Keyword: FEL
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MOPP019 Development and Evaluation of an Alternative Sensor Lifetime Enhancement Technique Used with the Online-Radiation-Monitoring System (DosiMon) at the European XFEL at DESY, Hamburg radiation, operation, electron, controls 121
 
  • F. Schmidt-Föhre, S. Arab, D. Nölle, R. Susen
    DESY, Hamburg, Germany
 
  The European XFEL (E-XFEL), that started operation in September 2017 at the DESY/XFEL site in Hamburg/Germany uses a single-tunnel concept, forcing all frontend machine devices and electronics to be located inside the accelerator tunnel. Electro-magnetic showers, mainly produced by gun dark-current, RF cavity field-emission and beam-losses expose these devices to damaging irradiation. The new Online-Radiation-Monitoring-System (DosiMon) is mainly used for surveillance of radiation sensitive permanent magnet structures, diagnostic devices and rack-housed electronics. The integrated dose from Gamma- and optional future Neutron-radiation measurements can be monitored online by the DosiMon system. Safety limits ensure the correct function of monitored devices, provided by lifecycle estimations as measures for on time part exchange, to prevent significant radiation damage. A first expansion state currently enables more than 500 gamma measuring points. The development of a new sensor lifetime enhancement technique for the utilized RadFet sensors is presented together with corresponding evaluation measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP019  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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MOPP020 First Tests Using Sipm Based Beam Loss Monitors at the European XFEL undulator, detector, photon, radiation 126
 
  • T. Wamsat, P.A. Smirnov
    DESY, Hamburg, Germany
 
  The European XFEL MTCA based Beam Loss Monitor System (BLM) is composed of about 450 monitors using photomultiplier tubes (PMTs). BLMs installed in the SASE undulator intersections show high signals at electron energy higher 16 GeV or photon energy higher 14 keV due to background synchrotron radiation which directly affects the PMT. The amplitude of this signal can get that high that, also without using any scintillating material, the BLMs get blind for real losses. Also different lead arrangements did not shield the signal sufficiently. First tests show that a Silicon photomultiplier (SiPM) is not affected. Also there are several advantages to use SiPM, they are cheaper by factor of 40 and operating voltage is below 45V. First test will be presented and how it can get implemented in the existing BLMs and BLM system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP020  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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MOPP035 Electron Beam Diagnostics Concept for the LWFA Driven FEL at ELI-Beamlines electron, diagnostics, cavity, plasma 185
 
  • K.O. Kruchinin, D. Kocon, A.Y. Molodozhentsev
    ELI-BEAMS, Prague, Czech Republic
  • A. Lyapin
    JAI, Egham, Surrey, United Kingdom
 
  Uniquely short high energy electron bunches produced by compact Laser Wakefield Accelerators (LWFA) are attractive for the development of new generation Free Electron Lasers (FEL). Although the beam quality of LWFA is still significantly lower than provided by conventional accelerators, with persistent progress seen in the area of laser plasma acceleration, they have a great potential to be considered the new generation drivers for FELs and even colliders. A new LWFA based FEL project called "LUIS" is currently being commissioned at ELI-beamlines in Czech Republic. LUIS aims to demonstrate a stable generation of X-ray photons with a wavelengths of 6 nm and lower, suitable for user applications. Electron beam diagnostics are absolutely crucial for achieving LUIS’s aims. Low charge, poor beam stability and other beam properties inherent for a LWFA require rethinking and adaptation of the conventional diagnostic tools and, in some cases, development of new ones. In this paper we provide an overview of the electron beam instrumentation in LUIS with a focus on the current challenges and some discussion of the foreseen future developments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP035  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUBO02 FERMI-PSI Collaboration on Nano-Fabricated Wire-Scanners With Sub-Micrometer Resolution: Developments and Measurements. electron, experiment, operation, emittance 243
 
  • G.L. Orlandi, S. Borrelli, Ch. David, E. Ferrari, V. Guzenko, B. Hermann, O. Huerzeler, R. Ischebeck, C. Lombosi, C. Ozkan Loch, E. Prat
    PSI, Villigen PSI, Switzerland
  • N. Cefarin, S. Dal Zilio, M. Lazzarino
    IOM-CNR, Trieste, Italy
  • M. Ferianis, G. Penco, M. Veronese
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  Wire-scanners with micrometer resolution are in operation at SwissFEL and FERMI for measurements of the beam emittance and for beam profile monitoring (*,**). In addition, both laboratories are developing and testing innovative nano-fabricated wire-scanners capable of providing sub-micrometer resolution and being quasi non-destructive to the beam. Nano-fabricated wire-scanners with a free-standing design (***) and a sub-micrometer resolution (****) has been already successfully tested. In the present work, innovative nano-fabricated wire-scanners joining both features of a free-standing design and sub-micrometer resolution are presented. Experimental tests carried out at SwissFEL demonstrated the capability of such innovative wire-scanner solutions to resolve transverse profiles of the electron beams with a size of 400-500 nm without incurring in any resolution limit constraint and with a minimal beam perturbation. An overview on current status and results along with future developments of these nano-fabricated wire-scanners are here presented.
(*)G.L.Orlandi et al. PRAB 19, 092802 (2016).
(**)M.Veronese et al.this Conference.
(***)M.Veronese et al.NIM-A 891, 32-36, (2018)
(****)S.Borrelli et al. Comm. Phys.-Nature, 1, 52 (2018).
 
slides icon Slides TUBO02 [10.551 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUBO02  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUPP001 KALYPSO: Linear Array Detector with Continuous Read-Out at MHz Frame Rates detector, electron, radiation, laser 266
 
  • C. Gerth, B. Steffen
    DESY, Hamburg, Germany
  • M. Caselle, L. Rota
    KIT, Karlsruhe, Germany
  • D.R. Makowski, A. Mielczarek
    TUL-DMCS, Łódź, Poland
 
  The novel linear array detector KALYPSO has been developed for beam diagnostics based on 1-dimensional profile measurements at high-repetition rate free-electron lasers (FEL) and synchrotron radiation facilities. The current version of KALYPSO has 256 pixels with a maximum frame rate of 2.7~MHz. The detector board, which comprises the radiation sensor, analog signal amplification, and analog-to-digital signal conversion, has been designed as a mezzanine card that can be plugged onto application-specific carrier boards for data pre-processing and transmission. Either a Si or InGaAs sensor can be mounted for the detection of visible or near infrared radiation. Results obtained in several beam diagnostics applications at the European XFEL and FLASH are presented to demonstrate the powerful capabilities of the KALYPSO detector.
* The KAYLYPSO detector is a collaboration between the Karlsruhe Institute of Technology, Paul Scherrer Institut, Łódź University of Technology, and Deutsches-Elektronen Synchrotron.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP001  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUPP002 Direct-Sampling Coarse Bunch Arrival Time Monitor in the Free Electron Laser FLASH Based on the Fast Digitizer Implemented in the FMC VITA 57.1 Standard pick-up, electron, timing, laser 270
 
  • J. Zink, M.K. Czwalinna, M. Fenner, S. Jabłoński, J. Marjanovic, H. Schlarb
    DESY, Hamburg, Germany
  • F. Gerfers
    Technische Universität Berlin, Berlin, Germany
 
  At the free-electron lasers FLASH and European-XFEL bunch arrival times are monitored with a high-accuracy electro-optical based data acquisition system (BAM). Due to only a couple of picoseconds time measurement range of this system, large timing changes might cause the monitor to fail. To remove any ambiguity and for health status monitoring a high-speed direct-sampling FPGA mezzanine card (FMC) and an analogue RF front-end was added. The circuitry has lower precision than the electro-optical based BAM, but it can determine bunch arrival time with respect to a reference signal over a large time range, i.e. of the order of 1 ms. After restarts or larger energy changes during operation, the electron bunch arrival time may have been changed by tens or even hundreds of picoseconds, which causes that the BAM is out of its operation range and needs to be recalibrated. With the solution developed, the BAM gets the coarse bunch timing from the digitizer and adjusts its optical delay lines accordingly. This allows for finding the operation point fast and automatically. Performance data of the fast direct-sampling digitizer FMC and first measurement data from FLASH will be presented.  
poster icon Poster TUPP002 [3.810 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP002  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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TUPP010 A Fast Wire Scanner System for the European XFEL timing, operation, detector, optics 299
 
  • T. Lensch, B. Beutner, T. Wamsat
    DESY, Hamburg, Germany
 
  The European-XFEL is an X-ray Free Electron Laser facility located in Hamburg (Germany). The 17.5 GeV superconducting accelerator will provide photons simultaneously to several user stations. Currently 14 Wire Scanner stations are used to image transverse beam profiles in the high energy sections. These scanners provide a slow scan mode for beam halo studies and beam optics matching. When operating with long bunch trains (>100 bunches) fast scans will be used to measure beam sizes in an almost non-destructive manner. This paper briefly describes the wire scanner setup and focusses on the fast scan concept and first measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP010  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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TUPP011 Observation of Scintillators Charging Effects at the European XFEL electron, diagnostics, operation, site 303
 
  • A.I. Novokshonov, B. Beutner, G. Kube
    DESY, Hamburg, Germany
  • S.A. Strokov
    TPU, Tomsk, Russia
 
  Scintillating screens are widely used for beam profile diagnostics at various kinds of particle accelerators. At modern linac based electron machines with ultrashort bunches as the European XFEL in Hamburg (Germany), scintillators help to overcome the limitation of standard OTR based monitors imposed by the emission of coherent radiation. The XFEL injector section is equipped with four off-axis screens allowing to perform online beam profile diagnostics, i.e. a single bunch out of a bunch train is kicked onto the screen and the profile is analyzed. However, during user operation a decrease of the SASE level was observed in cases that one of the of-axis screens was used. The observation is explained by charging of the scintillator screen: each deflected bunch hitting the screens causes ionization and charging of the screen. The scintillator as good insulator keeps the charge for some time such that the non-deflected part of the bunch-train feels their Coulomb force and experiences a kick, resulting in a drop of the SASE level. This report summarizes the observations at the European XFEL and introduces a simple model for quantification of this effect.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP011  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUPP014 New Combined Function Wire Scanner-Screen Station for the High Resolution Transverse Profile Measurements at FERMI electron, vacuum, operation, laser 317
 
  • M. Veronese, A. Abrami, M. Bossi, M. Ferianis, S. Grulja, G. Penco, M. Tudor
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  We present the upgrade of the transverse profile diagnostics at the end of the FERMI Linac with a new high resolution instrumentation with the aim of improving the accuracy of the measurement of the twiss parameters and of the emittance. A scintillating screen, has been adopted instead of OTR screen due to known COTR issues. We used the same COTR suppression geometry that we had already implemented on our intra undulator screens and YAG:Ce as scintillating material. Screen based transverse profile diagnostics provide single shot measurements with a typical resolution of the order of tens of microns mainly due to refraction effects, geometry and other physical material properties. To extend the resolution to the micron level needed in case of low charge operation, we have equipped the same vacuum chamber with a wire scanner housing 10 micron tungsten wires. This paper describes the design and the first operational experience with the new device and discusses advantages as well as limitations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP014  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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TUPP041 Observations of Long-Range and Short-Range Wakefield Effects on Electron-Beam Dynamics in TESLA-type Superconducting RF Cavities cavity, HOM, wakefield, detector 423
 
  • A.H. Lumpkin, N. Eddy, D.R. Edstrom, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Fermilab Accelerator Science and Technology (FAST) facility has a unique configuration of a photocathode rf gun beam injecting two TESLA-type single cavities (CC1 and CC2) in series prior to the cryomodule. Beam propagation off axis in these cavities can result in both long-range and short-range transverse wakefields which can lead to emittance dilution within the macropulses and micropulses, respectively. Two configurations of a Hamamatsu C5680 streak camera viewing a downstream OTR screen were utilized to track centroid shifts during the macropulse (framing mode) for the long-range case and during the micropulse for the short-range case (~10-micron spatial resolution and 2-ps temporal resolution). Steering off axis before CC1, resulted in a 100-kHz bunch centroid oscillation within the macropulse that was detected by the downstream rf BPMs and the streak camera*. At 500 pC/b, 50b, and 4-mrad off-axis vertical steering into CC2, we observed an ~ 100-micron head-tail centroid shift in the streak camera image y(t) profiles which we attributed to a short-range wakefield effect. Additional results for kick-angle compensations and model results will be presented.
*A.H. Lumpkin et al., Phys. Rev. Accel. and Beams 21,064401 (2018).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP041  
About • paper received ※ 10 September 2019       paper accepted ※ 11 September 2019       issue date ※ 10 November 2019  
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WEAO01 Technological Review of Beam Position Button Design and Manufacture resonance, electron, electronics, SRF 445
 
  • A.F.D. Morgan
    DLS, Oxfordshire, United Kingdom
 
  A workshop in May 2019, hosted by DLS (UK), reviewed both the design and the manufacturing aspects of beam position monitor (BPM) pick-up buttons with an integrated UHV feedthrough and coaxial connector. The UHV feedthrough technology (e.g. ceramic brazing vs glass-sealing), the limits on mechanical tolerances, reproducibility and material choices for high reliability were examined by more than 20 diagnostics users of these devices and a number of reputed manufacturers. Calibration techniques and tools and methods for inspection & testing were also assessed. This talk will present the outcome & conclusions of this workshop and identify challenges and opportunities for future BPM manufacture.  
slides icon Slides WEAO01 [1.824 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEAO01  
About • paper received ※ 05 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEAO02 Pile-Up Effect of Cold Button BPMs in the European XFEL Accelerator resonance, cavity, electron, electronics 450
 
  • D. Lipka, B. Lorbeer
    DESY, Hamburg, Germany
 
  The European XFEL facility is in operation with a maximum of 2700 bunches in one train. The highest bunch repetition rate is 4.5 MHz; this corresponds to a minimum time separation of 222 ns. The measurement of the beam properties for each bunch in a train is required. Therefore the beam position monitor (BPM) system needs to separate the signals from each bunch. All BPM types (button, re-entrant and cavity) fulfill this requirement except a few button BPMs installed inside of the cold accelerator module, where Pile-Up from the train can be observed. To identify the cause of this effect we measured the S-parameters during a shutdown of the accelerator, compared it with a similar BPM at the FLASH accelerator but located in a warm section and finally measured the spectrum of the button signal during beam operation. As a result, resonances were found at about 2.46 GHz with relatively high quality factor that remains within the frequency range accepted by the electronics.  
slides icon Slides WEAO02 [5.621 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEAO02  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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WEPP019 Concept of a Novel High-Bandwidth Arrival Time Monitor for Very Low Charges as a Part of the All-Optical Synchronization System at ELBE pick-up, laser, electron, FEM 553
 
  • A. Penirschke
    THM, Friedberg, Germany
  • W. Ackermann
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M.K. Czwalinna, H. Schlarb
    DESY, Hamburg, Germany
  • M. Kuntzsch
    HZDR, Dresden, Germany
 
  Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05K19RO1.
Numerous advanced applications of X-ray free-electron lasers require pulse durations and time resolutions in the order of only a few femtoseconds or better. The generation of these pulses to be used in time-resolved experiments require synchronization techniques that can simultaneously lock all necessary components to a precision in the range of a few fs only. The CW operated electron accelerator ELBE at the Helmholtzzentrum Dresden Rossendorf uses a all-optical synchronization system to ensure a timing stability on the few 10 fs scale. ELBE requires a minimum beam pipe diameter of 43mm that limits the achievable output voltage of the pickup structure to drive the attached electro-optical modulator. This contribution presents a concept for a novel high-bandwidth arrival time monitor with sufficient output signal for the attached EOMs for very low charges as a part of the all-optical synchronization system at ELBE.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP019  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP026 Electron Bunch Compression Monitors for Short Bunches - Commissioning Results from SwissFEL electron, linac, detector, radiation 571
 
  • F. Frei, R. Ischebeck
    PSI, Villigen PSI, Switzerland
 
  In SwissFEL, by using three magnetic chicanes, 3ps long electron bunches can by compressed by a factor of more than 100 down to a few fs in order to generate ultra short X-ray pulses. In order to meet the envisaged beam performance, noninvasive longitudinal diagnostic after each compression stage is essential. These bunch compression monitors measure relative bunch length changes on a shot-to-shot basis by detecting coherent edge, synchrotron or diffraction radiation emitted by the electron bunches. While after the first two magnetic chicanes, a wide spectral part is integrated on a single broadband detector, an infrared spectrometer installed after the third magnetic chicane is providing more detailed information. Here, we will mainly report on commissioning results of the third bunch compression monitor for electron bunches of a few fs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP026  
About • paper received ※ 03 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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