T2K (Tokai to Kamioka) is a long baseline neutrino experiment with the primary goal of measuring the neutrino mixing angle θ 13 . It uses a muon neutrino beam, produced at the J-PARC accelerator facility in Tokai, sent through a near detector complex on its way to the far detector, Super-Kamiokande. Appearance of electron neutrinos at the far detector due to oscillation is used to measure the value of θ 13 .

The T2K experiment is a long baseline neutrino oscillation experiment. Its main goal is to measure the last unknown lepton sector mixing angle θ13θ13 by observing νeνe appearance in a νμνμ beam. It also aims to make a precision measurement of the known oscillation parameters, View the MathML sourceΔm232 and sin22θ23sin22θ23, via νμνμ disappearance studies. Other goals of the experiment include various neutrino cross-section measurements and sterile neutrino searches. The experiment uses an intense proton beam generated by the J-PARC accelerator in Tokai, Japan, and is composed of a neutrino beamline, a near detector complex (ND280), and a far detector (Super-Kamiokande) located 295 km away from J-PARC. This paper provides a comprehensive review of the instrumentation aspect of the T2K experiment and a summary of the vital information for each subsystem

The results of the third phase of the Super-Kamiokande solar neutrino measurement are presented and compared to the first and second phase results. With improved detector calibrations, a full detector simulation, and improved analysis methods, the systematic uncertainty on the total neutrino flux is estimated to be ±2.1%, which is about two thirds of the systematic uncertainty for the first phase of Super-Kamiokande. The observed 8 B solar flux in the 5.0 to 20 MeV total electron energy region is 2.32± 0.04 (stat.) ± 0.05 (sys.) ×10 6 cm −2 sec −1 under the assumption of pure electron-flavor content, in agreement with previous measurements. A combined oscillation analysis 2 is carried out using SK-I, II, and III data, and the results are also combined with the results of other solar neutrino experiments. The best-fit oscillation parameters are obtained to be sin 2 θ12 = 0.30 by adding KamLAND result. In a three-flavor analysis combining all solar neutrino experiments, the upper limit of sin 2 θ13 is 0.060 at 95% C.L.. After combination with KamLAND results, the upper limit of sin 2 θ13 is found to be 0.059 at 95% C.L..

We present the result of an indirect search for high energy neutrinos from Weakly Interacting Massive Particle (WIMP) annihilation in the Sun using upward-going muon (upmu) events at Super-Kamiokande. Data sets from SKI-SKIII (3109.6 days) were used for the analysis. We looked for an excess of neutrino signal from the Sun as compared with the expected atmospheric neutrino background in three upmu categories: stopping, non-showering, and showering. No significant excess was observed. The 90% C.L. upper limits of upmu flux induced by WIMPs of 100 GeV c -2 were 6.4 × 10 −15 cm −2 s −1 and 4.0 × 10 −15 cm −2 s −1 for the soft and hard annihilation channels, respectively. These limits correspond to upper limits of 4.5 × 10 −39 cm −2 and 2.7 × 10 −40 cm −2 for spin-dependent WIMP-nucleon scattering cross sections in the soft and hard annihilation channels, respectively.

2A search for neutron-antineutron (n −n) oscillation was undertaken in Super-Kamiokande using the 1,489 day livetime or 2.45 × 10 34 neutron-year exposure data. This process violates both baryon and (baryon−lepton) numbers by two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the universe. No evidence for n −n oscillation was found, the lower limit of the lifetime for neutrons bound in 16 O, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be 1.9 × 10 32 years at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be 2.7 × 10 8 s using a theoretical value of the nuclear suppression factor of 0.517 × 10 23 s −1 and its uncertainty.