Strong Evidence for Flavor Oscillation in Atmospheric Neutrinos

As we go to press, the applause has barely subsided for a 5 June talk by Takaaki Kajita at the Neutrino ‘98 conference in Takayama in the Japanese Alps, not far from the 50‐kiloton Super Kamiokande underground water‐Cerenkov neutrino detector. Speaking for the Japanese‐American Super Kamiokande collaboration, Kajita reported by far the most convincing evidence to date of oscillation between different neutrino flavors. The evidence comes from the high‐statistics observation of neutrinos created by cosmic‐ray showers in the atmosphere. It appears that muon neutrinos on their way to the detector are exhibiting oscillatory metamorphosis into something other than electron neutrinos. Neutrino oscillation cannot happen if all flavors are massless. Details in the next issue.