced him to sign the letter, lending his prestige to the proposal. The

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would have to be used for that purpose. The Germans had failed to account for the importance of

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Fermi and Szilard still believed that enormous quantities of uranium would be required for an

6900: 6222: 5946: 5871: 5764: 5589: 5332: 5277: 3223: 2364: 2001: 1870: 1841: 1662:. Enough plutonium was produced for an atomic bomb by July 1945, and for two more in August. 1651: 1428: 1204: 770: 709: 689: 672: 415: 189: 4901: 4809: 4639:. The understanding the atomic series. Oak Ridge, Tennessee: U.S. Atomic Energy Commission. 3906: 3614: 6970: 5794: 5574: 5569: 5428: 5302: 3626: 3567: 2714: 2668: 2620: 2541: 2376: 2334: 2325:; Hanstein, H. (16 March 1939). "Production of Neutrons in Uranium Bombarded by Neutrons". 2280: 2192: 2122: 2054: 1775: 1595: 1278: 1181: 1121: 925: 890: 5073:

Audio files of Fermi recounting the success of the reactor on the 10th anniversary in 1952

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supplied 3 short tons (2.7 t), which it produced in a rush with a makeshift process.

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resulted in the establishment of research into nuclear fission by the U.S. government. An

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was created in 1966, it was immediately added to that as well. The site was also named a

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Chicago Pile-1 was encased within a balloon so that the air inside could be replaced by

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to become his collaborator. They conducted a simple experiment on the seventh floor of

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sheets nailed to flat wooden strips, cadmium being a potent neutron absorber, and the

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The Road to Trinity: A Personal Account of How America's Nuclear Policies Were Made

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Compton notified Conant by telephone. The conversation was in an impromptu code:

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several minutes before this causes a runaway reaction. If a neutron absorber, or

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The University of Chicago Library Archive. Includes photos and sketches of CP-1.

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reactor. High-level nuclear waste such as fuel and heavy water were shipped to

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had determined that the remaining materials posed no danger to public health.

1407:

wire over a pulley that also had two lead weights attached to ensure it would

506:

entirely devoid of them. As it turned out, both boron and cadmium were strong

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in 1938, and its theoretical explanation (and naming) by their collaborators

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assumed control of the nuclear weapons program in June 1942, and Compton's

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on 12 September 1933. Szilard realized that if a nuclear reaction produced

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The Day Tomorrow Began: The Story of Chicago Pile 1, the First Atomic Pile

4922: 4831: 4701:

Genius in the Shadows: A Biography of Leo Szilard: The Man Behind The Bomb

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Allardice, Corbin; Trapnell, Edward R. (December 1982). "The First Pile".

4064:"Enrico Fermi, Nuclear Fission, US Patent No. 2,708,656, Inducted in 1976" 3996:

Fermi, Enrico (1946). "The Development of the first chain reaction pile".

1455: 1414: 1346: 1265: 1144: 1091: 1049:

Fermi christened his apparatus a "pile". Emilio Segrè later recalled that:

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is the average distance that a neutron travels before it is absorbed, and

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Institute for the Study of Ancient Cultures, West Asia & North Africa

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Wattenberg, Albert (1975). "Present at Creation". In Wilson, Jane (ed.).

4726: 4539: 4352: 4086:"Leo Szilard, Nuclear Fission, US Patent No. 2,708,656, Inducted in 1996" 2523: 2104: 1997: 1807: 1803: 1795: 1787: 1697: 1647: 1484: 1404: 1387: 1314: 1258: 1216: 1177: 1161: 909: 898: 894: 812: 798: 693: 661: 645: 637: 626: 586: 554: 494: 454: 446: 438: 426: 419: 6191: 1215:, which was predicted to be around 1.04, thereby achieving criticality. 5687: 5631: 5368: 5358: 5287: 4011: 3183: 2109:"Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction" 2066: 1605: 804: 751: 630: 5045:"First-Hand Recollections of the First Self-Sustaining Chain Reaction" 4278:"First-Hand Recollections of the First Self-Sustaining Chain Reaction" 3638: 2680: 2633: 1688:

Today the site of the old Stagg Field is occupied by the university's

1400: 30: 6737: 5729: 5595: 5363: 5166: 3278: 3276: 3274: 3272: 2486: 2484: 2204: 2134: 2034: 1900:"Site of the First Self-Sustaining Controlled Nuclear Chain Reaction" 1548:, the first heavy water reactor, which went critical on 15 May 1944. 1408: 1014:. The neutrons in succeeding reactions will be amplified by a factor 832: 786: 665: 574: 562: 466: 5077: 3976: 3974: 3224:""Site A" at Red Gate Woods & The World's First Nuclear Reactor" 6356: 6065:

Site of the First Self-Sustaining Controlled Nuclear Chain Reaction

5853:

Site of the First Self-Sustaining Controlled Nuclear Chain Reaction

5769: 5602: 5136: 4686:. Washington, D.C.: United States Army Center of Military History. 3959: 2888: 2886: 2834: 2832: 1551: 1231: 1100: 657: 538: 91: 6115:

Main Building and Machinery Hall, Illinois Institute of Technology

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The First Nuclear Era: The Life and Times of a Technological Fixer

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languished partly because of the belief that scarce and expensive

6896:

Energy infrastructure on the National Register of Historic Places

5759: 5626: 3971: 1831: 1560: 1496: 1460: 1379: 1125: 816: 566: 558: 502: 474: 106: 87: 4934:. Chicago: Bulletin of the Atomic Scientists. pp. 105–123. 4112: 3887: 3096: 2883: 2871: 2829: 2817: 2805: 1253:

near Chicago for a plutonium pilot plant; this became known as "

1211:

Fermi designed a new pile, which would be spherical to maximize

1034:

must be at least 3 or 4 percent greater than 1. In other words,

5145: 4407:. Chicago: Bulletin of the Atomic Scientists. pp. 66–104. 3755: 3401: 3238: 1529: 1522: 653: 514: 418:, CP-1 was built under the west viewing stands of the original 3809: 2705:

Eatherly, W. P. (1981). "Nuclear graphite – the first years".

2569: 2419: 2161: 882:, Thomas Brill, Robert Nobles, Warren Nyer, Marvin Wilkening. 484:

The pursuit of a reactor had been touched off by concern that

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All In Our Time: The Reminiscences of Twelve Nuclear Pioneers

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All In Our Time: The Reminiscences of Twelve Nuclear Pioneers

3307: 3305: 3303: 3259: 3257: 3255: 3253: 2496: 2375:(4). Educational Foundation for Nuclear Science, Inc.: 8–12. 1383: 831:

produced 28 μg of plutonium-239 in the 60-inch (150 cm)

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Graham School of Continuing Liberal and Professional Studies

5824: 3391: 3389: 2995: 2993: 2932: 2930: 991:{\displaystyle R_{crit}\approx {\frac {\pi M}{\sqrt {k-1}}}} 6762: 5707: 5176: 3745: 3743: 3741: 3739: 2859: 2733: 1941:"The Nobel Prize in Chemistry 1956 – Award Ceremony Speech" 1506:

Compton: The Italian navigator has landed in the New World.

386:. On 2 December 1942, the first human-made self-sustaining 4869:. Bologna: Società Italiana di Fisica: Springer. pp. 4477:

Currie, L. M.; Hamister, V. C.; MacPherson, H. G. (1955).

4426:. Bologna: Società Italiana di Fisica: Springer. pp. 4373:. Bologna: Società Italiana di Fisica: Springer. pp. 4044: 3300: 3250: 2457: 1718:

in Chicago. On 2 December 2017, the 75th anniversary, the

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Site of the Fermi's "Atomic Pile" – First Nuclear Reactor

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now marks the experiment site's location, which is now a

4600:. University Park: Pennsylvania State University Press. 4503:

Biographical Memoirs of the National Academy of Sciences

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Szilard drafted a confidential letter to the President,

3833: 3615:"Experimental Production of a Divergent Chain Reaction" 3341: 1955: 1120:

Compton felt that having teams at Columbia University,

1018:, the second generation of fission events will produce 4561:

Now It Can Be Told: The Story of the Manhattan Project

4479:

The Production and Properties of Graphite for Reactors

4100: 3594: 3288: 3195: 3132: 3044: 3005: 2954: 2910: 2844: 1758:, Richard J. Fox, Stewart Fox, Carl C. Gamertsfelder, 1234:

arrived, mainly from National Carbon, and high-purity

6817: 3821: 3720: 3718: 3716: 3714: 3712: 3494: 3374: 3353: 3329: 3171: 3147: 3120: 3029: 2966: 2659:

Bethe, Hans A. (2000). "The German Uranium Project".

2619:(7). National Academy of Engineering Press: 143–147. 2317: 1578:

The Red Gate Woods later became the original site of

942: 3697: 3482: 3317: 2942: 2514: 2179: 1863:"Site of the First Self-Sustaining Nuclear Reaction" 793:

of uranium-235. He also discussed the prospects for

696:, the AGOT graphite is considered as the first true 3159: 3084: 1358:. Anderson had a dark gray balloon manufactured by 473:) and was fueled by 5.4 short tons (4.9 tonnes) of 5065:Video of two of the last surviving CP-1 pioneers, 4970: 4900: 4778: 4759: 4730: 4558: 4457: 4403:(1975). "Assisting Fermi". In Wilson, Jane (ed.). 3965: 3907:"Early Exploration: CP-1 (Chicago Pile 1 Reactor)" 3881: 3709: 1917: 990: 811:had theorized that heavy isotopes with odd atomic 688:Ordinary Temperature") by National Carbon. With a 553:was first hypothesized by the Hungarian scientist 544:was first suggested in 1913 by the German chemist 390:was initiated in CP-1 during an experiment led by 220:Site of the First Self Sustaining Nuclear Reaction 4658: 4337: 4118: 3999:Proceedings of the American Philosophical Society 3980: 3893: 3761: 3659: 3412: 1636: 1586:at the Argonne National Laboratory's new site in 769:, a Nobel-Prize-winning physics professor at the 660:as a moderator. As a back-up plan, he considered 6877: 5942:Clarence Buckingham Memorial Fountain and Garden 2789:. The Atomic Heritage Foundation. Archived from 1802:, Marvin H. Wilkening, Volney C. (Bill) Wilson, 1648:development of heavy water production facilities 724:, he approached his old friend and collaborator 6921:National Register of Historic Places in Chicago 4698: 4587: 3941:Argonne's Nuclear Science and Technology Legacy 3911:Argonne's Nuclear Science and Technology Legacy 3857:Argonne's Nuclear Science and Technology Legacy 3815: 3680:Argonne's Nuclear Science and Technology Legacy 3282: 3226:. Forest Preserves of Cook County. October 2013 3189: 3102: 2904: 2892: 2877: 2838: 2823: 2811: 2502: 2490: 2425: 2413: 2401: 2233: 2167: 1976:"Szilard's chain reaction: visionary or crank?" 1450: 1411:and return to its zero position when released. 6031: 5973:Site of the Origin of the Chicago Fire of 1871 4180:"U. of C. to Raze Stagg Field's Atomic Cradle" 3426:"How the first chain reaction changed science" 2599: 2597: 2595: 2528:"Neutron Production and Absorption in Uranium" 2033: 1746:, Wayne Arnold, Hugh M. Barton, Thomas Brill, 1257:". 1,025 acres (415 ha) were leased from 6207: 6017: 5810: 5093: 4308:"Milestone for new LEU research reactor fuel" 2099: 1247:Office of Scientific Research and Development 785:using uranium-235 or the recently discovered 6110:Immaculata High School and Convent Buildings 2765:"Einstein's Letter to Franklin D. Roosevelt" 1148:Carpenter Augustus Knuth, in the process of 1083:and eventually a big room was discovered in 1038:must be greater than 1 without crossing the 5952:Illinois–Indiana State Line Boundary Marker 4807: 4205: 4203: 3670: 3668: 2751: 2667:(7). American Institute of Physics: 34–36. 2592: 2441:. American Physical Society. Archived from 1973: 1602:. It is marked by a commemorative boulder. 765:(NDRC) created a special project headed by 6214: 6200: 6024: 6010: 5817: 5803: 5100: 5086: 4929: 4050: 3775:"George Weil – from activator to activist" 3514:"Frontiers: Research Highlights 1946–1996" 1867:National Historic Landmark Summary Listing 1196:became part of what came to be called the 29: 6221: 4699:Lanouette, William; Silard, Bela (1992). 3991: 3989: 3428:. University of Chicago. 10 December 2012 3218: 3216: 3214: 3212: 3210: 3065:"Where Football and Higher Education Mix" 2632: 2603: 228:U.S. National Register of Historic Places 6499:Francis and Rose Yuen (Hong Kong) campus 6281:Pritzker School of Molecular Engineering 5978:Site of the Origins of the I&M Canal 4946: 4907:. Chicago: University of Chicago Press. 4862: 4785:. New York: William Morrow and Company. 4629: 4399: 4200: 4106: 3929: 3839: 3665: 3600: 3395: 3347: 3294: 3141: 3011: 2984: 2960: 2921: 2865: 2853: 2739: 2704: 2698: 2687: 2654: 2652: 2359: 1604: 1550: 1454: 1413: 1345: 1264: 1143: 1090: 1042:threshold that would result in a rapid, 866: 746: 16:World's first human-made nuclear reactor 6327:Chicago Project on Security and Threats 6286:School of Social Service Administration 4773: 4769:. Washington, D.C.: Manhattan District. 4684:Manhattan: The Army and the Atomic Bomb 4452: 4419: 3899: 3335: 3311: 3263: 2565: 2563: 2463: 477:metal and 45 short tons (41 tonnes) of 6916:National Historic Landmarks in Chicago 6878: 6322:Center for Research in Security Prices 6266:Harris School of Public Policy Studies 4838: 4553: 4525:(December 1982). "Fermi's Own Story". 4493: 4366: 4024: 4018: 3986: 3827: 3728:. Department of Energy. Archived from 3703: 3500: 3380: 3368: 3323: 3207: 3177: 3153: 3126: 3114: 3062: 3038: 3023: 2999: 2972: 2936: 2694:Currie, Hamister & MacPherson 1955 2475: 2305: 2155: 2087: 2021: 1961: 1832:"National Register Information System" 1826: 1824: 1822: 1028:self-sustaining nuclear chain reaction 839:, and found that it had 1.7 times the 740:, a scientist and the director of the 269: 6195: 6120:Mundelein College Skyscraper Building 6101:National Register of Historic Places, 6005: 5968:Site of the John and Mary Jones House 5899:National Register of Historic Places, 5890:Jean Baptiste Point Du Sable Homesite 5798: 5107: 5081: 4895: 4725: 4681: 4521: 4464:. New York: Oxford University Press. 4166: 4154: 4142: 4130: 3995: 3749: 3612: 3548: 3488: 3244: 3201: 3165: 3090: 2948: 2658: 2649: 1923: 1857: 1855: 1853: 1851: 1720:Massachusetts Institute of Technology 1600:Site A/Plot M Disposal Site 1190:United States Army Corps of Engineers 703: 6926:Nuclear history of the United States 6858:National Register of Historic Places 6463:Housing at the University of Chicago 6181:Wendell Phillips Academy High School 6085:National Register of Historic Places 6047:National Register of Historic Places 5991:Wigwam (Site of the Sauganash Hotel) 5883:National Register of Historic Places 5840:National Register of Historic Places 4665:Argonne National Laboratory, 1946–96 4027:"The Way Things Work: Nuclear waste" 3845: 2560: 1894: 1892: 1837:National Register of Historic Places 1692:, which was opened in 1970, and the 1679:National Register of Historic Places 1631:Illinois Department of Public Health 1532:in the Argonne Forest, now known as 1499:, which they drank from paper cups. 6161:Lindblom Math & Science Academy 4968: 3063:Bearak, Barry (16 September 2011). 3050: 1996: 1935: 1819: 1418:CP-1 under construction: 10th layer 1152:a wooden block for the timber frame 763:National Defense Research Committee 382:) was the world's first artificial 99:Main parameters of the reactor core 13: 6125:St. Ignatius College Prep Building 5565:Bombings of Hiroshima and Nagasaki 4810:"Graphite in the Nuclear Industry" 3790:(822): 530–531. 30 November 1972. 3523:. 1996. p. 11. Archived from 2571:International Atomic Energy Agency 2269:(1939). "The Fission of Uranium". 1848: 1738:The Chicago Pile 1 Pioneers were: 1622:United States Department of Energy 1516: 1350:CP-1 under construction: 7th layer 1269:CP-1 under construction: 4th layer 1249:(OSRD) had selected a site in the 14: 6982: 6627:Kenwood Astrophysical Observatory 6312:Center for Middle Eastern Studies 6141:American School of Correspondence 5001: 4866:Enrico Fermi: His Work and Legacy 4703:. New York: Skyhorse Publishing. 4496:"George Braxton Pegram 1876–1958" 4423:Enrico Fermi: His Work and Legacy 4370:Enrico Fermi: His Work and Legacy 4088:. National Inventors Hall of Fame 4066:. National Inventors Hall of Fame 2369:Bulletin of the Atomic Scientists 1974:Wellerstein, Alex (16 May 2014). 1889: 1139: 1046:in the number of fission events. 127:Neutron energy spectrum 6966:Infrastructure completed in 1942 6911:History of the Manhattan Project 6863: 6851: 6839: 6827: 6407:Sonia Shankman Orthogenic School 6392:National Opinion Research Center 5781: 5780: 4848:. London: Simon & Schuster. 4667:. University of Illinois Press. 4300: 4270: 4256:"Stagg Field / Mansueto Library" 4248: 4220: 4172: 4078: 4056: 3551:"A Manhattan Project Postscript" 1360:Goodyear Tire and Rubber Company 690:neutron absorption cross section 268: 261: 136:Primary control method 6946:1942 establishments in Illinois 6693:University Athletic Association 6597:Cannon v. University of Chicago 6484:George Herbert Jones Laboratory 6317:Center for Population Economics 6092:George Herbert Jones Laboratory 4119:Holl, Hewlett & Harris 1997 4025:McNear, Claire (5 March 2009). 3981:Holl, Hewlett & Harris 1997 3894:Holl, Hewlett & Harris 1997 3767: 3660:Holl, Hewlett & Harris 1997 3606: 3542: 3506: 3448:"Chapter 1: Wartime Laboratory" 3440: 3418: 3413:Holl, Hewlett & Harris 1997 3056: 2779: 2757: 2508: 2431: 2353: 2311: 2239: 2173: 2093: 2027: 1732: 1714:; another is on display at the 1555:Commemorative boulder at Site A 1341: 1293:Fermi argued that by using the 1106:radium-beryllium neutron source 823:was likely to be. In May 1941, 596:in New York, Italian physicist 461:. The reactor contained 45,000 237:U.S. National Historic Landmark 6489:Gerald Ratner Athletics Center 6417:Toyota Technological Institute 4812:. In Nightingale, R.E. (ed.). 2389:10.1080/00963402.1973.11455466 2365:"Early Days of Chain Reaction" 1990: 1967: 1929: 1716:Museum of Science and Industry 1696:, which was opened in 2011. A 1677:on 18 February 1965. When the 1637:Significance and commemoration 862: 329: 1: 6622:University of Chicago sit-ins 6519:Joe and Rika Mansueto Library 5867:Site of the Haymarket Tragedy 4973:Squash: A History of the Game 4845:The Making of the Atomic Bomb 4591:; Anderson, Oscar E. (1962). 4330: 3853:"The Italian Navigator Lands" 3762:Allardice & Trapnell 1982 3676:"The Chicago Pile 1 Pioneers" 3580:10.1126/science.212.4501.1369 2575:"Nuclear Data for Safeguards" 1694:Joe and Rika Mansueto Library 1650:. An air-cooled reactor, the 1508:Conant: How were the natives? 1320:Compton later explained that: 1245:On 25 June, the Army and the 1012:neutron multiplication factor 734:Advisory Committee on Uranium 714:German nuclear weapon project 6733:Contemporary Chamber Players 6382:Marine Biological Laboratory 5725:Oppenheimer security hearing 4228:"Remove Nuclear Site Plaque" 2727:10.1016/0022-3115(81)90519-5 2707:Journal of Nuclear Materials 1451:First nuclear chain reaction 742:National Bureau of Standards 600:collaborated with Americans 7: 6906:Graphite moderated reactors 6886:Argonne National Laboratory 6422:University of Chicago Press 6347:Comprehensive Cancer Center 6342:Committee on Social Thought 6332:Chicago school of economics 6302:Argonne National Laboratory 6276:Pritzker School of Medicine 6083:National Historic Landmark, 5881:National Historic Landmark, 4760:Manhattan District (1947). 4737:. New York: Crane, Russak. 4481:. National Carbon Company. 3945:Argonne National Laboratory 3915:Argonne National Laboratory 3861:Argonne National Laboratory 3816:Hewlett & Anderson 1962 3684:Argonne National Laboratory 3619:American Journal of Physics 3521:Argonne National Laboratory 3283:Hewlett & Anderson 1962 3190:Hewlett & Anderson 1962 3103:Hewlett & Anderson 1962 2905:Hewlett & Anderson 1962 2893:Hewlett & Anderson 1962 2878:Hewlett & Anderson 1962 2839:Hewlett & Anderson 1962 2824:Hewlett & Anderson 1962 2812:Hewlett & Anderson 1962 2787:"Pa, this requires action!" 2503:Hewlett & Anderson 1962 2491:Lanouette & Silard 1992 2426:Lanouette & Silard 1992 2414:Lanouette & Silard 1992 2402:Lanouette & Silard 1992 2234:Lanouette & Silard 1992 2168:Lanouette & Silard 1992 1629:for disposal. By 2002, the 1580:Argonne National Laboratory 1435:and his team had developed 1230:. Shipments of high-purity 1057:'s use of the Italian term 513:In 1943, CP-1 was moved to 10: 6987: 6536:Lorado Taft Midway Studios 6146:Assumption School Building 6060:Lorado Taft Midway Studios 6042:National Historic Landmark 5835:National Historic Landmark 4808:Nightingale, R.E. (1962). 4663:; Harris, Ruth R. (1997). 4630:Hogerton, Hohn F. (1970). 3247:, pp. 71–72, 111–114. 1675:National Historic Landmark 1520: 1439:to produce uranium metal. 1026:and so on. In order for a 675:and Victor C. Hamister at 532: 523:National Historic Landmark 435:non-fission chain reaction 349:15 October 1966 (66000314) 6956:1942 in the United States 6931:Nuclear research reactors 6771: 6701: 6650: 6637:Old University of Chicago 6584: 6471: 6441: 6397:Obama Presidential Center 6337:Comer Children's Hospital 6307:Becker Friedman Institute 6294: 6238: 6231: 6133: 6100: 6082: 6040: 5926: 5898: 5880: 5833: 5778: 5668:Bismuth phosphate process 5663:Atomic Energy Act of 1946 5650: 5619: 5552: 5341: 5210: 5124: 5115: 4494:Embrey, Lee Anna (1970). 369: 361: 353: 345: 340: 328:NRHP reference 327: 319: 282: 256: 252: 243: 234: 225: 218: 214: 210: 203:World's first artificial 199: 185: 177: 169: 164: 156: 143: 135: 125: 117: 103: 98: 83: 75: 57: 47: 37: 28: 23: 6632:Metallurgical Laboratory 6251:Booth School of Business 6156:James Ward Public School 5935:Abraham Lincoln: The Man 5040:11-page story about CP-1 5025:27 February 2021 at the 4594:The New World, 1939–1946 3192:, pp. 65–66, 83–88. 2347:10.1103/PhysRev.55.797.2 2293:10.1103/physrev.55.511.2 1725: 1528:dismantled and moved to 1194:Metallurgical Laboratory 837:University of California 412:Metallurgical Laboratory 63: (81 years ago) 52:Metallurgical Laboratory 6961:20th century in Chicago 6678:Lascivious Costume Ball 6617:Graduate Library School 5828:memorials and monuments 5745:S-1 Executive Committee 5693:Einstein–Szilard letter 4954:. New York: AIP Press. 4903:Enrico Fermi, Physicist 4682:Jones, Vincent (1985). 4258:. University of Chicago 3966:Manhattan District 1947 3882:Manhattan District 1947 2609:"Herbert G. MacPherson" 2047:Die Naturwissenschaften 1776:Harold V. Lichtenberger 1708:Bradbury Science Museum 1512:Compton: Very friendly. 1441:Westinghouse Lamp Plant 730:Einstein–Szilard letter 6683:Latke–Hamantash Debate 6494:Henry Crown Fieldhouse 6362:James Franck Institute 6352:Enrico Fermi Institute 5187:Salt Wells Pilot Plant 4977:. New York: Scribner. 3613:Fermi, Enrico (1952). 2554:10.1103/PhysRev.56.284 1943:. The Nobel Foundation 1712:Los Alamos, New Mexico 1671: 1656:Clinton Engineer Works 1613: 1556: 1514: 1471: 1419: 1351: 1331: 1270: 1219:was detailed to build 1164:originally built as a 1153: 1096: 1089: 1075: 1000: 992: 924:In a nuclear reactor, 921: 758: 698:nuclear-grade graphite 551:nuclear chain reaction 388:nuclear chain reaction 6941:University of Chicago 6702:Student organizations 6651:Sports and traditions 6372:Institute of Politics 6224:University of Chicago 5963:Site of Fort Dearborn 5947:Heald Square Monument 5872:Union Stock Yard Gate 5765:X-10 Graphite Reactor 5720:Nobel Prize laureates 5590:509th Composite Group 4727:Libby, Leona Marshall 3937:"Promethean Boldness" 1871:National Park Service 1842:National Park Service 1667: 1652:X-10 Graphite Reactor 1608: 1554: 1504: 1458: 1429:Iowa State University 1417: 1349: 1322: 1268: 1205:Leslie R. Groves, Jr. 1147: 1094: 1080: 1051: 993: 935: 870: 771:University of Chicago 750: 710:Franklin D. Roosevelt 673:Herbert G. MacPherson 416:University of Chicago 304:41.79250°N 87.60111°W 190:University of Chicago 48:Designed and built by 6453:Burton–Judson Courts 5673:British contribution 5575:Operation Peppermint 5570:Operation Crossroads 5429:Maria Goeppert Mayer 5049:Department of Energy 4565:. New York: Harper. 4401:Anderson, Herbert L. 4282:Department of Energy 3732:on 22 November 2010. 3726:"CP-1 Goes Critical" 1794:, Richard J. Watts, 1786:, William J. Sturm, 1685:on 27 October 1971. 1596:Oak Ridge, Tennessee 1575:no. 2,708,656. 1228:Chicago's south side 1182:Anthony L. Turkevich 1122:Princeton University 1044:exponential increase 940: 891:Harold Lichtenberger 873:From left, Back row: 775:radiological weapons 465:blocks weighing 360 429:(who had previously 6936:South Side, Chicago 6758:Voices in Your Head 6571:Smart Museum of Art 6551:Renaissance Society 6524:John Crerar Library 6151:DuSable High School 5434:George Kistiakowsky 5389:Charles Critchfield 4775:Nichols, Kenneth D. 4661:Hewlett, Richard G. 4589:Hewlett, Richard G. 4169:, pp. 222–223. 4157:, pp. 210–212. 4145:, pp. 204–205. 4133:, pp. 191–192. 3752:, pp. 120–123. 3631:1952AmJPh..20..536F 3572:1981Sci...212.1369W 3566:(4501): 1369–1371. 3458:(3 & 4). 2002. 3314:, pp. 137–138. 3285:, pp. 107–109. 3266:, pp. 136–137. 3117:, pp. 427–428. 3053:, pp. 134–135. 3026:, pp. 400–401. 3002:, pp. 399–400. 2939:, pp. 396–397. 2907:, pp. 180–181. 2868:, pp. 192–193. 2742:, pp. 177–203. 2719:1981JNuM..100...55E 2673:2000PhT....53g..34B 2625:1993PhT....46g.103W 2546:1939PhRv...56..284A 2493:, pp. 194–195. 2478:, pp. 153–156. 2466:, pp. 347–352. 2439:"Alfred O. C. Nier" 2416:, pp. 186–187. 2404:, pp. 182–183. 2381:1973BuAtS..29d...8A 2339:1939PhRv...55..797A 2308:, pp. 267–270. 2285:1939PhRv...55..511A 2236:, pp. 172–173. 2197:1934Natur.134..880B 2158:, pp. 267–271. 2127:1939Natur.143..239M 2090:, pp. 256–263. 2059:1939NW.....27...11H 2024:, pp. 251–254. 1764:Crawford Greenewalt 1744:Herbert L. Anderson 1654:, was built at the 1538:radiation shielding 1476:Crawford Greenewalt 1065:as synonymous with 918:Herbert L. Anderson 761:In April 1941, the 756:Columbia University 606:Herbert L. Anderson 594:Columbia University 573:by German chemists 519:memorial quadrangle 463:ultra-pure graphite 443:Herbert L. Anderson 410:. Developed by the 354:Designated NHL 309:41.79250; -87.60111 300: / 6870:Nuclear technology 6846:History of Science 6805:School of Business 6788:School of Business 6753:Student Government 6715:The Chicago Maroon 6673:Women's basketball 6642:Yerkes Observatory 6561:Rockefeller Chapel 6529:Regenstein Library 6504:Hutchinson Commons 6377:Laboratory Schools 6171:Schurz High School 6166:Rockefeller Chapel 5499:Henry DeWolf Smyth 5278:Robert Oppenheimer 5233:Priscilla Duffield 4816:. Academic Press. 4733:The Uranium People 4314:. 22 December 2017 4312:World Nuclear News 4031:The Chicago Maroon 3549:Walsh, J. (1981). 3070:The New York Times 2793:on 29 October 2012 2067:10.1007/BF01488241 1964:, pp. 13, 28. 1690:Regenstein Library 1614: 1611:the site memorial. 1557: 1472: 1420: 1352: 1326:President Hutchins 1271: 1154: 1097: 988: 922: 795:uranium enrichment 779:nuclear propulsion 759: 704:Government support 650:neutron moderators 491:the German program 451:Martin D. Whitaker 431:formulated an idea 362:Designated CL 178:Criticality (date) 6891:Chicago Landmarks 6815: 6814: 6437: 6436: 6412:Stieglitz Lecture 6402:Paulson Institute 6189: 6188: 5999: 5998: 5957:Rosehill Cemetery 5792: 5791: 5714:Los Alamos Primer 5703:Interim Committee 5658:African Americans 5610:The Great Artiste 5469:Isidor Isaac Rabi 5464:Norman Ramsey Jr. 5263:Franklin Matthias 5202:Heavy water sites 5109:Manhattan Project 4984:978-0-7432-2990-6 4961:978-1-56396-358-2 4914:978-0-226-74473-5 4880:978-88-7438-015-2 4855:978-0-671-44133-3 4823:978-1-4832-5848-5 4792:978-0-688-06910-0 4744:978-0-8448-1300-4 4710:978-1-62636-023-5 4674:978-0-252-02341-5 4607:978-0-520-07186-5 4572:978-0-306-70738-4 4528:The First Reactor 4437:978-88-7438-015-2 4384:978-88-7438-015-2 4341:The First Reactor 3662:, pp. 16–17. 3639:10.1119/1.1933322 3470:on 25 August 2009 3398:, pp. 91–92. 3204:, pp. 67–68. 3105:, pp. 74–75. 2987:, pp. 86–87. 2895:, pp. 54–55. 2880:, pp. 50–51. 2841:, pp. 46–49. 2826:, pp. 36–38. 2814:, pp. 19–21. 2681:10.1063/1.1292473 2634:10.1063/1.2808987 2613:Memorial Tributes 2526:(1 August 1939). 2121:(3615): 239–240. 1978:. Restricted Data 1792:Albert Wattenberg 1752:Arthur H. Compton 1748:Robert F. Christy 1573:neutronic reactor 1395:, controlling an 1393:variable resistor 1308:electromechanical 1224:neutron detectors 1221:boron trifluoride 1202:Brigadier General 1198:Manhattan Project 1158:Samuel K. Allison 1085:Schermerhorn Hall 986: 985: 914:Albert Wattenberg 889:, William Sturm, 736:was formed under 664:. This contained 642:Alfred O. C. Nier 459:neutron moderator 402:effort to create 396:Manhattan Project 373: 372: 341:Significant dates 194:Manhattan Project 145:Primary moderator 6978: 6951:1942 in Illinois 6868: 6867: 6866: 6856: 6855: 6854: 6844: 6843: 6842: 6832: 6831: 6830: 6823: 6775: 6668:Men's basketball 6588: 6541:Midway Plaisance 6445: 6236: 6235: 6225: 6216: 6209: 6202: 6193: 6192: 6134:Chicago Landmark 6103:Chicago Landmark 6052:Chicago Landmark 6033:Chicago Landmark 6026: 6019: 6012: 6003: 6002: 5927:Chicago Landmark 5918:Victory Monument 5901:Chicago Landmark 5845:Chicago Landmark 5826:Chicago Landmark 5819: 5812: 5805: 5796: 5795: 5784: 5783: 5735:Quebec Agreement 5519:John von Neumann 5459:George B. Pegram 5268:Dorothy McKibbin 5102: 5095: 5088: 5079: 5078: 5069:and Warren Nyer. 5064: 5062: 5060: 5055:on 27 March 2019 5051:. Archived from 5016:– AEC Video 1967 5010: 4996: 4976: 4969:Zug, J. (2003). 4965: 4943: 4926: 4906: 4892: 4859: 4835: 4814:Nuclear Graphite 4804: 4784: 4770: 4768: 4756: 4736: 4722: 4695: 4678: 4655: 4653: 4651: 4638: 4633:Nuclear Reactors 4626: 4624: 4622: 4599: 4584: 4564: 4550: 4548: 4546: 4533: 4518: 4516: 4514: 4500: 4490: 4473: 4463: 4449: 4416: 4396: 4363: 4361: 4359: 4346: 4324: 4323: 4321: 4319: 4304: 4298: 4297: 4295: 4293: 4288:on 27 March 2019 4284:. Archived from 4274: 4268: 4267: 4265: 4263: 4252: 4246: 4245: 4243: 4241: 4236:. 16 August 1957 4224: 4218: 4212: 4207: 4198: 4197: 4195: 4193: 4176: 4170: 4164: 4158: 4152: 4146: 4140: 4134: 4128: 4122: 4116: 4110: 4104: 4098: 4097: 4095: 4093: 4082: 4076: 4075: 4073: 4071: 4060: 4054: 4048: 4042: 4041: 4039: 4037: 4022: 4016: 4015: 3993: 3984: 3978: 3969: 3963: 3957: 3956: 3954: 3952: 3933: 3927: 3926: 3924: 3922: 3903: 3897: 3891: 3885: 3879: 3873: 3872: 3870: 3868: 3849: 3843: 3837: 3831: 3825: 3819: 3813: 3807: 3806: 3804: 3802: 3779: 3771: 3765: 3759: 3753: 3747: 3734: 3733: 3722: 3707: 3701: 3695: 3694: 3692: 3690: 3672: 3663: 3657: 3651: 3650: 3610: 3604: 3598: 3592: 3591: 3555: 3546: 3540: 3539: 3537: 3535: 3529: 3518: 3510: 3504: 3498: 3492: 3486: 3480: 3479: 3477: 3475: 3466:. Archived from 3444: 3438: 3437: 3435: 3433: 3422: 3416: 3410: 3399: 3393: 3384: 3378: 3372: 3366: 3351: 3345: 3339: 3333: 3327: 3321: 3315: 3309: 3298: 3292: 3286: 3280: 3267: 3261: 3248: 3242: 3236: 3235: 3233: 3231: 3220: 3205: 3199: 3193: 3187: 3181: 3175: 3169: 3163: 3157: 3151: 3145: 3139: 3130: 3124: 3118: 3112: 3106: 3100: 3094: 3088: 3082: 3081: 3079: 3077: 3060: 3054: 3048: 3042: 3036: 3027: 3021: 3015: 3009: 3003: 2997: 2988: 2982: 2976: 2970: 2964: 2958: 2952: 2946: 2940: 2934: 2925: 2919: 2908: 2902: 2896: 2890: 2881: 2875: 2869: 2863: 2857: 2851: 2842: 2836: 2827: 2821: 2815: 2809: 2803: 2802: 2800: 2798: 2783: 2777: 2776: 2774: 2772: 2767:. Atomic Archive 2761: 2755: 2752:Nightingale 1962 2749: 2743: 2737: 2731: 2730: 2702: 2696: 2691: 2685: 2684: 2656: 2647: 2646: 2636: 2601: 2590: 2589: 2587: 2585: 2579:www-nds.iaea.org 2567: 2558: 2557: 2512: 2506: 2500: 2494: 2488: 2479: 2473: 2467: 2461: 2455: 2454: 2452: 2450: 2435: 2429: 2423: 2417: 2411: 2405: 2399: 2393: 2392: 2357: 2351: 2350: 2315: 2309: 2303: 2297: 2296: 2243: 2237: 2231: 2225: 2224: 2205:10.1038/134880a0 2177: 2171: 2165: 2159: 2153: 2147: 2146: 2135:10.1038/143239a0 2097: 2091: 2085: 2079: 2078: 2031: 2025: 2019: 2013: 2012: 2010: 2008: 1994: 1988: 1987: 1985: 1983: 1971: 1965: 1959: 1953: 1952: 1950: 1948: 1933: 1927: 1921: 1915: 1914: 1912: 1910: 1896: 1887: 1886: 1884: 1882: 1873:. Archived from 1859: 1846: 1845: 1828: 1811: 1800:Eugene P. Wigner 1736: 1683:Chicago Landmark 1660:Washington state 1565:white blood cell 1364:block and tackle 1295:delayed neutrons 1283:fission products 1279:runaway reaction 1275:nuclear meltdown 997: 995: 994: 989: 987: 975: 974: 966: 961: 960: 686:Acheson Graphite 623:George B. Pegram 618:Francis G. Slack 614:G. Norris Glasoe 579:Fritz Strassmann 527:Chicago Landmark 357:18 February 1965 331: 315: 314: 312: 311: 310: 305: 301: 298: 297: 296: 293: 272: 271: 265: 246:Chicago Landmark 150:Nuclear graphite 110: 107:fissile material 71: 69: 64: 42:Research reactor 33: 21: 20: 6986: 6985: 6981: 6980: 6979: 6977: 6976: 6975: 6876: 6875: 6874: 6864: 6862: 6852: 6850: 6840: 6838: 6828: 6826: 6818: 6816: 6811: 6773: 6767: 6728:CMAC (UChicago) 6697: 6646: 6586: 6580: 6546:Quadrangle Club 6467: 6458:Snell–Hitchcock 6444:Residence halls 6443: 6433: 6290: 6256:Divinity School 6227: 6223: 6220: 6190: 6185: 6129: 6102: 6096: 6084: 6078: 6050: 6045: 6036: 6030: 6000: 5995: 5922: 5900: 5894: 5882: 5876: 5843: 5838: 5829: 5823: 5793: 5788: 5774: 5740:RaLa Experiment 5646: 5615: 5580:Project Alberta 5548: 5544:Chien-Shiung Wu 5474:James Rainwater 5409:Richard Feynman 5399:John R. Dunning 5374:Norris Bradbury 5337: 5323:Stafford Warren 5293:William Purnell 5273:Kenneth Nichols 5253:Ernest Lawrence 5228:James B. Conant 5206: 5120: 5111: 5106: 5058: 5056: 5043: 5027:Wayback Machine 5008: 5004: 4999: 4985: 4962: 4948:Weinberg, Alvin 4915: 4881: 4856: 4840:Rhodes, Richard 4824: 4793: 4766: 4745: 4711: 4675: 4659:Holl, Jack M.; 4649: 4647: 4636: 4620: 4618: 4608: 4597: 4573: 4544: 4542: 4531: 4512: 4510: 4498: 4454:Compton, Arthur 4438: 4385: 4357: 4355: 4344: 4333: 4328: 4327: 4317: 4315: 4306: 4305: 4301: 4291: 4289: 4276: 4275: 4271: 4261: 4259: 4254: 4253: 4249: 4239: 4237: 4233:Chicago Tribune 4226: 4225: 4221: 4210: 4208: 4201: 4191: 4189: 4185:Chicago Tribune 4178: 4177: 4173: 4165: 4161: 4153: 4149: 4141: 4137: 4129: 4125: 4117: 4113: 4105: 4101: 4091: 4089: 4084: 4083: 4079: 4069: 4067: 4062: 4061: 4057: 4051:Wattenberg 1975 4049: 4045: 4035: 4033: 4023: 4019: 3994: 3987: 3979: 3972: 3968:, p. 3.13. 3964: 3960: 3950: 3948: 3935: 3934: 3930: 3920: 3918: 3905: 3904: 3900: 3892: 3888: 3880: 3876: 3866: 3864: 3851: 3850: 3846: 3838: 3834: 3826: 3822: 3814: 3810: 3800: 3798: 3777: 3773: 3772: 3768: 3760: 3756: 3748: 3737: 3724: 3723: 3710: 3702: 3698: 3688: 3686: 3674: 3673: 3666: 3658: 3654: 3611: 3607: 3599: 3595: 3553: 3547: 3543: 3533: 3531: 3527: 3516: 3512: 3511: 3507: 3499: 3495: 3487: 3483: 3473: 3471: 3446: 3445: 3441: 3431: 3429: 3424: 3423: 3419: 3411: 3402: 3394: 3387: 3379: 3375: 3367: 3354: 3346: 3342: 3334: 3330: 3322: 3318: 3310: 3301: 3293: 3289: 3281: 3270: 3262: 3251: 3243: 3239: 3229: 3227: 3222: 3221: 3208: 3200: 3196: 3188: 3184: 3176: 3172: 3164: 3160: 3152: 3148: 3140: 3133: 3125: 3121: 3113: 3109: 3101: 3097: 3089: 3085: 3075: 3073: 3061: 3057: 3049: 3045: 3037: 3030: 3022: 3018: 3010: 3006: 2998: 2991: 2983: 2979: 2971: 2967: 2959: 2955: 2947: 2943: 2935: 2928: 2920: 2911: 2903: 2899: 2891: 2884: 2876: 2872: 2864: 2860: 2852: 2845: 2837: 2830: 2822: 2818: 2810: 2806: 2796: 2794: 2785: 2784: 2780: 2770: 2768: 2763: 2762: 2758: 2750: 2746: 2738: 2734: 2703: 2699: 2692: 2688: 2657: 2650: 2605:Weinberg, Alvin 2602: 2593: 2583: 2581: 2568: 2561: 2533:Physical Review 2513: 2509: 2501: 2497: 2489: 2482: 2474: 2470: 2462: 2458: 2448: 2446: 2445:on 19 July 2018 2437: 2436: 2432: 2424: 2420: 2412: 2408: 2400: 2396: 2358: 2354: 2327:Physical Review 2319:Anderson, H. L. 2316: 2312: 2304: 2300: 2272:Physical Review 2247:Anderson, H. L. 2244: 2240: 2232: 2228: 2178: 2174: 2166: 2162: 2154: 2150: 2098: 2094: 2086: 2082: 2032: 2028: 2020: 2016: 2006: 2004: 1995: 1991: 1981: 1979: 1972: 1968: 1960: 1956: 1946: 1944: 1934: 1930: 1922: 1918: 1908: 1906: 1904:City of Chicago 1898: 1897: 1890: 1880: 1878: 1877:on 5 April 2015 1861: 1860: 1849: 1830: 1829: 1820: 1815: 1814: 1768:Norman Hilberry 1760:Alvin C. Graves 1737: 1733: 1728: 1639: 1525: 1519: 1517:Later operation 1509: 1507: 1481:cadmium nitrate 1453: 1344: 1336:James B. Conant 1311:control systems 1299:prompt neutrons 1236:uranium dioxide 1142: 1040:prompt critical 1010:is the average 967: 965: 947: 943: 941: 938: 937: 876:Norman Hilberry 865: 857:Ernest Lawrence 846:nuclear reactor 841:thermal neutron 783:nuclear weapons 781:for ships, and 738:Lyman J. Briggs 726:Albert Einstein 712:, warning of a 706: 677:National Carbon 656:in the form of 610:Eugene T. Booth 571:nuclear fission 535: 508:neutron poisons 404:nuclear weapons 384:nuclear reactor 365:27 October 1971 308: 306: 302: 299: 294: 291: 289: 287: 286: 278: 277: 276: 275: 274: 273: 248: 239: 230: 221: 205:nuclear reactor 181:2 December 1942 157:Primary coolant 121:Solid (pellets) 113:Natural uranium 104: 67: 65: 62: 38:Reactor concept 17: 12: 11: 5: 6984: 6974: 6973: 6968: 6963: 6958: 6953: 6948: 6943: 6938: 6933: 6928: 6923: 6918: 6913: 6908: 6903: 6898: 6893: 6888: 6873: 6872: 6860: 6848: 6836: 6813: 6812: 6810: 6809: 6808: 6807: 6797: 6796: 6795: 6790: 6779: 6777: 6769: 6768: 6766: 6765: 6760: 6755: 6750: 6745: 6743:Off-Off Campus 6740: 6735: 6730: 6725: 6722:Chicago Review 6718: 6711: 6705: 6703: 6699: 6698: 6696: 6695: 6690: 6688:Scavenger Hunt 6685: 6680: 6675: 6670: 6665: 6660: 6654: 6652: 6648: 6647: 6645: 6644: 6639: 6634: 6629: 6624: 6619: 6614: 6613: 6612: 6609:Nuclear Energy 6603:Chicago Pile-1 6600: 6592: 6590: 6582: 6581: 6579: 6578: 6573: 6568: 6566:Seminary Co-op 6563: 6558: 6553: 6548: 6543: 6538: 6533: 6532: 6531: 6526: 6521: 6511: 6509:Ida Noyes Hall 6506: 6501: 6496: 6491: 6486: 6481: 6475: 6473: 6469: 6468: 6466: 6465: 6460: 6455: 6449: 6447: 6439: 6438: 6435: 6434: 6432: 6431: 6430: 6429: 6419: 6414: 6409: 6404: 6399: 6394: 6389: 6387:Medical Center 6384: 6379: 6374: 6369: 6364: 6359: 6354: 6349: 6344: 6339: 6334: 6329: 6324: 6319: 6314: 6309: 6304: 6298: 6296: 6292: 6291: 6289: 6288: 6283: 6278: 6273: 6268: 6263: 6258: 6253: 6248: 6242: 6240: 6233: 6229: 6228: 6219: 6218: 6211: 6204: 6196: 6187: 6186: 6184: 6183: 6178: 6173: 6168: 6163: 6158: 6153: 6148: 6143: 6137: 6135: 6131: 6130: 6128: 6127: 6122: 6117: 6112: 6106: 6104: 6098: 6097: 6095: 6094: 6088: 6086: 6080: 6079: 6077: 6076: 6075: 6074: 6071:Nuclear Energy 6062: 6056: 6054: 6038: 6037: 6029: 6028: 6021: 6014: 6006: 5997: 5996: 5994: 5993: 5988: 5980: 5975: 5970: 5965: 5960: 5954: 5949: 5944: 5939: 5930: 5928: 5924: 5923: 5921: 5920: 5915: 5910: 5904: 5902: 5896: 5895: 5893: 5892: 5886: 5884: 5878: 5877: 5875: 5874: 5869: 5864: 5863: 5862: 5859:Nuclear Energy 5849: 5847: 5831: 5830: 5822: 5821: 5814: 5807: 5799: 5790: 5789: 5779: 5776: 5775: 5773: 5772: 5767: 5762: 5757: 5752: 5747: 5742: 5737: 5732: 5727: 5722: 5717: 5710: 5705: 5700: 5695: 5690: 5685: 5683:Chicago Pile-1 5680: 5678:Calutron Girls 5675: 5670: 5665: 5660: 5654: 5652: 5651:Related topics 5648: 5647: 5645: 5644: 5639: 5634: 5629: 5623: 5621: 5617: 5616: 5614: 5613: 5606: 5599: 5592: 5587: 5582: 5577: 5572: 5567: 5562: 5556: 5554: 5550: 5549: 5547: 5546: 5541: 5536: 5531: 5526: 5521: 5516: 5514:Stanisław Ulam 5511: 5506: 5501: 5496: 5491: 5486: 5481: 5476: 5471: 5466: 5461: 5456: 5451: 5449:Edwin McMillan 5446: 5441: 5436: 5431: 5426: 5421: 5416: 5411: 5406: 5401: 5396: 5394:Harry Daghlian 5391: 5386: 5384:John Cockcroft 5381: 5379:James Chadwick 5376: 5371: 5366: 5361: 5356: 5351: 5345: 5343: 5339: 5338: 5336: 5335: 5330: 5325: 5320: 5315: 5310: 5305: 5303:Charles Thomas 5300: 5298:Frank Spedding 5295: 5290: 5285: 5280: 5275: 5270: 5265: 5260: 5258:James Marshall 5255: 5250: 5245: 5240: 5238:Thomas Farrell 5235: 5230: 5225: 5223:Arthur Compton 5220: 5214: 5212: 5211:Administrators 5208: 5207: 5205: 5204: 5199: 5194: 5189: 5184: 5179: 5174: 5169: 5164: 5159: 5154: 5149: 5139: 5134: 5128: 5126: 5122: 5121: 5116: 5113: 5112: 5105: 5104: 5097: 5090: 5082: 5076: 5075: 5070: 5041: 5038:The First Pile 5035: 5030: 5020:Photos of CP-1 5017: 5003: 5002:External links 5000: 4998: 4997: 4983: 4966: 4960: 4944: 4927: 4913: 4893: 4879: 4860: 4854: 4836: 4822: 4805: 4791: 4771: 4757: 4743: 4723: 4709: 4696: 4679: 4673: 4656: 4627: 4606: 4585: 4571: 4555:Groves, Leslie 4551: 4519: 4491: 4474: 4450: 4436: 4417: 4397: 4383: 4364: 4334: 4332: 4329: 4326: 4325: 4299: 4269: 4247: 4219: 4199: 4188:. 26 July 1957 4171: 4159: 4147: 4135: 4123: 4111: 4099: 4077: 4055: 4053:, p. 123. 4043: 4017: 3985: 3983:, p. 428. 3970: 3958: 3947:. 10 July 2012 3928: 3898: 3886: 3884:, p. 3.9. 3874: 3863:. 10 July 2012 3844: 3832: 3830:, p. 440. 3820: 3818:, p. 174. 3808: 3766: 3754: 3735: 3708: 3696: 3664: 3652: 3625:(9): 536–558. 3605: 3593: 3541: 3530:on 17 May 2013 3505: 3503:, p. 434. 3493: 3491:, p. 119. 3481: 3439: 3417: 3400: 3385: 3383:, p. 436. 3373: 3371:, p. 433. 3352: 3350:, p. 197. 3340: 3338:, pp. 66. 3328: 3316: 3299: 3287: 3268: 3249: 3237: 3206: 3194: 3182: 3180:, p. 430. 3170: 3158: 3156:, p. 429. 3146: 3131: 3129:, p. 431. 3119: 3107: 3095: 3083: 3055: 3043: 3041:, p. 401. 3028: 3016: 3004: 2989: 2977: 2975:, p. 385. 2965: 2953: 2951:, p. 116. 2941: 2926: 2909: 2897: 2882: 2870: 2858: 2843: 2828: 2816: 2804: 2778: 2756: 2744: 2732: 2713:(1–3): 55–63. 2697: 2686: 2648: 2591: 2559: 2540:(3): 284–286. 2507: 2495: 2480: 2468: 2456: 2430: 2428:, p. 227. 2418: 2406: 2394: 2363:(April 1973). 2361:Anderson, H.L. 2352: 2333:(8): 797–798. 2310: 2298: 2279:(5): 511–512. 2255:Dunning, J. R. 2238: 2226: 2172: 2170:, p. 148. 2160: 2148: 2092: 2080: 2039:Strassmann, F. 2026: 2014: 1989: 1966: 1954: 1928: 1916: 1888: 1847: 1844:. 9 July 2010. 1817: 1816: 1813: 1812: 1784:Frank Spedding 1730: 1729: 1727: 1724: 1703:Nuclear Energy 1638: 1635: 1584:Chicago Pile-5 1546:Chicago Pile-3 1534:Red Gate Woods 1521:Main article: 1518: 1515: 1452: 1449: 1433:Harley Wilhelm 1397:electric motor 1356:carbon dioxide 1343: 1340: 1304:neutron poison 1251:Argonne Forest 1141: 1140:Choice of site 1138: 984: 981: 978: 973: 970: 964: 959: 956: 953: 950: 946: 880:Samuel Allison 864: 861: 819:. If so, then 767:Arthur Compton 705: 702: 546:Max Bodenstein 542:chain reaction 537:The idea of a 534: 531: 376:Chicago Pile-1 371: 370: 367: 366: 363: 359: 358: 355: 351: 350: 347: 343: 342: 338: 337: 332: 325: 324: 321: 317: 316: 284: 280: 279: 267: 266: 260: 259: 258: 257: 254: 253: 250: 249: 244: 241: 240: 235: 232: 231: 226: 223: 222: 219: 216: 215: 212: 211: 208: 207: 201: 197: 196: 187: 186:Operator/owner 183: 182: 179: 175: 174: 171: 167: 166: 162: 161: 158: 154: 153: 147: 141: 140: 137: 133: 132: 129: 123: 122: 119: 115: 114: 111: 101: 100: 96: 95: 85: 81: 80: 77: 73: 72: 59: 55: 54: 49: 45: 44: 39: 35: 34: 26: 25: 24:Chicago Pile-1 15: 9: 6: 4: 3: 2: 6983: 6972: 6969: 6967: 6964: 6962: 6959: 6957: 6954: 6952: 6949: 6947: 6944: 6942: 6939: 6937: 6934: 6932: 6929: 6927: 6924: 6922: 6919: 6917: 6914: 6912: 6909: 6907: 6904: 6902: 6899: 6897: 6894: 6892: 6889: 6887: 6884: 6883: 6881: 6871: 6861: 6859: 6849: 6847: 6837: 6835: 6825: 6824: 6821: 6806: 6803: 6802: 6801: 6798: 6794: 6791: 6789: 6786: 6785: 6784: 6781: 6780: 6778: 6776: 6770: 6764: 6761: 6759: 6756: 6754: 6751: 6749: 6746: 6744: 6741: 6739: 6736: 6734: 6731: 6729: 6726: 6724: 6723: 6719: 6717: 6716: 6712: 6710: 6707: 6706: 6704: 6700: 6694: 6691: 6689: 6686: 6684: 6681: 6679: 6676: 6674: 6671: 6669: 6666: 6664: 6661: 6659: 6656: 6655: 6653: 6649: 6643: 6640: 6638: 6635: 6633: 6630: 6628: 6625: 6623: 6620: 6618: 6615: 6611: 6610: 6606: 6605: 6604: 6601: 6599: 6598: 6594: 6593: 6591: 6589: 6583: 6577: 6574: 6572: 6569: 6567: 6564: 6562: 6559: 6557: 6554: 6552: 6549: 6547: 6544: 6542: 6539: 6537: 6534: 6530: 6527: 6525: 6522: 6520: 6517: 6516: 6515: 6512: 6510: 6507: 6505: 6502: 6500: 6497: 6495: 6492: 6490: 6487: 6485: 6482: 6480: 6479:Bartlett Hall 6477: 6476: 6474: 6470: 6464: 6461: 6459: 6456: 6454: 6451: 6450: 6448: 6446: 6440: 6428: 6425: 6424: 6423: 6420: 6418: 6415: 6413: 6410: 6408: 6405: 6403: 6400: 6398: 6395: 6393: 6390: 6388: 6385: 6383: 6380: 6378: 6375: 6373: 6370: 6368: 6365: 6363: 6360: 6358: 6355: 6353: 6350: 6348: 6345: 6343: 6340: 6338: 6335: 6333: 6330: 6328: 6325: 6323: 6320: 6318: 6315: 6313: 6310: 6308: 6305: 6303: 6300: 6299: 6297: 6293: 6287: 6284: 6282: 6279: 6277: 6274: 6272: 6269: 6267: 6264: 6262: 6259: 6257: 6254: 6252: 6249: 6247: 6244: 6243: 6241: 6237: 6234: 6230: 6226: 6217: 6212: 6210: 6205: 6203: 6198: 6197: 6194: 6182: 6179: 6177: 6176:Sexton School 6174: 6172: 6169: 6167: 6164: 6162: 6159: 6157: 6154: 6152: 6149: 6147: 6144: 6142: 6139: 6138: 6136: 6132: 6126: 6123: 6121: 6118: 6116: 6113: 6111: 6108: 6107: 6105: 6099: 6093: 6090: 6089: 6087: 6081: 6073: 6072: 6068: 6067: 6066: 6063: 6061: 6058: 6057: 6055: 6053: 6048: 6043: 6039: 6034: 6027: 6022: 6020: 6015: 6013: 6008: 6007: 6004: 5992: 5989: 5987: 5986: 5981: 5979: 5976: 5974: 5971: 5969: 5966: 5964: 5961: 5958: 5955: 5953: 5950: 5948: 5945: 5943: 5940: 5938: 5936: 5932: 5931: 5929: 5925: 5919: 5916: 5914: 5911: 5909: 5906: 5905: 5903: 5897: 5891: 5888: 5887: 5885: 5879: 5873: 5870: 5868: 5865: 5861: 5860: 5856: 5855: 5854: 5851: 5850: 5848: 5846: 5841: 5836: 5832: 5827: 5820: 5815: 5813: 5808: 5806: 5801: 5800: 5797: 5787: 5777: 5771: 5768: 5766: 5763: 5761: 5758: 5756: 5753: 5751: 5748: 5746: 5743: 5741: 5738: 5736: 5733: 5731: 5728: 5726: 5723: 5721: 5718: 5716: 5715: 5711: 5709: 5706: 5704: 5701: 5699: 5698:Franck Report 5696: 5694: 5691: 5689: 5686: 5684: 5681: 5679: 5676: 5674: 5671: 5669: 5666: 5664: 5661: 5659: 5656: 5655: 5653: 5649: 5643: 5640: 5638: 5635: 5633: 5630: 5628: 5625: 5624: 5622: 5618: 5612: 5611: 5607: 5605: 5604: 5600: 5598: 5597: 5593: 5591: 5588: 5586: 5583: 5581: 5578: 5576: 5573: 5571: 5568: 5566: 5563: 5561: 5560:Alsos Mission 5558: 5557: 5555: 5551: 5545: 5542: 5540: 5537: 5535: 5534:Robert Wilson 5532: 5530: 5529:Eugene Wigner 5527: 5525: 5522: 5520: 5517: 5515: 5512: 5510: 5509:Edward Teller 5507: 5505: 5502: 5500: 5497: 5495: 5492: 5490: 5487: 5485: 5484:Glenn Seaborg 5482: 5480: 5477: 5475: 5472: 5470: 5467: 5465: 5462: 5460: 5457: 5455: 5454:Mark Oliphant 5452: 5450: 5447: 5445: 5444:Willard Libby 5442: 5440: 5437: 5435: 5432: 5430: 5427: 5425: 5422: 5420: 5417: 5415: 5412: 5410: 5407: 5405: 5402: 5400: 5397: 5395: 5392: 5390: 5387: 5385: 5382: 5380: 5377: 5375: 5372: 5370: 5367: 5365: 5362: 5360: 5357: 5355: 5354:Robert Bacher 5352: 5350: 5347: 5346: 5344: 5340: 5334: 5333:Roscoe Wilson 5331: 5329: 5326: 5324: 5321: 5319: 5316: 5314: 5311: 5309: 5306: 5304: 5301: 5299: 5296: 5294: 5291: 5289: 5286: 5284: 5281: 5279: 5276: 5274: 5271: 5269: 5266: 5264: 5261: 5259: 5256: 5254: 5251: 5249: 5248:John Lansdale 5246: 5244: 5243:Leslie Groves 5241: 5239: 5236: 5234: 5231: 5229: 5226: 5224: 5221: 5219: 5218:Vannevar Bush 5216: 5215: 5213: 5209: 5203: 5200: 5198: 5195: 5193: 5190: 5188: 5185: 5183: 5180: 5178: 5175: 5173: 5170: 5168: 5165: 5163: 5160: 5158: 5155: 5153: 5150: 5147: 5143: 5140: 5138: 5135: 5133: 5130: 5129: 5127: 5123: 5119: 5114: 5110: 5103: 5098: 5096: 5091: 5089: 5084: 5083: 5080: 5074: 5071: 5068: 5054: 5050: 5046: 5042: 5039: 5036: 5034: 5031: 5028: 5024: 5021: 5018: 5015: 5011: 5006: 5005: 4994: 4990: 4986: 4980: 4975: 4974: 4967: 4963: 4957: 4953: 4949: 4945: 4941: 4937: 4933: 4928: 4924: 4920: 4916: 4910: 4905: 4904: 4898: 4897:Segrè, Emilio 4894: 4890: 4886: 4882: 4876: 4872: 4868: 4867: 4861: 4857: 4851: 4847: 4846: 4841: 4837: 4833: 4829: 4825: 4819: 4815: 4811: 4806: 4802: 4798: 4794: 4788: 4783: 4782: 4776: 4772: 4765: 4764: 4758: 4754: 4750: 4746: 4740: 4735: 4734: 4728: 4724: 4720: 4716: 4712: 4706: 4702: 4697: 4693: 4689: 4685: 4680: 4676: 4670: 4666: 4662: 4657: 4646: 4642: 4635: 4634: 4628: 4617: 4613: 4609: 4603: 4596: 4595: 4590: 4586: 4582: 4578: 4574: 4568: 4563: 4562: 4556: 4552: 4541: 4537: 4530: 4529: 4524: 4523:Fermi, Enrico 4520: 4508: 4504: 4497: 4492: 4488: 4484: 4480: 4475: 4471: 4467: 4462: 4461: 4455: 4451: 4447: 4443: 4439: 4433: 4429: 4425: 4424: 4418: 4414: 4410: 4406: 4402: 4398: 4394: 4390: 4386: 4380: 4376: 4372: 4371: 4365: 4354: 4350: 4343: 4342: 4336: 4335: 4313: 4309: 4303: 4287: 4283: 4279: 4273: 4257: 4251: 4235: 4234: 4229: 4223: 4217: 4213: 4206: 4204: 4187: 4186: 4181: 4175: 4168: 4163: 4156: 4151: 4144: 4139: 4132: 4127: 4121:, p. 47. 4120: 4115: 4108: 4107:Hogerton 1970 4103: 4087: 4081: 4065: 4059: 4052: 4047: 4032: 4028: 4021: 4013: 4009: 4005: 4001: 4000: 3992: 3990: 3982: 3977: 3975: 3967: 3962: 3946: 3942: 3938: 3932: 3917:. 21 May 2013 3916: 3912: 3908: 3902: 3896:, p. 23. 3895: 3890: 3883: 3878: 3862: 3858: 3854: 3848: 3842:, p. 95. 3841: 3840:Anderson 1975 3836: 3829: 3824: 3817: 3812: 3797: 3793: 3789: 3785: 3784: 3783:New Scientist 3776: 3770: 3764:, p. 14. 3763: 3758: 3751: 3746: 3744: 3742: 3740: 3731: 3727: 3721: 3719: 3717: 3715: 3713: 3706:, p. 54. 3705: 3700: 3685: 3681: 3677: 3671: 3669: 3661: 3656: 3648: 3644: 3640: 3636: 3632: 3628: 3624: 3620: 3616: 3609: 3603:, p. 93. 3602: 3601:Anderson 1975 3597: 3589: 3585: 3581: 3577: 3573: 3569: 3565: 3561: 3560: 3552: 3545: 3526: 3522: 3515: 3509: 3502: 3497: 3490: 3485: 3469: 3465: 3461: 3457: 3453: 3449: 3443: 3427: 3421: 3415:, p. 16. 3414: 3409: 3407: 3405: 3397: 3396:Anderson 1975 3392: 3390: 3382: 3377: 3370: 3365: 3363: 3361: 3359: 3357: 3349: 3348:Salvetti 2001 3344: 3337: 3332: 3326:, p. 53. 3325: 3320: 3313: 3308: 3306: 3304: 3297:, p. 17. 3296: 3295:Weinberg 1994 3291: 3284: 3279: 3277: 3275: 3273: 3265: 3260: 3258: 3256: 3254: 3246: 3241: 3225: 3219: 3217: 3215: 3213: 3211: 3203: 3198: 3191: 3186: 3179: 3174: 3168:, p. 85. 3167: 3162: 3155: 3150: 3144:, p. 91. 3143: 3142:Anderson 1975 3138: 3136: 3128: 3123: 3116: 3111: 3104: 3099: 3093:, p. 86. 3092: 3087: 3072: 3071: 3066: 3059: 3052: 3047: 3040: 3035: 3033: 3025: 3020: 3014:, p. 88. 3013: 3012:Anderson 1975 3008: 3001: 2996: 2994: 2986: 2985:Anderson 1975 2981: 2974: 2969: 2963:, p. 86. 2962: 2961:Anderson 1975 2957: 2950: 2945: 2938: 2933: 2931: 2924:, p. 15. 2923: 2922:Weinberg 1994 2918: 2916: 2914: 2906: 2901: 2894: 2889: 2887: 2879: 2874: 2867: 2866:Salvetti 2001 2862: 2856:, p. 82. 2855: 2854:Anderson 1975 2850: 2848: 2840: 2835: 2833: 2825: 2820: 2813: 2808: 2792: 2788: 2782: 2766: 2760: 2753: 2748: 2741: 2740:Salvetti 2001 2736: 2728: 2724: 2720: 2716: 2712: 2708: 2701: 2695: 2690: 2682: 2678: 2674: 2670: 2666: 2662: 2661:Physics Today 2655: 2653: 2644: 2640: 2635: 2630: 2626: 2622: 2618: 2614: 2610: 2606: 2600: 2598: 2596: 2580: 2576: 2572: 2566: 2564: 2555: 2551: 2547: 2543: 2539: 2535: 2534: 2529: 2525: 2521: 2517: 2511: 2505:, p. 28. 2504: 2499: 2492: 2487: 2485: 2477: 2472: 2465: 2460: 2444: 2440: 2434: 2427: 2422: 2415: 2410: 2403: 2398: 2390: 2386: 2382: 2378: 2374: 2370: 2366: 2362: 2356: 2348: 2344: 2340: 2336: 2332: 2328: 2324: 2320: 2314: 2307: 2302: 2294: 2290: 2286: 2282: 2278: 2274: 2273: 2268: 2264: 2263:Glasoe, G. N. 2260: 2256: 2252: 2248: 2242: 2235: 2230: 2222: 2218: 2214: 2210: 2206: 2202: 2198: 2194: 2191:(3397): 880. 2190: 2186: 2185: 2176: 2169: 2164: 2157: 2152: 2144: 2140: 2136: 2132: 2128: 2124: 2120: 2116: 2115: 2110: 2106: 2105:Frisch, O. R. 2102: 2101:Meitner, Lise 2096: 2089: 2084: 2076: 2072: 2068: 2064: 2060: 2056: 2052: 2048: 2044: 2040: 2036: 2030: 2023: 2018: 2003: 1999: 1993: 1977: 1970: 1963: 1958: 1942: 1938: 1937:Ölander, Arne 1932: 1926:, p. 24. 1925: 1920: 1905: 1901: 1895: 1893: 1876: 1872: 1868: 1864: 1858: 1856: 1854: 1852: 1843: 1839: 1838: 1833: 1827: 1825: 1823: 1818: 1809: 1805: 1801: 1797: 1793: 1789: 1785: 1781: 1777: 1773: 1772:David L. 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