An international collaboration of scientists at the Department of Energy’s Fermi National Accelerator Laboratory will announce on July 21, 2000, the first direct evidence for the subatomic particle called the tau neutrino, the third kind of neutrino known to particle physicists.

Deep in a former iron mine in what is now a Minnesota state park, scientists and government officials today (July 20) wielded pickaxes to chip away, at least symbolically, at the mysteries surrounding the subatomic particles known as neutrinos.