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IT06 Short Bunch Beam Profiling diagnostics, instrumentation, free electron laser, photon, optics, SPPS, LCLS 25
 
  • P. Krejcik
    SLAC, Stanford Linear Accelerator, Stanford, CA, USA
  The complete longitunal profiling of short electron bunches is discussed in the context of 4th generation light sources. The high peak current required for the SASE lasing process is achieved by longitudinal compression of the electron bunch. The lasing process also depends on of the preservation of the transverse emittance along the bunch during this manipulation in longitudinal phase space. Beam diagnostic instrumentation needs to meet several challenges: The bunch length and longitudinal profile should be measured on a single bunch to characterize the instantaneous, peak current along the bunch. Secondly, the transverse emittance and longitudinal energy spread should be measured for slices of charge along the bunch. Several techniques for invasive and noninvasive bunch profiling will be reviewed, using as examples recent measurements from the SLAC Sub Picosecond Photon Source (SPPS) and the planned diagnostics for the Linac Coherent Light Source (LCLS). These include transverse RF deflecting cavities for temporal streaking of the electron bunch, RF zero-phasing techniques for energy correlation measurements, and electro-optic measurements of the wake-field profile of the bunch.  
 
CT02 Single Shot Measurements of the 4-Dimensional Transverse Phase Space Distribution of Intense Ion Beams at the UNILAC at GSI diagnostics, instrumentation, ion, transverse-dynamics 56
 
  • L. Groening, W. Barth
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  • D.A. Liakin
    ITEP, Institute for Theoretical and Experimental Physics, Moscow, Russia
  The UNILAC is used as an injector for the synchrotron SIS. It is designed to fill the synchrotron up to its space charge limit. The upper limit for the useful beam emittance of the UNILAC is given by the finite acceptance of the SIS during the injection process. In order to remain within this acceptance the emittance growth during beam acceleration and transportation due to space charge effects must be minimized by applying an appropriate beam focusing. Therefore, the influence of the magnetic focusing strength on the beam emittance growth was investigated experimentally for different beam currents. Measurements of transverse phase space distributions were performed before and after the Alvarez accelerator with a periodic focusing channel, respectively. In order to perform such a wide parameter scan within a reasonable time with respect to machine stability, the pepper pot technique was applied. The pepper pot method allows for single-pulse measurements. For comparison several measurements using the slit-grid technique, which averages over many pulses, were performed. Both transverse planes were measured simultaneously. Using two pepper pot devices more than 60 single shot measurements of the full 4-dimensional transverse phase space distribution were performed within 8 hours. In this paper we report on the results of the measurements and we compare them to beam dynamic simulations and we give an outlook on further developments on pepper pot devices.  
 
CT03 Beam Instrumentation for the Single Electron DAΦNE Beam Test Facility diagnostics, instrumentation, controls, electron, positrons 59
 
  • G. Mazzitelli, F. Sannibale, P. Valente, M. Vescovi
    INFN-LNF, Laboratori Nazionali di Frascati dell'INFN, Frascati, Italy
  • P. Privitera, V. Verzi
    INFN-Roma, Istituto Nazionale di Fisica Nucleare, Sez. di Roma, Roma, Italy
  The DAΦNE Beam Test Facility (BTF) has been successfully commissioned in February 2002, and started operation in November of the same year. Although the BTF is a beam transfer line optimized for single particle production, mainly for high energy detectors calibration, it can provide electrons and positrons in a wide range of multiplicity: between 1-1010, with energies from a few tens of MeV up to 800 MeV. The large multiplicity range requires many different diagnostic devices, from high-energy calorimeters and ionization/fluorescence chambers in the few particles range, to standard beam diagnostics systems. The schemes of operation, the commissioning results, as well as the beam diagnostics are presented.  
 
CT04 The Beam Inhibit System for TTF II diagnostics, instrumentation, electron, free-electron-laser 62
 
  • D. Nölle, P. Göttlicher, R. Neumann, D. Pugachov, K. Wittenburg, M. Wendt, M. Werner, H. Schlarb, M. Staack
    DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
  • M. Desmons, A. Hamdi, M. Jablonka, M. Loung
    CEA, Commissariat à l'Energie Atomique, Saclay, France
  The new generation of light sources based on SASE Free-Electron-Lasers driven by LINACs operate with electron beams with high beam currents and duty cycles. This is especially true for the superconducting machines like TTF II and the X-RAY FEL, under construction or planning at DESY. Elaborate fast protections systems are required not only to protect the machine from electron beams hitting and destroying the vacuum chamber, but also to prevent the machine from running at high loss levels, dangerous for components like the FEL undulator. This paper will give an overview over the different protection systems currently under construction for TTF II. The very fast systems, based on transmission measurements and distributed loss detection monitors, will be described in detail. This description will include the fast electronics to collect and to transmit the different interlock signals.  
 
CT05 Beam Loss Detection at Radiation Source ELBE diagnostics, instrumentation, electron, radiation, beam-losses, beam-transport 65
 
  • P. Michel, J. Teichert, R. Schurig, H. Langenhagen
    FZR, Forschungszentrum Rossendorf, Dresden, Germany
  The Rossendorf superconducting Electron Linac of high Brilliance and low Emittance (ELBE) delivers an 40 MeV, 1 mA cw-beam for different applications such as bremsstrahlung production, electron channelling, free-electron lasers or secondary particle beam generation. In this energy region in case of collisions of the electron beam with the pipe nearly all beam power will be deposited into the pipe material. Therefore a reliable beam loss monitoring is essential for machine protection at ELBE. Different systems basing on photo multipliers, compton diodes and long ionization chambers were studied. The pros and cons of the different systems will be discussed. Ionization chambers based on air-isolated RF cables installed some cm away parallel to the beam line turned out to be the optimal solution. The beam shut-off threshold was adjusted to 1 μC integral charge loss during a 100 ms time interval. Due to the favourable geometry the monitor sensitivity varies less than ±50% along the beam line (different shielding conditions).  
 
CT11 Beam Based HOM Analysis of Acceleating Structures at the TESLA Test Facility LINAC diagnostics, instrumentation, higher-order-mode, wakefield 83
 
  • M. Wendt, S. Schreiber, A. Gössel
    DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
  • M. Hüning
    FNAL, Fermi National Accelerator Laboratory, Batavia, IL, USA
  • G. Devanz, M. Jablonka, C. Magne, O. Napoly
    CEA, Commissariat à l'Energie Atomique, Saclay, France
  • N. Baboi* (on leave from NTLPRP)
    SLAC, Stanford Linear Accelerator, Stanford, CA, USA
  The beam emittance in future linear accelerators for high energy physics and SASE-FEL applications depends highly on the field performance in the accelerating structures, i.e. the damping of higher order modes (HOM). Besides theoretical and laboratory analysis (network analyzer), a beam based analysis technique was established [S. Fartoukh, et.al., Proceedings of the PAC99 Conference] at the TESLA Test Facility (TTF) linac. It uses a charge modulated beam of variable modulation frequency to excite dipole modes. This causes a modulation of the transverse beam displacement, which is observed at a downstream BPM and associated with a direct analysis of the modes at the HOM couplers. Emphasis of this presentation is put on beam instrumentation and signal analysis aspects. A brief introduction of eigenmodes in resonant structures, as well as some interesting measurement results are further presented.  
 
PM10 Characterisation of Fast Faraday Cups at the ELETTRA Linac diagnostics, electron, ELETTRA, instrumentation 113
 
  • M. Ferianis, S. Bassanese, G. D'Auria
    ELETTRA, Sincrotrone Trieste, Trieste, Italy
  • C. Deibele
    SNS, Spalation Neutron Source, Oak Ridge, TN, USA
  • M. Poggi
    INFN-LNL, Laboratori Nazionali di Legnaro, Legnaro, Italy
  A major upgrade of the ELETTRA injector is currently on going: the 1 GeV LINAC will be replaced with a 100 MeV LINAC and a 2.5 GeV Booster Synchrotron. A new set of diagnostics is now under development for these two new machines. The new Fast Tune measurement system for the Booster represents a significant improvement as compared to the present Tune measurement system. With the Booster cycling at 3 Hz, horizontal and vertical tunes have to be measured during the energy ramp, whose duration is 160 ms. To completely characterise the dynamics of the Booster during the energy ramp, a set of 25 tune values has been required, corresponding to a 6.4 ms interval between successive measurements. The accuracy of this measurement is <10-3. Such frequency spans are achievable using a Real Time Spectrum Analyser (Tektronix 3026), which is a fast sampling instrument with built-in FFT algorithm and data presentation. In this paper, after describing the system specifications and architecture, we present the results of the preliminary tests, which have been carried out both in the laboratory and on the Storage Ring.  
 
PM14 Upgrade Of The ESRF Fluorescent Screen Monitors instrumentation, emittance, luminosity 125
 
  • K. Scheidt
    ESRF, European Synchrotron Radiation Facility, Grenoble, France
  The ESRF injector system contains 23 Fluorescent Screen monitors: 4 in the TL-1 transferline (200 MeV), 8 in the Booster, and 11 in the TL-2 transferline (6 GeV). They are based on Chromium doped Alumina screens that are pneumatically inserted at 45o angle in the beam path with an optical system, at 90o angle, collecting and focusing the emitted light onto a low-cost CCD camera with standard 75Ω video output. Serving mainly alignment purposes in the past 10 years, the present upgrade aims at a 200 μm fwhm resolution for beam-size and profile measurements. The particularity of the Alumina screen not in vacuum but in atmosphere will be explained. Details of the mechanics, the optic system and a cost-efficient way of light flux adjustment will be given. The analysis of the factors determining the ultimate spatial resolution will show that it is dominated by the screen characteristics. Results obtained with different screen material will be presented.  
 
PM18 Residual Gas Fluorescence for Profile Measurements at the GSI UNILAC diagnostics, instrumentation, photon, optics 137
 
  • A. Bank, P. Forck
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  The high beam currents, delivered at the LINAC at GSI (UNILAC) can destroy intercepting diagnostics within one macro-pulse. As an alternative for a non-destructive profile measurement the methode for residual-gas-fluorescence is investigated. The fluorescence light is emitted by the N2 molecules of the residual gas at the blue wavelength range and can be monitored with a modern CCD-camera. The images are transferred via digital bus (IEEE 1394 'FireWire') and the profiles are generated by analysis of the images with a modern software tool (National Instruments 'LabView'). Due to the short beam pulses (about 0.2 ms) the light intensities emitted by the residual gas are low and require a high amplification (gain >106) which is realized with an image intensifier with double MCP (multi channel plate), connected with a fiber taper to the CCD-chip. The design parameters of the optics and electronics are discussed as well as the advantages of the digital data transmission. Measurements with heavy ion beams of several 100 μA and a comparison to other profile measurement methods show a good signal-to-noise ratio and prove a good applicability.  
 
PM28 Application of Beam Diagnostics for Intense Heavy Ion Beams at the GSI UNILAC heavy ion, space charge, longitudinal-dynamics 161
 
  • W. Barth, L. Dahl, J. Glatz, L. Groening, S. Richter, S. Yaramishev
    GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
  With the new High Current Injector (HSI) of the GSI UNILAC the beam pulse intensity had been increased by approximately two orders of magnitudes. The HSI was mounted and commissioned in 1999; since this time the UNILAC serves as an injector for the synchrotron SIS, especially for high uranium intensities. Considering the high beam power of up to 1250 kW and the short stopping range for the UNILAC beam energies (≤12 MeV/u), accelerator components could be destroyed, even during a single beam pulse. All diagnostic elements had to be replaced preferably by non-destructive devices. The beam current is mainly measured by beam transformers instead of Faraday cups, beam positions are measured with segmented capacitive pick-ups and secondary beam monitors instead of profile harps. The 24 installed pick-ups are also used to measure intensities, widths and phase of the bunches, as well beam energies by evaluating pick-ups at different positions. The residual gas ionization monitors allow on-line measurements of beam profiles. The knowledge of the real phase space distribution at certain position along the linac is necessary for optimizing the machine tuning, for the improvement of the matching to the synchrotron and for a better understanding of beam dynamic issues under space charge conditions. The paper will report the application of different beam diagnostic devices for the measurement of transverse beam emittances at different UNILAC beam energies and for different beam intensities. Additionally, measurements of the bunch structure after the HSI and a the design of a new device for the measurement of the longitudinal emittance at the end of the UNILAC will be included.  
 
PT02 Pill-Box Cavity BPM For TESLA Cryomodul diagnostics, monitoring, position, resonance, single bunch 172
 
  • V. Sargsyan
    TU-Berlin, Technische Universität, Berlin, Germany
  A new cavity BPM with 10 μm resolution is designed and fabricated to perform single bunch measurements at the TESLA linear collider. In order to have a low energy dissipation in the cryogenic supermodule, the inner surface of the cavity is copper plated. Cross-talk is minimised by a special polarisation design. The electronics, at 1.5 GHz, is a homodyne receiver normalised to the bunch charge. Its LO-signal for down-conversion is taken from the same cavity.  
 
PT15 Performance of the ELBE BPM Electronics diagnostics, instrumentation, monitoring, pick-up, ELBE 202
 
  • P. Evtushenko, R. Schurig
    FZR, Forschungszentrum Rossendorf, Dresden, Germany
  The ELBE radiation source is based on a superconducting linac. Initially it was designed to be used in CW mode with repetition rates either 13 MHz either 260 MHz. Later it was decided to operate the accelerator with reduced repetition rates for diagnostic reasons and for certain users. Now it is possible to operate at repetition rate 13/n MHz, where n can be 2, 4, 8, 16, 32, 64, and 128. It is required that the BPM system supports any of these operation modes. A core element of the BPM electronics is a logarithmic amplifier AD8313 made by Analog Devices Inc. The logarithmic amplifier is a direct RF to DC converter rated up to 2.5 GHz. Initial design of the BPM electronic was sophisticated only for CW operation with repetition rate more than 10 MHz, since bandwidth of the AD8313 is about of 10 MHz. Additionally a sample and hold amplifier is built in to provide enough time for an ADC to make measurements. The sample and hold amplifier is synchronized with a micropulse frequency. In the paper we present results of the modified BPM electronics test.  
 
PT16 A High Dynamic Range Beam Position Measurement System for ELSA-2 electron, diagnostics, instrumentation 205
 
  • Ph. Guimbal, P. Balleyguier, D. Deslandes
    CEA-DPTA, Commissariat à l'Energie Atomique, Bruyères-le-Châtel, France
  • H. Borrion
    EE-UCL, Electrical and Electronic Engineering Dept., University College, London, UK
  New beamlines are presently under construction for ELSA, a 20 MeV electron linac located at Bruyères-le-Châtel. These lines need a beam position measurement system filling the following requirements: small footprint, wide dynamic range, single-bunch/multi-bunch capability, simple design. We designed a compact 4-stripline sensor and an electronic treatment chain based on logarithmic amplifiers. This paper presents the design, cold and hot test results.  
 
PT23 Transverse Emittance Measurements at the Photo Injector Test Facility at DESY Zeuthen (PITZ) diagnostics, emittance, free-electron-laser, transverse-dynamics, PITZ 225
 
  • V. Miltchev, K. Abrahamyan, J. Bähr, I. Bohnet, M. Krasilnikov, D. Lipka, A. Oppelt, F. Stephan
    DESY-Zeuthen, Deutsches Elektronen-Synchrotron, Zeuthen, Germany
  • K. Flöttmann
    DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
  • I. Tsakov
    NRNE, Institute for Nuclear Reseach and Nuclear Energy of the Bulgarian Academy of Science, Sofia, Bulgaria
  The main research goal of the Photo Injector Test Facility at DESY Zeuthen (PITZ) is the development of electron sources with minimized transverse emittance like they are required for the successful operation of Free Electron Lasers and future linear colliders. The process of electron beam optimization requires characterization of the transverse emittance at a wide range of operation parameters. The design and functionality of the emittance measurement system at PITZ is presented. The methods applied as well as the resolution limits of the system are discussed. The latest measurements of the transverse properties of the electron beam are presented.  
 
PT24 Development of a Bunch-Length Monitor with Sub-Picosecond Time Resolution and Single-Shot Capability
Funding: SNF (Schweizer National Fonds)
diagnostics, instrumentation, electron, bunching, SLS 228
 
  • D. Sütterlin, V. Schlott, H. Sigg
    PSI, Paul Scherrer Institut, Villigen, Switzerland
  • H. Jackel
    ETHZ, Institute of Electronics, Zürich, Switzerland
  A bunch-length monitor with single-shot capability is under development at the 100 MeV pre-injector LINAC of the Swiss Light Source (SLS). It is based on the electro-optical effect in a ZnTe crystal induced by coherent transition radiation (CTR). A spatial autocorrelation of the CTR in the EO-crystal rotates the polarisation of a mode-locked Nd:YAG laser to produce an image on an array detector representing the Fourier components of the CTR spectrum. Up to now a theoretical model for the emission of transition radiation has been developed in order to design optics allowing efficient transport of the CTR onto the EO-crystal. The frequency dependency of the CTR due to the finite size of the target screen has been measured in the sub-THz regime at the SLS Linac. The results strongly support the theoretical descriptions of the radiation source. By expanding the intensity pattern in higher-order Laguerre-Gaussian modes, the transmission through the optical transfer system is calculated.