T. Matsubara
A5004493290- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Astrophysics and Cosmic Phenomena
- Quantum Chromodynamics and Particle Interactions
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- High-Energy Particle Collisions Research
- Medical Imaging Techniques and Applications
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Gamma-ray bursts and supernovae
- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Muon and positron interactions and applications
- Nuclear Physics and Applications
- Nuclear physics research studies
- Enzyme Structure and Function
- Gyrotron and Vacuum Electronics Research
- Ionosphere and magnetosphere dynamics
- Atomic and Molecular Physics
- Advancements in Semiconductor Devices and Circuit Design
- Pulsars and Gravitational Waves Research
- Crystallography and Radiation Phenomena
- Integrated Circuits and Semiconductor Failure Analysis
High Energy Accelerator Research Organization
2018-2024
The University of Tokyo
2000-2022
Tokyo Metropolitan University
2012-2021
Laboratoire Leprince-Ringuet
2021
Japan Proton Accelerator Research Complex
2021
Centre National de la Recherche Scientifique
2021
École Polytechnique
2021
RWTH Aachen University
2017
Campbell Collaboration
2012
Tokyo Institute of Technology
2008
The Double Chooz experiment has observed 8249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years ($\mathrm{\text{reactor power}}\ifmmode\times\else\texttimes\fi{}\mathrm{\text{detector mass}}\ifmmode\times\else\texttimes\fi{}\mathrm{\text{live time}}$) exposure using a $10.3\text{ }\text{ }{\mathrm{m}}^{3}$ fiducial volume detector located at 1050 m from the reactor cores of nuclear power plant France. expectation case ${\ensuremath{\theta}}_{13}=0$ is 8937...
A new search for the diffuse supernova neutrino background (DSNB) flux has been conducted at Super-Kamiokande (SK), with a $22.5\times2970$-kton$\cdot$day exposure from its fourth operational phase IV. The analysis improves on existing reduction techniques and systematic uncertainties takes advantage of an improved neutron tagging algorithm to lower energy threshold compared previous phases SK. This allows setting world's most stringent upper limit extraterrestrial $\bar{\nu}_e$ flux,...
As a baryon number violating process with $\mathrm{\ensuremath{\Delta}}B=2$, neutron-antineutron oscillation ($n\ensuremath{\rightarrow}\overline{n}$) provides unique test of conservation. We have performed search for $n\ensuremath{\rightarrow}\overline{n}$ bound neutrons in Super-Kamiokande, the full dataset from its first four run periods, representing an exposure $0.37\text{ }\text{ }\mathrm{Mton}\text{\ensuremath{-}}\mathrm{years}$. The used multivariate analysis trained on simulated...
We report measurements of the branching fractions for B0→π+π−, K+π−, K+K−, and K0π0 B+→π+π0, K+π0, K0π+, K+¯K0, based on 10.4fb−1 data collected Υ(4S) resonance with Belle detector. find B(B0→π+π−)=(0.56+0.23+0.04−0.20−0.05)×10−5, B(B0→K+π−)=(1.93+0.34+0.15−0.32−0.06)×10−5, B(B+→K+π0)=(1.63+0.35+0.16−0.33−0.18)×10−5, B(B+→K0π+)=(1.37+0.57+0.19−0.48−0.18)×10−5, B(B0→K0π0)=(1.60+0.72+0.25−0.59−0.27)×10−5. also set upper limits B0→K+K−, B+→K+¯K0.Received 17 April...
The production of prompt $J/\ensuremath{\psi}$, $\ensuremath{\psi}(2S)$, ${\ensuremath{\chi}}_{c1}$, and ${\ensuremath{\chi}}_{c2}$ is studied using a $32.4{\mathrm{fb}}^{\ensuremath{-}1}$ data sample collected with the Belle detector at $\ensuremath{\Upsilon}(4S)$ $60\mathrm{MeV}$ below resonance. yield $J/\ensuremath{\psi}$ mesons in compatible that continuum production; we set an upper limit...
A synchrotron radiation X-ray powder diffractometer for samples of very small amount has been developed to collect high-quality diffraction patterns under extreme conditions, i.e. at low temperature and/or high pressure. new cylindrical imaging plate (CIP) is used as a detector, in addition conventional flat-type (FIP). By using the CIP system, data angle range −44 ≤ 2θ 122° are collected with dynamic about 10 6 . The alignment diffractometer, measurement and analysis automatically operated...
Due to a very low production rate of electron anti-neutrinos ($\bar{\nu}_e$) via nuclear fusion in the Sun, flux solar $\bar{\nu}_e$ is unexpected. An appearance neutrino opens new window for physics beyond standard model. In particular, spin-flavor precession process expected convert an into anti-neutrino (${\nu_e\to\bar{\nu}_e}$) when has finite magnetic moment. this work, we have searched Super-Kamiokande experiment, using neutron tagging identify their inverse beta decay signature. We...
The Double Chooz experiment measures the neutrino mixing angle θ 13 by detecting reactor $$ {\overline{\nu}}_e via inverse beta decay. positron-neutron space and time coincidence allows for a sizable background rejection, nonetheless liquid scintillator detectors would profit from positron/electron discrimination, if feasible in large detector, to suppress remaining background. Standard particle identification, based on dependent profile of photon emission scintillator, can not be used given...
We present a search for signatures of neutrino mixing electron anti-neutrinos with additional hypothetical sterile flavors using the Double Chooz experiment. The is based on data from 5 years operation Chooz, including 2 in two-detector configuration. analysis profile likelihood, i.e.\ comparing to model prediction disappearance data-to-data comparison two respective detectors. optimized three active and one neutrino. It sensitive typical mass range $5 \cdot 10^{-3} $ eV$^2 \lesssim \Delta...
We report observations of the Cabibbo suppressed decays B-->D((*))K- using a 10.4 fb(-1) data sample accumulated at Upsilon(4S) resonance with Belle detector KEKB e(+)e(-) storage ring. find that ratios to favored branching fractions are B(B--->D0K-)/B(B--->D0pi(-)) = 0.079+/-0.009+/-0.006, B(B(0)-->D+K-)/B(B(0)-->D+pi(-)) 0.068+/-0.015+/-0.007, B(B--->D(*0)K-)/B(B--->D(*0)pi(-)) 0.078+/-0.019+/-0.009, and B(B(0)-->D(*+)K-)/B(B(0)-->D(*+)pi(-)) 0.074+/-0.015+/-0.006. These first B-->D+K-,...
Using a sample of $31.3\ifmmode\times\else\texttimes\fi{}{10}^{6}B\overline{B}$ pairs collected with the Belle detector at $\ensuremath{\Upsilon}(4S)$ resonance, we make first observation charged $B$ meson decay to ${\ensuremath{\chi}}_{c0}$ and kaon. The measured branching fraction is...
We studied radiation damage of MPPC using 60 Co γ-rays, up to total accumulated dose 240 Gy.Leakage current and dark noise rate increase as a function dose.On the other hand, no significant change was observed for gain crosstalk.After Gy irradiation, we large dark-noise pulses well localized spots with leakage along outer edge bias line device.This study will provide important information practical application identification issues future developments.
One of the current most-demanded experiments in neutrino physics is to measure last mixing angle theta_13. KASKA an experiment detect new type reactor oscillation and sin^2 2theta_13 accurately using world's most powerful nuclear complex; Kashiwazaki-Kariwa power station. utilizes near far detectors identical structure at nearly optimized baselines underground depths cancel systematics reduce backgrounds. The expected sensitivity 2theta_13~0.015, which 10 times better than upper limit...
Upgrade work towards increasing the beam intensity of neutrino production beamline at J-PARC is underway. Tertiary muon monitoring essential for stable operation beamline. Accordingly, we are planning to replace present monitor detectors with electron multiplier tubes (EMTs). We investigated linearity and radiation tolerance EMTs using a 90 MeV Research Center Electron Photon Science. show higher than Si sensors which presently used as one T2K long-baseline oscillation experiment J-PARC. The...
Abstract Upgrade work towards increasing the beam intensity of neutrino beamline at Japan Proton Accelerator Research Complex (J-PARC) is underway. Monitoring tertiary muon beams essential for stable operation beamline. Accordingly, we plan to replace present monitor sensors with electron multiplier tubes (EMTs). We investigated radiation tolerance and linearity response EMTs using a 90 MeV beam. were irradiated electrons up 470 nC. show higher than Si which are presently used as one...
Long-baseline neutrino oscillation experiments rely on detailed models of interactions nuclei. These constitute an important source systematic uncertainty, partially because detectors to date have been unable detect final state neutrons. A novel three-dimensional projection scintillator tracker will be a component the upgraded off-axis near detector T2K experiment. Due good timing resolution and fine granularity, this technology is capable measuring neutron kinematics in event-by-event basis...
We report first results of a search for the non-zero neutrino mixing angle \theta_{13} from Double Chooz experiment. aims to measure based on anti-electron-neutrino disappearance as consequence oscillation. A new generation detector having 10 m^3 fiducial volume is located 1 km two 4.25 GW_{th} reactors at Power Plant in France. Physics data taking has been continuing since April 2011. ratio observed-to-predicted event rate 0.944 +/- 0.016 (stat) 0.040 (syst) was obtained 101 days running....
A search for neutrinos produced in coincidence with Gamma-Ray Bursts(GRB) was conducted the Super-Kamiokande (SK) detector. Between December 2008 and March 2017, Gamma-ray Coordinates Network recorded 2208 GRBs that occurred during normal SK operation. Several time windows around each GRB were used to coincident neutrino events. No statistically significant signal excess of estimated backgrounds detected. The $\bar\nu_e$ fluence range from 8 MeV 100 positron total energy...