J-PARC (link opens in a new window) (Japan Proton Accelerator Research Complex) accelerates protons to 50GeV. These then collide with a target producing pions, which decay to muons, which subsequently decay to muon neutrinos. The beam, 0.75 MW, is directed slightly away from the Super-Kamiokande detector so that the flux of the neutrinos is lowered, providing a more useful neutrino energy spectrum. Off-axis the highest energy levels are low. This is useful as at the distance between Tokai and Kamioka, maximal neutrino oscillation is predicted to occur at energies lower than 1GeV.
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