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With the electron and the muon neutrinos having been discovered, it seemed that the entirety of the neutrino could be grouped neatly into one or the other: The fundamental constituents of matter could logically be grouped into families each containing two quarks and two leptons (u, d, e, nu_e, and c, s, mu, nu_mu). Ordinary […]
In 1964, Raymond Davis Jr. and John N. Bahcall proposed that an experiment with 100,000 gallons of cleaning fluid (perchloroethylene, which is mostly composed of chlorine) could provide a critical test of the idea that nuclear fusion reactions are the ultimate source of solar radiation which was eventually conducted in the year 1968. “We argued […]
Leon Lederman, Melvin Schwartz, and Jack Steinberger, at the time all of Columbia University, made their discovery at the brand-new Alternating Gradient Synchrotron (AGS). At the time, only the electron-neutrino was known, and the scientists wondered if they could find more types of these ghostlike particles that pass through everything. The AGS, then the most […]
In this experiment, for which they were awarded a Nobel Prize in Physics in 1995, Clyde L. Cowan and Frederick Reines used a nuclear reactor, expecting to produce neutrino fluxes on the order of 1012 to 1013 neutrinos per second per cm2, far higher than any attainable flux from other radioactive sources. The neutrinos would […]
1933, Enrico Fermi had developed a theory of beta decay to include the neutrino, presumed to be massless as well as chargeless. Treating the beta decay as a transition that depended upon the strength of coupling between the initial and final states, Fermi developed a relationship which is now referred to as Fermi’s Golden Rule. […]
Historically, the study of beta decay provided the first physical evidence of the neutrino. In 1911 Lise Meitner and Otto Hahn performed an experiment that showed that the energies of electrons emitted by beta decay had a continuous rather than discrete spectrum. This was in apparent contradiction to the law of conservation of energy, as […]