KEK-Report: 2001-4

Abstract

The JHF-Kamioka neutrino project is a second generation long base line neutrino oscillation experiment that probes physics beyond the Standard Model by high precision measurements of the neutrino masses and mixing. A high intensity narrow band neutrino beam is produced by secondary pions created by a high intensity proton synchrotron at JHF (JAERI). The neutrino energy is tuned to the oscillation maximum at about 1 GeV for a baseline length of 295 km towards the world largest water Cerenkov detector, Super-Kamiokande. Its excellent energy resolution and particle identification enable the reconstruction of the initial neutrino energy, which is compared with the narrow band neutrino energy, through the quasi-elastic interaction. The physics goal of the first phase is an order of magnitude better precision in the nu(sub mu) to nu(sub tau) oscillation measurement (delta(Delta-m(sub 23)(exp 2) = 10(sub -4) eV(exp 2) and delta(sin(exp 2) 2theta(sub 23)) = 0.01), a factor of 20 more sensitive search in the nu(sub mu) to nu(sub e) appearance (sin(exp 2) 2theta(sub mu-e) approximately equal to 0.5 sin(exp 2) 2theta(sub 13) is greater than 0.003), and a confirmation of the nu(sub mu) to nu(sub tau) oscillation or discovery of sterile neutrinos by detecting the neutral current events. In the second phase, an upgrade of the accelerator from 0.75 MW to 4 MW in beam power and the construction of 1 Mt Hyper-Kamiokande detector at Kamioka site are envisaged. Another order of magnitude improvement in the nu(sub mu) to nu(sub e) oscillation sensitivity, a sensitive search of the CP violation in the lepton sector (CP phase delta down to 10 deg 20 deg), and an order of magnitude improvement in the proton decay sensitivity is also expected.