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M. Sakuda

Publications and source records attributed to M. Sakuda.

32 records · Page 2Linked to original sources
arXiv2011

Letter of Intent: The Hyper-Kamiokande Experiment --- Detector Design and Physics Potential ---

We propose the Hyper-Kamiokande (Hyper-K) detector as a next generation underground water Cherenkov detector. It will serve as a far detector of a long baseline neutrino oscillation experiment envisioned for the upgraded J-PARC, and as a detector capable of observing -- far beyond the sensitivity of the Super-Kamiokande (Super-K) detector -- proton decays, atmospheric neutrinos, and neutrinos from astronomical origins. The baseline design of Hyper-K is based on the highly successful Super-K, taking full advantage of a well-proven technology. (to be continued)

hep-ex↗
arXiv2011

Study of Non-Standard Neutrino Interactions with Atmospheric Neutrino Data in Super-Kamiokande I and II

In this paper we study non-standard neutrino interactions as an example of physics beyond the standard model using atmospheric neutrino data collected during the Super-Kamiokande I(1996-2001) and II(2003-2005) periods. We focus on flavor-changing-neutral-currents (FCNC), which allow neutrino flavor transitions via neutral current interactions, and effects which violate lepton non-universality (NU) and give rise to different neutral-current interaction-amplitudes for different neutrino flavors. We obtain a limit on the FCNC coupling parameter, varepsilon_{mu tau}, |varepsilon_{mu tau}|<1.1 x 10^{-2} at 90%C.L. and various constraints on other FCNC parameters as a function of the NU coupling, varepsilon_{e e}. We find no evidence of non-standard neutrino interactions in the Super-Kamiokande atmospheric data.

hep-ex↗
arXiv2011

The γ-ray production in neutral-current neutrino oxygen interaction in the energy range above 100 MeV

We calculate the cross section of the gamma-ray production from neutral-current neutrino-oxygen quasi-elastic interaction, $ν+\^{16}O \rightarrow ν+p+^{15}N*$, or $ν+^{16}O \rightarrow ν+n+^{15}O*$, in which the residual nuclei (15N* or 15O*) lead to the gamma-ray emission with gamma-ray energy >6 MeV at the branching ratio of 41%. Above 200 MeV, this cross section dominates over that of gamma-ray production from the inelastic reaction, $ν+^{16}O->ν+^{16}O*$. In the present calculation, spectral function and the spectroscopic factors of $1p_{1/2}, 1p_{3/2} and 1s_{1/2}$ states are essential. The gamma-ray production is dominated by the deexcitation of $1p_{3/2}$ state of the residual nucleus.

hep-ph↗
arXiv2010

Atmospheric neutrino oscillation analysis with sub-leading effects in Super-Kamiokande I, II, and III

We present a search for non-zero theta_{13} and deviations of sin^2 theta_{23} from 0.5 in the oscillations of atmospheric neutrino data from Super-Kamiokande -I, -II, and -III. No distortions of the neutrino flux consistent with non-zero theta_{13} are found and both neutrino mass hierarchy hypotheses are in agreement with the data. The data are best fit at Delta m^2 = 2.1 x 10^-3 eV^2, sin^2 theta_{13} = 0.0, and sin^2 theta_{23} =0.5. In the normal (inverted) hierarchy theta_{13} and Delta m^2 are constrained at the one-dimensional 90% C.L. to sin^2 theta_{13} < 0.04 (0.09) and 1.9 (1.7) x 10^-3 < Delta m^2 < 2.6 (2.7) x 10^-3 eV^2. The atmospheric mixing angle is within 0.407 <= sin^2 theta_{23} <= 0.583 at 90% C.L.

hep-ex↗
arXiv2005

Lepton-nucleus scattering in the impulse approximation regime

We discuss theoretical calculations of electron- and neutrino-nucleus scattering, carried out using realistic nuclear spectral functions and including the effect of final state interactions. Comparison between electron scattering data and the calculated inclusive cross sections off oxygen shows that the Fermi gas model fails to provide a satisfactory description of the measured cross sections, and inclusion of nuclear dynamics is needed. The role of Pauli blocking in charged-current neutrino induced reactions at low $Q^2$ is also analyzed.

hep-ph↗
arXiv2005

New Method of Enhancing Lepton Number Nonconservation

The lepton number nonconserving (LENNON) conversion of type $ e^- \to e^+$ in heavy atoms, when irradiated by intense laser beam, is considered to determine the Majorana nature and precise values of neutrino masses. When the photon energy is fine tuned, the LENNON process is greatly enhanced by both the resonance effect and a large occupancy of photons. The signal of this process would be a positron of definite energy, and a further nuclear $γ$-ray in a favorable case of transition to an excited nuclear level. By constructing a united target-detector system, it is possible to explore $O[1meV]$ range of the neutrino mass parameter with a good positron energy resolution.

hep-ph↗
arXiv2004

Comparison of a new Delta resonance production model with electron and neutrino data

We consider resonance production by neutrinos focusing on the dominant resonance $P_{33}$ at low energies with a detailed discussion of its form factors. The results are presented for free nucleon targets. The $Δ$ resonance is described by two form factors $C_3^V$ and $C_5^A$ and its differential cross sections are compared with experimental data. Further, we apply this approach to the electroproduction case and calculate its differential cross sections which are compared with electroproduction experimental data. Our approach to the analysis of $Δ$ resonance is particularly simple and self-contained such that it could be helpful for the physical interpretation.

hep-ph↗
arXiv2004

Search for Dark Matter WIMPs using Upward Through-going Muons in Super-Kamiokande

We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs) with 1679.6 live days of data from the Super-Kamiokande detector using neutrino-induced upward through-going muons. The search is performed by looking for an excess of high energy muon neutrinos from WIMP annihilations in the Sun, the core of the Earth, and the Galactic Center, as compared to the number expected from the atmospheric neutrino background. No statistically significant excess was seen. We calculate flux limits in various angular cones around each of the above celestial objects. We obtain conservative model-independent upper limits on WIMP-nucleon cross-section as a function of WIMP mass and compare these results with the corresponding results from direct dark matter detection experiments.

hep-ex↗
arXiv2004

Development of a multi-pixel hybrid photo-detector with high quantum efficiency and gain

A hybrid photo-detector (HPD) consisting of a photocathode and a multi-pixel avalanche diode (MP-AD) was developed a few years ago. Our previous studies showed that its inherent potential for high resolution photon counting could be further enhanced by reducing fluctuations in charge loss in the dead layer at the entrance of the MP-AD. In this paper, we report on the improvement with the newly developed HPD whose encapsulated MP-AD has a thinner dead layer than before. It is demonstrated that the new HPD has much better energy resolution, which enables clearer counting up to nine photoelectrons. Further enhancement of the photocathode sensitivity of the HPD is also discussed.

physics.ins-det↗
arXiv2001

Near Muon Range Detector for the K2K Experiment -Construction and Performance-

A muon range detector (MRD) has been constructed as a near detector for the KEK-to-Kamioka long-baseline neutrino experiment (K2K). It monitors the neutrino beam properties at the near site by measuring the energy, angle and production point of muons produced by charged-current neutrino interaction. The detector has been working stably since the start of the K2K experiment.

hep-ex↗
arXiv2001

The JHF-Kamioka neutrino project

The JHF-Kamioka neutrino project is a second generation long base line neutrino oscillation experiment that probes physics beyond the Standard Model by high precision measurements of the neutrino masses and mixing. A high intensity narrow band neutrino beam is produced by secondary pions created by a high intensity proton synchrotron at JHF (JAERI). The neutrino energy is tuned to the oscillation maximum at ~1 GeV for a baseline length of 295 km towards the world largest water Cerenkov detector, Super-Kamiokande. Its excellent energy resolution and particle identification enable the reconstruction of the initial neutrino energy, which is compared with the narrow band neutrino energy, through the quasi-elastic interaction. The physics goal of the first phase is an order of magnitude better precision in the nu_mu to nu_tau oscillation measurement (delta(Delta m_23^2)=10^-4 eV^2 and delta(sin^22theta_23)=0.01), a factor of 20 more sensitive search in the nu_mu to nu_e appearance (sin^22theta_{mu e} ~ 0.5sin^22theta_{13}>0.003), and a confirmation of the nu_mu to nu_tau oscillation or discovery of sterile neutrinos by detecting the neutral current events. In the second phase, an upgrade of the accelerator from 0.75 MW to 4 MW in beam power and the construction of 1 Mt Hyper-Kamiokande detector at Kamioka site are envisaged. Another order of magnitude improvement in the nu_mu to nu_e oscillation sensitivity, a sensitive search of the CP violation in the lepton sector (CP phase "delta" down to 10-20 degrees), and an order of magnitude improvement in the proton decay sensitivity is also expected.

hep-ex↗
arXiv2000

Bound on the tau neutrino magnetic moment from the TRISTAN experiments

We set limits on the magnetic moment and charge radius of the tau neutrino by examining an extra contribution to the electroweak process $e^+ e^- \to ν\barνγ$ using VENUS, TOPAZ and AMY results. We find that $κ(ν_τ) < 9.1\times{10}^{-6}$ (i.e. $μ(ν_τ) < 9.1\times{10}^{-6}μ_B, μ_B = e/2m_e$) and $ < 3.1\times{10}^{-31}$cm$^2$ with Poisson statistics by combining their results. Whereas, similar to this method, with the Unified Approach we find that $κ(ν_τ) < 8.0\times{10}^{-6}$ and $ < 2.7\times{10}^{-31}$cm$^2$.

hep-ph↗
arXiv1994

Transition radiation of the neutrino magnetic moment

If the neutrino has a finite mass and a magnetic moment it would produce transition radiation when crossing the interface between two media. We found that the probability of transition radiation is larger by an order of magnitude using the quantum theory than that recently reported by one of us using classical electrodynamics, and that the energy spectrum of the radiation is nearly uniform.

hep-ph↗