K. Hiraide
A5039549970- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Cosmology and Gravitation Theories
- Muon and positron interactions and applications
- Gamma-ray bursts and supernovae
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Nuclear physics research studies
- Astronomy and Astrophysical Research
- Nuclear reactor physics and engineering
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- Superconducting Materials and Applications
- Radio Astronomy Observations and Technology
- Radioactivity and Radon Measurements
- Quantum Chromodynamics and Particle Interactions
- Particle Accelerators and Free-Electron Lasers
- Atmospheric Ozone and Climate
- Magnetic confinement fusion research
- Research Data Management Practices
The University of Tokyo
2016-2025
Kavli Institute for the Physics and Mathematics of the Universe
2015-2024
Institute for Cosmic Ray Research
2021-2024
Tokyo University of Science
2020-2024
Tokyo Institute of Technology
2024
University of Fukui
2020
Tohoku University
2020
Miyagi University of Education
2020
Kyoto University
2004-2012
Colorado State University
2011
We present measurements of nu_mu disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One hundred and twelve beam-originated events are observed fiducial volume Super-Kamiokande with an expectation 158.1^{+9.2}_{-8.6} without oscillation. A distortion energy spectrum is also seen 58 single-ring muon-like reconstructed energies. The probability that observations explained by for no 0.0015% (4.3sigma). In a two flavor scenario, allowed Delta m^2 region at...
We report results from searches for new physics with low-energy electronic recoil data recorded the XENON1T detector. With an exposure of 0.65 tonne-years and unprecedentedly low background rate 76±2stat events/(tonne×year×keV) between 1 30 keV, enable one most sensitive solar axions, enhanced neutrino magnetic moment using neutrinos, bosonic dark matter. An excess over known backgrounds is observed at energies prominent 2 3 keV. The axion model has a 3.4σ significance, three-dimensional 90%...
We present results for ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ oscillation in the KEK to Kamioka (K2K) long-baseline neutrino experiment. K2K uses an accelerator-produced beam with a mean energy of 1.3 GeV directed at Super-Kamiokande detector. observed energy-dependent disappearance ${\ensuremath{\nu}}_{\ensuremath{\mu}}$, which we presume have oscillated ${\ensuremath{\nu}}_{\ensuremath{\tau}}$. The probability that would observe these if there is no 0.0050% ($4.0\ensuremath{\sigma}$).
The results of the second phase Super-Kamiokande solar neutrino measurement are presented and compared to first phase. flux spectrum time variation as well oscillation statistically consistent with do not show spectral distortion. time-dependent combined phases coincides full period cycle 23 shows no correlation activity. measured $^{8}\mathrm{B}$ total is...
XENONnT is a dark matter direct detection experiment, utilizing 5.9 t of instrumented liquid xenon, located at the INFN Laboratori Nazionali del Gran Sasso. In this work, we predict experimental background and project sensitivity to weakly interacting massive particles (WIMPs). The expected average differential rate in energy region interest, corresponding (1, 13) keV (4, 50) for electronic nuclear recoils, amounts $12.3 \pm 0.6$ (keV y)$^{-1}$ $(2.2\pm 0.5)\times 10^{-3}$ y)$^{-1}$,...
The weak nucleon axial-vector form factor for quasi-elastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in beam at KEK. More than 12,000 events are analyzed, of which half charged-current nu-mu n to mu- p occurring primarily oxygen nuclei. We use a relativistic Fermi gas model and assume approximately dipole with one parameter, axial vector mass M_A, fit shape distribution square momentum transfer nucleus. Our best result M_A = 1.20...
The result of a search for neutrino bursts from supernova explosions using the Super-Kamiokande detector is reported. sensitive to core-collapse via observation their emissions. expected number events comprising such burst ~10^4 and average energy neutrinos in few tens MeV range case explosion at typical distance our galaxy (10 kiloparsecs); this large signal means that detection efficiency anywhere within well past Magellanic Clouds 100%. We examined data set which was taken May, 1996 July,...
We report on a search for nuclear recoil signals from solar $^8$B neutrinos elastically scattering off xenon nuclei in XENON1T data, lowering the energy threshold 2.6 keV to 1.6 keV. develop variety of novel techniques limit resulting increase backgrounds near threshold. No significant neutrino-like excess is found an exposure 0.6 t $\times$ y. For first time, we use non-detection constrain light yield 1-2 recoils liquid xenon, as well non-standard neutrino-quark interactions. Finally,...
A new search for the diffuse supernova neutrino background (DSNB) flux has been conducted at Super-Kamiokande (SK), with a $22.5\times2970$-kton$\cdot$day exposure from its fourth operational phase IV. The analysis improves on existing reduction techniques and systematic uncertainties takes advantage of an improved neutron tagging algorithm to lower energy threshold compared previous phases SK. This allows setting world's most stringent upper limit extraterrestrial $\bar{\nu}_e$ flux,...
We report the first search result for flux of astrophysical electron antineutrinos energies O(10) MeV in gadolinium-loaded Super-Kamiokande (SK) detector. In June 2020, gadolinium was introduced to ultra-pure water SK detector order detect neutrons more efficiently. this new experimental phase, SK-Gd, we can via inverse beta decay with efficient background rejection and higher signal efficiency thanks high neutron tagging technique. paper, initial stage SK-Gd a $22.5\times552$ $\rm kton\cdot...
We report a search for cosmic-ray boosted dark matter with protons using the 0.37 megaton×years data collected at Super-Kamiokande experiment during 1996-2018 period (SKI-IV phase). searched an excess of proton recoils above atmospheric neutrino background from vicinity Galactic Center. No such is observed, and limits are calculated two reference models either constant interaction cross section or through scalar mediator. This first experimental hadrons directional information. The results...
An analysis of solar neutrino data from the fourth phase Super-Kamiokande (SK-IV) October 2008 to May 2018 is performed and results are presented. The observation time dataset SK-IV corresponds 2970 days total live for all four phases 5805 days. For more precise measurements, several improvements applied in this analysis: lowering acquisition threshold 2015, further reduction spallation background using neutron clustering events, energy reconstruction considering variation PMT gain. observed...
We present a measurement of neutrino oscillation parameters with the Super-Kamiokande detector using atmospheric neutrinos from complete pure-water SK I–V (April 1996–July 2020) dataset, including events an expanded fiducial volume. The dataset corresponds to 6511.3 live days and exposure 484.2 kiloton-years. Measurements <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi...
The SciBooNE and MiniBooNE collaborations report the results of a ν_μdisappearance search in Δm^2 region 0.5-40 eV^2. neutrino rate as measured by tracking detectors is used to constrain at Cherenkov detector first joint analysis data from both collaborations. Two separate analyses combined samples set 90% confidence level (CL) limits on eV^2 region, with an improvement over previous experimental constraints between 10 30
The SciBooNE Collaboration reports a measurement of inclusive charged current interactions muon neutrinos on carbon with an average energy 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our two neutrino interaction simulations: NEUT and NUANCE. rates (product flux cross section) are extracted by fitting kinematics, precision 6-15% for dependent 3% integrated analyses. also extract CC sections from observed rates, 10-30% 8% This is first section around 1 GeV. These results can...
XMASS, a low-background, large liquid-xenon detector, was used to search for solar axions that would be produced by bremsstrahlung and Compton effects in the Sun. With an exposure of 5.6 ton days liquid xenon, model-independent limit on coupling mass ≪1 keV is |gaee|<5.4×10−11 (90% C.L.), which factor two stronger than existing experimental limit. The bounds axion masses DFSZ KSVZ models are 1.9 250 eV, respectively. In range 10–40 keV, this study most stringent limit, better previously...
We discuss the electron heating in course of magnetic reconnection by using both Geotail observation and particle-in-cell simulation. observes several unique non-Maxwellian velocity distribution functions during plasma sheet crossing association with a fast flow. find that observed distributions can be classified into four different types depending on position sheet. In boundary between lobe sheet, consists cold flowing toward X-type region hot escaping from along field. side boundary,...
Abstract Xenon dual-phase time projection chambers designed to search for weakly interacting massive particles have so far shown a relative energy resolution which degrades with above $$\sim $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>∼</mml:mo></mml:math> 200 keV due the saturation effects. This has limited their sensitivity in rare events like neutrinoless double-beta decay of $$^{136} \hbox {Xe}$$...
The selection of low-radioactive construction materials is the utmost importance for rare-event searches and thus critical to XENONnT experiment. Results an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, 222 Rn emanation measurements. Furthermore, cleanliness procedures applied remove or mitigate surface contamination detector described. Screening results, used as inputs a Monte Carlo simulation, predict...
The first loading of gadolinium (Gd) into Super-Kamiokande in 2020 was successful, and the neutron capture efficiency on Gd reached 50%. To further increase to 75%, 26.1 tons Gd2(SO4)3⋅8H2O additionally loaded (SK) from May 31 July 4, 2022. As amount doubled compared loading, capacity powder dissolving system doubled. We also developed new batches sulfate with even reduced radioactive impurities. In addition, a more efficient screening method devised implemented evaluate these...
We report the result from a search for charged-current coherent pion production induced by muon neutrinos with mean energy of 1.3 GeV. The data are collected fully active scintillator detector in K2K long-baseline neutrino oscillation experiment. No evidence is observed, and an upper limit set on cross section ratio to total interaction at 90% confidence level. This first experimental charged region few
The SciBooNE Collaboration has performed a search for charged current coherent pion production from muon neutrinos scattering on carbon, ${\ensuremath{\nu}}_{\ensuremath{\mu}}^{12}\mathrm{C}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}^{12}\mathrm{C}{\ensuremath{\pi}}^{+}$, with two distinct data samples. No evidence is observed. We set 90% confidence level upper limits the cross section ratio of to total at $0.67\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$ mean...