Samuel King Allison

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Samuel King Allison
Samuel King Allison.jpg
Born November 13, 1900
Chicago, Illinois.
Died September 15, 1965
Nationality U.S.
Fields Physics
Institutions University of California, Berkeley
University of Chicago
Los Alamos National Laboratory
Alma mater University of Chicago
Doctoral advisor William Draper Harkins
Known for Manhattan Project

Samuel King Allison (November 13, 1900 – September 15, 1965) was an American physicist,[1] most notable for his role in the Manhattan Project — where among other things he read the countdown for the detonation of the "Trinity" test — and his postwar work in the "scientists' movement".


Samuel K. Allison was born in Chicago, Illinois, and attended the University of Chicago for his undergraduate degree as well as for his PhD (in chemistry under the supvervision of William Draper Harkins, though his thesis was related to experimental physics). From 1923 until 1925 he was a research fellow at Harvard University and from 1925 until 1926 he was a research fellow at the Carnegie Institution. From 1926 until 1928 he taught physics at University of California, Berkeley, after which he returned to the University of Chicago, where he studied the Compton effect and the dynamical theory of x-ray diffraction. He developed a high resolution x-ray spectrometer with a graduate student, John Harry Williams (1908–1966). In the late 1930s, he studied with John Cockcroft at the Cavendish Laboratory, learning about linear accelerators, and after returning to Chicago he built one. He authored a textbook on x-rays with Arthur Compton which became widely used.

During World War II, Allison was a consultant to the National Defense Research Committee and the S-1 Uranium Committee, the early investigations into the feasibility of an atomic bomb which would later become the Manhattan Project. He worked at the Chicago Metallurgical Laboratory and was its director from 1943 until 1944. He then went to work at the secret Los Alamos laboratory in New Mexico. Notably, he was the one who read the countdown over the loudspeakers for the "Trinity" test in 1945.

Allison's ID badge photo from Los Alamos.

After the war, Allison became director of the Enrico Fermi Institute of Nuclear Studies from 1946 until 1957, and again from 1963 until 1965. He was active in the "scientist's movement" for the control of atomic weapons, and was a founder of the Bulletin of the Atomic Scientists. He was a strong opponent of secrecy in science, and, in an influential speech announcing the creation of the Enrico Fermi Institute said:

We are determined to return to free research as before the war. If secrecy is imposed on scientific research in physics, we will find all first-rate scientists working on subjects as innocuous as the colors of butterfly wings.[2]

Allison died in 1965 while attending the Plasma Physics and Controlled Nuclear Fusion Research Conference in Culham, England of complications following an aortic aneurism. His papers are kept at the American Institute of Physics.


  • Arthur Holly Compton and Samuel K. Allison (1935). X-rays in Theory and Experiment. Van Nostrand Reinhold Inc. 
  • Glenn T. Seaborg, Ronald L. Kathren, and Jerry B. Gough (1994). The Plutonium Story: The Journals of Professor Glenn T. Seaborg 1939-1946. Battelle Press. p. 117. 
  1. ^ "Obituary: Samuel K. Allison". Physics Today 18 (12): 88. December 1965. Bibcode:1965PhT....18l..88.. doi:10.1063/1.3047071. 
  2. ^ Roger H. Hildebrand (1999). "Samuel King Allison November 13, 1900 - September 15, 1965". Biographical Memoirs (National Academy of Sciences) 76: 8. 

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