Yoshihisa Iwashita
A5089756290- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Gyrotron and Vacuum Electronics Research
- Laser-Plasma Interactions and Diagnostics
- Magnetic confinement fusion research
- Radiation Therapy and Dosimetry
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Laser-Matter Interactions and Applications
- Laser-induced spectroscopy and plasma
- Quantum, superfluid, helium dynamics
- Particle physics theoretical and experimental studies
- Muon and positron interactions and applications
- Plasma Diagnostics and Applications
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Atomic and Molecular Physics
- High-pressure geophysics and materials
- Physics of Superconductivity and Magnetism
- Electric Motor Design and Analysis
- Nuclear reactor physics and engineering
- Acoustic Wave Resonator Technologies
Kyoto University
2016-2025
High Energy Accelerator Research Organization
2016-2024
Japan Atomic Energy Agency
2022-2024
Japan Proton Accelerator Research Complex
2022
Nagoya University
2017-2022
Obayashi (Japan)
2022
Kyushu University
2022
The University of Tokyo
2022
Kyoto University Institute for Chemical Research
2008-2021
Kyoto Bunkyo University
2012-2021
This paper introduces a new approach to measure the muon magnetic moment anomaly |$a_{\mu} = (g-2)/2$| and electric dipole (EDM) |$d_{\mu}$| at J-PARC facility. The goal of our experiment is |$a_{\mu}$| using an independent method with factor 10 lower momentum, 20 smaller diameter storage-ring solenoid compared previous ongoing |$g-2$| experiments unprecedented quality storage field. Additional significant differences from present experimental include 1000 transverse emittance beam...
With detailed experimental studies and hydrodynamics particle-in-cell simulations we investigate the role of prepulse in laser proton acceleration. The or pedestal (amplified spontaneous emission) can completely evaporate irradiated region a sufficiently thin foil; therefore, main part pulse interacts with an underdense plasma. multiparametric demonstrate that generates quasistatic magnetic field, which its turn produces long-lived charge separation electrostatic accelerating ions.
A system for inspecting the inner surface of superconducting rf cavities is developed in order to study relation between achievable field gradient and defects surface. The inspection consists a high resolution complementary metal-oxide-semiconductor camera special illumination built cylinder that has diameter 50 mm. can be inserted into L-band 9 cell cavity. provides about $7.5\text{ }\text{ }\ensuremath{\mu}\mathrm{m}/\mathrm{pixel}$. Thus far, there have been good correlations locations...
We have newly developed a Cockcroft-Walton (CW) multiplier that can be used in gas time projection chamber (TPC). TPC requires high voltage to form an electric field drifts ionization electrons. Supplying the from outside pressure vessel dedicated high-voltage feedthrough. An alternative approach is generate inside with relatively low introduced outside. CW convert AC input DC output, making it suitable for this purpose. integrated into high-pressure xenon TPC, called AXEL (A Xenon...
A high-current, long-pulsed beam operation without loss was demonstrated at the Superconducting rf Test Facility (STF) of High Energy Accelerator Research Organization. The primary purpose STF to validate superconducting radio-frequency (rf) acceleration technology for International Linear Collider (ILC) using accelerator components in line with ILC design. Thus, most critical objective perform operations a pulse length (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"...
Fast protons are observed by a newly developed online time-of-flight spectrometer, which provides shot-to-shot proton-energy distributions immediately after the irradiation of laser pulse having an intensity ∼1018W∕cm2 onto 5-μm-thick copper foil. The maximum proton energy is found to increase when fs prepulse arriving 9ns before main increases from 1014 1015W∕cm2. Interferometric measurement indicates that preformed-plasma expansion at front surface smaller than 15μm, corresponds spatial...
A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This has many advantageous properties over previously studied schemes, including being significantly shorter a given energy having better bandwidth. Experimental results from ATF2 accelerator at KEK are presented that validate operating principle such by demonstrating demagnification 1.3 GeV electron beam down to below 65 nm height...
A scheme for spot scanning using 11 C beams has been developed in order to form and verify a three-dimensionally conformal irradiation field cancer radiotherapy. By selecting the momentum spread of beam, we could considerably decrease distal falloff field, thus conserving beam quality. To estimate optimize dose distribution it is essential evaluate precise beams. The coupling lateral depth-dose distributions originating from wide should be taken into account calculate reconstructed was good...
A scheme of the real-time optimization proton production by an intense short-pulse laser interacting with a foil target was developed using time-of-flight measurement plastic scintillator. Owing to special treatments, detection protons scintillation counter has become possible under heavy backgrounds such as light itself, laser-generated hard X-ray, self-emission light, and electrons from laser-produced plasma. With protons, energy spectrum could be obtained shot shot, experimental...
A multilayered structure with a single superconductor layer and insulator formed on bulk is studied. General formulae for the vortex-penetration field of magnetic superconductor, which shielded by layers, are derived rigorous calculation attenuation in structure. The achievable peak surface depends thickness its material layer, superconductor. shows good agreement an experimental result. combination thicknesses layers to enhance limit can be given any materials.
We have developed an interdigital H-mode (IH) drift-tube linac (DTL) design with alternative phase focusing (APF) scheme for a muon linac, in order to measure the anomalous magnetic moment and electric dipole (EDM) of muons at Japan Proton Accelerator Research Complex (J-PARC). The IH-DTL accelerates from $\ensuremath{\beta}=v/c=0.08$ 0.28 operational frequency 324 MHz. output beam emittances are calculated as $0.315\ensuremath{\pi}$ $0.195\ensuremath{\pi}\text{ }\text{ }\mathrm{mm}\text{...
Superconducting radiofrequency (SRF) cavities for accelerators is the only superconductivity application that operates in Meissner state. For decades, bulk niobium, which exhibits highest 1st critical field among all known superconductors, has been material to achieve high accelerating fields combination with a quality factor. Specific nanostructures tailored SRF applications, form of superconducting/insulating/superconducting multilayers, were proposed surpass Nb performances could improve...
ATF2 is a final-focus test beam line which aims to focus the low emittance from ATF damping ring vertical size of about 37 nm and demonstrate nanometer level stability. Several advanced diagnostics feedback tools are used. In December 2008, construction installation were completed commissioning started, supported by an international team Asian, European, U.S. scientists. The present status first results described.
The results of a search for hydrogen-like atoms consisting $\pi^{\mp}K^{\pm}$ mesons are presented. Evidence $\pi K$ atom production by 24 GeV/c protons from CERN PS interacting with nickel target has been seen in terms characteristic pairs their breakup the same ($178 \pm 49$) and Coulomb final state interaction ($653 42$). Using these analysis yields first value lifetime $\tau=(2.5_{-1.8}^{+3.0})$ fs model-independent measurement S-wave isospin-odd scattering length...
In order to widely spread out particle beams utilized in cancer therapy, laser-produced ions are developed as the injection beam for an ion synchrotron dedicated therapy. Such a laser source is expected contribute largely realization of compactness size and low cost therapy accelerator. The energy spectrum ions, however, has no peak, but their intensities decrease exponentially according increase energy. For purpose modifying such situation, we have proposed scheme rotate longitudinal phase...
A short-pulse (∼210 fs) high-power (∼1 TW) laser was focused on a tape target 3 and 5 µm in thickness to size of 11×15 µm2 with an intensity 3×1017 W/cm2. Protons produced by this energy spread 100% were found be improved create peaks the distribution ∼7% application RF electric field amplitude ±40 kV synchronous pulsed laser. This scheme combines conventional acceleration technique laser-produced protons for first time. It is possible operated up 10 Hz, have good reproducibility every shot...
Magnesium diboride (MgB 2 ) has a transition temperature (T c of 40 K, i.e., about 4 times as high that niobium (Nb).We have been evaluating MgB candidate material for radio-frequency (RF) cavities future particle accelerators.Studies in the last 3 years shown it could one order magnitude less RF surface resistance (R s than Nb at K.A power dependence test using 6 GHz TE 011 mode cavity little up to 12 mT (120 Oe), limited by available power, compared other high-T materials such YBCO.A...
An ion spectrometer, composed of a time-of-flight spectrometer (TOFS) and Thomson parabola (TPS), has been developed to measure energy spectra analyze species laser-driven ions. Two spectrometers can be operated simultaneously, thereby facilitate compare the independently measured data combine advantages each spectrometer. Real-time shot-to-shot characterizations have possible with TOFS, ions analyzed TPS. The two show very good agreement maximum proton even for single laser shot. composite...
With the recent progress in surface cleaning, performance of superconducting RF cavities is mostly limited by a quench. It important to understand nature quench origin. In common SRF cavity design magnetic field concentrated near equatorial weld cavity. This has long been major suspect forming defect, either as an impurity or increased roughness, that eventually gives rise We used mounted thermometers obtain temperature map region. A high temperature, temporal, and spatial resolution...
The field strength generated by permanent magnets has been further extended introduction of saturated iron. A magnet quadrupole (PMQ) lens with such iron is one the candidates for final focus an e/sup +/e/sup -/ linear collider accelerator, because its compactness and low power consumption. first prototype PMQ fabricated demonstrated to have integrated 28.5 T overall length 10 cm a 7 mm bore radius. Two drawbacks should be considered: negative temperature coefficient fixed strength. thermal...
A laser-driven proton beam with a maximum energy of few MeV is stably obtained using an ultra-short and high-intensity Ti:sapphire laser. At the same time, keV X-ray also generated at almost place where protons are emitted. Here, we show successful demonstration simultaneous projection images test sample placed close to source resolution ∼10 µm, which determined from sizes. Although experimental configuration very simple, simultaneity better than hundreds ps. CR-39 track detector imaging...