Results on neutrino oscillations from Super-Kamiokande Original Research Article

Super-Kamiokande (Super-K) is the worldʹs most massive (50 kTon) underground neutrino observatory. In June, 1998, Super-K had the pleasure of announcing striking results: observation of what would become the first widely-accepted evidence for neutrino mass. These results came from studies of atmospheric neutrino events, including interactions contained in the detector as well as those observed as upward-going muons from the rock beneath. This paper has been updated to reflect results on these topics as of July, 1999. In March, 1999, the K2K (KEK to Kamioka) long-baseline neutrino beam experiment began directing a high-purity muon neutrino beam onto the Super-K detector. Results from K2K are expected to refine our estimates of neutrino oscillation parameters.