Observation of atmospheric neutrinos

• DOI: 10.1103/revmodphys.73.85
• Publication Date: 2002-07-27T03:38:27Z
• Authors: Takaaki Kajita; Yoji Totsuka
• Keywords: Muon neutrino; Solar neutrino problem; Tau neutrino

Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei the atmosphere. Electron and muon mainly by chain charged pions to muons electrons. have been observed large underground detectors. Depending on their energy, these fully contained events, partially or upward going events. The energy range covered events is a few hundred MeV above 100 GeV. It has known for about ten years that some data suggested existence neutrino oscillations. With recent increase event data, especially Super-Kamiokande, it concluded atmospheric give evidence Two-flavor ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ oscillations, ${\mathrm{sin}}^{2}2\ensuremath{\theta}>0.88$ $\ensuremath{\Delta}{m}^{2}$ region $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}{\mathrm{eV}}^{2},$ explain all data.