Every day millions of neutrinos zip through Earth with hardly
a scratch to them or to Earth. Neutrinos are particles with
no charge that are produced in the sun, stars, and by the cosmic
rays that rain down on Earth's atmosphere. They can travel immense
distances at the speed of light without being stopped by galaxies,
stars, or planets.
come in three flavors: electron, muon, and tau.|
Super-K detects the electron and muon neutrinos that were created
at the top of the atmosphere by cosmic rays. Surprisingly, the
muon flavor of neutrinos have a greater chance of disappearing
when going through Earth than do the electron flavor. The physicists
assume that they changed into undetectable tau neutrinos. Such
a change in flavor is called neutrino oscillation. The very
successful "Standard Model" states that oscillations can occur
only if the two neutrinos have different masses. But, if one
flavor has a mass, it is very likely that all three do.
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the Super-K neutrino detector, the number of neutrinos entering
the tank of water from the top is compared with the number coming
in from the bottom. Why would the physicists use these two measurements
to see if neutrino oscillations have occurred? |
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results suggest that the mass difference, which is likely to
be close to the mass of a neutrino, is about 20 million times
smaller than that of the electron. To get a feel for how small
that is, let the electron have the mass of the USS Normandy.
What would be a typical object with the mass of the neutrino?
| (1.0K)|| Additional
news on the measuring the neutrino's mass can be found at http://hep.bu.edu/~superk/news.html.
Clicking will launch a new window. |
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