Keyword: optics
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MOPG40 Performance Studies of a Single Vertical Beam Halo Collimation System at ATF2 background, collimation, simulation, wakefield 139
  • N. Fuster-Martínez, A. Faus-Golfe
    IFIC, Valencia, Spain
  • P. Bambade, A. Faus-Golfe, S. Wallon, R.J. Yang
    LAL, Orsay, France
  • K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
    Sokendai, Ibaraki, Japan
  • K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
    KEK, Ibaraki, Japan
  • I. Podadera, F. Toral
    CIEMAT, Madrid, Spain
  Funding: Work supported by IDC-20101074, FPA2013-47883-C2-1-P and ANR-11-IDEX-0003-02
In order to reduce the background that could limit the precision of the diagnostics located in the ATF2 post-IP beamline, a single vertical beam halo collimation system was installed in March 2016. In this paper we present the measurements done in March and May 2016 in order to characterize the collimation system performance. Furthermore, the collimator wakefield impact has also been measured and compared with theoretical calculations and numerical simulations in order to determine the most efficient operation mode of the collimation system in terms of halo cleaning and negligible wakefield impact.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG40  
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MOPG70 Transverse Beam Profiling and Vertical Emittance Control with a Double-Slit Stellar Interferometer controls, electron, coupling, radiation 236
  • W.J. Corbett, X. Huang, J. Wu
    SLAC, Menlo Park, California, USA
  • C.L. Li, W.J. Zhang
    East China University of Science and Technology, Shanghai, People's Republic of China
  • T.M. Mitsuhashi
    KEK, Ibaraki, Japan
  • Y.H. Xu
    DongHua University, Songjiang, People's Republic of China
  • W.J. Zhang
    University of Saskatchewan, Saskatoon, Canada
  Double-slit interferometers are useful tools to measure the transverse the cross-section of relativistic charged particle beams emitting incoherent synchrotron radiation. By rotating the double-slit about the beam propagation axis, the transverse beam profile can be reconstructed including beam tilt at the source. The interferometer can also be used as a sensitive monitor for vertical emittance control. In this paper we outline a simple derivation of the Van Cittert-Zernike theorem, present results for a rotating double-slit measurement and demonstrate application of the interferometer to vertical emittance control using the Robust Conjugate Direction Search (RCDS) optimization algorithm.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG70  
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TUPG72 Calibration of X-ray Monitor during the Phase I of SuperKEKB commissioning emittance, factory, detector, scattering 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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TUPG74 Spot Size Measurements in the ELI-NP Compton Gamma Source target, linac, diagnostics, radiation 532
  • F. Cioeta, E. Chiadroni, G. Di Pirro, G. Franzini, V. Shpakov, A. Stella, A. Variola
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • M. Marongiu
    INFN-Roma, Roma, Italy
  • A. Mostacci, L. Palumbo
    University of Rome La Sapienza, Rome, Italy
  A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with an OTR (optical transition radiation) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy desired considering design and technological constraints; we will compare several configurations of the optical detection line to justify the one chosen for the implementation in the Linac.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG74  
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TUPG77 Experimental Results of a Compact Laserwire System for Non-Invasive H Beam Profile Measurements at CERN's Linac4 laser, linac, detector, electron 544
  • S.M. Gibson, G.E. Boorman, A. Bosco
    Royal Holloway, University of London, Surrey, United Kingdom
  • T. Hofmann, U. Raich, F. Roncarolo
    CERN, Geneva, Switzerland
  Funding: Support from UK STFC, grant ST/N001753/1.
A non-invasive laserwire system is being developed for quasi-continuous monitoring of the transverse profile and emittance of the final 160 MeV beam at CERN's LINAC4. As part of these developments, a compact laser-based profile monitor was recently tested during LINAC4 commissioning at beam energies of 50 MeV, 80 MeV and 107 MeV. A laser with a tunable pulse width (1-300 ns) and ~200 W peak power in a surface hutch delivers light via a 75 m LMA transport fibre to the accelerator. Automated scanning optics deliver a free space <150 micron width laserwire to the interaction chamber, where a transverse slice of the hydrogen ion beam is neutralised via photo-detachment. The liberated electrons are deflected by a low field dipole and captured by a sCVD diamond detector, that can be scanned in synchronisation with the laserwire position. The laserwire profile of the LINAC4 beam has been measured at all commissioning energies and is found in very good agreement with interpolated profiles from conventional SEM-grid and wire scanner measurements, positioned up and downstream of the laserwire setup. Improvements based on these prototype tests for the design of the final system are presented.
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG77  
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WEBL01 Beam Diagnostics Challenges for Beam Dynamics Studies emittance, linac, diagnostics, quadrupole 577
  • O.R. Jones
    CERN, Geneva, Switzerland
  This presentation will review the performance and limitations of present beam instrumentation in relation to beam dynamics studies, and give an overview of the main requirements from the accelerator physics community for new or improved measurements that need R&D effort from the beam diagnostics side.  
slides icon Slides WEBL01 [47.201 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEBL01  
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WEPG09 Development of a Prototype Electro-Optic Beam Position Monitor at the CERN SPS pick-up, polarization, laser, proton 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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WEPG49 A High Resolution Single-Shot Longitudinal Profile Diagnostic Using Electro-Optic Transposition laser, diagnostics, electron, real-time 752
  • D.A. Walsh, S.P. Jamison, E.W. Snedden
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • T. Lefèvre
    CERN, Geneva, Switzerland
  Funding: This work was funded by CERN through contract KE1866/DG/CLIC and carried out at STFC Daresbury Laboratory.
Electro-Optic Transposition (EOT) is the basis for an improved longitudinal bunch profile diagnostic we are developing in ASTeC as part of the CLIC UK research program. The scheme consists of transposing the Cou-lomb field profile of an electron bunch into the intensity envelope of an optical pulse via the mixing processes that occur between a CW laser probe and Coulomb field in an electro-optic material. This transposed optical pulse can then be amplified and characterised using robust laser techniques ' in this case chirped pulse optical parametric amplification and frequency resolved optical gating, allowing the Coulomb field to be recovered. EOT is an improvement over existing techniques in terms of the achievable resolution which is limited by the EO material response itself, reduced complexity of the laser system required since nanosecond rather than femtosecond lasers are used, and insensitivity of the system to bunch-laser arrival time jitter due to using a nanosecond long probe. We present results showing the retrieval of a THz pulse (Coulomb field stand-in) which confirms the principle behind the EOT system.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG49  
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WEPG51 A Transverse Deflecting Structure for the Plasma Wakefield Accelerator Experiment, FLASHForward plasma, emittance, cavity, quadrupole 759
  • R.T.P. D'Arcy, V. Libov, J. Osterhoff
    DESY, Hamburg, Germany
  The FLASHForward project at DESY is an innovative plasma-wakefield acceleration experiment, aiming to accelerate electron beams to GeV energies over a few centimeters of ionized gas. These accelerated beams must be of sufficient quality to be used in a free-electron laser; achievable only through rigorous analysis of both the drive- and accelerated-beam's longitudinal phase space. The pulse duration of these accelerated beams is typically in the few femtosecond range, and thus difficult to resolve with traditional diagnostic methods. In order to longitudinally resolve these very short bunch-lengths, it is necessary to utilize the properties of a transverse RF deflector (operating in the hybrid electromagnetic mode, HEM11), which provides a relation between longitudinal and transverse co-ordinates. It is proposed that this type of device, commonly known as a Transverse Deflecting Structure (TDS) due to its 'streaking' in the transverse plane, will be introduced to the FLASHForward beamline in order to perform these single-shot longitudinal phase space measurements. The initial investigations into the realization of this diagnostic tool are outlined.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG51  
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WEPG78 BPM Based Optics Correction of the Solaris 1.5 GeV Storage Ring storage-ring, closed-orbit, alignment, simulation 836
  • A. Kisiel, P.B. Borowiec, P.P. Goryl, M.B. Jaglarz, M.P. Kopeć, A.M. Marendziak, S. Piela, P.S. Sagalo, M.J. Stankiewicz, A.I. Wawrzyniak
    Solaris, Kraków, Poland
  The Solaris is a novel approach for the third generation synchrotron light sources. The machine consists of 600 MeV linear injector and 1.5 GeV storage ring based on 12 compact Double Bend Achromat (DBA) magnets designed in MAX-IV Laboratory in Sweden. After the commissioning phase of the Solaris storage ring the optimization phase has been started along with the commissioning of the first beamline. An essential part of the beam diagnostics and instrumentation system in the storage ring are Beam Position Monitors (BPMs) based on 36 quarter-wave button BPMs spread along the ring. Proper calibration allowed to measure and correct several beam parameters like closed orbit, tune, chromaticity, dispersion and orbit response matrix. The results of the latest machine optimization including the orbit correction, beam-based alignment and BPM phase advance will be presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG78  
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WEPG80 Optical Effects in High Resolution and High Dynamic Range Beam Imaging Systems electron, background, diagnostics, radiation 844
  • J. Wolfenden, R.B. Fiorito, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • M. Bergamaschi, R. Kieffer, T. Lefèvre, S. Mazzoni
    CERN, Geneva, Switzerland
  • P. Karataev, K.O. Kruchinin
    JAI, Egham, Surrey, United Kingdom
  Optical systems are used to transfer light in beam diagnostics for a variety of imaging applications. The effect of the point spread function (PSF) of these optical systems on the resulting measurements is often approximated or misunderstood. It is imperative that the optical PSF is independently characterised, as this can severely impede the attainable resolution of a diagnostic measurement. A high quality laser and specially chosen optics have been used to generate an intense optical point source in order to accomplish such a characterisation. The point source was used to measure the PSFs of various electron-beam imaging systems. These systems incorporate a digital micro-mirror array, which was used to produce very high (>105) dynamic range images. The PSF was measured at each intermediary image plane of the optical system; enabling the origin of any perturbations to the PSF to be isolated and potentially mitigated. One of the characterised systems has been used for optical transition radiation (OTR) measurements of an electron beam at KEK-ATF2 (Tsukuba, Japan).  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG80  
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