SNO
The Sudbury Neutrino Observatory is a collaborative effort among physicists
from Canada, the U.K., and the U.S. Using 1,000 tons of so-called heavy water
and almost 10,000 photon detectors, they measure the flux, energy, and
direction of solar neutrinos, which originate in the sun. SNO, located 6,800
feet underground in an active Ontario nickel mine, can also detect the other
two types of neutrinos, muon neutrinos and tau neutrinos. In 2001, just two
years after the observatory opened, physicists at SNO solved the 30-year-old
mystery of the "missing solar neutrinos." They found that the answer lies not
with the sun—where many physicists had suspected that solar neutrinos
undergo changes—but with the journey they take from the core of the sun
to the Earth.
