CP Violation, 1980

Just four years after Ting and Richter received their prize, the 1980 physics Nobel went to two researchers whose discovery at Brookaven's Alternating Gradient Synchrotron (AGS) was the opposite of what they had expected to find when they began their experiment in 1963.

James W. Cronin and Val L. Fitch, both then of Princeton University, proposed using Brookhaven's AGS to verify a fundamental tenet of physics, known as CP symmetry, by showing that two different particles did not decay into the same products. They picked as their example neutral K mesons, which are routinely produced in collisions between a proton beam and a stationary metal target.

The experiment set out to show that in millions of collisions, the short-lived variety of K meson always decayed into two pi mesons, while the long-lived variety never did. But to their surprise, a "suspicious-looking hump" in the data showed an unexpected result that years of subsequent experimentation and theory have been unable to explain: occasionally, the long-lived neutral K meson does decay into two pi mesons. Cronin and Fitch had found an example of CP violation.

Schematic of the experimental apparatus used by Cronin and Fitch.

The discovery's ramifications stretched far beyond the neutral K mesons; Cronin and Fitch had discovered a flaw in physics' central belief that the universe is symmetrical.

Val Fitch was actively involved with the Board of Trustees of Associated Universities, Inc., which managed Brookhaven Lab for the U.S. Department of Energy from 1947 to 1997. From 1961-1967, and 1988-1991, he was a trustee; from 1991-1993, he served as Chairman of the Board; and in 1993, he returned to the Board as a member.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

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