Solar neutrinos change their tune

Neutrinos created deep inside the Sun can change from one type to another as they stream towards Earth, according to the first results from the Sudbury Neutrino Observatory in Canada. The shortfall in the number of solar neutrinos observed in the last 30 years had cast doubt on the so-called standard solar model. But the new results confirm instead that electron neutrinos can 'oscillate' into muon and tau neutrinos and vice versa. Such oscillations can only occur if neutrinos have mass. Scientists from the Sudbury Neutrino Observatory presented their findings today at the Canadian Association of Physicists Annual Conference in Victoria and at seminars in the UK and US.