Keyword: polarization
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MOPG71 Polarization Measurement and Modeling of Visible Synchrotron Radiation at Spear3 radiation, extraction, synchrotron, synchrotron-radiation 240
  • C.L. Li, W.J. Zhang
    East China University of Science and Technology, Shanghai, People's Republic of China
  • W.J. Corbett
    SLAC, Menlo Park, California, USA
  • Y.H. Xu
    DongHua University, Songjiang, People's Republic of China
  • W.J. Zhang
    University of Saskatchewan, Saskatoon, Canada
  Synchrotron radiation from dipole magnets is linearly polarized in the plane of acceleration and evolves toward circular polarization with increasing vertical observation angle. The intensity of the x-y field components can be modeled with Schwinger's theory for the angular-spectral power distribution. Combined with Fresnel's laws for reflection at a mirror surface, it is possible to model field polarization of visible SR light in the laboratory. The polarization can also be measured with a polarizer and quarter wave plate to yield Stokes' parameters S0-S3. In this paper we present measurements and modeling of the visible SPEAR3 SR beam in terms of Stokes' parameters and plot on the results on the Poincaré sphere.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG71  
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TUBL03 Synchronous Laser-Microwave Network for Attosecond-Resolution Photon Science timing, laser, network, detector 286
  • K. Shafak, F.X. Kärtner, A. Kalaydzhyan, O.D. Mücke, W. Wang, M. Xin
    CFEL, Hamburg, Germany
  • F.X. Kärtner, M.Y. Peng, M. Xin
    MIT, Cambridge, Massachusetts, USA
  Funding: This work was supported by the Center for Free-Electron Laser Science at Deutsches Elektronen-Synchrotron, a research center of the Helmholtz Association in Germany.
Next-generation photon-science facilities such as X-ray free-electron lasers (X-FELs)* and intense-laser beamline centers** are emerging world-wide with the goal of generating sub-fs X-ray pulses with unprecedented brightness to capture ultrafast chemical and physical phenomena with sub-atomic spatiotemporal resolution. The only obstacle preventing this long-standing scientific dream to come true is a high- precision timing distribution system*** synchronizing various microwave and optical sub-sources across multi-km distances which is required for seeded X-FELs and attosecond pump-probe experiments. Here, we present, for the first time, a synchronous laser-microwave network that will enable attosecond precision photon science facilities. By developing new ultrafast metrological timing devices and carefully balancing fiber nonlinearities and fundamental noise contributions, we have achieved timing stabilization of a 4.7 km fiber network with 580 attosecond precision over 52 hours. Furthermore, we have realized a complete laser-microwave network incorporating two mode-locked lasers and one microwave source with total 950 attosecond jitter integrated from 1 microsecond to 18 hours.
*J. Stohr, LCLS-II Conceptual Design Report. No. SLAC-R-978. (SLAC, 2011).
**G. Mourou, T. Tajima, Optics & Photonics News 22, 47 (2011).
***J. Kim, et al., Nat. Photonics 2(12), 733-736 (2008).
slides icon Slides TUBL03 [11.692 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUBL03  
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TUPG42 Design of a Very Compact 130 MeV Møller Polarimeter for the S-DALINAC electron, target, scattering, detector 438
  • T. Bahlo, J. Enders, T. Kürzeder, N. Pietralla, J. Wissmann
    TU Darmstadt, Darmstadt, Germany
  Funding: Supported by the DFG through grants SFB 634 and GRK 2128
At the Superconducting Darmstadt Linear Accelerator S-DALINAC it is possible to accelerate electron beams to a maximum energy of up to 130 MeV. In the S-DALINAC Polarized Injector SPIN polarized electrons with a polarization of up to 86% can be produced. The polarization can be measured with two already mounted Mott polarimeters in the injector beamline where the electrons can have energies of up to 10 MeV. To allow polarization measurements behind the main accelerator a Moeller polarimeter suitable for energies between 50 MeV and 130 MeV is currently being developed. The rather low and variable beam energies result in a big and also variable scattering angle distribution. Combined with strict spatial boundary conditions at the designated mounting area necessitate a very compact set-up for the polarimeter. In addition to an overview over the planned polarimeter we will present drafts of the target chamber, the beam separation chamber including a angle-defining aperture and the separation dipole as well as the beamline to the detectors and the beam dump.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG42  
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TUPG54 Novel Approach to the Elimination of Background Radiation in a Single-Shot Longitudinal Beam Profile Monitor radiation, detector, background, electron 471
  • H. Harrison, G. Doucas, I.V. Konoplev, A.J. Lancaster, H. Zhang
    JAI, Oxford, United Kingdom
  • A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  It is proposed to use the polarization of coherent Smith-Purcell radiation (cSPr) to distinguish between the cSPr signal and background radiation in a single-shot longitudinal bunch profile monitor. A preliminary measurement of the polarization has been carried out using a 1mm periodic metallic grating installed at the 8MeV electron accelerator LUCX, KEK (Japan). The measured degree of polarization at '=90° (300GHz) is 72.6 ±%. To make a thorough test of the theoretical model, measurements of the degree of polarization must be taken at more emission angles - equivalent to more frequencies.
This work was supported (in parts) by the: STFC UK, the Leverhulme Trust, JAI University of Oxford and the Photon and Quantum Basic Research Coordinated Development (Japan).
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG54  
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WEPG09 Development of a Prototype Electro-Optic Beam Position Monitor at the CERN SPS pick-up, laser, proton, optics 634
  • A. Arteche, A. Bosco, S.M. Gibson
    Royal Holloway, University of London, Surrey, United Kingdom
  • N. Chritin, D. Draskovic, T. Lefèvre, T.E. Levens
    CERN, Geneva, Switzerland
  Funding: Project funded by UK STFC grant, ST/N001583/1
A novel electro-optic beam position monitor capable of rapidly (<50ps) monitoring transverse intra-bunch perturbations is under development for the HL-LHC project. The EO-BPM relies on the fast optical response of two pairs of electro-optic crystals, whose birefringence is modified by the passing electric field of a 1ns proton bunch. Analytic models of the electric field are compared with electromagnetic simulations. A preliminary opto-mechanical design of the EO-BPM was manufactured and installed at the CERN SPS in 2016. The prototype is equipped with two pairs of 5mm cubic LiNbO3 crystals, mounted in the horizontal and vertical planes. A polarized CW 780nm laser in the counting room transmits light via 160m of PM fibre to the SPS, where delivery optics directs light through a pair of crystals in the accelerator vacuum. The input polarization state to the crystal can be remotely controlled. The modulated light after the crystal is analyzed, fibre-coupled and recorded by a fast photodetector in the counting room. Following the recent installation, we present the detailed setup and report the latest status on commissioning the device in-situ at the CERN SPS.
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG09  
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WEPG62 Incoherent and Coherent Polarization Radiation as Instrument of the Transversal Beam Size Diagnostics radiation, factory, target, diagnostics 792
  • D.Yu. Sergeeva, M.N. Strikhanov, A.A. Tishchenko
    MEPhI, Moscow, Russia
  Polarization radiation, which includes diffraction radiation (DR), transition radiation (TR), Smith-Purcell radiation, and others, can be a good instrument for beam diagnostics. All information about the beam size is contained in the so-called form-factor of the beam. The form-factor represents the sum of two parts corresponding to the coherent and incoherent radiation*. Contrary to the general opinion the incoherent part does not always equal unity*, **. In this report we give theoretical description of the incoherent and coherent parts of the form-factor both for Gaussian and uniform distribution of the ultrarelativistic particles in the bunch*, ***. The theory constructed describes also the case of beam skimming the target, which leads to mixing of DR and TR***. We show that the incoherent part depends on the transversal size of the beam, and dependence differs for different distributions. The role of the incoherent part of the form-factor of the bunch for different parameters is discussed.
* D.Yu. Sergeeva, A.A. Tishchenko et al., NIM B (2013)
** J.H. Brownell et al., PRE (1998); G. Doucas et al., PR STAB (2002)
*** A.A. Tishchenko, D.Yu. Sergeeva et al., Vacuum (2016)
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG62  
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