Keyword: scattering
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MOPG73 Transverse Beam Size Diagnostics using Brownian Nanoparticles at ALBA radiation, synchrotron, diagnostics, synchrotron-radiation 248
  • M. Siano, B. Paroli, M.A.C. Potenza
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • A. Goldblatt, S. Mazzoni, G. Trad
    CERN, Geneva, Switzerland
  • U. Iriso, A.A. Nosych, L. Torino
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  In this work we describe a novel beam diagnostic method based on coherence characterization of broad-spectrum bending magnet radiation through the Heterodyne Near Field Scattering (HNFS) technique. HNFS is a self-referencing technique based on the interference between the transmitted beam and the spherical waves scattered by each particle of a colloidal suspension. The resulting single-particle interferogram shows circular fringes modulated by the spatio-temporal Complex Coherence Factor (CCF) of the radiation. Superposition of a number of these patterns results in a stochastic speckle field, from which spatial and temporal coherence information of the source can be retrieved in near field conditions. Here we describe the basics of this technique, the experimental setup mounted along the hard X-ray pinhole at the ALBA synchrotron light source, and the possibility of transverse electron beam size retrieval from the spatial coherence function of the emitted dipole radiation. We also show preliminary results concerning power spectral density of visible synchrotron radiation as obtained from temporal coherence.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG73  
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MOPG74 Design and Performance of Coronagraph for Beam Halo Measurements in the LHC injection, vacuum, synchrotron, background 253
  • A. Goldblatt, E. Bravin, F. Roncarolo, G. Trad
    CERN, Geneva, Switzerland
  • T.M. Mitsuhashi
    KEK, Ibaraki, Japan
  The CERN Large Hadron Collider is equipped with two Beam Synchrotron Radiation (BSR) systems, one per beam, used to monitor the transverse distribution of the beam, its longitudinal distribution and the abort gap population. During the 2015-2016 winter shut-down period, one of the two BSR systems was equipped with a prototype beam halo monitor, based on the coronagraph technique, classically used in astrophysics telescopes to measure the sun corona. The system design, as well as its optics, was inherited from the coronagraph used in the KEK Photon Factory with some modifications made in order to satisfy the LHC BSR source constraints. This project is in the framework of the HL-LHC project, for which there is the requirement to monitor the beam halo at the level of 10-6 of the core intensity. This first prototype has been designed as a demonstrator system aimed at resolving a halo-core contrast in the 10-3 to 10-4 range. After discussing the design of the LHC coronagraph and its technical implementation, this contribution presents the result of the first tests with beam and the planned system upgrades for 2017.  
poster icon Poster MOPG74 [1.671 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG74  
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TUPG42 Design of a Very Compact 130 MeV Møller Polarimeter for the S-DALINAC electron, target, polarization, 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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TUPG72 Calibration of X-ray Monitor during the Phase I of SuperKEKB commissioning emittance, factory, detector, optics 524
  • E. Mulyani
    Sokendai, Ibaraki, Japan
  • J.W. Flanagan
    KEK, Ibaraki, Japan
  X-ray monitors (XRM) have been installed in each SuperKEKB ring, the Low Energy Ring (LER) and High Energy Ring (HER), primarily for vertical beam size measurement. Both rings have been commissioned in Phase I of SuperKEKB operation (February-June 2016), and several XRM calibration studies have been carried out. The geometrical scale factors seems to be well understood for both LER and HER. The emittance knob ratio method yielded results consistent with expectations based on the machine model optics (vertical emittance εy is {§I{≈8}{pm}}). For the HER, the vertical emittance εy is {§I{≈41}{pm}}, which is 4× greater than the optics model expectation. Analysis of beam size and lifetime measurements suggests unexpectedly large point response functions, particularly in the HER.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG72  
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WEPG41 Measurement of Coupling Impedances using a Goubau Line impedance, simulation, resonance, coupling 719
  • F. Stulle, J.F. Bergoz
    BERGOZ Instrumentation, Saint Genis Pouilly, France
  • H.-W. Glock
    HZB, Berlin, Germany
  Longitudinal coupling impedances can be deduced from S-Parameter measurements performed on a Goubau Line. The Goubau Line, also known as single wire line, is a variant of the coaxial wire method. Both setups use a wire for mimicking the particle beam. Coaxial tapers at the wire ends adapt wave impedance to the 50ohm impedance of coaxial cables, sources and receivers. But for guiding the electromagnetic wave, the Goubau Line relies on the realistic boundary conditions imposed by an insulated wire instead of using a coaxial shield. Equations for the deduction of longitudinal coupling impedances are reviewed and applied to Goubau Line measurements. Goubau Line measurements and CST Studio simulations are compared, showing good agreement.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG41  
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