T. Iwamoto
A5003010038- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Atomic and Subatomic Physics Research
- Astrophysics and Cosmic Phenomena
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- GaN-based semiconductor devices and materials
- Terahertz technology and applications
- Acoustic Wave Resonator Technologies
- Ga2O3 and related materials
- Semiconductor materials and interfaces
- Photonic and Optical Devices
- Spectroscopy and Laser Applications
- Quantum, superfluid, helium dynamics
- Semiconductor materials and devices
- Optical Coatings and Gratings
- Luminescence Properties of Advanced Materials
- Advanced Surface Polishing Techniques
- Advancements in Photolithography Techniques
- Graphene research and applications
- Nanofabrication and Lithography Techniques
- Quantum Chromodynamics and Particle Interactions
- Infrared Thermography in Medicine
- Spectroscopy and Chemometric Analyses
The University of Tokyo
2015-2024
Osaka University
1994-2024
Institute for Laser Technology
2022
Tokyo University of Agriculture and Technology
2021
University of California, Berkeley
2014
Paul Scherrer Institute
2007-2013
High Energy Accelerator Research Organization
2013
Tohoku University
1993-2005
Osaka Research Institute of Industrial Science and Technology
1998
Hiroshima University
1993
We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure the Super-Kamiokande detector. The exhibit zenith angle dependent deficit muon neutrinos which is inconsistent with expectations based on calculations flux. Experimental biases and uncertainties in prediction fluxes cross sections are unable to explain our observation. consistent, however, two-flavor...
KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected standard assumptions about propagation at 99.95% C.L. In a 162 ton.yr exposure ratio observed inverse beta-decay to number without disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for energies >3.4 MeV. context two-flavor neutrino oscillations with CPT invariance, all solutions solar problem except "large mixing angle" region are excluded.
We present results of a study neutrino oscillation based on 766 ton-year exposure KamLAND to reactor anti-neutrinos. observe 258 \nuebar\ candidate events with energies above 3.4 MeV compared 365.2 expected in the absence oscillation. Accounting for 17.8 background events, statistical significance \nuebar disappearance is 99.998%. The observed energy spectrum disagrees spectral shape at 99.6% and prefers distortion from effects. A two-neutrino analysis data gives \DeltaMSq =...
The final results of the search for lepton flavour violating decay $$\mathrm {\mu }^+ \rightarrow \mathrm {e}^+ {\gamma }$$ based on full dataset collected by MEG experiment at Paul Scherrer Institut in period 2009–2013 and totalling $$7.5\times 10^{14}$$ stopped muons target are presented. No significant excess events is observed with respect to expected background a new upper limit branching ratio this $$ \mathcal{B} (\mu ^+ \mathrm{e}^+ \gamma ) < 4.2 \times 10^{-13}$$ (90 % confidence...
A total of 614 upward throughgoing muons 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)]×10−13cm−2s−1sr−1 compared to an expected [1.97±0.44(theor)]×10−13cm−2s−1sr−1. absolute in agreement with the prediction within errors. However, zenith-angle dependence does not agree no-oscillation predictions. distortion shape consistent νμ↔ντ oscillation hypothesis sin22θ>0.4 and 1×10−3<Δm2<1×10−1eV2 at 90%...
The analysis of a combined data set, totaling 3.6 × 10(14) stopped muons on target, in the search for lepton flavor violating decay μ(+) → e(+)γ is presented. collected by MEG experiment at Paul Scherrer Institut show no excess events compared to background expectations and yield new upper limit branching ratio this 5.7 10(-13) (90% confidence level). This represents four times more stringent than previous world best set MEG.
The MEG experiment, designed to search for the mu+->e+ gamma decay at a 10^-13 sensitivity level, completed data taking in 2013. In order increase reach of experiment by an magnitude level 6 x 10-14 branching ratio, total upgrade, involving substantial changes has been undertaken, known as II. We present both motivation upgrade and detailed overview design expected detector performance.
We present a new result based on an analysis of the data collected by MEG detector at Paul Scherrer Institut in 2009 and 2010, search lepton-flavor-violating decay μ+→e+γ. The likelihood combined sample, which corresponds to total 1.8×1014 muon decays, gives 90% C.L. upper limit 2.4×10−12 branching ratio μ+→e+γ decay, constituting most stringent existence this date.Received 31 July 2011DOI:https://doi.org/10.1103/PhysRevLett.107.171801© 2011 American Physical Society
Since the demonstration of p-type gallium nitride (GaN) through doping with substitutional magnesium (Mg) atoms
Abstract The MEG II experiment, based at the Paul Scherrer Institut in Switzerland, reports result of a search for decay $$\upmu ^+ \rightarrow {\textrm{e}}^+ \upgamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>μ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>→</mml:mo> <mml:mtext>e</mml:mtext> </mml:mrow> <mml:mi>γ</mml:mi> </mml:math> from data taken first physics run 2021. No excess events over expected background is observed, yielding an...
A search for day-night variations in the solar neutrino flux resulting from oscillations has been carried out using 504 day sample of data obtained at Super-Kamiokande. The absence a significant variation set an absolute independent exclusion region two oscillation parameter space.
A measurement of the energy spectrum recoil electrons from solar neutrino scattering in Super-Kamiokande detector is presented. The results shown here were obtained 504 days data taken between 31 May 1996 and 25 March 1998. shape measured compared with expectation for ${}^{8}\mathrm{B}$ neutrinos. comparison takes into account both kinematic related effects process. spectral observation gives a ${\ensuremath{\chi}}^{2}$ 25.3 15 degrees freedom, corresponding to $4.6%$ confidence level.
The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 search for decay μ +→e+ γ by using one of most intense continuous + beams in world. This paper presents components: positron spectrometer, including a thin target, superconducting magnet, set drift chambers measuring muon vertex and momentum, timing counter time, liquid xenon detector photon energy, position time. trigger system, read-out electronics data acquisition system...
Homoepitaxial film and semi-insulating bulk β-Ga2O3 with (001) orientation were studied using terahertz time-domain spectroscopy (THz-TDS) in the frequency region from 0.2 to 3.0 THz parallel [100] [010] directions. The static permittivity of was determined be 10.0 10.4 along a-axis b-axis, respectively, refractive index values at are 3.17 3.23 for each axis. electrical resistivity epilayer extracted good accuracy by employing Drude–Lorentz model without use contacts. This noninvasive...
Abstract The MEG II experiment, located at the Paul Scherrer Institut (PSI) in Switzerland, is successor to which completed data taking 2013. started fully operational 2021, with goal of improving sensitivity $$\upmu ^+ \rightarrow {\textrm{e}}^+ \upgamma $$ <mml:math...
Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used search for nu;(e)'s in the energy range 8.3<E(nu;(e))<14.8 MeV. No candidates were found an expected background 1.1+/-0.4 events. This result can be obtain limit on nu;(e) fluxes any origin. Assuming that all flux its origin Sun and characteristic 8B solar nu(e) spectrum, we upper 3.7 x 10(2) cm(-2) s(-1) (90% C.L.) flux. We interpret this limit, 2.8 10(-4) standard model flux, framework spin-flavor precession...
The difference in photochemistry and radiation chemistry of sulfonium salt acid generator was investigated by product analysis time resolved spectroscopic methods for chemically amplified resist application. After KrF excimer laser electron beam irradiation salt, yields decomposed products including were determined. ultra fast in-cage reactions after directly observed the femtosecond flash photolysis method. Intermediates nanosecond pulse radiolysis. From both methods, contribution each...
We present results of a search for proton decays, p→¯νK+, using data from 33kt˙yr exposure the Super-Kamiokande detector. Two decay modes kaon, K+→μ+νμ and K+→π+π0, were studied. The consistent with background expected atmospheric neutrinos; therefore lower limit on partial lifetime τ/B(p→¯νK+) was found to be 6.7×1032years at 90% confidence level.Received 22 February 1999DOI:https://doi.org/10.1103/PhysRevLett.83.1529©1999 American Physical Society
The MEG experiment took data at the Paul Scherrer Institute in years 2009–2013 to test violation of lepton flavor conservation law, which originates from an accidental symmetry that Standard Model elementary particle physics has, and published most stringent limit on charged violating decay μ+→e+γ: BR(μ+→e+γ) <4.2×10−13 90% confidence level. detector has been upgraded order reach a sensitivity 6×10−14. basic principle II is achieve highest possible using full muon beam intensity (7×107...
The east-west anisotropy, caused by the deflection of primary cosmic rays in Earth's magnetic field, is observed for first time flux atmospheric neutrinos. Using a 45 kt yr exposure Super-Kamiokande detector, 552 $e$-like and 633 $\ensuremath{\mu}$-like horizontally going events are selected momentum range between 400 $3000\mathrm{MeV}/c$. azimuthal distributions agree with expectation from neutrino calculations, verifying that neutrinos GeV energy reasonably well modeled calculations...