A5023066341- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Gyrotron and Vacuum Electronics Research
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Magnetic confinement fusion research
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Photocathodes and Microchannel Plates
- Plasma Diagnostics and Applications
- Electron and X-Ray Spectroscopy Techniques
- Neutrino Physics Research
- Advanced X-ray Imaging Techniques
- Advanced NMR Techniques and Applications
- Electromagnetic Simulation and Numerical Methods
- Laser-Plasma Interactions and Diagnostics
- Muon and positron interactions and applications
- Laser Design and Applications
- Nuclear physics research studies
- Atomic and Molecular Physics
- Crystallography and Radiation Phenomena
- Advanced Data Storage Technologies
- Atomic and Subatomic Physics Research
- Advancements in Photolithography Techniques
High Energy Accelerator Research Organization
2015-2024
Institute of High Energy Physics
2002-2023
Japan Proton Accelerator Research Complex
2021
The University of Tokyo
2020
The Graduate University for Advanced Studies, SOKENDAI
1998-2018
Brookhaven National Laboratory
2004-2007
European Organization for Nuclear Research
2001-2007
Los Alamos National Security (United States)
2004
Chinese Academy of Sciences
2002-2003
Chuo University
2003
The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade is under construction, to increase luminosity by two orders magnitude during a three-year shutdown, with ultimate goal 8E35 /cm^2 /s luminosity. To exploit increased luminosity, been proposed. A new international collaboration Belle-II, being formed. Technical Design Report presents physics motivation, basic methods accelerator upgrade, as...
The machine commissioning of KEKB started in December 1998 and its operation was terminated at the end June 2010 to upgrade SuperKEKB. In this paper, we summarize history show achievements made there.
The SuperKEKB project requires a positron and electron collider with peak luminosity of 8 × 1035 cm−2 s−1. This is 40 times that the KEKB B-factory, which operated for 11 years up to 2010. an asymmetry-energy double-ring collider; beam energy (LER) 4 GeV (HER) 7 GeV. An extremely small beta function at interaction point (IP) low emittance are necessary. In addition, in order achieve target luminosity, large horizontal crossing angle between two colliding beams adopted, as bunch length much...
The electron-positron collider DAPhiNE, the Italian Phi factory, has been recently upgraded in order to implement an innovative collision scheme based on large crossing angle, small beam sizes at point, and compensation of beam-beam interaction by means sextupole pairs creating a "crab-waist" configuration region. Experimental tests novel exhibited increase factor 3 peak luminosity with respect performances reached before upgrade. In this Letter we present new scheme, discuss its advantages,...
We theoretically demonstrate for the first time that a single free electron in circular/spiral motion emits twisted photons carrying well defined orbital angular momentum along axis of circulation, adding to spin momentum. show that, when velocity is relativistic, radiation field contains harmonic components and l-th carry lhbar total each. This work indicates are naturally emitted by electrons more ubiquitous laboratories nature than ever been thought.
In positron or proton storage rings with many closely spaced bunches, an electron cloud can build up in the vacuum chamber due to photoemission secondary emission. We discuss possibility of a single-bunch two-stream instability driven by this cloud. Depending on strength beam-electron interaction, chromaticity and synchrotron oscillation frequency, either resembles linac beam breakup head-tail instability. present computer simulations instabilities, compare simulation results analytical estimates.
The possibility of a coupled-bunch instability caused by beam-photoelectron interactions is discussed. Very many photoelectrons are produced in storage ring when photons emitted synchrotron radiation hit the beam chamber. Since electrons not trapped positron ion-trapping theory, they considered to affect beam. However, it possible that an enormous number would have sufficient density cause instability. A simulation has shown such may be serious for rings with high current and multibunches.
We report measurements of the properties D(+)(sJ)(2317) and D(+)(sJ)(2457) resonances produced in continuum e(+)e(-) annihilation near sqrt[s]=10.6 GeV. The analysis is based on an 86.9 fb(-1) data sample collected with Belle detector at KEKB. determine masses to be M(D(+)(sJ)(2317))=2317.2+/-0.5(stat)+/-0.9(syst) MeV/c(2) M(D(+)(sJ)(2457))=2456.5+/-1.3(stat)+/-1.3(syst) MeV/c(2). observe radiative decay mode D(+)(sJ)(2457)-->D(+)(s)gamma dipion D(+)(sJ)(2457)-->D(+)(s)pi(+)pi(-) their...
SuperKEKB is an electron-positron collider with asymmetric energies located at the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan. After more than five years of upgrading work on KEKB, phase-1 commissioning commenced February 2016 and ended June same year. Following a 20-month shutdown for installation particle detector, BELLE II, phase-2 March 2018 July This paper describes one major issue faced by SuperKEKB: electron cloud effect (ECE) positron ring, which was...
The equilibrium state of an electron in a storage ring can be described most accurately by the envelope matrix, as long motion is linear. calculated same way barycenter (closed orbit). This suited for accurate numerical calculations. ``emittances'' extracted from approximate quantities. radiation integrals, which express emittances terms Twiss parameters, dispersions, and other optical are extended to cover general 6\ifmmode\times\else\texttimes\fi{}6 dynamics. Without any coupling between...
High-statistics data on the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\eta}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}n$ at 8.06 GeV/c were obtained. An isobarmodel partial-wave analysis was performed for $\ensuremath{\eta}\ensuremath{\pi}\ensuremath{\pi}$ system. The $\ensuremath{\eta}(1275)$ meson confirmed as a narrow $I{J}^{\mathrm{PC}}={00}^{\ensuremath{-}+}$ resonance. It decays through both $\ensuremath{\delta}\ensuremath{\pi}$ and...
A beam optics scheme has been designed for the future circular collider-${e}^{+}{e}^{\ensuremath{-}}$ (FCC-ee). The main characteristics of design are: energy 45 to 175 GeV, 100 km circumference with two interaction points (IPs) per ring, horizontal crossing angle 30 mrad at IP and crab-waist [P. Raimondi, D. Shatilov, M. Zobov, arXiv:physics/0702033; P. in Proceedings 22nd Particle Accelerator Conference, PAC-2007, Albuquerque, NM (IEEE, New York, 2007), p. TUPAN037.] local chromaticity...
In positron and proton storage rings, electrons produced by photoemission, ionization, secondary emission accumulate in the vacuum chamber during multibunch operation with close spacing. A or bunch passing through this "electron cloud" experiences a force similar to short-range wake field. This effective field can cause transverse-mode-coupling instability, if electron-cloud density exceeds threshold value. report, we compute induced region without external magnetic both analytically via...
The slow cycling main ring synchrotron (MR) is located the furthest downstream in J-PARC accelerator cascade. It became available for user operation 2009 and provides high-intensity 30 GeV proton beams various experiments on particle nuclear physics. MR has two beam extraction systems: a fast system delivery to neutrino line of Tokai-to-Kamioka (T2K) experiment hadron experimental hall. After nine-month shutdown during recovery from Great East Japan Earthquake, facility resumed December...
The crab-waist scheme becomes the baseline for future circular ${e}^{+}{e}^{\ensuremath{-}}$ colliders, where a large Piwinski angle is must. It has been first found that strong coherent head-tail instability in vertical direction may be induced by interplay of beam-beam interaction and ring impedance below conventional transverse mode-coupling threshold. collision would stable only considering pure interaction. That to say, new combined effect impedance. can limit performance colliders...
In recent years the "crab-waist collision" scheme [P. Raimondi, Proceedings of 2nd SuperB Workshop, Frascati, 2006.; M. Zobov et al., Phys. Rev. Lett. 104, 174801 (2010)PRLTAO0031-900710.1103/PhysRevLett.104.174801] has become popular for circular e^{+} e^{-} colliders. The designs several future colliders are based on this scheme. So far beam-beam effects collisions under a large crossing angle with or without crab waist were mostly studied using weak-strong simulations. We present here...
In SuperKEKB, movable collimators reduce the beam background noise in Belle II particle detector and protect crucial machine components, such as final focusing superconducting quadrupole magnets (QCS), from abnormal losses. The challenges related to collimator, which were not properly considered at time of SuperKEKB design, have surfaced through experience with its operation. this paper, we report collimator operation strategy SuperKEKB. addition, a significant challenge collimation due...
We have carried out a strong-strong simulation to study the beam-beam effect in circular electron-positron collider. In simulation, both positron and electron beams are represented by macroparticles, interaction between two is obtained solving Poisson equation for charge distribution of macroparticles. Using we investigate limit coherent tune shift, characteristic phenomena effect. also collision with finite crossing angle, verify its feasibility KEKB factory. Our results yield an estimated...
Recent studies have shown a novel coherent head-tail instability induced by beam-beam interaction with large Piwinski angle. The has become an important issue during the designs of CEPC and FCC-ee. Simulations further revealed that longitudinal impedance strong impact on beam stability, squeezing horizontal stable tune area seriously. cross-wake force been introduced to represent interaction. A mode coupling theory based localized wake (impedance) developed explain instability. However, did...
The effects of electron clouds on positively charged beams have been an active area research in recent years at particle accelerators around the world. Transverse beam-size blowup due to has observed some machines and is considered be a major limiting factor development higher-current, higher-luminosity electron-positron colliders. leading proposed mechanism for beam excitation fast head-tail instability short-range wakes within cloud. We present here observations betatron oscillation...
For the past generation ${e}^{+}{e}^{\ensuremath{-}}$ storage ring colliders, we usually used natural bunch length or its impedance lengthened value in beam-beam simulations instead of considering directly. In future such as FCC-ee and CEPC, interaction becomes essentially three dimensional. order to increase luminosity, accelerators will collide very intense beams high energy with low emittances small beta functions at collision points exploiting crab waist scheme a large Piwinski angle....