Frederick Reines
1918–1998, Paterson, New Jersey, USA, Orange, California, USA
American physicist who shared the 1995 Nobel Prize in Physics for the first experimental detection of the neutrino, in 1956.
Born in Paterson, New Jersey, Reines earned his PhD at New York University in 1944, then joined Los Alamos where he directed nuclear weapons test diagnostics and chaired the Greenhouse test evaluation at Bikini. Convinced neutrinos could be observed, he and Clyde Cowan proposed in 1953 to use a nuclear reactor's intense antineutrino flux; the detection at Savannah River in 1956 — via inverse beta decay — earned them a telegram to Pauli: 'We are happy to inform you that we have definitely detected neutrinos.' He later built the Irvine-Michigan-Brookhaven (IMB) proton-decay detector that serendipitously recorded neutrinos from supernova SN 1987A.
Nobel-winning work
Reines and Cowan exploited inverse beta decay, ν̄ₑ + p → n + e⁺, in a tank of water and cadmium chloride: the positron's annihilation gamma rays and the neutron's delayed capture on cadmium produced a characteristic coincidence signature. Moving to the Savannah River reactor's ~10¹³ ν̄/cm²·s flux, they recorded ~3 events/hour, publishing the detection in Science in 1956 — 26 years after Pauli's desperate postulate of the particle.
The experiment opened neutrino physics as an experimental science; Reines's later work included the first observation of neutrinos from outside the solar system (SN 1987A) at IMB, precursor of neutrino astronomy.
Workplaces: Los Alamos National Laboratory, University of California, Irvine, Case Institute of Technology
United States