6. Transverse profiles and emittance monitors
Paper Title Page
WEOC01
Summary of Emmittance Measurements Workshop for SLS and FELs  
 
  • U. Iriso
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • F. Ewald
    ESRF, Grenoble, France
  • G. Kube, K. Wittenburg
    DESY, Hamburg, Germany
  • T.M. Mitsuhashi
    KEK, Ibaraki, Japan
  • V. Schlott
    PSI, Villigen PSI, Switzerland
 
  Funding: This project has received funding from the EU Horizon 2020 Research and Innovation programme, under Grant Agreement No 730871.
In January 2018, a Topical Workshop on Emittance Measurements for Synchrotron Light Sources and FELs was held at ALBA inside the ARIES network. This talk will summarize the state of the art of the different emittance measurements techniques for these type of accelerators, and will present the relevant topics shown during the workshop.
 
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WEOC02 Review of Recent Status of Coded Aperture X-ray Monitors for Beam Size Measurement 361
 
  • J.W. Flanagan
    KEK, Ibaraki, Japan
 
  Funding: US-Japan Cooperation in High Energy Physics (Japan Monbukagakusho and US DOE). Kakenhi.
X-ray beam profile monitors based on coded aperture imaging use an array of pinholes or slits to achieve large open apertures, which provide improved photon collection efficiency over single pinholes or slits. The resulting improvement in photon statistics makes possible single-bunch, single-turn measurements at lower bunch currents than are possible with a single pinhole or slit. In addition, the coded aperture pattern provides extra information for beam profile reconstruction, which makes possible somewhat improved resolution, as compared to a single slit. The reconstruction algorithm for coded aperture imaging is more complicated and computing-intensive than that for a single slit, though with certain classes of coded pertures a faster reconstruction method is possible. This talk will provide a survey of efforts to use coded aperture imaging for beam profile diagnostics at accelerators to date, covering principles and practical experiences with the technique, as well as prospects for the future at SuperKEKB, where it forms the primary means of measuring vertical beam sizes.
 
slides icon Slides WEOC02 [4.065 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOC02  
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WEOC03 A Simple Model to Describe Smoke Ring Shaped Beam Profile Measurements With Scintillating Screens at the European XFEL 366
 
  • G. Kube, S. Liu, A.I. Novokshonov, M. Scholz
    DESY, Hamburg, Germany
 
  Standard beam profile measurements of high-brightness electron beams based on OTR may be hampered by coherence effects. Therefore it was decided for the European XFEL to measure transverse beam profiles based on scintillating screen monitors using LYSO:Ce. While it is possible to resolve beam sizes down to a few micrometers with this scintillator, the experience during the XFEL commissioning showed that the measured emittance values were significantly larger than the expected ones. In addition, beam profiles measured at bunch charges of a few hundred pC showed a 'smoke ring' structure. While coherent OTR emission and beam dynamical influence can be excluded, it is assumed that the profile distortions are caused by effects from the scintillator material. Following the experience in high energy physics, a simple model was developed which takes into account quenching effects of excitonic carriers inside a scintillator in a heuristic way. Based on this model, the observed beam profiles can be understood qualitatively. Together with the model description, first comparisons with experiments will be presented, and new scintillators suitable for beam profile diagnostics will be discussed.  
slides icon Slides WEOC03 [2.411 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOC03  
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WEOC04 Space Charge Effects Studies for the ESS Cold Linac Beam Profiler 371
 
  • F. Belloni, F. Benedetti, G. Coulloux
    CEA/DRF/IRFU, Gif-sur-Yvette, France
  • P. Abbon, F. Gougnaud, C. Lahonde-Hamdoun, P. Le Bourlout, Y. Mariette, J. Marroncle, J.-Ph. Mols, V. Nadot, L. Scola
    CEA/DSM/IRFU, France
  • C.A. Thomas
    ESS, Lund, Sweden
 
  Five Ionization Profile Monitors are being built by CEA in the framework of the in-kind contribution agreement signed with ESS. The IPMs will be installed in the Cold Linac where the proton energy range they need to cover extends from 90 MeV to 2 GeV. The ESS fields intensity of 1.10+09 protons/bunch delivered at a frequency of 352 or 704 MHz, with a duty cycle of 4%, may strongly affect the trajectories of the ionized molecules and electrons created by the passage of the beam through the residual gas. In order to quantify and to develop a correction algorithm for these space charge effects, a code was initiated at ESS and completed at CEA Saclay with the possibility to include real case electric fields calculated with Comsol Multiphysics. A general overview of the code and its preliminary results are presented here.  
slides icon Slides WEOC04 [5.186 MB]  
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WEPB01 Photon Beam Imager at SOLEIL 425
 
  • M. Labat, J. Da Silva, N. Hubert, F. Lepage
    SOLEIL, Gif-sur-Yvette, France
 
  In one of the long straight sections of SOLEIL is installed a pair of canted in-vacuum undulators for the ANATOMIX and NANOSCOPIUM beamlines. Since the upstream undulator radiation can potentially damage the downstream undulator magnets, an accurate survey of the respective alignment of the two devices is mandatory. An XBPM has been initially installed for this purpose in the beamline frontend. For redundancy and further analysis, an X-ray imager was then designed and added just downstream the XBPM. It is made of a diamond plate that can be inserted into the upstream beamline frontend at low current. Fluorescence of the Nitrogen impurities in the diamond is imaged on a CCD to check that the upstream radiation is not hitting the downstream insertion device. We present the commissioning of this new device together with its first results in operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB01  
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WEPB02 Development of a a YAG/OTR Monitor 429
 
  • R.J. Yang, P. Bambade, S. Wallon
    LAL, Orsay, France
  • A. Aryshev, T. Naito, N. Terunuma
    KEK, Ibaraki, Japan
  • M. Bergamaschi
    CERN, Geneva, Switzerland
 
  To study the mechanisms of beam halo formation and its dynamics, a YAG/OTR monitor has been developed and tested at the KEK-ATF. The monitor has four ceramic Ce:YAG screens for the visualization of the beam core and beam halo and an OTR target to provide complementary measurements of beam core. A high dynamic range (DNR>105) and a high resolution (<10 um) have been demonstrated through the optimization of light detection, reduction of background and suppression of scintillation saturation. Measurements using this monitor are consistent with previous results and theoretical modeling of beam halo at ATF, and have allowed further progress in the characterization of the driving mechanisms.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB02  
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WEPB03 First Prototype of a Coronagraph-based Halo Monitor for BERLinPro 434
 
  • J.G. Hwang, J. Kuszynski
    HZB, Berlin, Germany
 
  Since particle losses by beam halo induced by space charge force and scattering of trapped ions are critical issues for superconducting-linac based high power machines such as BERLinPro, a halo monitor is demanded to monitor and control particle distribution at the level of 10-4 ~ 10-5 of the core intensity. A coronagraph-based halo monitor was adopted and the first prototype has been designed as a demonstrator system aimed at resolving a halo-core contrast in the 10-3 to 10-4 range. This monitor was tested at BESSY II with various operation modes such as Transverse Resonance Island Buckets (TRIBs) and Pulse-Picking by Resonant Excitation (PPRE). We show our design parameters, experimental criterion, and experimental results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB03  
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WEPB04 Comparison of YAG Screens and LYSO Screens at PITZ 438
 
  • R. Niemczyk, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, H.J. Qian, Y. Renier, F. Stephan, Q.T. Zhao
    DESY Zeuthen, Zeuthen, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  The Photo Injector Test facility at DESY in Zeuthen (PITZ) is dedicated to the development of high-brightness electron sources for free-electron lasers. At PITZ, to measure the emittance of space-charge-dominated beams, the slit scan technique is used. For slice emittance measurements a transverse deflecting structure (TDS) is employed. The electron beam distribution is measured by means of scintillator screens. Both the TDS and the slit mask reduce the signal strength, giving stringent requirements on the sensitivity of the screens. At PITZ, high-sensitivity Ce:LYSO screens have been installed at the same screen stations as the standard Ce:YAG screens to solve low-intensity issues. A comparison of both screens is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB04  
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WEPB06 Time-Synchronous Measurements of Transient Beam Dynamics at Spear3* 441
 
  • Q. Lin, Z.H. Sun
    Donghua University, Shanghai, People's Republic of China
  • W.J. Corbett, D.J. Martin, K. Tian
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the China Scholarship Council and the US Department of Energy Contract DE-AC03-76SF00515, Office of Basic Energy Sciences.
Multi-bunch beam instabilities can often be controlled with high-speed digital bunch-by-bunch feedback systems. The detected motion is based on charge centroid measurements that, for short bunches, cannot resolve intrabunch charge dynamics. To compliment the BxB data, we installed a fast-gated camera with a rotating mirror to sweep visible-light synchrotron radiation across the camera CCD. The SR measurements present a complimentary view of the motion. For this work we generated transient beam events in SPEAR3 using the BxB feedback system and synchronously observed the motion on the camera. Results are presented for a high-order multibunch beam instability and for single bunch drive-damp experiments.

 
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WEPB09 Wire Scanner Measurements at the PAL-XFEL 445
 
  • G. Kim, H.-S. Kang, C. Kim, B.G. Oh, D.C. Shin
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The PAL-XFEL, an X-ray Free electron laser user facility based on a 10 GeV normal conducting linear accelerator, have been operational at Pohang, South Korea. The wire scanners are installed for transverse beam profile measurement of the Linac and the Hard X-ray undulator section. The wire scanner is a useful device for emittance measurements in the Hard X-ray undulator section. In this paper, we describe the details of the wire scanner and the results of the measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB09  
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WEPB10 Grating Scanner for Measurement of Micron-size Beam Profiles 448
 
  • L.G. Sukhikh, A. Potylitsyn, S.A. Strokov
    TPU, Tomsk, Russia
  • G. Kube, K. Wittenburg
    DESY, Hamburg, Germany
 
  Funding: The work was partly supported by the program ‘‘Nauka' of the Russian Ministry of Education and Science, grant # 3.1903.2017
Wire scanners are widely used for transverse beam size diagnostics. The minimum detectable beam size is affected by the diameter of a single wire. The smallest carbon or tungsten wires used so far have diameters of about 4 microns. With the development of modern electron accelerators and the demands from future linear electron-positron colliders, sub-micron beam sizes have to be resolved. In order to increase the resolution, the decrease of the wire diameter is required. The authors of Ref. * proposed to manufacture thin gold stripes of rectangular shape (widths are equal to 1 µm or 2 µm and height is equal to 3 µm) on Si3N4 membrane. We propose to use another arrangement of gold stripes with varying period on a Si substrate. A set of 11 stripes with 1 µm width and 10 micron height with varying gap width in the range 3-0.25 µm ("grating scanner") was simulated by using an analytical model and by the Geant4 code. By moving this scanner across the beam one could measure the Bremsstrahlung yield vs. the coordinate, resulting in an oscillating dependence. The visibility of the resulting image allows defining the beam sizes in the range of 0.5-1.5 µm for the proposed scanner parameters.
* S. Borrelli et al., "Generation and Measurement of Sub-Micrometer Relativistic Electron Beams", arXiv:1804.04252v1 [physics.acc-ph] 11 Apr 2018
 
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WEPB11 Spatial Resolution Improvement of OTR Monitors by Off-axis Light Collection 451
 
  • A. Potylitsyn, A.I. Novokshonov, L.G. Sukhikh
    TPU, Tomsk, Russia
  • G. Kube, A.I. Novokshonov
    DESY, Hamburg, Germany
 
  Funding: The work was partly supported by the program "Nauka" of the Russian Ministry of Education and Science, grant #3.1903.2017
The spatial resolution of an OTR monitor for electron beam profile diagnostics is determined by the resolution of the optical system and by the Point Spread Function (PSF) representing the single electron image. In the image plane, the PSF has a typical lobe-shape distribution with an inter-peak distance depending on wavelength and lens aperture ratio [*]. For a beam with a transverse rms size smaller than the distance, the reconstruction of the beam profile has several difficulties [**, ***]. We propose to reduce the PSF contribution and to improve the spatial resolution of an OTR monitor simply by rotating the lens optical axis with respect to the specular reflection direction. If the difference between the rotational angle and the lens aperture is much larger than the inverse Lorentz factor, the PSF has a Gaussian-like distribution which matches practically with the Airy distribution. Thus the resolution depends on wavelength and lens aperture. In principle, for lens apertures in the order of 0.1 rad such an approach should allow to measure beam sizes comparable to the wavelength of observation, using a simple deconvolution procedure for the measured image and the PSF.
* M. Castellano, V.Verzilov, Phys. Rev. ST-AB, 1 (1998).
** K.Kruchinin, S.T.Boogert, P.Karataev et al., Proc. IBIC 2013 (2013).
*** L.G. Sukhikh, A.P. Potylitsyn, G. Kube, Phys. Rev. AB 20 (2017).
 
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WEPB12 Design and Implementation of Non-Invasive Profile Monitors for the ESS LEBT 455
 
  • C.A. Thomas, T.J. Grandsaert, H. Kocevar, Ø. Midttun, N. Milas, R. Miyamoto, T.J. Shea
    ESS, Lund, Sweden
 
  Non-invasive Profile Monitors are designed and distributed along the ESS Linac. In the Low Energy Beam Transport (LEBT), a specific one has been designed to be primarily a beam position monitor. Its main requirement is to measure the beam position with 100µm accuracy, and in addition it provides the beam profile and size. This performance have been shown to be possible and remains to be demonstrated experimentally. The instrument is also potentially capable of measuring the angle of the beam and its divergence. In this paper we will study the accuracy of such a measurement as function of the instrument image quality.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB12  
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WEPB13 Beam-Gas Imaging Measurements at LHCb 459
 
  • G.R. Coombs, M. Ferro-Luzzi, R. Matev
    CERN, Geneva, Switzerland
 
  The LHCb detector is one of the four large particle physics experiments situated around the LHC ring. The excellent spatial resolution of the experiment's vertex locator (VELO) and tracking system allows the accurate reconstruction of interactions between the LHC beam and either residual or injected gas molecules. These reconstructed beam-gas interactions gives LHCb the ability, unique among experiments, to measure the shape and the longitudinal distribution of the beams. Analysis methods were originally developed for the purpose of absolute luminosity calibration, achieving an unprecedented precision of 1.2% in Run I. They have since been extended and applied for online beam-profile monitoring that is continuously published to the LHC, for dedicated cross-calibration with other LHC beam profile monitors and for studies of the dynamic vacuum effects due to the proximity of the VELO subdetector to the beam. In this talk, we give an overview of the LHCb experience with beam-gas imaging techniques, we present recent results on the outlined topics and we summarise the developments that are being pursued for the ultimate understanding of the Run II measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB13  
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WEPB14 Recent Results on Non-invasive Beam Size Measurement Methods Based on Polarization Currents 464
 
  • S. Mazzoni, M. Bergamaschi, O.R. Jones, R. Kieffer, T. Lefèvre, F. Roncarolo
    CERN, Geneva, Switzerland
  • A. Aryshev, N. Terunuma
    KEK, Ibaraki, Japan
  • L.Y. Bartnik, M.G. Billing, J.V. Conway, M.J. Forster, Y.L.P. Fuentes, J.P. Shanks, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V.V. Bleko, A.S. Konkov, A. Potylitsyn
    TPU, Tomsk, Russia
  • L. Bobb
    DLS, Oxfordshire, United Kingdom
  • P. Karataev, K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
  • P. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
 
  We present recent results on non-invasive beam profile measurement techniques based on Diffraction Radiation (DR) and Cherenkov Diffraction Radiation (ChDR). Both methods exploit the analysis of broadband electromagnetic radiation resulting from polarization currents produced in, or at the boundary of, a medium in close proximity of a charged particle beam. To increase the resolution of DR, measurements were performed in the UV range at a wavelength of 250 nm. With such configurations, sensitivity to the beam size of a 1.2 GeV electron beam below 10 um was observed at the Accelerator Test Facility (ATF) at KEK, Japan. In the case of the ChDR, a proof of principle study was carried out at the Cornell Electron Storage Ring (CESR) where beam profiles were measured in 2017 on a 5.3 GeV positron beam. At the time of writing an experiment to measure the resolution limit of ChDR has been launched at ATF where smaller beam sizes are available. We will present experimental results and discuss the application of such techniques for future accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB14  
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WEPB15 A Multipurpose Scintillating Fibre Beam Monitor for the Measurement of Secondary Beams at CERN 468
 
  • I. Ortega Ruiz, L. Fosse, J. Franchi, A. Frassier, J. Fullerton, J. Kral, J. Lauener, T. Schneider, J. Spanggaard, G. Tranquille
    CERN, Geneva, Switzerland
 
  A scintillating fibre beam monitor has been developed at CERN for the measurement of low energy and low intensity secondary beams. This monitor can track the passage of individual particles up to intensities of 107 particles per second per mm2, over an active area of 20 cm x 20 cm, and with a spatial resolution of 1 mm. Thanks to an external trigger system, the achieved detection efficiency is 95% and the noise level is kept below 10-4 events/second. The simple design of this monitor avoids the common production difficulties of scintillating fibre detectors and makes its maintenance easier, when compared to other tracking detectors, due to the absence of gas or cooling. Using special electronics, a version of the monitor can also be used for time-of-flight measurements, achieving a time resolution of 900 ps. Thanks to its versatility, the monitor will perform several functions when measuring the secondary beams of the CERN Neutrino Platform: beam profile, position and intensity measurement, magnetic momentum spectrometry, particle identification through time-of-flight, and trigger generation for the experiments.  
poster icon Poster WEPB15 [1.172 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB15  
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WEPB16 Development of a Beam-Gas Curtain Profile Monitor for the High Luminosity Upgrade of the LHC 472
 
  • R. Veness, M. Ady, N. Chritin, J. Glutting, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider
    CERN, Geneva, Switzerland
  • P. Forck, S. Udrea
    GSI, Darmstadt, Germany
  • A. Salehilashkajani
    The University of Liverpool, Liverpool, United Kingdom
  • P. Smakulski
    WRUT, Wroclaw, Poland
  • C.P. Welsch, H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  High luminosity upgrades to the LHC at CERN and future energy frontier machines will require a new generation of minimally invasive profile measurement instruments. Production of a dense, focussed gas target allows beam-gas fluorescence to be exploited as an observable, giving an instrument suitable for installation even in regions of high magnetic field. This paper describes the development of a device based on these principles that would be suitable for operation in the LHC. It focusses on mechanisms for the production of a homogeneous gas curtain, the selection of an appropriate working gas and the optical fluorescence detection system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB16  
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WEPB18 Performance of a Reflective Microscope Objective in an X-ray Pinhole Camera 477
 
  • L. Bobb, G. Rehm
    DLS, Oxfordshire, United Kingdom
 
  X-ray pinhole cameras are used to measure the transverse beam profile of the electron beam in the storage ring from which the emittance is calculated. As improvements to the accelerator lattice reduce the beam emittance, e.g. with upgrades to fourth generation synchrotron light sources, likewise the beam size will be reduced such that micron and sub-micron scale resolution is required for beam size measurement. Therefore the spatial resolution of the pinhole camera imaging system must be improved accordingly. Here, the performance of a reflective microscope objective is compared to the high quality refractive lens which is currently in use to image the scintillator screen to the camera. The modulation transfer functions for each system have been assessed and will be discussed.  
poster icon Poster WEPB18 [0.751 MB]  
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WEPB20 Experimental Setup of Apodization Techniques for Beam Diagnostics Performed at ELBE 482
 
  • B.G. Freeman, J. Gubeli, K. Jordan
    JLab, Newport News, Virginia, USA
  • P.E. Evtushenko
    HZDR, Dresden, Germany
 
  The ELBE (Electron Linac for beams with high Brilliance and low Emittance) facility in Dresden, Germany is a multipurpose user facility, which is also used for accelerator R&D purposes. The beam line was set up for transverse beam profile measurements, where the imaging system includes a series of three apodizers and five circular apertures. During beam operations both of these were changed remotely through automated LabView routines. The bunch structure and charge were varied to collect a series of images that were acquired automatically, and then stored for later analysis. Over 12,000 images were captured and then analyzed using software written at Jefferson Lab that runs ImageJ as it's main image processing library.  
poster icon Poster WEPB20 [0.357 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPB20  
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WEPB21 Transverse Beam Emittance Measurements with Multi-Slit and Moving-Slit Devices for LEReC 486
 
  • C. Liu, A.V. Fedotov, D.M. Gassner, X. Gu, D. Kayran, J. Kewisch, T.A. Miller, M.G. Minty, V. Ptitsyn, S. Seletskiy, A. Sukhanov, D. Weiss
    BNL, Upton, Long Island, New York, USA
  • A. Fuchs
    Ward Melville High School, Setauket- East Setauket, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Low Energy RHIC electron cooling (LEReC) [1] is the first bunched electron cooler, designed to cool low energy ion beams at RHIC. The beam quality, including the transverse beam emittance, is critical for the success of cooling. The transverse electron beam emittance was characterized with a multi-slit and moving-slit device at various locations in the beamline. The beam emittance measurement and analysis are presented in this report.
 
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WEPC02 Synchrotron Emittance Analysis Procedure at MedAustron 490
 
  • L. Adler, A. De Franco, F. Farinon, N. Gambino, G. Guidoboni, C. Kurfürst, S. Myalski, M.T.F. Pivi, C. Schmitzer, I. Strašík, A. Wastl
    EBG MedAustron, Wr. Neustadt, Austria
 
  MedAustron is a synchrotron based medical accelerator facility for particle therapy providing protons and carbon ions with clinical energies from 60 MeV to 250 MeV and 120 MeV/n to 400 MeV/n respectively. The facility features four irradiation rooms, three of which are dedicated to clinical operation and a fourth one to non-clinical research. Commissioning of all fixed lines has been completed for protons, while the commissioning for carbon ions and a proton gantry is ongoing. For the commissioning of carbon ions, precise measurements of the transverse beam emittance in the synchrotron are of importance, to minimize beam losses and to correct for possible emittance variations due to the different clinically relevant beam intensities defined by a degrader at the end of the Linac. The transverse beam emittance in the MedAustron synchrotron is measured via scraping at non-dispersive regions of the ring. The analysis procedure as well as emittance reconstruction accuracy for simulated data will be described in this paper, together with measurement results from the carbon commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC02  
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WEPC04 Setup for Beam Profile Measurements using Optical Transition Radiation* 494
 
  • J. Pforr, M. Arnold, T. Bahlo, L.E. Jürgensen, N. Pietralla, A. Rost
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
 
  Funding: *Work supported by DFG through GRK 2128.
The S-DALINAC is a thrice-recirculating, superconducting linear electron accelerator at TU Darmstadt. It can provide beams of electrons with energies up to 130 MeV and currents of 20 µA. The accelerator performance was improved by an extension of the beam diagnostics, as this increases the reproducibility of the machine settings. Therefore, the installation of several beam profile measurement stations is planned, which should be operational down to a beam current of 100 nA, as this current is used for beam tuning. Combining these devices with a quadrupole scan also allows for emittance measurements. The beam profile measurements shall be done based on optical transition radiation (OTR), resulting from the penetration of relativistic electrons from vacuum into a metal target. The radiation can be detected using standard cameras that provide information on the two-dimensional particle distribution. This contribution will address the layout of the measurement stations and a first test measurement will be presented.
 
poster icon Poster WEPC04 [1.189 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC04  
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WEPC05 The European XFEL Wire Scanner System 498
 
  • T. Lensch, S. Liu, M. Scholz
    DESY, Hamburg, Germany
 
  The European-XFEL (E-XFEL) is an X-ray Free Electron Laser facility located in Hamburg (Germany). The superconducting accelerator for up to 17.5 GeV electrons will provide photons simultaneously to several user stations. Currently 12 Wire Scanner units are used to image transverse beam profiles in the high energy sections. These scanners provide a slow scan mode which is currently used to measure beam emittance and beam halo distributions. When operating with long bunch trains (>100 bunches) also fast scans are planned to measure beam sizes in an almost nondestructive manner. Scattered electrons can be detected with regular Beam Loss Monitors (BLM) as well as dedicated wire scanner detectors. Latter are installed in different variants at certain positions in the machine. Further developments are ongoing to optimize the sensitivity of the detectors to be able to measure both, beam halo and beam cores within the same measurement with the same detector. This paper describes the current status of the system and examples of different slow scan measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC05  
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WEPC06 The New Diagnostic Suite for the Echo Enabled Harmonic Generation Experiment at FERMI 501
 
  • M. Veronese, A. Abrami, E. Allaria, M. Bossi, I. Cudin, M.B. Danailov, R. De Monte, M. Ferianis, F. Giacuzzo, S. Grulja, G. Kurdi, P. Rebernik Ribič, R. Sauro, G. Strangolino
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  The Echo Enabled Harmonic Generation (EEHG) experiment has been implemented on the FEL2 line of the FERMI FEL at Elettra (Italy). The main purpose is to validate the expected performance improvements at short wavelengths before a dedicated major upgrade is deployed. This paper describes the new diagnostics and the operational experience with them during the EEHG experiment. By means of a multi position vacuum vertical manipulator, different optical components are positioned on the electron and seed laser path. Both transverse and longitudinal measurements are performed. A YAG:Ce screen (e beam) and a terbium doped UV scintillator (laser) are imaged on a dedicated CMOS camera. For the temporal alignment, an OTR screen and a scattering surface are used to steer radiation from the e-beam and laser, onto a fast photodetector. Also coherent OTR radiation, due to micro-bunching, is acquired by means of a PbSe photodetector. Finally, for the normal EEHG operation, the laser beam is injected on the electron beam axis by means of a UV reflecting mirror. The results of the installed diagnostics commissioning are here presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC06  
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WEPC08 Optical System of Beam Induced Fluorescence Monitor Toward MW Beam Power at the J-PARC Neutrino Beamline 505
 
  • S.V. Cao, M.L. Friend, K. Sakashita
    KEK, Tsukuba, Japan
  • M. Hartz
    Kavli IPMU, Kashiwa, Japan
  • A. Nakamura
    Okayama University, Okayama, Japan
 
  A Beam Induced Fluorescence (BIF) monitor is being developed as an essential part of the monitor update toward MW beam power operation at the J-PARC neutrino beamline. By measuring the fluorescence light from proton-gas interactions, the BIF monitor will be used as a continuous and non-destructive diagnostic tool for monitoring the proton beam profile spill-by-spill, with position and width precision on the order of 200 µm. The main challenge lies in collecting a sufficient amount of fluorescence light for the beam profile reconstruction while controlling the beam-induced noise with the current beamline configuration. A study is presented with a particular focus on the optical system under development, which allows us to transport fluorescence light away from the high radiation environment near the proton beamline and detect the optical signal with a Multi-Pixel Photon-Counter-based fast readout.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC08  
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WEPC09 Design and Test Results of a Double-Slit Emittance Meter at XiPAF 509
 
  • W. Wang, X. Guan, W.-H. Huang, X.W. Wang, Q.Z. Xing, S.X. Zheng
    TUB, Beijing, People's Republic of China
  • M.T. Qiu, D. Wang, Z.M. Wang, C.Y. Wei
    NINT, Shannxi, People's Republic of China
 
  Xi'an Proton Application Facility (XiPAF) is composed of a linac injector, a 230-MeV synchrotron and a high energy transport line. To study the beam dynamics along beamline, a double-slit emittance meter is used to measure beam phase space in the linac. To have knowledge of phase space upstream of the emittance meter, an inverse transport method is proposed in the presence of space charge. The design and preliminary test results of the emittance meter are shown in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC09  
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WEPC15 Machine Learning Applied to Predict Transverse Oscillation at SSRF 512
 
  • B. Gao, J. Chen, Y.B. Leng, Y.M. Zhou
    SINAP, Shanghai, People's Republic of China
 
  A fast beam size diagnostic system has been developed at SSRF (Shanghai Synchrotron Radiation Facility) storage ring for turn-by-turn and bunch-by-bunch beam transverse oscillation study. This system is based on visible synchrotron radiation direct imaging system. Currently, this system already has good experimental results. However, this system still has some limitations, the resolution is subject to the point spread function and the speed of online data processing is limited by the complex algorithm. We present a technique that applied machine learning tools to predict transverse oscillation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC15  
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WEPC16 Design and Radiation Simulation of the Scintillating Screen Detector for Proton Therapy Facility 516
 
  • P. Tian, Q.S. Chen, K. Fan, J.Q. Li, K. Tang
    HUST, Wuhan, People's Republic of China
 
  A proton therapy facility based on a superconducting cyclotron is under construction in Huazhong University of Science and Technology (HUST). In order to achieve precise treatment or dose distribution, the beam current would vary from 0.4 nA to 500 nA, in which case conventional non-intercepting instruments would fail due to their low sensitivity. So we propose to use a retractable scintillating screen to measure beam position and beam profile. In this paper, a comprehensive description of our new designed screen monitor is presented, including the choice of material of the screen, optical calibration and simulation of radiation protection. According to the off-line test, the resolution of the screen monitor can reach 0.13 mm/pixel.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC16  
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WEPC17 X-ray Pinhole Camera in the Diagnostics Beamlime BL7B at PLS-II 519
 
  • J.J. Ko, J.Y. Huang, D. Kim, D.W. Lee, B.H. Oh, S. Shin, J. U. Yu
    PAL, Pohang, Kyungbuk, Republic of Korea
  • M. Yoon
    POSTECH, Pohang, Kyungbuk, Republic of Korea
 
  The beam diagnostics beamline BL7B using synchrotron radiation with 8.6 keV critical photon energy from bending magnet has been used to measure the electron-beam size and photon-beam profile on real-time basis. After the completion of the PLS-II, the Compound Refractive Lens (CRL) system was implemented in the optical hutch at BL7B to measure the electron-beam size from X-ray imaging. But we could not have a good image due to short focal length caused by limited space of the optical hutch. To solve this problem a Pinole Camera is implemented in the front-end of BL7B in return for the beamline extension. The progresses on the new x-ray imaging system is introduced in this presentation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC17  
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WEPC19 Selection of Wires for the New Generation of Fast Wire Scanners at CERN 523
 
  • A. Mariet, R. Veness
    CERN, Geneva, Switzerland
 
  A new generation of fast wire scanners is being produced as part of the LHC Injector Upgrade (LIU) project at CERN. The LIU beam parameters imply that these wire scanners will need to operate with significantly brighter beams. This requires wires scanner systems with micron level accuracy and wires with a considerably increased tolerance to beam damage. This paper presents the method of selection of such wires in terms of material choice and geometry. It also reports on studies with novel materials with a potential to further extend the reach of wire scanners for high brightness beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEPC19  
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THOA03 Progress on Transverse Beam Profile Measurement Using the Heterodyne Near Field Speckles Method at ALBA 538
 
  • S. Mazzoni, F. Roncarolo, G. Trad
    CERN, Geneva, Switzerland
  • U. Iriso, C. Kamma-Lorger, A.A. Nosych
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • M.A.C. Potenza
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • M. Siano
    Università degli Studi di Milano, Milano, Italy
 
  We present the recent developments of a study aiming at measuring the transverse beam profile using the Heterodyne Near Field Speckles (HNFS) method. The HNFS technique consists of a suspension of nanoparticles suspended in a liquid and illuminated by synchrotron radiation (either in the visible or in X-ray wavelength range). The transverse coherence of the source, and therefore, under the conditions of validity of the Van Cittert and Zernike theorem, the transverse electron beam size is retrieved from the interference between the transmitted beam and the spherical waves scattered by each nanoparticle. We here describe the fundamentals of this technique, as well as the recent experimental results obtained with 12 keV radiation at the NCD beamline at ALBA. The applicability of such technique for future accelerators (e.g. CLIC or FCC) is also discussed.  
slides icon Slides THOA03 [2.414 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-THOA03  
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