An upgrade of the long baseline neutrino experiment T2K ND280 near detector is under development with the goal to reduce systematic uncertainties in the prediction of number of events at the ...Super-Kamiokande far detector. The upgrade program includes the design and construction of a new neutrino target, a novel highly granular fully active scintillator detector with 3D WLS fiber readout. The ∼2 tonnes 192 × 192 × 56 cm3 detector will be assembled from 2 × 106 plastic scintillator cubes of 1 × 1 × 1 cm3 size. Each cube is read out by three orthogonal Kuraray Y11 WLS fibers threaded through the detector. A detector prototype made of 125 cubes was assembled and tested in a charged particle beam at CERN in October 2017. This paper presents results from studies of light yield, time resolution and optical cross-talk between the cubes.
Hyper-Kamiokande consists of two identical water-Cherenkov detectors of total 520 kt, with the first one in Japan at 295 km from the J-PARC neutrino beam with 2.5 degrees off-axis angles (OAAs), and ...the second one possibly in Korea at a later stage. Having the second detector in Korea would benefit almost all areas of neutrino oscillation physics, mainly due to longer baselines. There are several candidate sites in Korea with baselines of 1000-1300 km and OAAs of 1 degrees-3 degrees. We conducted sensitivity studies on neutrino oscillation physics for a second detector, either in Japan (JD x 2) or Korea (JD + KD), and compared the results with a single detector in Japan. Leptonic charge-parity (CP) symmetry violation sensitivity is improved, especially when the CP is non-maximally violated. The larger matter effect at Korean candidate sites significantly enhances sensitivities to non-standard interactions of neutrinos and mass ordering determination. Current studies indicate the best sensitivity is obtained at Mt. Bisul (1088 km baseline, 1.3 degrees OAA). Thanks to a larger (1000 m) overburden than the first detector site, clear improvements to sensitivities for solar and supernova relic neutrino searches are expected.
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