Neutrinos are similar to the more familiar electron,
with one crucial difference:neutrinos do not carry electric charge.


  • neutrinos are electrically neutral sub-atomic particles that are produced in great numbers by the nuclear reactions that take place inside stars.
  • neutrinos travel through space at the speed of light in straight lines, and only affected by the weak nuclear force and gravity.
  • neutrinos interact very weakly with matter and countless trillions of neutrinos travel straight through our Earth each day.

Raymond Davis

  • US astronomer Raymond Davis Jr  –  awarded a Nobel Prize in 2002; he was the first to detect neutrinos produced by the Sun.
  • made his discovery, he built a large steel tank deep underground and filled it with 600 tonnes of dry-cleaning fluid. (diagram)
  • three types of neutrinos  –  electron neutrino, muon neutrino, and tau neutrino; they sometimes change from one type to another.
  • a team of Japanese scientists  –  using a tank containing 45,000 tonnes of water, were the first to observe the transformation of a muon neutrino to a tau neutrino in the late 1990s.

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