S. Yoshida
A5064591529- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
- Nuclear physics research studies
- Particle Detector Development and Performance
- Quantum Chromodynamics and Particle Interactions
- Cosmology and Gravitation Theories
- Nuclear reactor physics and engineering
- Gamma-ray bursts and supernovae
- Quantum, superfluid, helium dynamics
- Advanced Semiconductor Detectors and Materials
- Particle accelerators and beam dynamics
- Radioactive Decay and Measurement Techniques
- Radiation Therapy and Dosimetry
- Radioactivity and Radon Measurements
- CCD and CMOS Imaging Sensors
- Medical Imaging Techniques and Applications
- Laser Design and Applications
- Scientific Research and Discoveries
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
Tohoku University
2006-2024
Kavli Institute for the Physics and Mathematics of the Universe
2024
The University of Tokyo
2022-2024
Institute for Cosmic Ray Research
2022-2024
Osaka University
2014-2023
Friedrich-Alexander-Universität Erlangen-Nürnberg
2020
University of North Carolina at Chapel Hill
2016
Hiroshima University
2011
Tokushima University
2011
University of Fukui
2011
We present an improved search for neutrinoless double-beta (0νββ) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification xenon-loaded liquid scintillator, we achieved a significant reduction ^{110m}Ag contaminant identified previous searches. Combining results from first and second phase, obtain lower limit 0νββ half-life T_{1/2}^{0ν}>1.07×10^{26} yr at 90% C.L., almost sixfold improvement over limits. Using commonly adopted nuclear matrix element calculations, corresponding...
We present results from the first phase of KamLAND-Zen double-beta decay experiment, corresponding to an exposure 89.5 kg yr $^{136}\mathrm{Xe}$. obtain a lower limit for neutrinoless half-life ${T}_{1/2}^{0\ensuremath{\nu}}>1.9\ifmmode\times\else\texttimes\fi{}{10}^{25}\text{ }\text{ }\mathrm{yr}$ at 90% C.L. The combined and EXO-200 give ${T}_{1/2}^{0\ensuremath{\nu}}>3.4\ifmmode\times\else\texttimes\fi{}{10}^{25}\text{ C.L., which corresponds Majorana neutrino mass...
The recent long-term shutdown of Japanese nuclear reactors has resulted in a significantly reduced reactor ν¯e flux at KamLAND. This running condition provides unique opportunity to confirm and constrain backgrounds for the oscillation analysis. data set also improved sensitivity other signals, particular ν¯e’s produced β-decays from U238 Th232 within Earth’s interior, whose energy spectrum overlaps with that ν¯e’s. Including constraints on θ13 accelerator short-baseline neutrino...
The KamLAND-Zen experiment has provided stringent constraints on the neutrinoless double-beta (0νββ) decay half-life in ^{136}Xe using a xenon-loaded liquid scintillator. We report an improved search upgraded detector with almost double amount of xenon and ultralow radioactivity container, corresponding to exposure 970 kg yr ^{136}Xe. These new data provide valuable insight into backgrounds, especially from cosmic muon spallation xenon, have required use novel background rejection...
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...
From a sample of 1172 +/- 61 D(+)-->pi(-)pi(+)pi(+) decays, we find gamma(D(+)-->pi(-)pi(+)pi(+))/gamma(D(+)-->K-pi(+)pi(+)) = 0.0311 0.0018(+0.0016)(-0.0026). Using coherent amplitude analysis to fit the Dalitz plot these strong evidence that scalar resonance mass 478(+24)(-23) 17 MeV/c(2) and width 324(+42)(-40) 21 accounts for approximately half all decays.
We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg $^{136}$Xe. The measured two-neutrino half-life $^{136}$Xe is $T_{1/2}^{2\nu} = 2.38 \pm 0.02(stat) 0.14(syst) \times 10^{21}$ yr, consistent a recent measurement by EXO-200. also obtain lower limit for neutrinoless half-life, $T_{1/2}^{0\nu} > 5.7 10^{24}$ yr at 90% confidence level (C.L.), which corresponds to almost five-fold improvement over previous limits.
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 DONuT experiment collected data in 1997 and published first results 2000 based on four observed $ν_τ$ charged-current (CC) interactions. final analysis of the is presented this paper, $3.6 \times 10^{17}$ protons target using 800 GeV Tevatron beam at Fermilab. number CC interactions 9, from a total 578 neutrino We calculated energy-independent part tau-neutrino cross section ($ν+ \bar ν$), relative to well-known $ν_e$ $ν_μ$ sections. ratio $σ(ν_τ)$/$σ(ν_{e,μ})$ was found be...
We present limits on Majoron-emitting neutrinoless double-beta decay modes based an exposure of 112.3 days with 125 kg Xe-136. In particular, a lower limit the ordinary (spectral index n = 1) half-life Xe-136 is obtained as T_{1/2}^{0\nu\chi^{0}} > 2.6 x 10^{24} yr at 90% C.L., factor five more stringent than previous limits. The corresponding upper effective Majoron-neutrino coupling, using range available nuclear matrix calculations, <g_{ee}> < (0.8 - 1.6) 10^{-5}. This excludes previously...
We present a precision analysis of the $^{136}$Xe two-neutrino $\beta\beta$ electron spectrum above 0.8 MeV, based on high-statistics data obtained with KamLAND-Zen experiment. An improved formalism for rate allows us to measure ratio leading and subleading $2\nu\beta\beta$ nuclear matrix elements (NMEs), $\xi^{2\nu}_{31} = -0.26^{+0.31}_{-0.25}$. Theoretical predictions from shell model majority quasiparticle random-phase approximation (QRPA) calculations are consistent experimental limit....
We report on a search for electron antineutrinos ($\bar{\nu}_e$) from astrophysical sources in the neutrino energy range 8.3 to 30.8 MeV with KamLAND detector. In an exposure of 6.72 kton-year liquid scintillator, we observe 18 candidate events via inverse beta decay reaction. Although there is large background uncertainty neutral current atmospheric interactions, find no significant excess over model predictions. Assuming several supernova relic spectra, give upper flux limits 60--110...
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...
The PICO-LON project aims at search for cold dark matter by means of highly radio-pure and large volume NaI(Tl) scintillator. NaI powder was purifed chemical processing to remove lead isotopes selecting a high purity graphite crucible. concentrations radioactive impurities $^{226}$Ra $^{228}$Th were effectively reduced 58$\pm$4 $\mu$Bq/kg 1.5$\pm$1.9 $\mu$Bq/kg, respectively. It should be remarked that the concentration $^{210}$Pb, which is crucial sensitivity matter, 24$\pm$2 $\mu$Bq/kg....
ABSTRACT In the late stages of nuclear burning for massive stars ( M > 8 ⊙ ), production neutrino–antineutrino pairs through various processes becomes dominant stellar cooling mechanism. As star evolves, energy these neutrinos increases and in days preceding supernova a significant fraction emitted electron anti-neutrinos exceeds threshold inverse beta decay on free hydrogen. This is golden channel liquid scintillator detectors because coincidence signature allows reductions background...
Abstract Highly radiopure NaI(Tl) was developed to search for particle candidates of dark matter. Optimized methods were combined reduce various radioactive impurities. $^{40}$K effectively reduced by the recrystallization method. The progenies decay chains uranium and thorium appropriate resins. concentration natural potassium in crystal 20 ppb. Concentrations alpha-ray emitters successfully resin selection. present concentrations series $^{226}$Ra $1.2\pm1.4$$\mu$Bq/kg $13\pm4$$\mu$Bq/kg,...
Abstract The decay of the primordial isotopes 238 U, 235 232 Th, and 40 K has contributed to terrestrial heat budget throughout Earth's history. Hence, individual abundance those are key parameters in reconstructing contemporary Earth models. geoneutrinos produced by radioactive decays uranium thorium have been observed with Kamioka Liquid‐Scintillator Antineutrino Detector (KamLAND). Those measurements improved more than 18‐year observation time, improvement detector background levels...
We searched for proton decay via $p\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{K}^{0}$ in $0.37\text{ }\text{ }\mathrm{Mton}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{years}$ of data collected between 1996 and 2018 from the Super-Kamiokande water Cherenkov experiment. The selection criteria were defined separately ${K}_{S}^{0}$ ${K}_{L}^{0}$ channels. No significant event excess has been observed. As a result this analysis, which extends previous search by an additional $0.2\text{...
We report a measurement of the strange axial coupling constant ${g}_{A}^{s}$ using atmospheric neutrino data at KamLAND. This is component form factor neutral-current quasielastic (NCQE) interaction. The value significantly changes ratio proton and neutron NCQE cross sections. KamLAND suitable for measuring interactions as it can detect nucleon recoils with low-energy thresholds measure multiplicity high efficiency. data, including information on associated interactions, makes possible to...
Spectroscopic studies of neutrinoless double beta decays $(0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta})$ from ${}^{100}\mathrm{Mo}$ were made by means ELEGANT V. The most stringent limits on the $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ half-lives obtained for ground state transitions ${T}_{1/2}^{0\ensuremath{\nu}}{(m}_{\ensuremath{\nu}})>5.5(10.3)\ifmmode\times\else\texttimes\fi{}{10}^{22},$...