On June 18 2001 researchers working at the
Sudbury Neutrino Observatory released their first results, announcing that they have obtained new
evidence confirming the
hypothesis that the sun
does emit
electron neutrinos as predicted by the
Standard Model, but they
transform into other varieties of neutrino as they travel.
The detector only registers an
average of 10 events per day, so it's taken since November 1999 to get statisticaly significant results.
The fact that the transformation occurs at all shows that the Standard Model is either
wrong, or at best
incomplete. These observations prove that neutrinos have
mass, and also provide an upper limit on what that mass can be. It was long speculated that neutrinos might make up a large fraction of the 'missing mass' of the
universe, but upper energy/mass boundary is too low to allow them to make up more than a tiny
fraction of the total mass of the universe.
Primary source :-
http://www.sno.phy.queensu.ca/sno/first_results/