Author
H. Fujiyasu
Bio: H. Fujiyasu is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Neutrino & Neutrino detector. The author has an hindex of 10, co-authored 10 publications receiving 3173 citations.
Papers
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University of Tokyo1, Boston University2, Massachusetts Institute of Technology3, Brookhaven National Laboratory4, University of California, Irvine5, California State University, Dominguez Hills6, George Mason University7, Gifu University8, Kobe University9, Kyoto University10, Louisiana State University11, University of Maryland, College Park12, University of Minnesota13, Stony Brook University14, University of Utah15, Niigata University16, Osaka University17, Seoul National University18, Shizuoka University19, Tohoku University20, Tokai University21, Tokyo Institute of Technology22, University of Warsaw23, University of Washington24
TL;DR: Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented and the recoil electron energy spectrum is consistent with no spectral distortion.
Abstract: Solar neutrino measurements from 1258days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0{endash}20.0MeV. The measured solar neutrino flux is 2.32{+-}0.03(stat){sup +0.08}{sub {minus}0.07}(syst){times}10{sup 6} cm{sup {minus}2}s{sup {minus}1} , which is 45.1{+-}0.5(stat ){sup +1.6}{sub {minus}1.4}(syst) % of that predicted by the BP2000 SSM. The day vs night flux asymmetry ({Phi}{sub n}{minus}{Phi}{sub d})/ {Phi}{sub average} is 0.033{+-}0.022(stat){sup +0.013}{sub {minus}0.012}(syst) . The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a 90% C.L.upper limit of 40{times}10{sup 3} cm{sup {minus}2}s{sup {minus}1} , which is 4.3times the BP2000 SSM prediction.
878 citations
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01 Apr 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: Super-Kamiokande is the world's largest water Cherenkov detector, with net mass 50,000 tons as discussed by the authors, which collected 1678 live-days of data, observing neutrinos from the Sun, Earth's atmosphere, and the K2K long-baseline neutrino beam with high efficiency.
Abstract: Super-Kamiokande is the world's largest water Cherenkov detector, with net mass 50,000 tons. During the period April, 1996 to July, 2001, Super-Kamiokande I collected 1678 live-days of data, observing neutrinos from the Sun, Earth's atmosphere, and the K2K long-baseline neutrino beam with high efficiency. These data provided crucial information for our current understanding of neutrino oscillations, as well as setting stringent limits on nucleon decay. In this paper, we describe the detector in detail, including its site, configuration, data acquisition equipment, online and offline software, and calibration systems which were used during Super-Kamiokande I.
708 citations
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University of Tokyo1, Boston University2, University of Minnesota3, Brookhaven National Laboratory4, University of California, Irvine5, California State University, Dominguez Hills6, George Mason University7, Gifu University8, University of Hawaii at Manoa9, Kobe University10, Kyoto University11, Los Alamos National Laboratory12, Louisiana State University13, University of Maryland, College Park14, Stony Brook University15, Niigata University16, Osaka University17, Seoul National University18, Shizuoka University19, Tohoku University20, Tokai University21, Tokyo Institute of Technology22, University of Warsaw23, University of Washington24
TL;DR: Using data recorded in 1100 live days of the Super-Kamiokande detector, three complementary data samples are used to study the difference in zenith angle distribution due to neutral currents and matter effects and find no evidence favoring sterile neutrinos, and reject the hypothesis at the 99% confidence level.
Abstract: The previously published atmospheric neutrino data did not distinguish whether muon neutrinos were oscillating into tau neutrinos or sterile neutrinos, as both hypotheses fit the data. Using data recorded in 1100 live days of the Super-Kamiokande detector, we use three complementary data samples to study the difference in zenith angle distribution due to neutral currents and matter effects. We find no evidence favoring sterile neutrinos, and reject the hypothesis at the $99%$ confidence level. On the other hand, we find that oscillation between muon and tau neutrinos suffices to explain all the results in hand.
568 citations
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University of Tokyo1, Boston University2, Massachusetts Institute of Technology3, Brookhaven National Laboratory4, University of California, Irvine5, California State University, Dominguez Hills6, George Mason University7, Gifu University8, Kobe University9, Kyoto University10, Los Alamos National Laboratory11, University of Maryland, College Park12, Louisiana State University13, Korea Research Institute of Standards and Science14, University of Minnesota15, Stony Brook University16, University of Utah17, Niigata University18, Osaka University19, Seoul National University20, Shizuoka University21, Tohoku University22, Tokai University23, Tokyo Institute of Technology24, University of Warsaw25, University of Washington26
TL;DR: The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way, and two allowed regions at large mixing are found.
Abstract: We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino flux from 1258 days of neutrino-electron scattering data in Super-Kamiokande The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way Using the Super-Kamiokande flux measurement in addition, two allowed regions at large mixing are found
515 citations
01 Jan 1999
TL;DR: A total of 614 upward through-going muons of minimum energy 1.6 GeV were observed by Super-Kamiokande during 537 detector live days as discussed by the authors.
Abstract: A total of 614 upward through-going muons of minimum energy 1.6 GeV are observed by Super-Kamiokande during 537 detector live days. The measured muon flux is (1.74 ± 0.07(stat.) ± 0.02(sys.)) × 10 −13 cm −2 s −1 sr −1 compared to an expected flux of (1.97 ± 0.44(theo.)) × 10 −13 cm −2 s −1 sr −1 . The absolute measured flux is in agreement with the prediction within the errors. However, the zenith angle dependence of the observed upward through-going muon flux does not agree with no-oscillation predictions. The observed distortion in shape is consistent with the �µ ↔ �� oscillation hypothesis with sin 2 2� > 0.4 and 1 × 10 −3 < �m 2 < 1 × 10 −1 eV 2 at 90 % confidence level.
285 citations
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TL;DR: In this article, the Wilkinson Microwave Anisotropy Probe (WMAP) 5-year data were used to constrain the physics of cosmic inflation via Gaussianity, adiabaticity, the power spectrum of primordial fluctuations, gravitational waves, and spatial curvature.
Abstract: The Wilkinson Microwave Anisotropy Probe (WMAP) 5-year data provide stringent limits on deviations from the minimal, six-parameter Λ cold dark matter model. We report these limits and use them to constrain the physics of cosmic inflation via Gaussianity, adiabaticity, the power spectrum of primordial fluctuations, gravitational waves, and spatial curvature. We also constrain models of dark energy via its equation of state, parity-violating interaction, and neutrino properties, such as mass and the number of species. We detect no convincing deviations from the minimal model. The six parameters and the corresponding 68% uncertainties, derived from the WMAP data combined with the distance measurements from the Type Ia supernovae (SN) and the Baryon Acoustic Oscillations (BAO) in the distribution of galaxies, are: Ω b h 2 = 0.02267+0.00058 –0.00059, Ω c h 2 = 0.1131 ± 0.0034, ΩΛ = 0.726 ± 0.015, ns = 0.960 ± 0.013, τ = 0.084 ± 0.016, and at k = 0.002 Mpc-1. From these, we derive σ8 = 0.812 ± 0.026, H 0 = 70.5 ± 1.3 km s-1 Mpc–1, Ω b = 0.0456 ± 0.0015, Ω c = 0.228 ± 0.013, Ω m h 2 = 0.1358+0.0037 –0.0036, z reion = 10.9 ± 1.4, and t 0 = 13.72 ± 0.12 Gyr. With the WMAP data combined with BAO and SN, we find the limit on the tensor-to-scalar ratio of r 1 is disfavored even when gravitational waves are included, which constrains the models of inflation that can produce significant gravitational waves, such as chaotic or power-law inflation models, or a blue spectrum, such as hybrid inflation models. We obtain tight, simultaneous limits on the (constant) equation of state of dark energy and the spatial curvature of the universe: –0.14 < 1 + w < 0.12(95%CL) and –0.0179 < Ω k < 0.0081(95%CL). We provide a set of WMAP distance priors, to test a variety of dark energy models with spatial curvature. We test a time-dependent w with a present value constrained as –0.33 < 1 + w 0 < 0.21 (95% CL). Temperature and dark matter fluctuations are found to obey the adiabatic relation to within 8.9% and 2.1% for the axion-type and curvaton-type dark matter, respectively. The power spectra of TB and EB correlations constrain a parity-violating interaction, which rotates the polarization angle and converts E to B. The polarization angle could not be rotated more than –59 < Δα < 24 (95% CL) between the decoupling and the present epoch. We find the limit on the total mass of massive neutrinos of ∑m ν < 0.67 eV(95%CL), which is free from the uncertainty in the normalization of the large-scale structure data. The number of relativistic degrees of freedom (dof), expressed in units of the effective number of neutrino species, is constrained as N eff = 4.4 ± 1.5 (68%), consistent with the standard value of 3.04. Finally, quantitative limits on physically-motivated primordial non-Gaussianity parameters are –9 < f local NL < 111 (95% CL) and –151 < f equil NL < 253 (95% CL) for the local and equilateral models, respectively.
5,904 citations
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TL;DR: In this article, the authors give simple mass-matrices leading to tri-bimaximal mixing, and discuss its relation to the Fritzsch-Xing democratic ansatz.
1,347 citations
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TL;DR: Theoretical and phenomenological implications of R-parity violation in supersymmetric theories are discussed in the context of particle physics and cosmology in this paper, including the relation with continuous and discrete symmetries.
949 citations
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TL;DR: In this article, it was shown that the extension of the standard model by three right-handed neutrinos with masses smaller than the electroweak scale (the νMSM) can explain simultaneously dark matter and baryon asymmetry of the universe and be consistent with the experiments on neutrino oscillations.
915 citations
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21 Feb 2010-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: GENIE as mentioned in this paper is a large-scale software system, consisting of ∼ 120 000 lines of C++ code, featuring a modern object-oriented design and extensively validated physics content, which supports the full life-cycle of simulation and generator-related analysis tasks.
Abstract: GENIE [1] is a new neutrino event generator for the experimental neutrino physics community. The goal of the project is to develop a ‘canonical’ neutrino interaction physics Monte Carlo whose validity extends to all nuclear targets and neutrino flavors from MeV to PeV energy scales. Currently, emphasis is on the few-GeV energy range, the challenging boundary between the non-perturbative and perturbative regimes, which is relevant for the current and near future long-baseline precision neutrino experiments using accelerator-made beams. The design of the package addresses many challenges unique to neutrino simulations and supports the full life-cycle of simulation and generator-related analysis tasks. GENIE is a large-scale software system, consisting of ∼ 120 000 lines of C ++ code, featuring a modern object-oriented design and extensively validated physics content. The first official physics release of GENIE was made available in August 2007, and at the time of the writing of this article, the latest available version was v2.4.4.
859 citations