It is important to measure neutrinos in the energy range from a few hundreds of MeV to several GeV for the study of neutrino oscillation by atmospheric neutrino observation and long baseline experiments. It is also important for proton decay search as the major background is atmospheric neutrinos in the energy region. In this intermediate energy region charged-current quasi-elastic scattering...
Hyper-Kamiokande (HK) is a next generation water Cherenkov detector under construction with operation planned to start in 2027. With eight times larger fiducial volume than the Super-Kamiokande (SK) detector, it is expected to significantly improve the neutrino oscillation precision measurements and the proton decay discovery potential. In HK, about 20,000 50 cm-diameter photomultipliers will...
The T2K experiment showed the strongest constraint on the CP violation phase in the lepton sector using neutrino oscillation and is seeking further improvement of the measurement sensitivity. To reduce systematic uncertainties, an upgrade of the near detector is ongoing. At the beginning of 2023, a new type of detector, called SuperFGD, is planned to be installed. SuperFGD is a high granular...
The T2K experiment is a long-baseline neutrino oscillation experiment and aims at measuring leptonic charge-parity (CP) violation in neutrino oscillations. So far, T2K has shown results that disfavor CP conservation with a significance of two standard deviations. One of the most significant systematic uncertainties is the uncertainty of the electron neutrino cross-section. To reduce the...
Hyper-Kamiokande is a next-generation water Cherenkov detector under construction in Japan. One of the goals of the Hyper-Kamiokande experiment is to measure the CP phase value using the neutrino beam produced at J-PARC. To improve the precision of this measurement, a new water Cherenkov detector (IWCD) is planned to be constructed as a near detector located 1 km downstream from the beam...
The Hyper-Kamiokande is a next-generation neutrino and nucleon decay experiment. The Hyper-Kamiokande detector will be built in one of the world's largest underground caverns and its excavation begins in October this year, 2022. This presentation discusses the status and prospects of the HK cavern excavation.
The T2K is an experiment to study the neutrino oscillation to determine the CP violation in the lepton sector. The prediction of the neutrino flux plays an important role on evaluating the neutrino oscillation. One fundamental aspect in the process is to reduce the flux-related uncertainties. T2K experiment is currently undergoing upgrade processes such as the Near Detector ND280 and the...
The NINJA collaboration aims to study neutrino-nucleus interactions in the energy range of hundreds of MeV to a few GeV using an emulsion-based detector. Nuclear emulsion is suitable for precise measurement of positions and angles of charged particles from neutrino interactions since it has a sub-$\mu$m spatial resolution. It is capable of detecting slow protons as low as 200$\,$MeV/$c$, which...
Super-Kamiokande is a large water Cherenkov detector located 1,000 m underground in Kamioka, Japan. Cosmic-ray muons incident on Super-Kamiokande induce hadronic showers in water, and the showers producing neutrons and pions as well as unstable radioactive isotopes via spallation. These are a major background source at the MeV scale. Observations in Super-Kamiokande have been performed using...
BGO scintillator is widely used in underground particle physics experiments. As an example, it is used with Am/Be neutron source in Super-Kamiokande(SK) to evaluate the detection efficiency of neutron. In SK, a relative 10% discrepancy between the measured and simulated efficiency of neutrons detection was reported with the Am/Be source and the scattering of neutrons in BGO is considered one...
Super-Kamiokande (SK) is the world-largest water Cherenkov detector located at Kamioka mine in Japan. In 2020, we dissolved gadolinium sulfate in the SK water and started SK-Gd phase, where neutron detection efficiency and resolution for neutron capture vertex are improved. In this study, we developed a new atmospheric neutrino reconstruction algorithm using the capture vertex information of...
We discuss the discovery potential of JUNO experiment for neutrino lines from MeV dark matter (DM) annihilation and decay in a model-independent way. We find that JUNO will be able to give severe constraints on the cross section of DM annihilating into neutrinos and on the lifetime of DM decaying into neutrinos. More concretely, with $20$ years of data-taking in the fiducial volume $17$ kton,...
In the current cosmology, neutrinos generated in the early universe of $\sim$1 second old are predicted to remain in the present universe as the cosmic neutrino background($C\nu B$).
While $C\nu B$ can potentially be powerful tool to reveal the history of the universe, it has not been detected so far because its energy, expected to be smaller than 1 eV, is far below the detection threshold of...
Hyper-Kamiokande is a next-generation neutrino experiment that is under construction in Japan. The Hyper-Kamiokande far detector will be instrumented by thousands of photomultipliers (PMT) which detect the Cherenkov light emitted by charged particles produced by neutrino interactions in the water. The neutrino flavor can be specified by identifying the type of charged particles produced in...
The T2K long-baseline neutrino oscillation experiment showed the strongest constraint on the CP violating phase, which governs the matter/antimatter symmetry breaking in neutrino oscillation. To further improve the experimental sensitivity, T2K will accumulate more statistics with a higher beam intensity and reduce systematics with an upgrade of the off-axis near detector. A novel 3D high...
