H. Kawahara
A5038289037- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Particle Detector Development and Performance
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Neutrino Physics Research
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Medical Imaging Techniques and Applications
- Gamma-ray bursts and supernovae
- Advanced Optical Sensing Technologies
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Spectroscopy and Laser Applications
- Superconducting Materials and Applications
- Nuclear physics research studies
- Radiation Therapy and Dosimetry
- Cosmology and Gravitation Theories
- Quantum, superfluid, helium dynamics
- Laser Design and Applications
- Atmospheric Ozone and Climate
Kyushu University
2022-2024
Nagoya University
2013-2022
Hiroshima University
2019
National Defense Academy of Japan
2019
Stanford Synchrotron Radiation Lightsource
1992-2005
Stanford University
1994-2005
SLAC National Accelerator Laboratory
1992-2005
Osaka University
2005
Adelphi University
1995-2000
Aomori University
1999
A bstract The OPERA neutrino experiment is designed to perform the first observation of oscillations in direct appearance mode ν μ → τ channel, via detection -leptons created charged current interactions. detector, located underground Gran Sasso Laboratory, consists an emulsion/lead target with average mass about 1.2 kt, complemented by electronic detectors. It exposed CERN Neutrinos beam, a baseline 730 km and mean energy 17 GeV. candidate event analysis 2008-2009 sample have been reported...
We report the first direct observation of neutrino interactions at a particle collider experiment. Neutrino candidate events are identified in 13.6 TeV center-of-mass energy pp collision dataset 35.4 fb^{-1} using active electronic components FASER detector Large Hadron Collider. The candidates required to have track propagating through entire length and be consistent with muon charged-current interaction. infer 153_{-13}^{+12} significance 16 standard deviations above background-only...
The FASER experiment at the LHC is designed to search for light, weakly-interacting particles produced in proton-proton collisions ATLAS interaction point that travel far-forward direction. first results from a dark photons decaying an electron-positron pair, using dataset corresponding integrated luminosity of 27.0 fb−1 collected center-of-mass energy s=13.6 TeV 2022 Run 3, are presented. No events seen almost background-free analysis, yielding world-leading constraints on with couplings...
Abstract FASER, the ForwArd Search ExpeRiment, is an experiment dedicated to searching for light, extremely weakly-interacting particles at CERN's Large Hadron Collider (LHC). Such may be produced in very forward direction of LHC's high-energy collisions and then decay visible inside FASER detector, which placed 480 m downstream ATLAS interaction point, aligned with beam axis. also includes a sub-detector, ν , designed detect neutrinos LHC study their properties. In this paper, each...
A bstract The first FASER search for a light, long-lived particle decaying into pair of photons is reported. uses LHC proton-proton collision data at $$ \sqrt{s} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 . 6 TeV collected in 2022 and 2023, corresponding to an integrated luminosity 57 7 fb − 1 model with axion-like particles (ALPs) dominantly coupled weak gauge bosons the primary target. Signal events are...
The OPERA experiment is designed to search for ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ oscillations in appearance mode, i.e., through the direct observation of $\ensuremath{\tau}$ lepton ${\ensuremath{\nu}}_{\ensuremath{\tau}}$-charged current interactions. has taken data five years, since 2008, with CERN Neutrino Gran Sasso beam. Previously, two ${\ensuremath{\nu}}_{\ensuremath{\tau}}$ candidates a decaying into hadrons were...
Automatic nuclear emulsion readout systems have seen remarkable progress since the original idea was developed almost 40 years ago. After success of its full application to a large-scale neutrino experiment, OPERA, much faster system, hyper-track selector (HTS), has been developed. HTS, which an extremely wide-field objective lens, reached scanning speed 4700 cm|$^2$|/h, is nearly 100 times than previous system and therefore strongly promotes many new experimental projects. We will describe...
The first results of the study high-energy electron neutrino (ν_{e}) and muon (ν_{μ}) charged-current interactions in FASERν emulsion-tungsten detector FASER experiment at LHC are presented. A 128.8 kg subset volume was analyzed after exposure to 9.5 fb^{-1} sqrt[s]=13.6 TeV pp data. Four (eight) ν_{e} interaction candidate events observed with a statistical significance 5.2σ (5.7σ). This is direct observation particle collider includes highest-energy ν_{μ} ever detected from an artificial...
We present a precise measurement of the left-right cross section asymmetry (${A}_{\mathrm{LR}}$) for $Z$ boson production by ${e}^{+}{e}^{\ensuremath{-}}$ collisions. The was performed at center-of-mass energy 91.26 GeV with SLD detector SLAC Linear Collider (SLC). luminosity-weighted average polarization SLC electron beam (63.0 \ifmmode\pm\else\textpm\fi{} 1.1)%. Using sample 49 392 decays, we measure ${A}_{\mathrm{LR}}$ to be 0.1628 0.0071 (stat) 0.0028 (syst) which determines effective...
The OPERA experiment is searching for nu_mu -> nu_tau oscillations in appearance mode i.e. via the direct detection of tau leptons charged current interactions. evidence has been previously reported with three candidate events using a sub-sample data from 2008-2012 runs. We report here fourth event, decaying into hadron, found after adding 2012 run without any muon final state to sample. Given number analysed and low background, are established significance 4.2sigma.
The strong coupling αs(M2Z) has been measured using hadronic decays of Z0 bosons collected by the SLD experiment at SLAC. data were compared with QCD predictions both fixed order O(α2s) and including resummed analytic formulas based on next-to-leading logarithm approximation. In this comprehensive analysis we studied event shapes, jet rates, particle correlations, angular energy flow, checked consistency between values extracted from these different measures. Combining all results obtain...
This paper presents the first results of study high-energy electron and muon neutrino charged-current interactions in FASER$\nu$ emulsion/tungsten detector FASER experiment at LHC. A subset volume, which corresponds to a target mass 128.6~kg, was exposed neutrinos from LHC $pp$ collisions with centre-of-mass energy 13.6~TeV an integrated luminosity 9.5 fb$^{-1}$. Applying stringent selections requiring electrons reconstructed above 200~GeV, four interaction candidate events are observed...
The Forward Search Experiment (FASER) at CERN’s Large Hadron Collider (LHC) has recently directly detected the first collider neutrinos. Neutrinos play an important role in all FASER analyses, either as signal or background, and it is therefore essential to understand neutrino event rates. In this study, we update previous simulations present prescriptions for theoretical predictions of fluxes cross sections, together with their associated uncertainties. With these results, discuss potential...
We present measurements of ${\mathit{R}}_{\mathit{b}}$ using the SLD at SLC. The analyses use 2D and 3D impact parameter tags a displaced vertex tag which all exploit small size stability ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ interaction point precision CCD pixel detector to achieve high bb\ifmmode\bar\else\textasciimacron\fi{}-tagging efficiencies purities. combined measurement yields ${\mathit{R}}_{\mathit{b}}$=0.229\ifmmode\pm\else\textpm\fi{}0.011 is consistent with...
This paper reports the track multiplicity and kinematics of muons, charged pions, protons from charged-current inclusive $\bar{\nu}_{\mu}$ $\nu_{\mu}$ interactions on a water target, measured using nuclear emulsion detector in NINJA experiment. A 3-kg target was exposed to T2K antineutrino-enhanced beam with mean energy 1.3 GeV. Owing high-granularity emulsion, momenta down 200 MeV/$c$ neutrino-water were detected. We find good agreement between observed data model predictions for all...
We report a new measurement of Rb = Gamma(Z0->b-bbar) / Gamma(Z0->hadrons) using double tag technique, where the b hemisphere selection is based on reconstructed mass B hadron decay vertex. The was performed sample 130k hadronic Z0 events, collected with SLD at SLC. method utilizes 3-D vertexing abilities CCD pixel vertex detector and small stable SLC beams to obtain high b-tagging efficiency purity. Rb=0.2142+/-0.0034(stat.)+/-0.0015(syst.)+/-0.0002(R_c).
We present a new measurement of the left-right cross section asymmetry $({A}_{\mathrm{LR}})$ for $Z$ boson production by ${e}^{+}{e}^{\ensuremath{-}}$ collisions. The was performed at center-of-mass energy 91.28 GeV with SLD detector SLAC Linear Collider (SLC). luminosity-weighted average polarization SLC electron beam $(77.23\ifmmode\pm\else\textpm\fi{}0.52)%$. Using sample 93 644 decays, we measure pole value asymmetry, ${A}_{\mathrm{LR}}^{0}$, to be...
This study reports a new-type of nuclear emulsion that improves the track-finding efficiency charged particle detection. The is applied to GRAINE project, balloon-borne experiment observes cosmic γ-rays through an γ-ray telescope. new film dramatically detection for γ-rays. gel and films second (GRAINE-2015) were fully self-produced by ourselves. New handling methods novel have also been developed. Over time, stored gradually become desensitized minimum ionizing particles, but original...
We are developing the GRAINE project, which consists of a 10 MeV–100GeV cosmic |$\gamma$|-ray observation with precise (0.08|$^\circ$| at 1–2GeV) and polarization-sensitive (50% or below minimum detectable polarization for Vela pulsar above 100 MeV) large-aperture-area (|$\sim$|10m|$^2$|) emulsion telescope, by repetitive long duration balloon flights. In 2015, we performed Japan–Australia JAXA collaborative experiment Alice Springs balloon-launching station. The telescope had 3780cm|$^2$|...