Atomic Heritage Foundation

March 2, 1940

March 2, 1940

The first direct measurements of the enormous slow fission cross section of uranium-235 are made by John Dunning at Manhattan, NY.

Date Range:

1940CE Mar 2nd

Era:

1939 to 1941: Investigating Nuclear Weapons

Hear the stories of the Manhattan Project

Browse our collection of oral histories with workers, families, service members, and more about their experiences in the Manhattan Project.

Tour the Sites of the Manhattan Project

Tour some of the key locations of the Manhattan Project with an audio guide.

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Albert Einstein receiving his his certificate of U.S. citizenship in 1940 from Judge Philip Forman. Photo courtesy Al Aumuller/Library of Congress.

Scientist Refugees and the Manhattan Project

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