Ernest Orlando Lawrence

Physicist

  • Born: August 8, 1901
  • Birthplace: Canton, South Dakota
  • Died: August 27, 1958
  • Place of death: Palo Alto, California

American physicist

The inventor of the cyclotron, Lawrence used this particle accelerator to explore the atomic nucleus and became one of America’s most influential scientific leaders during and after World War II.

Areas of achievement Physics, invention and technology

Early Life

The son of a prominent South Dakota educator, Ernest Orlando Lawrence grew up in Canton and Pierre, South Dakota, where he experimented with crystal radio sets with another future nuclear physicist, Merle Tuve. He was educated in South Dakota public schools, at St. Olaf’s College, and at the University of South Dakota, where, under the influence of Dean Lewis Akeley of the College of Electrical Engineering, he turned from an early interest in medicine to one in physics. He pursued his graduate education with W. F. G. Swann, whom he followed from the University of Minnesota to Chicago and Yale, where he received the Ph.D. in 1925.

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Lawrence showed great promise as an experimental physicist during his graduate studies and succeeded in winning a National Research Fellowship to continue his researches at Yale with Swann. His experiments with Jesse Beams on measuring very short time intervals and the characteristics of light quanta brought him renown and an assistant professorship at Yale. The University of California succeeded in wooing Lawrence away with an associate professorship in 1928. Two years later, Lawrence became the youngest full professor in the history of the university.

Lawrence was brash, enthusiastic, and ambitious and attracted many admirers, including the daughter of the dean of the medical school at Yale, Mary Kimberly Blumer, whom he married in 1931. At Berkeley, he gathered around him a coterie of graduate students interested in studying the photoelectric effect and other aspects of light quanta.

Life’s Work

In the spring of 1929, Lawrence ran across a description of a particle accelerator devised by Rolf Wideröe to accelerate electrons by repeatedly passing them through gaps between cylindrical electrodes carrying an accelerating voltage. If the electrodes were properly spaced, the electrons traveled faster in each gap. Lawrence saw that such an accelerator would have to be very long to reach energies that might be useful in investigations of the atomic nucleus. Ernest Rutherford had proposed such investigations, and a number of physicists throughout the world were seeking suitable ways of accelerating charged particles to penetrate the electrostatic force that surrounded atomic nuclei.

Lawrence saw, however, that if the charged particles could be deflected so that they passed through the same electrode gaps over and over, a device might be built to accelerate them to high voltages without having to use high voltages. An electromagnet would serve to cause protons or electrons to travel in a spiral and, if the strengths of the magnetic field and the accelerating voltage were properly related to each other, the times at which the particles would cross the gaps between the electrodes would always be the same. To this idea he gave the name “magnetic resonance accelerator.” It later came to be known as the “cyclotron.”

Lawrence set one of his graduate students, Niels Edlefsen, to building a primitive cyclotron in the spring of 1930. Although the first cyclotrons gave ambiguous indications of working, Lawrence announced his invention in September, 1930, and set another graduate student, M. Stanley Livingston, to building a better model. At the same time, he asked David Sloan, whom he had recruited from the General Electric Laboratories, to build a linear accelerator similar to Wideröe’s for the acceleration of positive ions. It was characteristic of Lawrence to tackle two or more difficult experimental projects at once, and his reputation was built on the fact that he often succeeded, despite the odds.

Livingston’s cyclotron gave unequivocal evidence of acceleration, and Lawrence aspired to build a larger one. He succeeded in locating a giant electromagnet and in obtaining financial backing. Frederick Gardner Cottrell, the founder of the Research Corporation, provided seed money and taught him how to make his way about philanthropic foundations.

To attract medical funding, Lawrence developed, in collaboration with Sloan, a high-voltage X-ray machine that could be used for cancer therapy and industrial radiography. The discovery of the neutron in 1932 provided an alternative bullet to aim at cancer tumors, and Lawrence was soon investigating neutron production with the cyclotron. Enthusiasm for these and other medical applications grew. The discovery of artificially radioactive materials such as radio-sodium paved the way to radioisotope therapy using substances that could be produced in quantity by the cyclotron. Support for the machine increased, and Lawrence built larger and larger cyclotrons throughout the 1930’s. Many other cyclotrons were built in the United States and abroad. Although many were used for medical purposes, all were used to explore nuclear physics.

The application of the cyclotron to scientific problems led to the development of new specialties: nuclear chemistry, which was developed by Jack Livingood and Glenn Theodore Seaborg in Lawrence’s “Radiation Laboratory” in the late 1930’s; nuclear medicine, which was developed by Lawrence’s brother, John Hundale Lawrence, in the Radiation Laboratory, the Crocker Laboratory, and the Donner Laboratory in the late 1930’s and 1940’s; and nuclear engineering, which William Brobeck and other engineers who built the giant cyclotrons of the late 1930’s pioneered. Among the many isotopes discovered in the Radiation Laboratory was carbon-14, which opened up the field of radioactive tracing and radiocarbon dating.

In 1939, Lawrence’s achievements were recognized with the award of the Nobel Prize in Physics for the invention of the cyclotron and the work done with it. Lawrence was able to parley the award into support for a cyclotron costing $1.5 million from the Rockefeller Foundation. This cyclotron, 184 inches in diameter and weighing forty-five hundred tons, was begun in 1940.

The advent of World War II, however, drew Lawrence and many other American physicists into war research. After the discovery of fission in 1939, Lawrence’s associates in the Radiation Laboratory discovered that in some cases, rather than fissioning, uranium atoms produced heavier elements that had not been found in nature. In 1940, Edwin Mattison McMillan discovered element 93, neptunium, and Seaborg found plutonium in 1941. When British studies indicated that a small mass of uranium-235 ought to make an effective nuclear explosive, Lawrence and his associates turned to the production of machines that would separate this isotope, a very small fraction of natural uranium, from the heavier uranium-238, which made up most of the remainder of the material. Using electromagnetic techniques to whirl atoms of the element through a magnetic field, Lawrence believed that enough of the lighter isotope might be separated to make an atom (fission) bomb. His colleague at Berkeley, J. Robert Oppenheimer, who had often advised Lawrence on theoretical aspects of nuclear physics, was enlisted to help design such a weapon and eventually went to New Mexico to create and lead the Los Alamos laboratory to this goal. Lawrence’s “calutrons” succeeded well enough to produce most of the uranium used in the atomic bomb dropped on Hiroshima, while plutonium was made in large enough quantities by Enrico Fermi’s nuclear reactors to make up the bomb tested at Trinity and the one dropped on Nagasaki.

Lawrence’s success in scaling up the electromagnetic process of isotope separation and his leadership in other phases of the wartime atomic effort solidified his position at the top of America’s scientific hierarchy after World War II. Rather than taking on extensive advisory positions as did Oppenheimer, however, Lawrence chose to enlarge his laboratory at Berkeley, which began to sprawl across the hills behind the University of California campus, and to support the development of the Atomic Energy Commission Laboratories at Los Alamos and, later, at Livermore, where Lawrence and Edward Teller founded a second nuclear weapons laboratory in the early 1950’s.

On the national scene, Lawrence exerted great influence through his associates on the Atomic Energy Commission (AEC) and its general advisory committee. In the controversy over the development of the hydrogen bomb, he parted company with Oppenheimer, who had left the University of California for Princeton, and sided with Lewis L. Strauss, the chair of the AEC who launched the hearings that deprived the theorist of his clearance in 1954. Here, again, Lawrence worked through his associates Teller, Luis W. Alvarez, and Wendell Latimer rather than testifying personally against Oppenheimer. His increasingly conservative political stance in the 1950’s made him a favored scientist in the Eisenhower administration, where he fought moves to end nuclear testing and, at the very end of his life, was appointed to negotiate with Soviet technical representatives at Geneva for a means of verifying compliance with a proposed test ban.

The Radiation Laboratory saw an efflorescence of peacetime particle accelerator development after the war, thanks to Lawrence’s ability to win federal funding for his machines. The 184-inch cyclotron was completed and, by using the technique newly invented by McMillan to modulate the frequency of the accelerating voltage, produced the first human-made mesons, previously found only in cosmic rays, in 1948. Alvarez invented a linear accelerator of protons that was developed for production of radioactive materials in the early 1950’s and which was later used in many larger accelerators. McMillan also invented a frequency-modulated electron accelerator, the synchrotron, in 1945, which became a major tool of high-energy physics.

During the 1950’s, Lawrence’s laboratory continued its leadership in nuclear and high-energy physics, building the 6.2 billion-volt Bevatron, a proton synchrotron, by 1954, a strong-focused cyclotron for nuclear chemistry by 1958, and a heavy-ion linear accelerator by the end of that decade. These machines made possible much new work in nuclear sciences, including the discoveries of many new transuranium elements, including one that was named in honor of Lawrence.

After traveling to Geneva in the summer of 1958 to negotiate with Soviet scientists, Lawrence was taken ill and rushed back to California, where he died after surgery to relieve a severe ulcerative colitis. After his death, he was honored by the regents of the University of California, who founded a science education research center as his memorial and named both the Berkeley and Livermore radiation laboratories after him.

Significance

Lawrence’s institutional legacy is matched by the influence he had on the politics of American science and on the development of nuclear science in the United States. Large particle accelerators of the types he pioneered now probe the hearts of the protons and neutrons he studied, revealing scores of subatomic particles. Although the Lawrence Berkeley Laboratory could not maintain the leadership in high-energy physics that it held until 1959, every high-energy accelerator in the world owes much to Lawrence’s inventive and organizational skills, and his own laboratories have found new avenues for service to the nation. In many ways, Lawrence was the founder of modern “big science” and, in combining American technological know-how with pioneering scientific research, he proved a distinctly American genius.

Bibliography

Childs, Herbert. An American Genius: The Life of Ernest Orlando Lawrence. New York: E. P. Dutton, 1968. This official biography of Lawrence was commissioned by the regents of the University of California and is the most detailed exposition of Lawrence’s life and career.

Davis, Nuel Pharr. Lawrence and Oppenheimer. 1968. New ed. New York: Da Capo Press, 1986. Although less detailed and less accurate than other biographies, Davis captures, in the words of Lawrence’s associates, a variety of views about the physicist.

Galison, Peter. Image and Logic: A Material Culture of Microphysics. Chicago: University of Chicago Press, 1997. A study of the material culture of the most basic matter known. Interestingly, the book also focuses on the changes taking effect in experimental physics, notably Lawrence’s move to “industrialize” physics and make it a “big science” with huge laboratories, giant apparatus (the accelerator, for example), and private, extragovernmental funding.

Herken, Gregg. Brotherhood of the Bomb: The Tangled Lives and Loyalties of Robert Oppenheimer, Ernest Lawrence, and Edward Teller. New York: Henry Holt, 2002. A detailed study of the three scientists who worked together, but also competed against each other, to develop the atomic and hydrogen bombs.

Kevles, Daniel J. The Physicists: The History of a Scientific Community in Modern America. New York: Alfred A. Knopf, 1978. This is still the best treatment of the development of the profession of physics in the United States and places Lawrence’s career and contributions in the broadest historical perspective.

Livingston, M. Stanley. Particle Accelerators: A Brief History. Cambridge, Mass.: Harvard University Press, 1979. This short account, written by the coinventor of the cyclotron, places Lawrence’s contributions to particle-accelerator design in the context of the history of accelerator technology.

Seidel, Robert. “Accelerating Science: The Postwar Transformation of the Lawrence Radiation Laboratory.” Historical Studies in the Physical Sciences 13, no. 2 (1983): 375-400. Lawrence’s success in building the first great high-energy physics laboratory in the postwar era is recounted to show how he was successful in converting wartime support for military research to funding for peacetime fundamental physics research.

1901-1940: January 2, 1931: Lawrence Develops the Cyclotron; April, 1932: Cockcroft and Walton Split the Atom; January-September, 1937: Segrè Identifies the First Artificial Element.

1941-1970: November, 1946: Physicists Develop the First Synchrocyclotron; 1949: X Rays from a Synchrotron Are First Used in Medical Diagnosis and Treatment.