Neutrino Discovery (Cowan-Reines)
Pauli predicted an almost invisible particle in 1930; in 1956 Cowan and Reines caught its signal beside a nuclear reactor and proved that neutrinos exist.
Open in the interactive tree →Wolfgang Pauli proposed the neutrino in 1930 to save energy conservation in beta decay, and Fermi built his beta-decay theory on it in 1933. Clyde Cowan and Frederick Reines set up two tanks holding about 200 litres of water with 40 kg of dissolved cadmium chloride, ringed by scintillator, 11 m from the Savannah River reactor; they logged about three events an hour, checked the signal by shutting the reactor down, and published in Science on 20 July 1956 (Nobel Prize for Reines in 1995). Later large water detectors of the same kind caught neutrinos from supernova 1987A and showed that neutrinos change type in flight, so they have mass.
Prerequisites
- Antimatter1932The signal was a positron meeting an electron and annihilating.
- Nuclear Physics1938Inverse beta decay on protons is the detection reaction
- First Nuclear Reactor (CP-1)1942A fission reactor is an intense source of antineutrinos
Unlocks
- Neutrino Oscillations1998Oscillations were found with huge detectors built on the Cowan-Reines method
- IceCube & High-Energy Neutrinos2013IceCube is a giant detector for rare neutrino interactions