Owen Chamberlain won the 1959 Nobel Prize in physics for confirming the existence of the antiproton. He shared this honor with his colleague of many years, Emilio Segrè. The antiproton was hypothesized as being a mirror image of the proton, a particle found in the nucleus of atoms. Proving the existence of the antiproton confirmed that idea of atomic symmetry; it was also an important breakthrough for particle physicists in their study of antimatter. Chamberlain and Segrè's work in high-energy physics at the University of California, Berkeley, was made possible by the development of the bevatron particle accelerator. This powerful accelerator, which was built at Berkeley, was able to fire protons of 6.2 billion electron volts, a nuclear force far stronger than the energy generated by the hydrogen bomb or by stars. Prior to his work at Berkeley, Chamberlain had done atomic research for the Manhattan Project (the U.S. secret program to build the atomic bomb), in addition to carrying out early studies on alpha particle decay, neutron diffraction, and high-energy nuclear reactions. After proving the existence of the antiproton, he went on to discover the antineutron.
Chamberlain was born in San Francisco, California, on July 10, 1920, to Edward and Genevieve Owen Chamberlain. His father was a radiologist at Stanford University Hospital. The Chamberlains moved to Philadelphia when their son was 10 years old, and he entered the Germantown Friends School there. He received his undergraduate degree at Dartmouth College in 1941 and had begun graduate work at the University of California at Berkeley when the United States entered World War II. His education plans changed by the war, Chamberlain left school to join the Manhattan Project, researching uranium isotopes with Ernest O. Lawrence, inventor of the cyclotron, the first particle accelerator. Chamberlain was sent to Los Alamos in 1943 and took part in the testing of the first atom bomb. When the war ended, he continued his work in atomic physics at the Argonne National Laboratory in Chicago, studying with the atomic physicist Enrico Fermi. He received his Ph.D. from the University of Chicago in 1948 and returned to Berkeley that same year. Except for a brief period during the late 1950s when he was on leave for a Guggenheim fellowship in Rome and as Loeb lecturer at Harvard University, Chamberlain was to remain at Berkeley for his entire career, becoming professor emeritus in 1989.
The existence of antiparticles had been predicted in 1928 by the English physicist Paul Dirac. He theorized that mirror images of known particles, such as the electron and the proton, must exist, although he could offer no experimental proof. But in the early 1930s his theory was given a thrust forward when Carl D. Anderson discovered the positron (so called because it has a positive electrical charge), a twin of the negative electron. Anderson's discovery of this antiparticle created great excitement among particle physicists and was to spur further research, particularly in the area of high-energy particle accelerators, because the present accelerators could not deliver the energy needed for heavy particle creation.
Chamberlain's work with the cyclotron at Berkeley established the groundwork for his later attempts to produce and detect antiprotons. His investigation of the scattering of high-energy protons and neutrons succeeded in producing the first triple-scattering of polarized protons. These investigations took Chamberlain, Segrè and their research group into the next level of study, that of antiprotons. By the early 1950s, the Bevatron accelerator had been constructed at Berkeley. Its ability to propel particles to energy levels of a billion electron volts enabled the group to produce antiprotons. Finding the short-lived antiprotons amidst the collision debris generated by the atom smashing process was the next major hurdle to be overcome. Chamberlain and his group solved that problem by inventing a series of focusing and measuring devices that could isolate the antiprotons. Then a photographic process was developed to document protons and antiprotons colliding and destroying each other. The detection procedure was time-consuming. Only about one out of 30,000 particles was identified as an antiproton, and on average it took about one hour to record four antiproton sightings. In 1955, after 40 antiproton sightings had been recorded, the group felt confident enough to announce the results of their experiments.
The author of many scientific papers regarding his discoveries, Chamberlain's work was published in journals at home and abroad. His professional affiliations include the American Physical Society, the National Academy of Sciences, and the American Association for the Advancement of Science. He has also been a Fellow of the American Academy of Arts and Sciences.
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