The JHF-Kamioka Neutrino Project

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 ∼1 GeV for a baseline length of 295 km towards the world largest waterČerenkov 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 ν µ → ν τ oscillation measurement (δ(∆m 2 23 ) = 10 −4 eV 2 and δ(sin 2 2θ 23 ) = 0.01), a factor of 20 more sensitive search in the ν µ → ν e appearance (sin 2 2θ µe ≃ 0.5 sin 2 2θ 13 > 0.003), and a confirmation of the ν µ → ν τ 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 ν µ → ν e oscillation sensitivity, a sensitive search of the CP violation in the lepton sector (CP phase δ down to 10 • − 20 • ), and an order of magnitude improvement in the proton decay sensitivity is also expected.

Current Status and Future Developments of Micromegas Detectors for Physics and Applications

“…T2K is an experiment in Japan to study neutrino oscillation from artificially emitted neutrinos. The goal of this experiment is the measurement of the mixing parameters between different lepton flavors, which may lead to new insights of leptonic CP-violation [67].…”

Future projects on atmospheric neutrinos

“…In ν e appearance measurements [28], electron neutrino events can hardly be charge-classified and, in a water Cherenkov detector, only the inclusive spectrum of e-like events can be measured. The expectations for about 1 y of HyperKamiokande exposure are shown in Fig.7, assuming sin 2 2θ 13 at the CHOOZ limit and positive sign of ∆m 2 .…”

“…Errors are normalized to an exposure of 900 kty (adapted from Ref. [28]). tron density profile in the earth's mantle, where matter effects are observable, is known with sufficient precision.…”

Neutrino masses: from fantasy to facts

“…The expected m ντ values are illustrated in Fig. (3). The band shown in the figure is obtained through a scan over the parameter space requiring that the supersymmetric particles are not too light.…”

“…Since the pioneer geochemical experiments of Davis and collaborators, underground experiments have by now provided solid evidence for the solar and the atmospheric neutrino problems, two milestones in the search for physics beyond the Standard Model (SM) 1,2,3,4,5 . Of particular importance has been the recent confirmation by the Super-Kamiokande collaboration 3 of the atmospheric neutrino zenithangle-dependent deficit, which has marked a turning point in our understanding of neutrinos, providing a strong evidence for ν µ conversions. In addition to the neutrino data from underground experiments there is also some indication for neutrino oscillations from the LSND experiment 6,7 .…”