"SNO FLIES: THE SOLAR NEUTRINO PROBLEM RESOLVED"
More than a mile beneath the Canadian Shield is a detector
filled with 1000 tons of pure heavy water and 8000 tons of ordinary light
water. The Sudbury Neutrino Observatory, built by a Canada-US-UK collaboration,
has been taking data for three years. With heavy water, SNO is able
to show whether neutrinos emitted by the sun, created as electron
neutrinos, arrive at earth in a state with a different flavor (mu or tau).
The shortfall of the number of solar neutrinos observed in experiments
over the last 30 years compared to the predictions of solar models could
be explained if that happened. Such a transformation requires that neutrinos
have rest mass, but the "Standard Model" of physics, which does not allow
for neutrino mass, is then broken. Massive neutrinos may also play a significant
role in shaping the evolution of the universe.