Samuel King Allison

Background

Samuel King Allison was born on November 13, 1900 in Chicago, Illinois, the son of Samuel Buell Allison and Caroline King.

Education

Allison attended public schools in Chicago, where his father was a high school principal. He received the Bachelor of Science degree from the University of Chicago in 1921 and the Doctor of Philosophy Degree there in 1923, working with W. D. Harkins.

Career

Allison's research interests developed in precision X-ray spectroscopy, which he pursued as a National Research Council Fellow at Harvard in 1923-1925, and as a Carnegie Foundation Fellow at the Carnegie Institution of Washington during 1925-1926. In William Duane's laboratory at Harvard, Allison became involved in the controversy between Duane and Arthur H. Compton on the validity of the X-ray scattering experiments that were basic for the "Compton effect. "

Compton's now classic experiments, crucial for the support of the photon theory of radiation, were conducted at Washington University in St. Louis and had been challenged by several X-ray physicists, including Nobel laureate C. G. Barkla at Edinburgh and Bergen Davis at Columbia, but especially by Duane, for they were in direct conflict with J. J. Thomson's accepted theory of X-ray scattering. Duane had interpreted his own experiments, carried on in collaboration with students at Harvard, as being adequately explained as "tertiary radiation" of the bremsstrahlung type, produced from carbon and oxygen in the box enclosing the X-ray tube, by impact of photoelectrons ejected by the primary X rays. Compton had explained his results by the quantum theory and the photon hypothesis--not generally accepted at that time.

Duane's opposition to Compton's discovery is curious, for his own earlier X-ray work, leading to the basic Duane-Hunt law, had given important support for the photon theory of radiation.

After Allison joined Duane's group at Harvard, the experiments were repeated with greater care and precision. The earlier results were shown to be due to secondary X rays produced through scattering of the primary beam by the walls of the box housing the apparatus. When these results were known, Duane immediately withdrew his objections and supported Compton's work in a memorable session at the next meeting of the American Physical Society. The lifelong friendship of Allison and Arthur Compton began at this time.

Allison was a member of the physics faculty of the University of California at Berkeley from 1926 until 1930. During this period he continued his X-ray research, which included precise determinations of the widths and relative intensities of X-ray lines. These gave experimental confirmation of the dynamical theory of X-ray diffraction of P. P. Ewald and C. G. Darwin. For this work he made basic improvements in the design and extended the use of the double-crystal X-ray spectrometer (invented by Compton) in collaboration with John H. Williams.

In 1930 he was persuaded by Compton to return to the University of Chicago. Until 1935 he continued his X-ray researches, which culminated in the treatise X rays in Theory and Experiment (1935), prepared in collaboration with Compton. This work continues to be an authoritative reference.

From 1935 until World War II, Allison developed the first laboratory for nuclear physics in the University of Chicago physics department. W. D. Harkins had already begun work with neutrons in the Chicago chemistry department. Allison began by spending six months in Ernest Rutherford's laboratory at Cambridge, working with the Cockcroft-Walton apparatus. On his return to Chicago he and his students built (with a grant of $3, 000) a nuclear accelerator of this type. This apparatus, used by Allison with a succession of graduate students, produced much valuable research. Their results included precise measurements of the energy released in proton-induced nuclear transformations, and later in reactions induced by heavier ions. These gave precise values for the masses and energy content of a series of light elements and also confirmed the relativistic mass-energy changes in the reactions with a high degree of accuracy.

When Compton organized the "metallurgical laboratory" at the University of Chicago for work on the atomic bomb, he invited Allison to return to Chicago from Washington, where he was already engaged in rocket research. Allison organized a group and began work on the use of beryllium in nuclear energy. An important peacetime application of this effort was the use of beryllium as a reflector in the materials testing reactor (M. T. R. ) built at the National Reactor Testing Station in Idaho.

Allison was an important member of Enrico Fermi's group that built the historic natural uranium-graphite chain-reacting "pile" that went critical on December 2, 1942. He was responsible for the last-ditch safety measures for this test, which fortunately were not needed.

Compton appointed Allison director of the chemical division, and later overall coordinator of all scientific work, at the "Met Lab" when Compton himself became deeply involved with the Oak Ridge reactor and the reactors for producing plutonium at Hanford, Washington.

Later in 1943-1944, Allison was director of the "Met Lab" until he transferred to Los Alamos, New Mexico, in November 1944. During his final period at Chicago, Allison spent much time conferring with the Du Pont Company engineers and the Du Pont management on the engineering aspects of the design and construction of the Hanford reactors. At Los Alamos, Allison was chairman of the Technical and Scheduling Committee that brought work on the atomic bomb to a successful conclusion. He took part in the test of the first atomic bomb at Alamogordo, New Mexico, on July 16, 1945, and "called the countdown" across the desert for the first nuclear explosion.

After the war Allison returned to the University of Chicago, where he served as director of the Enrico Fermi Institute for Nuclear Studies from 1945 to 1958, and from 1963 until his death. This laboratory, with its distinguished staff, had a major influence under Fermi and Allison in reestablishing nuclear research in American universities after the war. At the time of his death in Oxford, England, he was official observer of the Atomic Energy Commission at the International Conference on Thermonuclear Programs.

Achievements

• Allison is most notable for his role in the Manhattan Project. During his career he researched linear accelerators, the Compton effect, and the dynamical theory of x-ray diffraction. After the war he was involved in the "scientists' movement", lobbying for civilian control of nuclear weapons. Allison was also awarded in 1946 the Medal for Merit with a special citation from President Harry Truman for the participation in the Manhattan Project.

Works

• book

  • Constructive uses of atomic energy,

Views

Allison was a strong advocate of civilian control of nuclear energy and its development for peaceful purposes.

Membership

Allison was a member of the National Academy of Sciences.

Connections

Allison married Helen Catherine Campbell on May 28, 1928. They had two children.

Father:

Samuel Buell Allison

Mother:

Caroline (King) Allison

Spouse:

Helen Catherine (Campbell) Allison