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J.R. Oppenheimer and General Groves
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The Uranium
Path to
the Bomb

The Plutonium
Path to
the Bomb

Bringing It All Together

Dawn of the
Atomic Era

Postscript --
The Nuclear Age

"Met Lab" alumni at the University of Chicago -- Fermi is on the far left of the front row; Zinn is on Fermi's left; Anderson is on the far right of the front row; and Szilard is over Anderson's right shoulder.DIFFICULT CHOICES

By early 1942, as the United States suffered a series of military defeats in the Pacific, top officials in Washington tentatively had decided to proceed with the construction of an atomic bomb.  Two paths seemed possible.  A uranium bomb could be achieved if sufficient uranium-235 could be produced by one or more of the three isotope separation methods under consideration: gaseous diffusion, centrifuge, and electromagnetic.  A plutonium bomb might provide a quicker route, but it required demonstration that plutonium could be produced in a uranium pile and then be separated in usable quantities.  To this end, Arthur Compton consolidated most plutonium research at the new Metallurgical Laboratory (Met Lab) at the University of Chicago.

Leslie Groves, Commanding General of the Manhattan Engineer DistrictA program review conducted in May 1942 determined that no front runner in the race for the bomb existed and recommended that the three isotope separation methods and the pile project be pushed as fast as possible to full production planning.  Construction and security needs suggested placing the program in the Army Corps of Engineers.  In August, the Corps set up the Manhattan Engineer District (MED) to manage the project.  A month later, Colonel Leslie R. Groves was promoted to brigadier general and appointed to head the effort.  Groves moved quickly to narrow the field and move the project along, selecting a site in east Tennessee (Oak Ridge) for the construction of production plants, dropping the centrifuge process from consideration, and choosing J. Robert Oppenheimer to head the bomb research and design laboratory to be built at Los Alamos, New Mexico.  In December, President Franklin Roosevelt gave his final authorization to proceed with construction of the atomic bomb.  

To learn more about any of these difficult choices that had to be made in 1942, choose a web page from the menu below.  To continue with a quick overview of the Manhattan Project, jump ahead to the description of the "Uranium Path to the Bomb, 1942-1944."

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Sources and notes for this page.

The text for this page is original to the Department of Energy's Office of History and Heritage Resources.  The photograph of Leslie Groves at his desk is reprinted in the inside front cover of Vincent C. Jones, Manhattan: The Army and the Atomic Bomb, United States Army in World War II (Washington: Center of Military History, United States Army, 1988).  Click here for more information on the photograph of "Met Lab" alumni.

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