Parity Violation, 1957

In 1957, two scientists who had worked as guest scientists at Brookhaven during the summer of 1956 received the Nobel Prize in physics for radically questioning one of physics' basic tenets.

T. D. Lee, of Columbia University, and C. N. Yang, then of Brookhaven, interpreted results of particle decay experiments at Brookhaven's Cosmotron particle accelerator and discovered that the fundamental and supposedly absolute law of parity conservation had been violated.

Their studies concerned two particles, the tau and the theta, which had the same masses, lifetimes and scattering behaviors, but which decayed differently in experiments at the Cosmotron. Because of this, the law of parity conservation required that these otherwise similar particles be considered different from one another.

Lee and Yang suggested experiments that showed that the weak interaction of radioactive decay could indeed violate parity conservation. When the experiments were later successfully completed, the puzzle of the two particles was solved -- they could be the same.

T.D. Lee is now the Director of the RIKEN BNL Research Center at Brookhaven.

This doodle pad was used by T.D. Lee during talks with C.N. Yang, while both were visiting scientists at Brookhaven in the summer of 1956. These discussions led to questioning the conservation of parity in weak interactions and resulted in their being awarded the Nobel Prize in 1957.

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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