John R. Dunning

John Ray Dunning (* September 24 1907 in Shelby, Nebraska; † August 25, 1975 in Key Biscayne, Florida) was an American nuclear physicist. He was involved in the development of nuclear weapons.

Dunning graduated in 1929, the Nebraska Wesleyan University. In 1934 he received his doctorate at Columbia University. In 1936, he directed the construction of a cyclotron.

Dunning was able to reproduce the experiments by Otto Hahn and Fritz Strassmann, nuclear fission and verify. In 1940, the group led by Dunning was able to show that the uranium isotope 235U is more suitable than the 238U fission.