Frederick Reines
Reines, Frederick (1918-1998) was an American physicist who discovered a fundamental particle called the neutrino. The neutrino is extremely resistant to interaction with other particles and has virtually no mass. For his work on the neutrino, Reines shared the 1995 Nobel Prize in physics.
Reines was born March 16, 1918, in Paterson, New Jersey. He received an M.S. degree in mathematical physics from Stevens Institute of Technology. In 1944, he earned a Ph.D. degree at New York University and joined the staff of Los Alamos National Laboratory, New Mexico, to work on the Manhattan Project, the Allied nuclear bomb program. He remained as a theoretical physicist on U.S. nuclear weapons for 15 years.
In 1930, Austrian physicist Wolfgang Pauli had proposed neutrinos as an explanation for a problem in beta decay (the emission of electrons or positrons by a particle). Since 1914, scientists had known that not all the energy shed by a decaying particle was emitted with the electron or positron. Pauli suggested that the remaining energy was carried away by an unknown particle. He theorized that this particle must be neutral (neither positive nor negative), extremely light in mass, and extremely elusive. It came to be called the neutrino, meaning little neutral one.
Reines and colleague Clyde Cowan discovered the neutrino through Project Poltergeist, which involved a large tank of liquid containing dissolved cadmium chloride. Enormous numbers of neutrinos passed through the tank every second. Out of this flood, a tiny number of neutrinos reacted with particles in the tank. These reactions produced other particles, some of which could be detected. The experiment detected about three neutrino reactions per hour. He later discovered neutrinos in the earth's atmosphere. They were produced by high-speed collisions between particles in the atmosphere and cosmic rays from the depths of space. In 1987, he and several others first observed neutrinos given off by a supernova, a distant exploding star.
Reines became a professor and administrator at the University of California, Irvine, from 1966 to 1988. He received the National Medal of Science in 1985.