Watching neutrinos change flavour

摘要

Some muon neutrinos that had been fired as a beam across the width of Japan changed into electron neutrinos on the way, physicists with the T2K (Tokai to Kamioka) multinational collaboration reported on 15 June. Previous experiments had found that neutrinos — almost massless fundamental particles — of one type (or 'flavour') seem to disappear as they travel.