Author
T. Omori
Bio: T. Omori is an academic researcher from Osaka University. The author has contributed to research in topics: Compton scattering & Collider. The author has an hindex of 10, co-authored 41 publications receiving 859 citations.
Papers
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TL;DR: The Large Hadron Electron Collider (LHeC) as discussed by the authors is a new collider for particle and nuclear physics, in which a newly built electron beam of up to possibly 140 GeV, energy collides with the intense hadron beams of the LHC.
Abstract: The physics programme and the design are described of a new collider for particle and nuclear physics, the Large Hadron Electron Collider (LHeC), in which a newly built electron beam of 60 GeV, up to possibly 140 GeV, energy collides with the intense hadron beams of the LHC. Compared to HERA, the kinematic range covered is extended by a factor of twenty in the negative four-momentum squared, $Q^2$, and in the inverse Bjorken $x$, while with the design luminosity of $10^{33}$ cm$^{-2}$s$^{-1}$ the LHeC is projected to exceed the integrated HERA luminosity by two orders of magnitude. The physics programme is devoted to an exploration of the energy frontier, complementing the LHC and its discovery potential for physics beyond the Standard Model with high precision deep inelastic scattering measurements. These are designed to investigate a variety of fundamental questions in strong and electroweak interactions. The physics programme also includes electron-deuteron and electron-ion scattering in a $(Q^2, 1/x)$ range extended by four orders of magnitude as compared to previous lepton-nucleus DIS experiments for novel investigations of neutron's and nuclear structure, the initial conditions of Quark-Gluon Plasma formation and further quantum chromodynamic phenomena. The LHeC may be realised either as a ring-ring or as a linac-ring collider. Optics and beam dynamics studies are presented for both versions, along with technical design considerations on the interaction region, magnets and further components, together with a design study for a high acceptance detector. Civil engineering and installation studies are presented for the accelerator and the detector. The LHeC can be built within a decade and thus be operated while the LHC runs in its high-luminosity phase. It thus represents a major opportunity for progress in particle physics exploiting the investment made in the LHC.
518 citations
TL;DR: In this article, GaAs-GaAsP and InGaAs-AlGaAs strained-layer superlattice photocathodes are presented as emission sources for highly polarized electron beams.
Abstract: GaAs–GaAsP and InGaAs–AlGaAs strained-layer superlattice photocathodes are presented as emission sources for highly polarized electron beams. The GaAs–GaAsP cathode achieved a maximum polarization of 92(±6)% with a quantum efficiency of 0.5%, while the InGaAs–AlGaAs cathode provides a higher quantum efficiency (0.7%) but a lower polarization [77(±5)%]. Criteria for achieving high polarization using superlattice photocathodes are discussed based on experimental spin-resolved quantum efficiency spectra.
68 citations
Stanford University1, Hiroshima University2, CERN3, Daresbury Laboratory4, University of Oxford5, Science and Technology Facilities Council6, University of Valencia7, University of Liverpool8, Polytechnic University of Catalonia9, Kyungpook National University10, University of Notre Dame11, Pohang University of Science and Technology12, Kyoto University13, University of Tokyo14, Tohoku University15
TL;DR: Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of a novel scheme for the focusing of high-energy leptons in future linear colliders by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.
Abstract: A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [ P. Raimondi and A. Seryi , Phys. Rev. Lett. 86 , 3779 ( 2001 ) ]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider.
51 citations
Kyoto University1, Stanford University2, Tokyo Metropolitan University3, Graduate University for Advanced Studies4, National Institute of Radiological Sciences5, Nagoya University6, University of Tokyo7, Tokyo University of Science8, Tohoku Gakuin University9, Waseda University10, Yokohama National University11, Lawrence Berkeley National Laboratory12, CERN13
TL;DR: The smallest vertical emittance achieved in single-bunch-mode operation of the Accelerator Test Facility is reported on, which satisfies the requirement of the x-band linear collider.
Abstract: For high luminosity in electron-positron linear colliders, it is essential to generate low vertical emittance beams. We report on the smallest vertical emittance achieved in single-bunch-mode operation of the Accelerator Test Facility, which satisfies the requirement of the x-band linear collider. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured at low intensity is 4 pm at a beam energy of 1.3 GeV, which corresponds to the normalized emittance of 1.0x1.0(-8) m. It increases by a factor of 1.5 for a bunch intensity of 10(10) electrons. The measured data agreed to the calculation of intrabeam scattering within much better than a factor of 2.
48 citations
TL;DR: Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK and a tuning method of the damping ring is established which achieves a small vertical dispersion and small x-y orbit coupling.
Abstract: Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than $1%$ of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than $2.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\mathrm{rad}\mathrm{m}$ at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance.
40 citations
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TL;DR: In this article, the authors provide an updated recommendation for the usage of sets of parton distribution functions (PDFs) and the assessment of PDF and PDF+$\alpha_s$ uncertainties suitable for applications at the LHC Run II.
Abstract: We provide an updated recommendation for the usage of sets of parton distribution functions (PDFs) and the assessment of PDF and PDF+$\alpha_s$ uncertainties suitable for applications at the LHC Run II. We review developments since the previous PDF4LHC recommendation, and discuss and compare the new generation of PDFs, which include substantial information from experimental data from the Run I of the LHC. We then propose a new prescription for the combination of a suitable subset of the available PDF sets, which is presented in terms of a single combined PDF set. We finally discuss tools which allow for the delivery of this combined set in terms of optimized sets of Hessian eigenvectors or Monte Carlo replicas, and their usage, and provide some examples of their application to LHC phenomenology.
1,098 citations
Perimeter Institute for Theoretical Physics1, Niigata University2, CERN3, University of Connecticut4, Leiden University5, Korea Astronomy and Space Science Institute6, Federico Santa María Technical University7, University of California, Santa Barbara8, University of Maryland, College Park9, Claude Bernard University Lyon 110, University of Lyon11, Northwestern University12, University of Victoria13, University of Manchester14, University of Bonn15, Technische Universität München16, École Polytechnique Fédérale de Lausanne17, Stony Brook University18, Autonomous University of Madrid19, University of Paris20, Centre national de la recherche scientifique21, Moscow Institute of Physics and Technology22, Autonomous University of Barcelona23, University of Copenhagen24, Université libre de Bruxelles25, University of La Serena26, University of Valencia27, Taras Shevchenko National University of Kyiv28, Heidelberg University29, Yonsei University30, Princeton University31, Harvard University32, University of Geneva33, Tomsk Polytechnic University34, University of Tübingen35, Tomsk State University36, University of Washington37, University of Florida38, University of Hamburg39, TRIUMF40, University of Iowa41, University of Grenoble42, International Centre for Theoretical Physics43, Hokkai Gakuen University44, University of Illinois at Urbana–Champaign45, Durham University46, University of Melbourne47, University of Naples Federico II48, York University49, University of California, Berkeley50, Lawrence Berkeley National Laboratory51
TL;DR: It is demonstrated that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.
Abstract: This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, $\tau \to 3\mu $ and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the standard model and describe interactions between new particles and four different portals—scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.
842 citations
TL;DR: In this article, the authors provide an updated recommendation for the usage of sets of parton distribution functions (PDFs) and the assessment of PDF and PDF+$\alpha_s$ uncertainties suitable for applications at the LHC Run II.
Abstract: We provide an updated recommendation for the usage of sets of parton distribution functions (PDFs) and the assessment of PDF and PDF+$\alpha_s$ uncertainties suitable for applications at the LHC Run II. We review developments since the previous PDF4LHC recommendation, and discuss and compare the new generation of PDFs, which include substantial information from experimental data from the Run I of the LHC. We then propose a new prescription for the combination of a suitable subset of the available PDF sets, which is presented in terms of a single combined PDF set. We finally discuss tools which allow for the delivery of this combined set in terms of optimized sets of Hessian eigenvectors or Monte Carlo replicas, and their usage, and provide some examples of their application to LHC phenomenology.
683 citations
TL;DR: The SHiP (Search for Hidden Particles) experiment at CERN as discussed by the authors was designed to search for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments.
Abstract: This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (Search for Hidden Particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, $\tau\to 3\mu$ and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the Standard Model and describe interactions between new particles and four different portals - scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the Standard Model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation
592 citations
J. L. Abelleira Fernandez1, J. L. Abelleira Fernandez2, C. Adolphsen3, A. Akay4 +195 more•Institutions (54)
TL;DR: The Large Hadron Electron Collider (LHeC) as discussed by the authors was designed to achieve an integrated luminosity of O(100 ),fb$^{-1}, which is the cleanest high resolution microscope of mankind.
Abstract: This document provides a brief overview of the recently published report on the design of the Large Hadron Electron Collider (LHeC), which comprises its physics programme, accelerator physics, technology and main detector concepts. The LHeC exploits and develops challenging, though principally existing, accelerator and detector technologies. This summary is complemented by brief illustrations of some of the highlights of the physics programme, which relies on a vastly extended kinematic range, luminosity and unprecedented precision in deep inelastic scattering. Illustrations are provided regarding high precision QCD, new physics (Higgs, SUSY) and electron-ion physics. The LHeC is designed to run synchronously with the LHC in the twenties and to achieve an integrated luminosity of O(100)\,fb$^{-1}$. It will become the cleanest high resolution microscope of mankind and will substantially extend as well as complement the investigation of the physics of the TeV energy scale, which has been enabled by the LHC.
553 citations