Keyword: laser
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MOCYB3 Longitudinal Laser Wire at SNS ion, background, electron, controls 12
 
  • A.P. Zhukov, A.V. Aleksandrov, Y. Liu
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
This paper describes a longitudinal H− beam profile scanner that utilizes laser light to detach convoy electrons and an MCP to collect and measure these electrons. The scanner is located in MEBT with H− energy of 2.5MeV and an RF frequency 402.5MHz. The picosecond pulsed laser runs at 80.5MHz in sync with the accelerator RF. The laser beam is delivered to the beam line through a 30m optical fiber. The pulse width after the fiber transmission measures about 10ps. Scanning the laser phase effectively allows measurements to move along ion bunch longitudinal position. We are able to reliably measure production beam bunch length with this method. The biggest problem we have encountered is background signal from electrons being stripped by vacuum. Several techniques of signal detection are discussed. 		 
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MOCZB2 Reference Distribution and Synchronization System for SwissFEL: Concept and First Results timing, detector, LLRF, controls 29
 
  • S. Hunziker, V.R. Arsov, F. Buechi, M.G. Kaiser, A. Romann, V. Schlott
    PSI, Villigen PSI, Switzerland
  • P. Orel, S. Zorzut
    I-Tech, Solkan, Slovenia
  
  The development of the reference distribution and synchronization system for SwissFEL is driven by ultra-high reference signal stability of SwissFEL LLRF-, beam arrival time monitors (BAM) and laser systems on one hand and cost issues, high reliability/availability and flexibility on the other. Key requirements are down to sub-10fs rms short term as well as sub-10fs peak-peak long term temporal stability for the most critical clients. The system essentially consists of an optical master oscillator with a fiber power amplifier and splitter, from which mutually phase locked optical reference pulses as well as RF reference signals are derived. The former are directly transmitted to the pulsed laser and BAM clients over group delay stabilized fiber-optic links whereas the latter are transmitted via newly developed group delay stabilized radio-over-fiber (RoF) links. Both s- and c-band reference signals use s-band RoF links, whereupon the c-band receiver incorporates an additional ultra-low drift frequency doubler. Furthermore, ultra-low jitter analog laser phase lock loops have been built and digital ones are under development. We will present concepts and first results of sub-10fs rms jitter and 20fs peak-peak long term drift subsystems, as e.g. RoF links, tested in the SwissFEL injector test facility.  
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MOCZB3 Comparison of Feedback Controller for Link Stabilizing Units of the Laser Based Synchronisation System used at the European XFEL controls, feedback, timing, electron 34
 
  • M. Heuer, S. Pfeiffer, H. Schlarb
    DESY, Hamburg, Germany
  • G. Lichtenberg
    HAW, Hamburg, Germany
  
  The European X-ray Free Electron Laser will allow scientists to perform experiments with an atomic scale resolution. To perform time resolved experiments at the end of the facility it is essential to provide a highly stable clock signal to all subsystems. The accuracy of this signal is extremely important since it defines limitations of precise measurement devices. A laser based synchronization system is used for the synchronization with an error in sub-femtosecond range. These light pulses are carried by an optical fiber and exposed to external disturbances which changes the optical length of the fiber. For that reason the up to 4 kilometer long fibers are actively stabilized using a controller implemented on the new MicroTCA Platform. Due to the high computation resources of this platform it is possible to attack the time delay of the link system with well known model based feedback control strategies. This contribution shows the design of a model based controller for such a system and compares the control performance of the previously used PID controller with advanced control algorithms at the currently installed laboratory setup.  
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MOPF15 Status of and Future Plans for the CERN LINAC4 Emittance Meter based on Laser Electron-Detachment and a Diamond Strip-Detector detector, linac, emittance, electron 83
 
  • T. Hofmann, E. Bravin, U. Raich, F. Roncarolo, F. Zocca
    CERN, Geneva, Switzerland
  • G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin
    Royal Holloway, University of London, Surrey, United Kingdom
  • E. Griesmayer
    CIVIDEC Instrumentation, Wien, Austria
  
  Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191
LINAC4 has started its staged commissioning at CERN. After completion it will accelerate high brightness H− beams to 160 MeV. To measure the transverse profile and emittance of the beam, a non-destructive method based on electron photo-detachment is proposed, using a pulsed, fibre-coupled laser to strip electrons from the H− ions. The laser can be focused and scanned through the H− beam, acting like a conventional slit. A downstream dipole separates the neutral H0 beamlet, created by the laser interaction, from the main H− beam, so that it can be measured by a diamond strip-detector. Combining the H0 beamlet profiles with the laser position allows the transverse emittance to be reconstructed. A prototype of this instrument was tested while commissioning the LINAC4 at 3 and 12 MeV. In this paper we shall describe the experimental setup, challenges and results of the measurements, and also address the characteristics and performance of the diamond strip-detector subsystem. In addition, the proposal for a permanent system at 160 MeV, including an electron detector for a direct profile measurement, will be presented. 		 
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MOPF22 Simultaneous Operation of Two FEL Undulator Beamlines at FLASH undulator, FEL, electron, operation 103
 
  • S. Ackermann, V. Ayvazyan, B. Faatz, E. Hass, K. Klose, S. Pfeiffer, M. Scholz, S. Schreiber
    DESY, Hamburg, Germany
  
  The FLASH FEL User Facility at DESY (Hamburg) is driven by a Photocathode RF gun and superconducting RF structures, producing up to 800 electron bunches per train with a repetition rate of 10 Hz. Because not all user experiments need the full pulse train (8000 FEL pulses per second), part of the electron bunches can be deflected into a second beamline, which can simultaneously deliver FEL pulses with different parameters to a second user experiment. To realize this possibility, the FLASH facility has been upgraded with a second undulator line and a second experimental Hall. In this contribution, we will present the new layout of the FLASH facility and the first results to operate it with different parameter sets. We will show present results achieved during the commissioning of the new beamline. Finally, we will give an outlook of further commissioning plans and user operation.
S. Ackermann for the FLASH II Team 		 
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MOPF27 Simulation and First Results of the ELBE SRF Gun II gun, SRF, simulation, cavity 106
 
  • P.N. Lu, A. Arnold, U. Lehnert, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
    HZDR, Dresden, Germany
  
  In Rossendorf, a 3 and one half cell cavity SRF photo injector has been installed, which promises to accelerate the electron beam to 9 MeV in 0.5 meter. The gun is expected to operate both in the 13 MHz mode with a bunch charge of 77 pC, or in the 500 kHz mode, with a 1 nC charge. The simulation presented in this contribution includes particle tracking in the new cavity itself with the ASTRA code, and in the bunch transport line in the ELBE beam lines with the elegant code. The measured profile and time structure of the UV laser on the cathode are utilized to specify the electron bunch parameters. Then a single bunch of electrons is tracked in the cavity field that was calculated by Superfish, with space charge effects considered. From the exit of the cavity, the electron bunch has a relatively high energy so we ignore the space charge effect there and apply elegant to track the particles through the magnet elements and accelerator modules. The main purpose of this simulation is to find the optimized parameters for different beam transport tasks. As a first experimental result of the photoinjector, energy and phase space measurement will be also presented in the paper. Both the slit mask and the quadrupole scan methods are applied to measure the beam emittance. An obvious progression will be to compare the results from this gun with those from the ELBE SRF gun I.  
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MOPD03 Performance and Upgrade of the Fast Beam Condition Monitor at CMS luminosity, electron, background, electronics 134
 
  • M. Hempel, H.M. Henschel, O. Karacheban, W. Lange, J.L. Leonard, M. Penno
    DESY Zeuthen, Zeuthen, Germany
  • K. Afanaciev
    NC PHEP BSU, Minsk, Belarus
  • A.I. Bell
    DLS, Oxfordshire, United Kingdom
  • P.R. Burtowy, A.E. Dabrowski, R. Loos, V. Ryjov, A.A. Zagozdzinska
    CERN, Geneva, Switzerland
  • W. Lohmann
    BTU, Cottbus, Germany
  • W. Lohmann, R. Walsh
    DESY, Hamburg, Germany
  • B.L. Pollack
    NU, Evanston, Illinois, USA
  • D. Przyborowski
    AGH, Cracow, Poland
  • S. Schuwalow
    Uni HH, Hamburg, Germany
  • D.P. Stickland
    PU, Princeton, New Jersey, USA
  
  The Fast Beam Condition Monitor BCM1F is a diamond based particle detector inside CMS. It is based on 8 single crystal CVD diamond sensors on both ends of the interaction point and is used for beam background and luminosity measurements. The system has been operated up to an integrated luminosity of 30fb-1, corresponding to a particle fluence of 8.78·1013 cm-2 (24GeV proton equivalent). To maintain the performance at a bunch spacing of 25ns and at the enhanced luminosity after the LHC Long Shutdown LS1, an upgrade of BCM1F is necessary. The upgraded system features 24 single crystal diamond sensors with a two pad metallization, a very fast front-end ASIC built with 130nm CMOS technology and new back-end electronics. A prototype of the upgraded BCM1F components were studied in the 5GeV electron beam at DESY. Measurements were done on the signal shape as function of time, the collection efficiency as a function of voltage and position of the impact point on the sensor surface. The preliminary results of this testbeam will be presented. In addition, the status of the new upgraded BCM1F will be given.  
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MOPD06 Electron Beam Diagnostics for Short Pulse FEL Schemes at CLARA electron, FEL, diagnostics, simulation 147
 
  • S. Spampinati, D. Newton
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • D. Newton
    The University of Liverpool, Liverpool, United Kingdom
  
  CLARA (Compact Linear Accelerator for Research and Applications) [1] is a proposed 250 MeV, 100-400 nm FEL test facility at Daresbury Laboratory. The purpose of CLARA is to test and validate new FEL schemes in areas such as ultra-short pulse generation, temporal coherence and pulse-tailoring. Some of the schemes that can be tested at CLARA depend on a manipulation of the electron beam properties with characteristic scales shorter than the electron beam and require a 30 - 50 μm modulation of the beam energy acquired via the interaction with an infrared laser beam in a short undulator. In this article we describe the electron beam diagnostics required to carry on these experiments.  
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MOPD07 New MTCA.4-based Hardware Developments for the Control of the Optical Synchronization Systems at DESY timing, controls, detector, LLRF 152
 
  • M. Felber, M.K. Czwalinna, H.T. Duhme, M. Fenner, C. Gerth, M. Heuer, T. Lamb, U. Mavrič, J.M. Mueller, P. Peier, H. Schlarb, S. Schulz, B. Steffen, C. Sydlo, M. Titberidze, T. Walter, R. Wedel, F. Zummack
    DESY, Hamburg, Germany
  • E. Janas
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  • T. Kozak, P. Prędki, K.P. Przygoda
    TUL-DMCS, Łódź, Poland
  • J. Szewiński
    NCBJ, Świerk/Otwock, Poland
  
  Funding: This work has partly been funded by the Helmholtz Validation Fund Project MTCA.4 for Industry (HVF-0016)
The optical synchronization group at DESY is operating and continuously enhancing their laser-based synchronization systems for various facilities which need femtosecond-stable timing. These include the free-electron lasers FLASH and the upcoming European XFEL as well as the electron diffraction machine REGAE and the plasma acceleration test facilities. One of the major upgrades under development is the migration of the entire electronic control hardware to the new MTCA.4 platform which was introduced as the new standard for accelerator control in many facilities worldwide. In this paper we present the applied modules and the topology of the new systems. Main advantages are a compact design with higher performance, redundancy, and remote management. 		 
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MOPD09 Longitudinal Phase Space Tomography Using a Booster Cavity at the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ) booster, electron, acceleration, gun 161
 
  • D. Malyutin, M. Groß, I.I. Isaev, M. Khojoyan, G. Kourkafas, M. Krasilnikov, B. Marchetti, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  
  One of the ways to measure the longitudinal phase space of the electron bunch in a linear accelerator is a tomographic technique based on measurements of the bunch momentum spectra while varying the bunch energy chirp. The energy chirp at PITZ can be controlled by varying the RF phase of the CDS booster – the accelerating structure installed downstream the electron source (RF gun). The resulting momentum distribution can be measured with a dipole spectrometer downstream. As a result, the longitudinal phase space at the entrance of the CDS booster can be reconstructed. In this paper the tomographic technique for longitudinal phase space measurements is described. Results of measurements at PITZ are presented and discussed.  
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MOPD10 New Results Of FERMI FEL1 EOS Diagnostics With Full Optical Synchronization FEL, electron, diagnostics, electronics 165
 
  • M. Veronese, E. Allaria, P. Cinquegrana, E. Ferrari, F. Rossi, P. Sigalotti, C. Spezzani
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • E. Ferrari
    Università degli Studi di Trieste, Trieste, Italy
  
  The Electro Optical Sampling diagnostics (EOS) of the FERMI FEL has been recently upgraded with a full optical synchronization of its dedicated femtosecond fiber laser to the ultra-stable optical pulsed timing system of FERMI. For this purpose a dual synchronization electronics has been developed and installed. It exploits a mixed error signal derived from both optical to electrical conversion and from a second harmonic generation based optical phase detection. For this second part a new optical setup including a cross correlator has been installed. The operation of the EOS has greatly benefited from the upgrade. The arrival time measurements have been compared with the ones from the bunch arrival monitor diagnostics (BAM) showing very good agreement. This new setup has also allowed to improve the bunch profile measurement. Some examples of measurement with ZnTe and GaP are presented. Finally, usability and operator friendliness of the new setup are also discussed.  
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MOPD11 Near-Saturation Single-Photon Avalanche Diode Afterpulse and Sensitivity Correction Scheme for the LHC Longitudinal Density Monitor photon, detector, synchrotron-radiation, synchrotron 169
 
  • M. Palm, E. Bravin, S. Mazzoni
    CERN, Geneva, Switzerland
  
  Funding: CERN
Single-Photon Avalanche Diodes (SPADs) monitor the longitudinal density of the LHC beams by measuring the temporal distribution of synchrotron radiation. The relative population of nominally empty RF-buckets (satellites or ghosts) with respect to filled bunches is a key figure for the luminosity calibration of the LHC experiments. Since afterpulsing from a main bunch avalanche can be as high as, or higher than, the signal from satellites or ghosts, an accurate correction algorithm is needed. Furthermore, to reduce the integration time, the amount of light sent to the SPAD is enough so that pile-up effects and afterpulsing cannot be neglected. The SPAD sensitivity has also been found to vary at the end of the active quenching phase. We present a method to characterize and correct for SPAD deadtime, afterpulsing and sensitivity variation near saturation, together with laboratory benchmarking. 		 
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MOPD12 Novel Femtosecond Level Synchronization of Titanium Sapphire Laser and Relativistic Electron Beams electron, polarization, plasma, timing 174
 
  • M. Titberidze, F.J. Grüner, A.R. Maier
    Uni HH, Hamburg, Germany
  • M. Felber, K. Flöttmann, T. Lamb, H. Schlarb, C. Sydlo
    DESY, Hamburg, Germany
  • F.J. Grüner, A.R. Maier, B. Zeitler
    CFEL, Hamburg, Germany
  • E. Janas
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  
  Laser driven plasma accelerators are offering high gradient (~ 10-100GV/m), high quality (low emittance, short bunch length) electron beams which can be suitable for future compact, bright and tunable light sources. In the framework of the Laboratory for Laser- and beam-driven plasma Acceleration (LAOLA) collaboration at Deutsches Elektronen-Synchrotron (DESY) the external injection experiment for injecting electron bunches from a conventional RF accelerator into the linear plasma wave is in progress. External injection experiments at REGAE (Relativistic Electron gun for Atomic Exploration) require sub-10 fs precision synchronization of laser and electron beams in order to perform a beam scan into the plasma wave by varying the delay between electron beam and laser pulses. In this paper we present a novel optical to microwave synchronization scheme, based on a balanced single output integrated Mach-Zehnder Modulator (MZM). The scheme offers a highly sensitive phase detector between a pulsed 800 nm Ti:Sa laser and a 3GHz microwave reference source. It is virtually independent of input laser power fluctuation and it offers femtosecond long-term precision. Together with the principal of operation of this setup, we will present promising preliminary experimental results of the detector stability.  
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MOPD15 CW Beam Stability Analysis in Time and Frequency Domain electron, diagnostics, high-voltage, radiation 179
 
  • M. Kuntzsch, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P. Michel, R. Schurig, J. Teichert
    HZDR, Dresden, Germany
  
  The superconducting quasi CW Linac ELBE has been characterized in terms of energy and timing stability. The measurement results presented show a combination of a laser-based bunch arrival-time measurements (BAM), a fast beam position monitor (BPM) readout with single bunch resolution and a compression monitor (BCM) based on a fast pyro-electric detector. By changing the bunch compression factor a separation and identification of jitter sources has been achieved. The quasi CW mode of operation enables frequency domain data analysis with high dynamic range, which gives a better understanding of the main sources of jitter. Experimental results for both injectors (thermionic DC, superconducting RF) are presented.  
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MOPD17 Single-Shot Electro-Optical Diagnostics at the ANKA Storage Ring storage-ring, wakefield, electron, operation 182
 
  • N. Hiller, A. Borysenko, E. Hertle, V. Judin, B. Kehrer, A.-S. Müller, M.J. Nasse, M. Schuh, P. Schönfeldt, N.J. Smale, J.L. Steinmann
    KIT, Karlsruhe, Germany
  • P. Peier, B. Steffen
    DESY, Hamburg, Germany
  • V. Schlott
    PSI, Villigen PSI, Switzerland
  
  Funding: This work is funded by the BMBF contract numbers: 05K10VKC, 05K13VKA.
ANKA is the first storage ring in the world with a near-field single-shot electro-optical (EO) bunch profile monitor. The method of electro-optical spectral decoding (EOSD) uses the Pockels effect to modulate the longitudinal electron bunch profile onto a long, chirped laser pulse passing through an EO crystal. The laser pulse is then analyzed with a single-shot spectrometer and from the spectral modulation, the temporal distribution can be extracted. The setup is tuned to a sub-ps resolution (granularity) and can measure down to bunch lengths of 1.5 ps RMS for bunch charges as low as 30 pC. With this setup it is possible to study longitudinal beam dynamics (e. g. microbunching) occurring during ANKA's low-alpha-operation, an operation mode with longitudinally compressed bunches to generate coherent synchrotron radiation in the THz range. In addition to measuring the longitudinal bunch profile, long-ranging wake-fields trailing the electron bunch can also be studied, hinting bunch-bunch interactions. 		 
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MOPD24 Diagnostics of and with Laser-Induced Energy Modulation at the DELTA Storage Ring electron, radiation, undulator, storage-ring 202
 
  • S. Khan, S. Hilbrich, H. Huck, M. Huck, M. Höner, C. Mai, A. Meyer auf der Heide, R. Molo, H. Rast, P. Ungelenk
    DELTA, Dortmund, Germany
  
  Funding: This work is supported by the BMBF (05K13PEC) and DFG (INST212/236-1) and by the Land NRW.
DELTA is a 1.5-GeV electron storage ring operated by the Center for Synchrotron Radiation at the TU Dortmund University. An interaction between electron bunches and femtosecond laser pulses is routinely used to generate ultrashort pulses of coherent synchrotron radiation at harmonics of the laser wavelength (coherent harmonic generation, CHG) as well as short and coherent pulses in the THz regime. The paper describes diagnostics methods to optimize the laser-electron overlap and to characterize the generated VUV and THz pulses. Furthermore, the laser-electron interaction can be employed as a beam diagnostics tool, e.g. to study the longitudinal steady-state bunch profile as well as dynamic properties during RF-phase modulation, which is applied to improve the beam lifetime. 		 
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MOPD25 Time Domain Pickup Signal characterization for Low Charge Arrival-Time Measurements at FLASH pick-up, simulation, operation, electron 209
 
  • A. Angelovski, R. Jakoby, A. Penirschke
    TU Darmstadt, Darmstadt, Germany
  • M.K. Czwalinna, H. Schlarb, C. Sydlo
    DESY, Hamburg, Germany
  • T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  For the low charge operation mode at the European XFEL, high bandwidth cone-shaped pickups were developed as a part of the Bunch Arrival-time Monitors (BAMs). The simulation showed that the signal parameters of interest, the signal slope and bandwidth are improved by more than a factor of six compared to the state of the art pickups. The pickups are installed at FLASH for verification. In this paper, time-domain measurements of the cone-shaped pickups at FLASH are presented. The pickup signal is recorded with a high bandwidth sampling oscilloscope. Two channel measurements are conducted with a single and a combined pickup signal in order to analyze the orbit and charge dependence of the pickup signal parameters. The measured time domain pickup signal wave form is compared to the CST PARTICLE STUDIO simulation.  
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TUCYB2 Pulsed Green Laser Wire System for Effective Inverse Compton Scattering electron, cavity, emittance, experiment 254
 
  • A.A. Rawankar, N. Terunuma, J. Urakawa
    Sokendai, Ibaraki, Japan
  • T. Akagi, A.S. Aryshev, Y. Honda, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • D. Jehanno
    LAL, Orsay, France
  • K. Sakaue
    Waseda University, Tokyo, Japan
  
  Funding: This work has been supported by the Quantum Beam Technology Program of the Japanese Ministry of Education, Culture, Sports, Science,and Technology(MEXT).
Laser-Compton scattering has become an important technique for beam diagnostics of the latest accelerators. In order to develop technologies for low emittance beams, an Accelerator Test facility (ATF) was built at KEK. It consists of an electron linac, a damping ring in which beam emittance is reduced, and an extraction line. For emittance measurement we are developing a new type of beam profile monitor which works on the principle of inverse Compton scattering between electron and laser light. In order to achieve effective collision of photon and electron, a pulsed and very thin size laser is required. Laser wire is one technique of measuring a small beam size. With green lasers, which are converted to second harmonics from IR pulsed laser, minimum beam waist is half of the beam waist obtained using infrared (IR) laser oscillator. Therefore, it is possible to obtain beam waist less than 5 μm using green laser pulse, which is required for effective photon-electron collision. First, pulsed IR seed laser is amplified with 1.5 meter long PCF based amplifier system. This pulsed IR laser is converted to second harmonics with a non-linear crystal. Pulsed green laser is injected inside four mirror optical cavity to obtain very small beam waist at interaction point (IP). Using a pulsed compact laser wire, we can measure 10 um electron beams in vertical directions. We report the development of the pulsed green laser and parameters of compact four mirror optical cavity for effective inverse Compton scattering. 		 
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TUCYB3 SwissFEL Beam Profile Monitor radiation, electron, vacuum, detector 259
 
  • R. Ischebeck, E. Prat, V. Schlott, V.G. Thominet
    PSI, Villigen PSI, Switzerland
  • P. Krejcik, H. Loos
    SLAC, Menlo Park, California, USA
  • M. Yan
    DESY, Hamburg, Germany
  
  We have developed a beam profile monitor that allows us to measure two-dimensional electron beam profiles for highly compressed electron bunches. Such bunches have plagued profile measurements in optical transition radiation monitors in the past, because coherent radiation entering the optical system has invalidated the images and even destroyed cameras. The present design makes use of a scintillating crystal, and directs coherent transition radiation away from the optical axis by careful choice of the angle. When observing Snell's law of refraction as well as the Scheimpflug imaging condition, a resolution better than the thickness of the scintillator can be achieved. We will present measurements performed at the SwissFEL Injector Test Facility and at the Linac Coherent Light Source. The high resolution and excellent sensitivity of this monitor make it ideal for installation in SwissFEL.  
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TUPF25 Characterization of the Laser Beam for HHG Seeding FEL, simulation, electron, undulator 380
 
  • S. Ackermann, B. Faatz
    DESY, Hamburg, Germany
  • V. Miltchev
    Uni HH, Hamburg, Germany
  
  Recently free-electron laser (FEL) facilities around the world have shown that the direct seeding approach can enhance the spectral, temporal and coherence properties of the emitted radiation as well as reducing the fluctuations in arrival time and output energy. To achieve this, a photon pulse of the desired wavelength ("seed") is overlapped transversely and temporally with the electrons in the undulator to start up the FEL process from a defined radiation pulse rather than from noise. To benefit from the advantages of this technique, the energy of the seed has to exceed the energy of the spontaneous emission. The ratio between these two energies is strongly influenced by the seed beam properties. In this contribution, we will present simulations on the achieveable power contrast in dependence on the beam quality of the seed, and compare the results to the experimental data of the seeded FEL experiment ("sFLASH") at DESY, Hamburg. Additionally we show up a way of creating FEL seed pulses for simulation purposes from Hermite-Gaussian generating functions.  
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TUPF26 Linear Focal Cherenkov-Ring Camera for Single Shot Observation of Longitudinal Phase Space Distribution for Non-Relativistic Electron Beam electron, vacuum, gun, photon 385
 
  • K. Nanbu, H. Hama, F. Hinode, S. Kashiwagi, A. Lueangaramwong, T. Muto, I. Nagasawa, S. Nagasawa, Y. Shibasaki, K. Takahashi, C. Tokoku
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  
  A test accelerator for the coherent THz source (t-ACTS) has been constructed at Tohoku University, in which the generation of intense coherent THz radiation from sub-picosecond electron bunches will be demonstrated. The final electron bunch length of accelerated beam is mostly dictated by the longitudinal phase space distribution at the exit of electron-gun. Therefore, measurement of Initial electron distribution in the longitudinal phase space produced by an electron gun is crucial for stable production of very short electron bunches, However, measurement of the longitudinal phase space of a relatively lower energy electron beam is especially difficult because space charge effects in drift spaces for measurement system might be strong. A method for measurement of electron energy (or momentum) applying velocity dependence of the opening angle of Cherenkov radiation in the radiator has been proposed for relatively lower energy electrons. Combined use of a streak camera and the “turtle-back” mirror that confines the Cherenkov light onto a linear focal line may allow us to observe the longitudinal phase space distribution directly. Current status of the system development will be reported in this conference.  
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TUPD03 Terahertz and Optical Measurement Apparatus for the Fermilab ASTA Injector radiation, dipole, optics, experiment 403
 
  • R.M. Thurman-Keup, A.H. Lumpkin, J.C.T. Thangaraj
    Fermilab, Batavia, Illinois, USA
  
  ASTA is a facility at Fermilab that, once completed, will consist of a photoinjector with two superconducting capture cavities, at least one superconducting ILC-style cryomodule, and a small ring for studying non-linear, integrable beam optics. This paper discusses the layout for the optical transport system that will provide THz radiation to a Martin-Puplett interferometer for bunch length measurements as well as optical radiation to an externally located streak camera, also for bunch length measurements. It will be able to accept radiation from two synchrotron radiation ports in the bunch compressor, a diffraction/transition radiation screen downstream of the compressor, and a transition radiation screen after the spectrometer magnet for measurements of energy-time correlations.  
poster icon Poster TUPD03 [3.202 MB]  
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TUPD10 An Ultrafast Linear Array Detector for Single-Shot Electro-Optical Bunch Profile Measurements detector, FPGA, synchrotron, radiation 435
 
  • L. Rota, C.M. Caselle, N. Hiller, A.-S. Müller, M. Weber
    KIT, Eggenstein-Leopoldshafen, Germany
  
  A new spectrometer system has been developed at ANKA for near-field single-shot Electro-Optical (EO) bunch profile measurements with a frame rate of 5 Mfps. The frame rate of commercial line detectors is limited to several tens of kHz, unsuitable for measuring fast dynamic changes of the bunch conditions. The new system aims to realize continuous data acquisition and over long observation periods without dead time. InGaAs or Si linear array pixel sensors are used to detect the near IR and visible spectrum radiation. The detector signals are fed via wire-bonding connections to the GOTTHARD ASIC, a charge-sensitive amplifier with analog outputs. The front-end board is also equipped with an array of fast ADCs. The digital samples are then acquired by an FPGA-based readout card and transmitted to an external DAQ system via a high-speed PCI-Express data link. The DAQ system uses high-end Graphics Processors Units (GPUs) to perform a real-time analysis of the beam conditions. In this paper we present the concept, the first prototype and the low-noise layout techniques used for fast linear detectors.  
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WEIXB1 LCLS Beam Diagnostics electron, undulator, diagnostics, cavity 475
 
  • H. Loos
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by DOE contract DE-AC03-76SF00515
An extensive set of beam diagnostics has been one of the factors in the successful commissioning and operation of the Linac Coherent Light Source (LCLS) x-ray FEL over the last seven years. The originally developed and installed diagnostics were geared towards measuring the electron beam parameters of the LCLS design specifications. Since then, a number of improved and new diagnostics have been implemented to accommodate a much wider range of beam parameters and to overcome the challenges of diagnostics for a high brightness electron beam. Plans for the diagnostics of the LCLS-II project with its high repetition rate and high beam power and ongoing developments will also be discussed. 		 
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WEPF09 Introduction to the Test Result of Turbo-ICT in PAL-ITF monitoring, diagnostics, electron, pick-up 553
 
  • H. J. Choi, M.S. Chae, H.-S. Kang, S.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Pohang Accelerator Laboratory (PAL) built a PAL-ITF (Injector Test Facility) at the end of 2012 to successfully complete PAL-XFEL (X-ray Free Electron Laser) in 2015. The PAL-ITF is equipped with various kinds of diagnostic equipment to produce high-quality electron bunches. The three main parameters that an injection testing facility should measure are charge, energy and emittance. Although ICT and Faraday Cup were installed to measure beam charge, the noise generated in a klystron modulator not only interrupted accurate measurement but prevented low charges under tens of pC from being measured. Due to the changes in the overall voltage level of ITF, integration of ICT measured value failed to maintain perfect accuracy in terms of methodology (measured value continuously changed by ± 5pC). Accordingly, to solve the noise problems and accurately measure the quantity of electron beam charge, Turbo-ICT was installed. This paper focuses on the processes and test result of electric bunch charge quantity measurements using Turbo-ICT.  
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WEPF26 The Brookhaven LINAC Isotope Production Facility (BLIP) Raster Scanning Upgrade controls, target, power-supply, radiation 608
 
  • R.J. Michnoff, Z. Altinbas, P. Cerniglia, R. Connolly, C. Cullen, C. Degen, D.M. Gassner, R.L. Hulsart, R.F. Lambiase, L.F. Mausner, D. Raparia, P. Thieberger, M. Wilinski
    BNL, Upton, Long Island, New York, USA
  
  Brookhaven National Laboratory’s BLIP facility produces radioisotopes for the nuclear medicine community and industry, and performs research to develop new radioisotopes desired by nuclear medicine investigators. A raster scanning system is being installed to provide a better distribution of the H− beam on the targets, allow higher beam intensities to be used, and ultimately increase production yield of the isotopes. The upgrade consists of horizontal and vertical dipole magnets sinusoidally driven at 5 kHz with 90 deg phase separation to produce a circular raster pattern, and a suite of new instrumentation devices to measure beam characteristics and allow adequate machine protection. The instrumentation systems include multi-wire profile monitors, a laser profile monitor, beam current transformers, and a beam position monitor. An overview of the upgrade and project status will be presented.
Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy 		 
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WEPD08 Beam Jitter Spectra Measurements of the APEX Photoinjector gun, feedback, timing, electron 652
 
  • H.J. Qian, J.M. Byrd, L.R. Doolittle, Q. Du, D. Filippetto, G. Huang, F. Sannibale, R.P. Wells
    LBNL, Berkeley, California, USA
  • J. Yang
    TUB, Beijing, People's Republic of China
  
  High repetition rate photoinjectors such as the APEX at LBNL are one of the enabling technologies for next generation MHz XFELs. Due to the higher repetition rate, a wider bandwidth is available for feedback systems to achieve ultra-stable beam performance. In a first step to improve APEX beam stability, the noise power spectra of the APEX laser beam and electron beam are characterized in terms of intensity and timing. Possible feedback systems are also discussed.  
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WEPD10 Front End Concept for a Wake Field Monitor wakefield, detector, radiation, alignment 660
 
  • M.M. Dehler, S. Hunziker
    PSI, Villigen PSI, Switzerland
  • M. Leich
    PSI, Villigen, Villigen, Switzerland
  
  Funding: EuCARD2 work package 12
Wake field monitors (WFMs) are used to directly measure the alignment between beam and RF accelerating structure via the transverse higher mode spectrum. As a sub task of the EuCARD2 project, we are developing a front end for the monitors of the multipurpose X band structure installed at the SwissFEL Injector Test facility SITF at PSI. We plan to use electro optical technology offering strong advantages in the robustness to interference and radiation, and in the ease of signal transport. We present the concept of the device, discuss the theoretical performance in terms of noise. For a proof of principle, we built a basic system, which we tested together with the existing monitors with beam at SITF. 		 
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WEPD26 Bunch-by-Bunch Feedback Systems at the DELTA Storage Ring used for Beam Diagnostics feedback, damping, storage-ring, radiation 703
 
  • M. Höner, S. Khan, M. Sommer
    DELTA, Dortmund, Germany
  
  Funding: Work supported by the BMBF.
At the 1.5-GeV electron storage ring DELTA operated by the TU Dortmund University, a bunch-by-bunch feedback system was installed in 2011. Since then, it is in operation for different beam diagnostic purposes. A fast analysis of bunch-position data allows a real-time multibunch mode analysis during machine operation. In addition, the data analysis can be triggered by external events, e.g. beam losses or the injection process. In this paper, a feedback-based method to measure the damping times of multi-bunch modes is presented. Furthermore, a chromaticity-dependent single-bunch instability is analyzed. Finally, the use of the feedback system in the presence of an RF-phase modulation is presented. 		 
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