UPTON, NY - Raymond Davis Jr., a retired chemist at the U.S. Department of Energy’s Brookhaven National Laboratory, has won the Nobel Prize in Physics for detecting solar neutrinos, ghostlike particles produced in the nuclear reactions that power the sun. Davis shares the prize with Masatoshi Koshiba of Japan, and Riccardo Giacconi of the U.S. In awarding the prize to Davis and Koshiba, the Royal Swedish Academy of Sciences cited both “for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos.” Giacconi was cited “for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources.” The Nobel laureates will be awarded their prizes at a ceremony in Stockholm, Sweden, on December 10. The prize consists of a diploma, a medal and 10 million Swedish kroner (roughly 1 million U.S. dollars) shared among the recipients. “Neutrinos are fascinating particles, so tiny and fast that they can pass straight through everything, even the earth itself, without even slowing down,” said Davis. “When I began my work, I was intrigued by the idea of learning something new. The interesting thing about doing new experiments is that you never know what the answer is going to be!” Davis was the first scientist to detect solar neutrinos, the signature of nuclear fusion reactions occurring in the core of the sun. Devising a method to detect solar neutrinos based on the theory that the elusive particles produce radioactive argon when they interact with a chlorine nucleus, Davis constructed his first solar neutrino detector in 1961, 2,300 feet below ground in a limestone mine in Ohio. Building on this experience, he mounted a full-scale experiment 4,800 feet underground, in the Homestake Gold Mine in South Dakota. In research that spanned from 1967-1985, Davis consistently found only one-third of the neutrinos that standard theories predicted. His results threw the field of astrophysics into an uproar, and, for nearly three decades, physicists tried to resolve the so-called “solar neutrino puzzle.” Experiments in the 1990s using different detectors around the world eventually confirmed the solar neutrino discrepancy. Davis’s lower-than-expected neutrino detection rate is now accepted by the international science community as evidence that neutrinos have the ability to change from one of the three known neutrino forms into another. This characteristic, called neutrino oscillations, implies that the neutrino has mass, a property that is not included in the current standard model of elementary particles (in contrast, particles of light, called photons, have zero mass). Davis’s detector was sensitive to only one form of the neutrino, so he observed less than the expected number of solar neutrinos. Raymond Davis Jr. earned a B.S. and an M.S. from the University of Maryland in 1937 and 1940, respectively, and a Ph.D. in physical chemistry from Yale University in 1942. After his 1942-1946 service in the U.S. Army Air Force and two years at Monsanto Chemical Company, he joined Brookhaven Lab’s Chemistry Department in 1948. He received tenure in 1956 and was named senior chemist in 1964. Davis retired from Brookhaven in 1984, but has an appointment in Brookhaven’s Chemistry Department as a research collaborator. In 1985, he joined the University of Pennsylvania to continue experiments at the Homestake Gold Mine with Professor Kenneth Lande. Davis has an affiliation with the university as a research professor. A member of the National Academy of Sciences and the American Academy of Arts and Sciences, Davis has won numerous scientific awards, including the 1978 Cyrus B. Comstock Prize from the National Academy of Sciences; the 1988 Tom W. Bonner Prize from the American Physical Society; the 1992 W.K.H. Panofsky Prize, also from APS; the 1999 Bruno Pontecorvo Prize from the Joint Institute for Nuclear Research in Dubna, Russia; the 2000 Wolf Prize in Physics, which he shared with Masatoshi Koshiba, University of Tokyo, Japan; and the 2002 National Medal of Science. Davis’s Nobel Prize is the fifth one in physics won by scientists connected with Brookhaven Lab. Previous prizes were awarded for discoveries at Brookhaven’s Alternating Gradient Synchrotron (AGS), a particle accelerator. Experiments at the AGS resulted in the discovery of the muon-neutrino, for which the Nobel Prize was awarded to Leon Lederman, Melvin Schwartz and Jack Steinberger in 1988; the discovery of CP violation by James Cronin and Val Fitch, who shared the 1980 prize; and the co-discovery of the J/psi particle by Samuel C.C. Ting at Brookhaven Lab and Burton Richter at the Stanford Linear Accelerator at Stanford University, both of whom shared the prize in 1976. T.D. Lee and C.N. Yang shared the 1957 Nobel Prize in Physics for a theoretical breakthrough on parity violation, work that was done at Brookhaven. Brookhaven Lab’s solar neutrino research at the Homestake Gold Mine was funded, in succession, by the chemistry office of the Atomic Energy Commission, the Energy Research and Development Administration, and then by the Department of Energy’s Division of Nuclear Physics. Brookhaven scientists have continued to make important contributions in the field of neutrino physics, first with the GALLEX experiment in Italy and, more recently, with the experiment run by the Sudbury Neutrino Observatory (SNO) in Canada. Brookhaven’s participation in GALLEX and SNO has been supported by DOE’s Office of High-Energy and Nuclear Physics under the Office of Science.