Enrico Fermi : biography
The scientists at Columbia decided that they should try to detect the energy released in the nuclear fission of uranium from neutron bombardment. On 25 January 1939, a Columbia team conducted the first nuclear fission experiment in the U.S., in the basement of Pupin Hall. The next day, the Fifth Washington Conference on Theoretical Physics began in Washington, D.C. under the joint auspices of The George Washington University and the Carnegie Institution of Washington. There, the news on nuclear fission was spread even further, which fostered many more experimental demonstrations.
Leó Szilárd obtained of uranium oxide, allowing Fermi and Anderson to conduct experiments with fission on a much larger scale. Fermi and Szilárd collaborated on a design of a device to achieve a self-sustaining nuclear reaction—a nuclear reactor. Fermi suggested that uranium oxide could be used in the form of blocks. The two agreed that water could not be used as a neutron moderator, and their attention turned to using graphite instead. In the end, Szilárd came up with what proved to be a workable design, a pile of uranium oxide blocks surrounded by graphite bricks. Szilárd, Anderson and Fermi jointly published a paper on "Neutron Production in Uranium", but their work habits and personalities were different, and Fermi had trouble working with Szilárd.
Fermi was the first to warn military leaders about the potential impact of nuclear energy, giving a lecture on the subject at the Navy Department on 18 March 1939. The response fell short of what he had hoped for, although the Navy agreed to provide $1,500 towards further research at Columbia. In August 1939, three Hungarian physicists—Szilárd, Eugene Wigner and Edward Teller—prepared the Einstein–Szilárd letter, which they persuaded Einstein to sign, warning President Franklin D. Roosevelt of the probability that the Nazis were planning to build an atomic bomb. Because of the German invasion of Poland on 1 September, it was October before they could arrange for the letter to be personally delivered. Roosevelt was concerned enough that the S-1 Uranium Committee was assembled. At Teller’s request, the committee awarded Columbia University $6,000 for Fermi to buy graphite. Less than a week later, Szilard had to inform the committee that the required graphite would cost $33,000. The money arrived in February 1940, and Fermi used it to build a pile of graphite bricks on the seventh floor of the Pupin laboratory. By August 1941, he had six tons of uranium oxide and thirty tons of graphite blocks, which he used to build a still larger pile in the Schermerhorn Hall at Columbia.
When the S-1 Uranium Committee met on 18 December 1941, the atmosphere had completely changed; because the U.S. was now at war, there was a heightened sense of urgency. While most of the effort thus far had been directed at three different processes for producing enriched uranium, S-1 Uranium Committee member Arthur Compton determined that plutonium was a feasible alternative which could be mass-produced in nuclear reactors by the end of 1944. To achieve this, he decided to concentrate the plutonium work at the University of Chicago. Fermi reluctantly moved, and his team became part of the new Metallurgical Laboratory there.
Given the number of unknown factors involved in creating a self-sustaining nuclear reaction, it seemed inadvisable to do so in a densely populated area. Compton arranged with Colonel Kenneth Nichols, the head of the Army’s Manhattan District, for land to be acquired in the Argonne Forest about from Chicago, and Stone & Webster was contracted to develop the site. However, this work was halted by an industrial dispute. Fermi then persuaded Compton that he could build a reactor in the squash court under Stagg Field at the University of Chicago. Construction of the pile began on 6 November 1942, and Chicago Pile-1 went critical on 2 December.
This experiment was a landmark in the quest for energy, and it was typical of Fermi’s approach. Every step was carefully planned, every calculation meticulously done. When the first self-sustained nuclear chain reaction was achieved, Compton made a coded phone call to James B. Conant, the chairman of the National Defense Research Committee.