Oppenheimer, Fermi, and Einstein Urge Roosevelt to Commence the Manhattan Project
29.3 هزار بار بازدید -
10 سال پیش
-
Manhattan Project, U.S. government research
Manhattan Project, U.S. government research project (1942–45) that produced the first atomic bombs.
American scientists, many of them refugees from fascist regimes in Europe, took steps in 1939 to organize a project to exploit the newly recognized fission process for military purposes. The first contact with the government was made by G.B. Pegram of Columbia University, who arranged a conference between Enrico Fermi and the Navy Department in March 1939. In the summer of 1939,Albert Einstein was persuaded by his fellow scientists to use his influence and present the military potential of an uncontrolled fission chain reaction to President Franklin D. Roosevelt. In February 1940, $6,000 was made available to start research under the supervision of a committee headed by L.J. Briggs, director of the National Bureau of Standards. On December 6, 1941, the project was put under the direction of the Office of Scientific Research and Development, headed by Vannevar Bush. After the U.S. entry into the war, the War Department was given joint responsibility for the project, since by mid-1942 it was obvious that a vast array of pilot plants, laboratories, and manufacturing facilities would have to be constructed by the U.S. Army Corps of Engineers so that the assembled scientists could carry out their mission. In June 1942 the Corps of Engineers’ Manhattan District was initially assigned management of the construction work (because much of the early research had been performed at Columbia University, in Manhattan), and in September 1942 Brigadier GeneralLeslie R. Groves was placed in charge of all Army activities (chiefly engineering activities) relating to the project. “Manhattan Project” became the code name for research work that would extend across the country.
It was known in 1940 that German scientists were working on a similar project and that the British were also exploring the problem. In the fall of 1941 Harold C. Urey and Pegram visited England to attempt to set up a cooperative effort, and by 1943 a combined policy committee with Great Britain and Canada was established. In that year a number of scientists of those countries moved to the United States to join the project there.
If the project were to achieve success quickly, several lines of research and development had to be carried on simultaneously before it was certain whether any might succeed. The explosive materials then had to be produced and be made suitable for use in an actual weapon.
Uranium-235, the essential fissionable component of the postulated bomb, cannot be separated from its natural companion, the much more abundant uranium-238, by chemical means; the atoms of these respective isotopes must rather be separated from each other by physical means. Several physical methods to do this were intensively explored, and two were chosen—the electromagnetic process developed at the University of California at Berkeley under Ernest Orlando Lawrence and the diffusion process developed under Urey at Columbia University. Both of these processes, and particularly the diffusion method, required large, complex facilities and huge amounts of electric power to produce even small amounts of separated uranium-235. Philip Hauge Abelson developed a third method called thermal diffusion, which was also used for a time to effect a preliminary separation. These methods were put into production at a 70-square-mile (180-square-km) tract nearKnoxville, Tennessee, originally known as the Clinton Engineer Works, later as Oak Ridge.
Thank you for watching don't forget to subscribe for more videos!
Visit our site for more information on our latest releases!
http://www.janson.com/
Like us on Facebook!
Facebook: jansonmedia
Tweet us!
Twitter: jansonmedia
American scientists, many of them refugees from fascist regimes in Europe, took steps in 1939 to organize a project to exploit the newly recognized fission process for military purposes. The first contact with the government was made by G.B. Pegram of Columbia University, who arranged a conference between Enrico Fermi and the Navy Department in March 1939. In the summer of 1939,Albert Einstein was persuaded by his fellow scientists to use his influence and present the military potential of an uncontrolled fission chain reaction to President Franklin D. Roosevelt. In February 1940, $6,000 was made available to start research under the supervision of a committee headed by L.J. Briggs, director of the National Bureau of Standards. On December 6, 1941, the project was put under the direction of the Office of Scientific Research and Development, headed by Vannevar Bush. After the U.S. entry into the war, the War Department was given joint responsibility for the project, since by mid-1942 it was obvious that a vast array of pilot plants, laboratories, and manufacturing facilities would have to be constructed by the U.S. Army Corps of Engineers so that the assembled scientists could carry out their mission. In June 1942 the Corps of Engineers’ Manhattan District was initially assigned management of the construction work (because much of the early research had been performed at Columbia University, in Manhattan), and in September 1942 Brigadier GeneralLeslie R. Groves was placed in charge of all Army activities (chiefly engineering activities) relating to the project. “Manhattan Project” became the code name for research work that would extend across the country.
It was known in 1940 that German scientists were working on a similar project and that the British were also exploring the problem. In the fall of 1941 Harold C. Urey and Pegram visited England to attempt to set up a cooperative effort, and by 1943 a combined policy committee with Great Britain and Canada was established. In that year a number of scientists of those countries moved to the United States to join the project there.
If the project were to achieve success quickly, several lines of research and development had to be carried on simultaneously before it was certain whether any might succeed. The explosive materials then had to be produced and be made suitable for use in an actual weapon.
Uranium-235, the essential fissionable component of the postulated bomb, cannot be separated from its natural companion, the much more abundant uranium-238, by chemical means; the atoms of these respective isotopes must rather be separated from each other by physical means. Several physical methods to do this were intensively explored, and two were chosen—the electromagnetic process developed at the University of California at Berkeley under Ernest Orlando Lawrence and the diffusion process developed under Urey at Columbia University. Both of these processes, and particularly the diffusion method, required large, complex facilities and huge amounts of electric power to produce even small amounts of separated uranium-235. Philip Hauge Abelson developed a third method called thermal diffusion, which was also used for a time to effect a preliminary separation. These methods were put into production at a 70-square-mile (180-square-km) tract nearKnoxville, Tennessee, originally known as the Clinton Engineer Works, later as Oak Ridge.
Thank you for watching don't forget to subscribe for more videos!
Visit our site for more information on our latest releases!
http://www.janson.com/
Like us on Facebook!
Facebook: jansonmedia
Tweet us!
Twitter: jansonmedia
10 سال پیش
در تاریخ 1393/05/06 منتشر شده
است.
29,337
بـار بازدید شده