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PIONEERING PARTICLE PHYSICIST AT UC SAN DIEGO DIES

Oreste Piccioni, a pioneer in the field of elementary particle physics and an emeritus professor of physics at the University of California, San Diego, died on April 13 at his home in nearby Rancho Santa Fe. He was 86.

Piccioni, a native of Italy who received his doctorate in 1938 at the University of Rome under the renowned physicist Enrico Fermi, was a professor of physics at UCSD from 1960 until his retirement in 1986. In 1999, he was awarded the Matteucci Medal from the Accademia Nazionale Delle Scienze of Italy for his seminal contributions to elementary particle physics. Previous recipients of the medal, which was instituted by the King of Italy in 1870, include Pierre and Marie Curie, Ernest Rutherford, Albert Einstein, Niels Bohr, Werner Karl Heisenberg and Freeman Dyson. In awarding the medal to Piccioni, the Italian academy praised him “for his scientific stature and the relevance of his discoveries.”

During World War II, while working at the University of Rome, Piccioni and his colleagues performed an experiment on the decay of mu mesons in a basement of a high school in Rome that demonstrated that mu mesons were not the mediators of the strong nuclear force. He came to the United States in 1946 and continued his research at Massachusetts Institute of Technology; Brookhaven National Laboratory in Upton, N.Y.; CERN in Geneva; and the Lawrence Berkeley Laboratory before coming to UCSD. While at Lawrence Berkeley Laboratory, Piccioni participated in experiments that led to the discovery of the antiproton and discovered the antineutron, forms of antimatter. He also predicted and discovered the transmission regeneration of the short-lived neutral K-meson from its long-lived counterpart, which is a dramatic demonstration of the superposition of quantum mechanical states. After his retirement from UCSD, he devoted himself to working on the foundations of quantum mechanics.

“In terms of physics accomplishments, he was one of the top physicists at UCSD and one of the top early elementary particle physicists in world,” said Thomas M. O’Neil, a professor of physics and former chair of the physics department at UCSD. “He was a brilliant and creative genius.”

“He founded the experimental particle physics group at UCSD,” said Norman M. Kroll, a research professor of physics at UCSD and a colleague of Piccioni. “This group is now involved in major experiments around the world.”

Piccioni is survived by his wife Marina; five children, Robert, Richard, Gabriella, Christopher and Julian; and four grandchildren.