SNO Flies: The Solar Neutrino Problem Resolved<br><br>

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 two years.  SNO uses heavy water in order to make an
unambiguous determination of whether neutrinos emitted by the sun,
created as electron neutrinos, arrive at earth in a state with a
different flavor (mu, tau, or possibly sterile).  The shortfall of the
number of solar neutrinos observed experimentally over the last 30 years
compared to the predictions of solar models could be explained if that
happened. Such a transformation can occur if physical neutrinos have rest
mass and not a unique flavor.  Neutrino mass is a major issue in physics
because the completely successful Standard Model does not include it, and
because massive neutrinos may play a role in shaping the evolution of the
universe.