John Ray Dunning was an American physicist who played key roles in the Manhattan Project that developed the first atomic bombs. He specialized in neutron physics, and did pioneering work in gaseous diffusion for isotope separation. He was dean of the school of engineering and applied science at Columbia University from 1950 to 1969.
John R. Dunning (left) and Hubert Thelen (right) – first cousins, March 1957 after funeral of John's father A.C. Dunning
The cyclotron built by Dunning in 1939, in the Pupin Hall physics building basement at Columbia University. Dunning (left) is with Enrico Fermi (center) and Dana P. Mitchell (right)
The Manhattan Project was a program of research and development undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist J. Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the bombs. The Army program was designated the Manhattan District, as its first headquarters were in Manhattan; the name gradually superseded the official codename, Development of Substitute Materials, for the entire project. The project absorbed its earlier British counterpart, Tube Alloys. The Manhattan Project employed nearly 130,000 people at its peak and cost nearly US$2 billion, over 80 percent of which was for building and operating the plants that produced the fissile material. Research and production took place at more than 30 sites across the US, the UK, and Canada.
The Trinity test of the Manhattan Project on 16 July 1945 was the first detonation of a nuclear weapon.
Enrico Fermi, John R. Dunning, and Dana P. Mitchell in front of the cyclotron in the basement of Pupin Hall at Columbia University, 1940
March 1940 meeting at Berkeley, California: Ernest O. Lawrence, Arthur H. Compton, Vannevar Bush, James B. Conant, Karl T. Compton, and Alfred L. Loomis
Oppenheimer and Groves at the remains of the Trinity test in September 1945, two months after the test blast and just after the end of World War II. The white overshoes prevented fallout from sticking to the soles of their shoes.