A5057420078- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Photocathodes and Microchannel Plates
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Electron and X-Ray Spectroscopy Techniques
- Atomic and Subatomic Physics Research
- Dark Matter and Cosmic Phenomena
- Superconducting Materials and Applications
- Laser Design and Applications
- High-Energy Particle Collisions Research
- Advanced X-ray Imaging Techniques
- Radiation Therapy and Dosimetry
- Muon and positron interactions and applications
- Plasma Diagnostics and Applications
- Crystallography and Radiation Phenomena
- Laser-Plasma Interactions and Diagnostics
- Pulsed Power Technology Applications
- Magnetic confinement fusion research
- International Science and Diplomacy
- Atomic and Molecular Physics
- Semiconductor materials and devices
Hiroshima University
2011-2024
Higashihiroshima Medical Center
2019-2024
Hiroshima University of Economics
2017-2022
Japan Atomic Energy Agency
2009-2014
High Energy Accelerator Research Organization
2000-2010
Nagoya University
2007-2009
Kharkiv Institute of Physics and Technology
2006
National Science Center
2006
Osaka University
2002
Brookhaven National Laboratory
2000-2001
Measurements are reported of the proton and deuteron spin structure functions ${g}_{1}^{p}$ ${g}_{1}^{d}$ at beam energies 29.1, 16.2, 9.7 GeV, ${g}_{2}^{p}$ ${g}_{2}^{d}$ a energy 29.1 GeV. The integrals ${\ensuremath{\Gamma}}_{p}={\ensuremath{\int}}_{0}^{1}{g}_{1}^{p}{(x,Q}^{2})dx$ ${\ensuremath{\Gamma}}_{d}={\ensuremath{\int}}_{0}^{1}{g}_{1}^{d}{(x,Q}^{2})dx$ were evaluated fixed ${Q}^{2}=3(\mathrm{GeV}{/c)}^{2}$ using full data set to yield...
We report on a precision measurement of the neutron spin structure function ${g}_{1}^{n}$ using deep inelastic scattering polarized electrons by ${}^{3}\mathrm{He}$. For kinematic range $0.014<x<0.7$ and $1<{Q}^{2}<17(\mathrm{GeV}/c{)}^{2}$, we obtain $\ensuremath{\int}{0.014}^{0.7}{g}_{1}^{n}(x)dx\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.036\ifmmode\pm\else\textpm\fi{}0.004(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{syst})$ at an average...
We have measured the ratio $\frac{{g}_{1}^{p}}{{F}_{1}^{p}}$ over range $0.029<x<0.8$ and $1.3<{Q}^{2}<10$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ using deep-inelastic scattering of polarized electrons from ammonia. An evaluation integral $\ensuremath{\int}{0}^{1}{g}_{1}^{p}(x, {Q}^{2})\mathrm{dx}$ at fixed ${Q}^{2}=3$ yields 0.127\ifmmode\pm\else\textpm\fi{}0.004(stat)\ifmmode\pm\else\textpm\fi{}0.010(syst), in agreement with previous experiments, but well below Ellis-Jaffe sum...
We report on a high-statistics measurement of the deuteron spin structure function ${g}_{1}^{d}$ at beam energy 29 GeV in kinematic range $0.029<x<0.8$ and $1<{Q}^{2}<10$ (GeV $/c$${)}^{2}$. The integral ${\ensuremath{\gamma}}_{1}^{d}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{\int}{1}^{}{g}_{1}^{d}\mathrm{dx}$ evaluated fixed ${Q}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3$ $/c$${)}^{2}$ gives...
We have measured proton and deuteron virtual photon-nucleon asymmetries ${A}_{2}^{p}$ ${A}_{2}^{d}$ structure functions ${g}_{2}^{p}$ ${g}_{2}^{d}$ over the range $0.03<x<0.8$ $1.3<{Q}^{2}<10(\mathrm{GeV}/c{)}^{2}$ by inelastically scattering polarized electrons off ammonia targets. Results for ${A}_{2}$ are significantly smaller than positivity limit $\sqrt{R}$ both Within experimental precision ${g}_{2}$ data well described twist-2 contribution, ${g}_{2}^{\mathrm{WW}}$. Twist-3 matrix...
Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to previously reported result. One event was observed pion momentum region examined, 211<P<229 MeV/c, bringing total combined two. Including all taken, backgrounds were estimated contribute 0.15+/-0.05 events. The branching ratio is B(K+-->pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).
An event consistent with the signature expected for rare kaon decay ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ has been observed. In pion momentum region examined, $211<P<230\mathrm{MeV}/c$, backgrounds are estimated to contribute $0.08\ifmmode\pm\else\textpm\fi{}0.03$ events. If is due ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$, branching ratio...
Experiment E949 at Brookhaven National Laboratory studied the rare decay \$K^+\to\pi^+\nu\bar{\nu}$ and other processes with an exposure of $1.77\times 10^{12}$ $K^+$'s. The data were analyzed using a blind analysis technique yielding one candidate event estimated background $0.30\pm0.03$ events. Combining this result observation two events by predecessor experiment E787 gave branching ratio ${\calB}(K^+\to\pi^+\nu\bar{\nu})=(1.47^{+1.30}_{-0.89})\times 10^{-10}$, consistent Standard Model...
The ratio g1F1 has been measured over the range 0.03 < x 0.6 and 0.3 Q2 10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from protons deuterons. We find to be consistent with no Q2-dependence at fixed in region > 1 (GeV/c)2. A trend is observed for decrease lower Q2. Fits world data without a possible are agreement Bjorken sum rule, but Δq substantially less than quark-parton model expectation.
We report the results of a search for decay ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ in kinematic region with ${\ensuremath{\pi}}^{+}$ momentum $140<P<195\mathrm{MeV}/c$ using data collected by E787 experiment at BNL. No events were observed. When combined our previous this region, one candidate event an expected background $1.22\ifmmode\pm\else\textpm\fi{}0.24$ 90% C.L. upper limit...
We have measured the neutron structure function g2n and virtual photon-nucleon asymmetry A2n over kinematic range 0.014 ⩽ × 0.7 1.0 Q2 17.0 by scattering 48.3 GeV longitudinally polarized electrons from 3He. Results for are significantly smaller than √R positivity limit most of data generally consistent with twist-2 Wandzura-Wilczek prediction. Using our we obtain results twist-3 reduced matrix element d2n, integral ∫ g2n(x) dx in 1.0. Data this experiment combined existing to an average d2n dx.
A search for additional evidence the rare kaon decay K+-->pi(+)nunu; has been made with a new data set comparable in sensitivity to previous exposure that produced single event. No events were found pion momentum region examined, 211<P<229 MeV/c. Including reanalysis of original set, backgrounds estimated contribute 0.08+/-0.02 events. Based on one observed event, branching ratio is B(K+-->pi(+)nunu;) = 1.5(+3.4)(-1.2)x10(-10).
We have measured the proton and deuteron spin structure functions g_1^p g_1^d in region of nucleon resonances for W^2 < 5 GeV^2 $Q^2\simeq 0.5$ 1.2$ by inelastically scattering 9.7 GeV polarized electrons off $^{15}NH_3$ $^{15}ND_3$ targets. observe significant resonance region. used present results, together with deep-inelastic data at higher W^2, to extract $\Gamma(Q^2)\equiv\int_0^1 g_1(x,Q^2) dx$. This is first information on low-Q^2 evolution Gamma toward Gerasimov-Drell-Hearn limit Q^2 = 0.
For high luminosity in electron-positron linear colliders, it is essential to generate low vertical emittance beams. We report on the smallest achieved single-bunch-mode operation of Accelerator Test Facility, which satisfies requirement x-band collider. The emittances were measured with a laser-wire beam-profile monitor installed damping ring. bunch length and momentum spread beam also recorded under same conditions. rms at intensity 4 pm energy 1.3 GeV, corresponds normalized 1.0x1.0(-8)...
We demonstrated the generation of a 500-keV electron beam from high dc voltage photoemission gun for an energy recovery linac light source [N. Nishimori et al., Appl. Phys. Lett. 102, 234103 (2013)]. This demonstration was achieved by addressing two discharge problems that lead to vacuum breakdown in gun. One is field emission generated central stem electrode. employed segmented insulator protect ceramic surface emission. The other microdischarge at anode electrode or chamber, which...
Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of Accelerator Test Facility at KEK. We established a tuning method damping ring which achieves small vertical dispersion x-y orbit coupling. The was less than 1% horizontal emittance. At zero-intensity limit, 2.8 x 10(-8) rad m beam energy 1.3 GeV. high intensity, strong effects intrabeam scattering observed, had been expected view extremely particle...
Extremely low emittance electron beams are required for next generation accelerators. GaAs semiconductor photocathodes with negative affinity (NEA) surfaces have an intrinsic advantage generating such and the thermal as 0.1 π mm mrad is expected in ideal case. The of photoelectrons was measured two different NEA photocathodes: a bulk-GaAs photocathode GaAs-GaAsP superlattice strained photocathode. normalized root-mean-sqare emittances beam radius 1.0 were 0.20−0.29±0.02 0.15±0.02 mrad,...
A high-voltage dc photocathode electron gun was successfully conditioned up to a voltage of 550 kV and long-time holding test for 8 h demonstrated at an acceleration 500 kV. The is designed future light sources based on energy-recovery linac consists Cockcroft–Walton generator, segmented cylindrical ceramic insulator, guard-ring electrodes, support-rod electrode, vacuum chamber, pressurized insulating gas tank. insulator the electrodes were utilized prevent any damage from electrons emitted...