John R. Dunning | |
|---|---|
 Dunning in c. 1940 | |
| Born | September 24, 1907 Shelby, Nebraska, US |
| Died | August 25, 1975 (1975-08-26) (aged 67) |
| Education | Nebraska Wesleyan University (BA) Columbia University (MS,PhD) |
| Awards | Medal for Merit (1946) |
| Scientific career | |
| Fields | physics |
| Thesis | The Emission and Scattering of Neutrons (1934) |
| Doctoral advisor | George B. Pegram |
John Ray Dunning (September 24, 1907 – August 25, 1975) was an Americanphysicist who played key roles in theManhattan Project that developed the firstatomic bombs. He specialized in neutron physics, and did pioneering work ingaseous diffusion forisotope separation. He was dean of theschool of engineering and applied science atColumbia University from 1950 to 1969.
John Ray Dunning was born inShelby, Nebraska, on September 24, 1907, the son of Albert Chester Dunning, a grain dealer, and his wife Josephine Dunning née Thelen. He graduated from Shelby High School in 1925, and enteredNebraska Wesleyan University where he became a member ofPhi Kappa Tau fraternity, and received aBachelor of Arts (B.A.) degree in 1929.[1]
After graduation, Dunning commenced a doctoral program atColumbia University. In 1932,James Chadwick discovered theneutron, which influenced Dunning's career, as he thereafter devoted much of his professional interest to the characteristics and uses of this particle. Dunning's research was enthusiastically supported at Columbia byGeorge B. Pegram. In 1933, Dunning was an instructor at Columbia University from 1929 to 1932, and a university fellow from 1932 to 1933.[2] He received his Ph.D. in 1934, writing his thesis on "The Emission and Scattering of Neutrons" under Pegram's supervision.[3]
Dunning married Esther Laura Blevins in 1930. They had two children, John Ray Jr., who became a professor of physics and astronomy atSonoma State University, and Ann Adele.[1]
After gaining his doctorate at Columbia, Dunning continued teaching and research there, becoming an assistant professor in 1935, and an associate professor there in 1938. Dunning was a central figure at Columbia on neutron research, and went on to publish 24 papers on neutrons between 1934 and 1938. In 1936, Dunning received a Traveling Fellowship, which he used to meet and discuss his neutron physics research with many eminent European nuclear physicists includingNiels Bohr,James Chadwick, Fermi,Werner Heisenberg, andErnest Rutherford.[2]
Dunning closely followed the work ofErnest Lawrence on thecyclotron. Dunning wanted a more powerful neutron source and the cyclotron appeared as an attractive tool to achieve this end. Government funding was not available for such projects in those days, and university budgets were tight. Nonetheless, during 1935 and 1936 he was able construct a cyclotron using many salvaged parts to reduce costs and funding from industrial and private donations.[4] It was announced in 2007 thatColumbia University has decided to junk a 70-year-old atom smasher, which is the nation's oldest artefact of the nuclear era. After being decommissioned in 1965, the machine sat in the basement ofPupin Hall, home of Columbia's physics department.[5] It was scrapped in 2008, although some components are in theSmithsonian Institution in Washington, DC.[6]
In December 1938, the German chemistsOtto Hahn andFritz Strassmann sent a manuscript toNaturwissenschaften reporting they had detected the elementbarium after bombardinguranium withneutrons.[7] They communicated these results toLise Meitner, who, with her nephewOtto Frisch, correctly interpreted these results as being the result ofnuclear fission.[8] Frisch then confirmed this experimentally on January 13, 1939.[9] Even before it was published, Meitner’s and Frisch’s interpretation of the work of Hahn and Strassmann crossed the Atlantic Ocean withNiels Bohr, who was to lecture atPrinceton University.Isidor Isaac Rabi andWillis Lamb, twoColumbia University physicists working at Princeton, heard the news and carried it back to Columbia. Rabi said he told Fermi; Fermi gave credit to Lamb. It was soon clear to a number of scientists at Columbia that they should try to detect the energy released in the nuclear fission of uranium from neutron bombardment. On 25 January 1939, Dunning was a member of the Columbia team that conducted the first nuclear fission experiment in the United States.[10] in the Other members of the team wereHerbert L. Anderson,Eugene T. Booth,Enrico Fermi,G. Norris Glasoe, andFrancis G. Slack.[11][12][13]
Bohr argued that it was theuranium-235 isotope that was responsible for fission. Dunning realised that if this was the case, then anatomic bomb would be possible.[14] His thoughts turned to devising a process foruranium enrichment, and by 1940 he was investigatinggaseous diffusion, which he felt appeared to be more effective than the electromagnetic method ofAlfred Nier[15] and offered the best route to enrichment on an industrial scale. The researchers at Columbia became theManhattan Project's Substitute Alloy Materials (SAM) Laboratories. Dunning headed the laboratory division responsible for all aspects of the gaseous diffusion program, including engineering problems, pilot plants and research activities.[16] Four papers co-written withJames Rainwater,William W. Havens Jr., andChien-Shiung Wu appeared in 1947 and 1948, but much remained classified.[17] Due to the secrecy of this work, Dunning and three of his colleagues were awarded $300,000 each in lieu of patent royalties.[18] For his part, Dunning was awarded theMedal for Merit byPresidentHarry S. Truman. His citation read:
for exceptionally meritorious conduct in the performance of outstanding service to the War Department, in accomplishments involving great responsibility and scientific distinction in connection with the development of the greatest military weapon of all time, the atomic bomb. As a physical researcher, he took a leading part in the initiation of the early phases of the project; then he was in charge of essential research in the SAM Laboratories for the Manhattan Engineer District, Army Service Forces, and then he served as advisor to the contractor for full scale operation of his process. A physicist of national distinction, Dr. Dunning's unselfish and unswerving devotion to duty have contributed significantly to the success of the Atomic Bomb project.[19]
In 1946, Dunning became Thayer Lindsley Professor of Applied Science at Columbia. In the immediate post-war years he was scientific director for construction of theNevis Laboratories, a collaborative effort of Columbia University, theUnited States Atomic Energy Commission, and theOffice of Naval Research. He became dean of the school of engineering and applied science in 1950. This ended his active research career, but he was active in fundraising for what became the Seeley Wintersmith Mudd Building and the Terrace Engineering Center extension. By the time he stepped down as dean in 1969, he had raised $50 million for the school.[20]
During the 1950s, Dunning was often consulted on nuclear technology matters by PresidentDwight D. Eisenhower andRear AdmiralHyman G. Rickover, the head of the Navy's nuclear powered ships project. Dunning was elected to theUnited States National Academy of Sciences in 1948,[20] and thePhi Kappa Tau Hall of Fame.[21] Over the years he served as chairman of the New York City Board of Education Advisory Committee on Science Manpower, the President's Committee on Supersonic Transport and the Science Advisory Council to the Legislature of the State of New York. He was a member of the board of theAmerican Association for the Advancement of Science and the science advisory committee of theDepartment of Defense.[20]
Fascinated by nuclear technology and eager to share his knowledge with the public, Dunning gave numerous public talks on the subject, and made frequent appearances on television and radio. He helped write aBlondie and Dagwood comic that explained nuclear energy in simple terms. In one experiment, he drank irradiated salt water, and used ageiger counter to demonstrate to his audience how his fingers became radioactive assodium-24, with itshalf life of 15 hours, circulated through his bloodstream.[22]
He died from a heart attack at his home inKey Biscayne, Florida, on August 25, 1975,[23] and was buried at North Cemetery inSherman, Connecticut, near where he had another home.
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