The Super-Kamiokande Experiment research team, a group of 120 scientists, presented its findings today at a physics conference in Takayama. But Arthur McDonald, who is professor of physics at Queen's University in Kingston, Ontario, and heads another team conducting similar research, cautioned that it will take time to verify the results.
Neutrinos are one of nature's basic building blocks but they are very tricky to track.
They have no electrical charge and are so small that they pass right through matter. The Kamiokande group, which includes researchers from Japan, the United States, Germany and Poland, used a 50,000-ton tank filled with purified water to catch a glimpse of some of the trillions of particles that pass through the Earth every second. Collisions between neutrinos and atoms in the tank create a spark detected by equipment surrounding the tank. Though the scientists have not measured neutrino mass, they say they detected that some neutrinos oscillate, or change type, as they pass through space or matter. A widely accepted theory says anything that oscillates must have mass.