WILSON, ROBERT R.

Robert Rathbun Wilson has been a central figure in accelerator design and development since the birth of the cyclotron in 1932. High-energy particle accelerators are the essential tool of physicists for the discovery and investigation of the properties of elementary particles the fundamental building blocks of matter. Wilson was the driving force in the creation of two of the four world-class high-energy physics laboratories in the United States: the Cornell Laboratory of Elementary Particle Physics (at that time called the Cornell Laboratory for Nuclear Studies) and the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, which houses the world's highest-energy accelerator (initially the five hundred billion electron volt [GeV] energy proton synchrotron and, since 1990, the trillion electron volt [TeV] Tevatron).

A brief review of his career cannot begin to describe his central role in high-energy experimental physics. His insistence on bolder, more compact, and economical design, seen clearly in the accelerators he built at Cornell, influenced the design of most

modern accelerators. His development of the first superconducting magnet accelerator at Fermilab made possible, both technically and economically, the very-high-energy accelerators that were later constructed.

Early Years

Wilson was born March 4, 1914, in Frontier, Wyoming, the son of Platt and Edith Rathbun Wilson, a pioneering ranching family. He was admitted to the University of California at Berkeley in 1932 and received the A.B. degree cum laude in 1936. During his junior year, he began research under E.O. Lawrence. His first work, in which he developed a new method of studying time lag in gaseous discharges, a work of considerable importance, was published in the Physical Review during his senior year. Wilson continued his studies under Lawrence as a graduate student. Among the four papers he published as a graduate student were the first theoretical analysis of the stability of cyclotron orbits, which he verified experimentally, and a paper on the theory of the cyclotron. During his graduate career, he made major contributions to the development of the cyclotron as an important tool in the study of the atomic nucleus. He received his Ph.D. in 1940.

The War Years

In 1940 he married Jane Inez Scheyer of San Francisco, accepted an appointment as instructor at Princeton, and very soon became involved in the scientific war effort. He collaborated with Enrico Fermi in some preliminary experiments on the production of a chain reaction. In the fall of 1941 he invented a new method of separating uranium isotopes and led a group of about fifty scientists and engineers in developing this technique.

Early in 1943 the work on the separation of uranium isotopes was limited to methods that were ready for production. The work at Princeton was terminated, and Wilson was asked to set up a cyclotron at the new Los Alamos laboratory. He and some of his Princeton staff moved the Harvard cyclotron to Los Alamos and began to study the fission process. At Los Alamos, he directed the Cyclotron Group, and in the summer of 1944 he was appointed head of the Physics Research Division that was responsible for experimental nuclear research and later for nuclear measurements made during the test of the first atomic bomb.

Wilson was greatly troubled by the bomb. After witnessing the first explosion, he wrote: "I determined that having played even a small role in bringing it about, I would go all out in helping to make it become a positive factor for humanity" (Wilson 1970b). He played a leading role in the formation of the Federation of Atomic Scientists, became its Chairman in 1946, and worked effectively for civilian control of atomic energy.

In the fall of 1946 Wilson accepted an associate professorship at Harvard where he designed a one hundred fifty million electron volt (MeV) cyclotron. His stay at Harvard was short, for in the winter of 1947 he went to Ithaca to become the director of the Laboratory of Nuclear Studies and Professor of Physics at Cornell University. He remained in that position until 1967, when he left Cornell to assume the directorship of Fermilab, in Batavia, Illinois.

The Cornell Years

During Wilson's tenure at Cornell, he and his colleagues built four successively more energetic electron synchrotrons, each with some unique capability. Wilson built accelerators because they were the best instruments for doing the physics he wanted to do. No one was more aware of the technical subtlety of accelerators, no one more ingenious in practical design, but it was the physics potential that came first, and Wilson had very clear ideas about that physics. During his twenty years at Cornell, he remained deeply embedded in the experimental program, both as mentor and experimenter. Among his many researches at Cornell, his work on the structure of the proton and neutron stand out.

Fermilab

In 1967, after completing the 10-GeV synchrotron, Wilson left Ithaca to become the director of Fermilab. Starting on a "greenfield" site with no staff, he began the job of building the most ambitious accelerator project ever undertaken. In addition to the challenge of building at a virgin site a cascade of large accelerators in six years, Wilson promised to double the energy of the accelerator over the original proposal without any increase in cost, and he did. He was able to do that primarily by redesigning the magnets and their arrangement. The new magnet was smaller with twice the magnetic field, thereby doubling the energy of the protons circulating in the same size tunnel. The achievement of higher energy and more physics capability at the same cost are hallmarks of Wilson's work. Many of Wilson's ideas, often considered risky and unrealistic when proposed, were later adopted in subsequent accelerators, a further tribute to Wilson's vision and courage.

In 1980 the accelerator's energy was doubled again, to 1,000 GeV, by the installation of superconducting magnets in the same tunnel. The Tevatron, the name given the new machine, was vintage Wilson. To guide its circulating beams, the accelerator required about one thousand very accurate and reliable superconducting magnets. Nothing of this scale and refinement had ever been undertaken before. Wilson provided the project's vision and leadership and was devotedly and personally involved in the difficult research and development (R&D) to establish the mass production technology required to bring the project to a successful and low cost conclusion. Without the superconducting technology, the capital and operating cost for multi-TeV accelerators, such as the Tevatron, would be prohibitive. Since 1980, the Tevatron has been the world's highest energy accelerator.

Though the demands of the directorship prevented Wilson's personal involvement in any particular experiment, his influence was crucial to the physics program. Two of the most important physics results at Fermilab have been the discovery of the family of heaviest quarks: the bottom quark in 1977 and the top quark in 1995. It was Wilson's decision to double the energy of the initial design and his insistence on running the accelerator at the highest energy that made the discovery of the bottom quark possible. The heavier top quark required the full energy of the Tevatron.

Fermilab was an architectural, as well as a scientific, triumph. It was designed with a grace and beauty unique among such facilities; and several of Wilson's own sculptures are installed on the grounds at Fermilab. Here the other side of Wilson is seen: the artist who believed art and science form a harmonious whole that advances both the science and culture of society. Wilson's concern is eloquently expressed in testimony before the Congressional Committee on Atomic Energy, April 1, 1947.

Senator John Pastore: Is there anything connected with the hopes of this accelerator that in any way involves the security of this country?

Robert Wilson: No sir, I don't believe so.

Pastore: Nothing at all?

Wilson: Nothing at all.

Pastore: It has no value in that respect?...

Wilson: It has only to do with the respect with which we regard one another, the dignity of men, our love of culture. It has to do with are we good painters, good sculptors, great poets? I mean all the things we venerate in our country and are patriotic about. It has nothing to do with defending our country except to make it worth defending.

Hadron Cancer Therapy

A paper of Wilson's published in the Journal of Radiology in 1946 entitled "Radiological Use of Fast Protons" has assumed great importance. In 1941, Wilson made an accurate measurement of how energetic protons lost energy as they traversed matter. He observed that protons deposit most of their energy at the end of their path. There was nothing unexpected in this measurement, but it led him to an exciting and far-reaching idea—to use protons for cancer therapy. Wilson noted that by carefully controlling the energy of a proton beam most of its energy could be deposited in a cancerous tumor inside the body, leaving other cells undamaged. This is in stark contrast to radiation treatment with electron or photon beams, which lose energy more or less uniformly in traversing matter and so attack healthy and cancerous tissues indiscriminately.

The first facility for proton therapy was at the Harvard Cyclotron that Wilson designed after the war. The last decade has seen an explosion of interest in this therapy. At present, proton cancer treatment facilities have been installed in hospitals in many different countries. Wilson was honored for his pioneering work in proton therapy at an international conference held at the European Laboratory for Particle Physics (CERN) in 1996.

Awards and Honors

Wilson was awarded honorary degrees from Notre Dame University, Harvard University, the University of Bonn in Germany, and Wesleyan University. Among many other honors he has received are the Elliot Cresson Medal from the Franklin Institute, the National Medal of Science, the Enrico Fermi Award, the Wright Prize, and the del Regato Medal. He was elected to the National Academy of Sciences, the American Academy of Arts and Sciences, and the American Philosophical Society. In 1985 he was elected president of the American Physical Society.

Wilson lived a very rich life. He was, in the words of the citation for the American Institute of Physics (AIP) Andrew Gemant Award granted him in 1995, "an outstanding experimenter, master-builder and designer, sculptor of stone, wood, metal," to which one could add architect, humanist, and, above all, physicist.

Robert Wilson died on January 16, 2000, in Ithaca, NY. He is survived by his wife Jane; sons Daniel, Jonathan, and Rand; and four grandchildren.

See also:Cornell Laboratory for Elementary Particle Physics; Fermilab

Bibliography

Wilson, R. R. "Radiological Use of Fast Protons." Radiology47 , 487–91 (1946).

Wilson, R. R. "An Anecdotal Account of Accelerators at Cornell" in Perspectives in Modern Physics (Interscience Publishers, New York, 1966, 225–46).

Wilson, R. R. "My Fight Against Team Research." Daedalus99 , 1076–1087 (1970a).

Wilson, R. R. "The Conscience of a Physicist." Bulletin of the Atomic Scientist26 , 30–34 (1970b).

Wilson, R. R. "The Batavia Accelerator." Scientific American230 (2), 72–83 (1974).

Wilson, R. R. "A Recruit for Los Alamos." Bulletin of the Atomic Scientist31 , 41–47 (1975).

Wilson, R. R. "High Energy Physics at Fermilab." Bulletin of the American Academy of Arts and Sciences29 , 18–24 (1975).

Wilson, R. R. "The Tevatron." Physics Today30 (10), 23–30 (1977).

Wilson, R. R. "Fantasies of Future Fermilab Facilities." Reviews of Modern Physics51 , 259–73 (1979).

Albert Silverman

Boyce D. McDaniel