Kajita, Takaaki

Kajita, Takaaki

1959–, Japanese physicist, Ph.D. Univ. of Tokyo, 1986. In 1988 he joined the faculty at the Univ. of Tokyo, where he is now professor and director of the Institute for Cosmic Ray Research. Kajita shared the 2015 Nobel Prize in Physics with Arthur McDonaldMcDonald, Arthur Bruce,
1943–, Canadian astrophysicist, Ph.D. California Institute of Technology, 1969. McDonald was a researcher at the Chalk River Nuclear Laboratories in Ottawa, Canada, from 1970 to 1982, when he joined the faculty at Princeton.
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 for the discovery of neutrino flavor oscillation, which showed that neutrinos have mass. In the late 1990s, working with Super-Kamiokande detector, an underground research facility that can detect subtle changes in neutrinosneutrino
[Ital.,=little neutral (particle)], elementary particle with no electric charge and a very small mass emitted during the decay of certain other particles. The neutrino was first postulated in 1930 by Wolfgang Pauli in order to maintain the law of conservation of energy
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, Kajita and his team found evidence that the neutrino oscillated among three different types, or flavors. This finding also indicated that, contrary to the Standard Model of particle physics, neutrinos must have mass. The discovery that neutrinos have mass provided the foundation for a better understanding of the evolution of the universe, the workings of the sun, and the mechanism of supernova explosions.
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