Nobel Laureate Raymond Davis Jr. Dies At 91

Raymond Davis Jr., a chemist at Brookhaven National Laboratory who won the 2002 Nobel Prize in Physics for his contributions to the discovery of solar neutrinos, died on May 31 from complications of Alzheimer's disease. He was 91.

"When I joined the chemistry department at Brookhaven, I asked the chairman, Richard Dodson, what he wanted me to do," Davis said in his Nobel address in 2002. "To my surprise and delight, he told me to go to the library and find something interesting to work on. I found a stimulating review on neutrinos." Davis shared the prize with Masatoshi Koshiba and Riccardo Giacconi.

Davis started investigating neutrinos in various reactors in the 1950s and conducted the landmark experiments that detected the solar neutrinos in the Homestake Gold Mine in Lead, S.D., in the 1970s.

The experiments were based on the prediction that if a solar neutrino hit a chlorine nucleus, radioactive argon would evolve. Davis developed a full-scale experiment on the basis of this idea. The experiments required placing a 100,000-gal tank of perchloroethylene in the mine, which was 4,800 feet below ground to avoid interference from cosmic rays. He also developed the techniques for quantitatively extracting the few argon atoms from that tank.

But Davis consistently detected only one-third the amount of neutrinos predicted by standard theories. In the 1990s, experiments with different detectors demonstrated that neutrinos exist in three forms. Davis' detector had only picked up one form.

"Davis single-handedly began a new field of scientific research," Brookhaven chemist Richard L. Hahn says. "Today, there are many hundreds of scientists involved in neutrino research."

Born in Washington, D.C., Davis earned B.S. and M.S. degrees from the University of Maryland in 1937 and 1940, respectively. He completed a Ph.D. in physical chemistry at Yale University in 1942.

Davis spent four years in the U.S. Army and two years working at Monsanto Chemical before joining the scientific staff at Brookhaven. He retired in 1984 but transferred his project to University of Pennsylvania and continued to collaborate on experiments in the Homestake mine into the 1990s.

Davis also enjoyed sailing and music. He is survived by his wife, Anna; three sons; two daughters; and 11 grandchildren.