A   B   C   D   E   F   G   H   I   K   L   M   O   P   Q   R   S   T   U   V  

electron

Paper Title Other Keywords Page
MOO1A02 High Resolution Transverse Profile Measurement laser, synchrotron, emittance, photon 1
 
  • E. Bravin
    CERN, Geneva
  In many cases the performance of a particle accelerator is in large part defined by the transverse emittance of the beams. In most cases, like colliders and light sources (Synchrotrons or Free Electron Lasers), the quality of the final product, i.e. luminosity and brilliance, is directly linked to this parameter. For this reason many techniques and devices have been developed over the years for monitoring the transverse distribution of particles along accelerator chains or over machine cycles. Moreover modern designs of accelerators allow smaller size and/or higher current beams. New, more demanding, emittance measurement techniques have to be introduced and existing ones expanded. This presentation will review the different methods and the different instruments developed so far.  
 
MOO2A01 Physics And Diagnostics Of Laser-Plasma Accelerators laser, focusing, target, radio-frequency 11
 
  • V. Malka
    LOA, Palaiseau
  The recent and continuing development of powerful laser systems, which can now deliver light pulses containing a few Joules of energy in pulse durations of a few tens of femto seconds, has permitted the emergence of new approaches for generating energetic particle beams. By focusing these laser pulses onto matter, extremely large electric fields can be generated, reaching the TV/m level. Such fields are 10,000 times greater than those produced in the radio-frequency cavities of conventional accelerators. As a result, the distance over which particles extracted from the target can be accelerated GeV energy range is reduced to distances on the order of millimetres. A few years ago, several experiments have shown that laser-plasma accelerators can produce electron beam with maxwellian-like distribution [1], in 2004 high-quality electron beams, with quasi-mono energetic energy distributions at the 100 MeV level [2] and recently in the GeV range using a capillary discharge [3]. These experiments were performed by focusing a single ultra short and ultra intense laser pulse into an under dense plasma. More recently we produced a high quality electron beam using two counter-propagating  
 
MOO2A02 Electron Beam Diagnostics for the European X-Ray Free-Electron Laser diagnostics, emittance, laser, linac 17
 
  • C. Gerth
    DESY, Hamburg
  At the European XFEL, dedicated diagnostic sections are located in the injector, downstream of the bunch compressors, in the beam distribution area and undulator systems. Very challenging is the measurement and control of the compression process based on magnetic chicanes in combination with off-crest acceleration in both fundamental and 3rd-harmonic structures. Non-linear effects, e.g. CSR or LSC, which also depend on the compression process may degrade the slice emittance or energy spread. Moreover, a beam energy jitter transforms into a time jitter in the magnetic chicanes, and the beam arrival time is of crucial importance for other synchronised laser systems, e.g. for diagnostics, seeding or pump-probe experiments. The overlap of the electron and photon beams in the up to 250m-long undulators is relevant for the lasing process. BPMs with high single-bunch resolution are being developed for orbit monitoring and beam based alignment procedures. The general layout of the electron beam diagnostics for the European XFEL is presented. The development status of various diagnostic components is discussed, and, where appropriate, experimental results obtained at FLASH* are presented.

* Many special diagnostic tools and prototypes are being developed and tested at the Free-Electron LASer in Hamburg FLASH.

 
 
MOO3A02 Beam Induced Fluorescence (BIF) Monitor for Transverse Profile Determination of 5 to 750 MeV/u Heavy Ion Beams ion, background, vacuum, photon 33
 
  • F. Becker, C. A. Andre, P. Forck
    GSI, Darmstadt
  • D. Hoffmann
    TU Darmstadt, Darmstadt
  In the frame of the FAIR-project (facility for antiproton and ion research) at GSI, high intensity beams from protons to Uranium ions in the energy range from 100 MeV/u to 30 GeV/u are foreseen. In transport lines between the synchrotrons and in front of production targets a precise beam alignment is mandatory. Since the beam energy will increase from 90 Joule to about 104 Joule per ion pulse, conventional intercepting beam diagnostics may not be used. For transverse profile determination we investigated a non-intercepting Beam Induced Fluorescence (BIF) monitor in residual nitrogen. An image intensified CCD camera was used to record the fluorescence images representing the beam profile. The photon yield and background contribution were determined for different ion species, beam energies and N2 pressures. Applying narrowband 10 nm interference filters we mapped the spectral response and associated it with the N2 transitions. Profile distortions were compared to simulations taking into account effects as momentum transfer, gas dynamics and the electrical field of the ion beam. Additionally the feasibility and appropriate layout for different diagnostic tasks is discussed.  
slides icon Slides  
 
TUPB03 Precision Beam Position Monitor for EUROTeV vacuum, pick-up, linear-collider, collider 57
 
  • I. Podadera Aliseda, L. Søby
    CERN, Geneva
  For future linear colliders (ILC, CLIC) a new Precision Beam Position Monitor (PBPM) has been designed within the framework of EUROTeV. The design goals are a resolution of 100nm and an overall precision of 10μm, in a circular vacuum chamber of 6mm in diameter. The required bandwidth is 100 kHz-30MHz. The PBPM is based on an inductive type BPM which measures the image current in four electrodes located outside the vacuum tube, from which the position is derived. In this paper, the design of the PBPM is presented together with the first bench measurements, where twoμmovers and a rotational stage, installed on a vibration damped table, have been used to characterize the PBPM.  
 
TUPB04 BPM detectors upgrade for the ELETTRA Fast Orbit Feedback feedback, controls, closed-orbit, diagnostics 60
 
  • M. Lonza, L. Battistello, D. Bulfone, R. De Monte, S. Fontanini, V. Forchi', G. Gaio, F. Giacuzzo, R. Marizza, R. Passuello, L. Pivetta, C. Scafuri
    ELETTRA, Basovizza, Trieste
  The project of a fast feedback system to stabilize the closed orbit of the Elettra storage ring is in an advanced stage. All of the existing BPMs have been equipped with new digital detectors in order to provide precise and high-rate position measurements to the feedback system. A new beam position interlock system has also been installed to protect the vacuum chamber from synchrotron radiation produced by insertion devices. This paper presents features and performance of the new orbit measurement system and reports some preliminary results of the feedback commissioning.  
 
TUPB05 A Tagged Photon Source at the Frascati Beam-Test Facility (BTF) photon, target, dipole, luminosity 63
 
  • B. Buonomo, G. Mazzitelli, F. Murtas, L. Quintieri
    INFN/LNF, Frascati (Roma)
  • L. G. Foggetta, S. Hasan, A. Mozzanica, M. Prest
    Univ. Insubria and INFN Milano, Como
  • P. Valente
    INFN-Roma, Roma
  • E. Vallazza
    INFN-Trieste, Trieste
  The DAΦNE Beam Test Facility, operating at the Frascati National Laboratory of INFN, provides electron or positron beams with tunable energy from 25 MeV to 750 MeV, while the intensity can be varied from 1010/pulse@ 0-50Hz down to a single particle per pulse. Recently a tagged photon source has been designed, built and tested. The photons are produced by bremsstrahlung of electrons with a maximum momentum of 750 MeV/c on a pair of x-y silicon micro-strip chambers(1), placed before the last bending magnet of the BTF transfer line. The photons are tagged in energy using the same bending dipole, whose internal walls have been covered by 10 modules of silicon micro-strip detectors. Depending on the energy loss in the photon production, the electrons impinge on a different strip once the dipole current has been set to the nominal value. The correlation between the directions on the electron measured by silicon chambers and the impinging position on the tagging module inside the magnet allows the tagging on the photons. In this paper the configuration of the system is presented with some results obtained during the latest test-beams.

(1)Profile monitors for wide multiplicity range electron beams. Proceeding DIPAC 2005 Lyon, France,pp166-168.

 
 
TUPB08 Measurement of Vertical Emittance with a system of Six -In-Air-X-Ray- Projection Monitors at the ESRF emittance, photon, controls, shielding 72
 
  • K. B. Scheidt
    ESRF, Grenoble
  The ESRF Storage Ring is now equiped with a system of 5 independent imaging monitors that measure the vertical emittance of the electron beam in the middle of the bending magnet through the very hard X-rays that fully traverse the 40mm thick Copper dipole absorbers and enter the free air space behind it. The tiny power that leaks through the absorber, and carried by X-rays of ~160KeV of very narrow vertical divergence, is simply projected onto a scintillator screen at ~1.8m from the source-point and imaged by optics & camera. These inexpensive and compact detectors are fully operated in free air and can be easily installed and maintained without any vacuum intervention. They now work reliably in routine fashion and have demonstrated their high precision and resolution of the ESRF’s vertical emittance. These results will be presented in this paper together with the underlying principles of the projection detector, aswell as the practical design solutions applied to obtain the high spatial resolution, to make the system resistant to the hostile radiation environment behind the absorber, and to reduce its sensitivity to stray signals generated at this point.  
 
TUPB11 A laserwire beam profile measuring device for the RAL Front End Test Stand ion, laser, diagnostics, emittance 81
 
  • D. A. Lee, P. Savage
    Imperial College of Science and Technology, Department of Physics, London
  • C. Gabor
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • J. K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon
  The Front End Test Stand at the Rutherford Appleton Laboratory (RAL) is being developed to demonstrate a chopped H- beam of 60 mA at 3 MeV with 50 pps and sufficiently high beam quality for future high-powered proton accelerators. As such, it requires a suite of diagnostic instruments to provide detailed measurements of the ion beam. Due to the high beam brightness and a desire to be able to have online instrumentation, a series of non-intrusive and non-destructive diagnostics based on laser-detachment are being developed. The progress that has been made towards construction of a laserwire instrument that can measure the beam profile at an arbitrary angle are described. In particular, the principle behind the instrument, the simulation and design of it and the vacuum vessel in which it will be mounted are given. In addition, the reconstruction software that will be used to reconstruct the 2D transverse beam density distribution from the profiles of the beam is described.  
 
TUPB17 Diagnostics for the CTF3 Probe Beam Linac CALIFES diagnostics, emittance, linac, acceleration 99
 
  • W. Farabolini, D. Bogard, A. Brabant, A. Curtoni, P. Girardot, F. Gobin, R. Granelli, F. Harrault, C. L.H. Lahonde-Hamdoun, T. Lerch, M. Luong, A. Mosnier, F. Orsini, F. Peauger, C. Simon
    CEA, Gif-sur-Yvette
  CALIFES is the probe beam linac developed by the CEA/DAPNIA and LAL in the frame of the CFT3 collaboration at CERN. Its objective is to "mimic" the main beam of CLIC in order to measure the performances of the 30 GHz CLIC accelerating structures. The requirements on the bunched electron beam in terms of emittance, energy spread and bunch-length are quite stringent and lead to use the most advanced techniques: laser triggered photo-injector, velocity bunching, RF pulse compression… In order to tune the machine and assess its performances before delivering the beam to the test stand a complete suit of diagnostics is foreseen including charge monitor, beam position and video profile monitors, deflecting cavity, RF pick-up and analysis dipole. All these diagnostics will be interfaced to the CERN command/control network. A special effort has been done on the Video Profile Monitors that make use of both scintillation and OTR (Optical Transition Radiation) screens and are fitted with 2 optical magnifications to fulfill field of view and resolution performances (<20μm). Their performances can be checked via an integrated resolution pattern.  
 
TUPB18 Measurement of Electron Beam Charge in the ESRF Accelerator Complex for Absolute and Injection Efficency Measurements Using an FPGA Based Digital BPM Electronics booster, storage-ring, injection, controls 102
 
  • G. A. Naylor, B. Joly
    ESRF, Grenoble
  A Beam Position Monitor (BPM) using Virtex II pro FPGAs (‘Libera Electron’ from Instrumentation Technologies) has been programmed with an alternative firmware in order to determine the charge by measuring integrated RF amplitude, over an adjustable time window, of signals from 4 strip lines. These strip lines are located on the transfer line from the linac to the booster, on the booster ring, on the transfer line from the booster to the storage ring and on the storage ring. By calibrating the RF loss in all the cables, knowing the geometry of the strip lines and using the crossbar switching before the 4 RF ADCs of the Libera, the charge/current can be compared in order to determine the efficiency of transfer at various locations during injection. Since the current in the storage ring is known to a high accuracy using a parametric current transformer (from Bergoz Instrumentation), the absolute charge can be determined at all locations.  
 
TUPB20 Large Horizontal Aperture BPM and Precision Bunch Arrival Pickup pick-up, laser, simulation, vacuum 108
 
  • K. E. Hacker, F. Löhl, H. Schlarb
    DESY, Hamburg
  The large horizontal aperture chicane BPM and the precision bunch arrival monitor at FLASH will be important tools to stabilize the arrival-time of the beam at the end of the linac. The pickups for these monitors will be paired with front-ends that sample the zero-crossing of the beam transient through the use of electro-optical modulators and sub-picosecond-long laser pulses delivered by the master-laser oscillator. The design of pickups for this front-end requires the consideration of the beam transient shape as well as the amplitude. Simulations and oscilloscope traces from pickups that use or will use the EOM based phase measurement and the expected limitations and benefits of each pickup are presented. In particular, the design for a 5 um resolution BPM with a 10 cm horizontal aperture is demonstrated in terms of its capability to measure the beam energy and its sensitivity to the shape and orientation of the beam.  
 
TUPB23 Design Considerations for Phase Space Tomography Diagnostics at the PITZ Facility quadrupole, space-charge, emittance, diagnostics 117
 
  • G. Asova, K. Flöttmann
    DESY, Hamburg
  • D. J. Holder, B. D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • S. Khodyachykh, M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen
  A major goal of the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is to build and to optimise high brightness electron sources for SASE FELs where the detailed knowledge of the phase-space density distribution of the electron beam is very important. The current upgrade of the machine includes a diagnostic section suitable for transverse phase space tomography and multiscreen emittance measurement. The designed module should be capable of operation over a range of beam momenta between 15 and 40MeV/c. It mainly consists of four observation screens with three FODO cells in between them. An upstream section of a number quadrupoles is used to match the electron beam Twiss parameters to the tomography section. The design considerations of the tomography section and results from numerical simulations will be presented in this contribution.  
 
TUPB24 First Results from the LEIR Ionisation Profile Monitors ion, vacuum, controls, accumulation 120
 
  • G. Tranquille, C. B. Bal, V. Prieto, R. S. Sautier
    CERN, Geneva
  The role of the Low Energy Ion Ring, LEIR is to transform long pulses of lead ions from the Linac 3 to short dense bunches for transfer to the LHC. This is accomplished by the accumulation of up to 4 Linac pulses by electron cooling. In order to non-destructively monitor the cooling performance and determine the accumulated beam characteristics, two prototype ionisation profile monitors have been built and were tested during the LEIR commissioning runs with O4+ and Pb54+ ions in 2006. In this paper we present the results obtained with the prototype monitors, the problems encountered and describe the modifications made for the final design. The modified monitors have been installed on the LEIR machine and are waiting for the next ion run planned in August.  
 
TUPB27 Recent Results from the Electron Beam Profile Monitor at the Swiss Light Source synchrotron, emittance, synchrotron-radiation, optics 129
 
  • Å. Andersson
    MAX-lab, Lund
  • O. V. Chubar
    SOLEIL, Gif-sur-Yvette
  • A. Lüdeke, M. Rohrer, V. Schlott, A. Streun
    PSI, Villigen
  Two different methods of beam profile measurements using a) visible-to-UV range synchrotron radiation and b) X-ray synchrotron radiation have been realized in a single diagnostics beam line at the Swiss Light Source (SLS). In the visible-to-UV case the vertically polarized synchrotron radiation renders an image heavily influenced by inherent emission and diffraction effects of synchrotron radiation. This nevertheless turns out to be an advantageous influence when determining rms beam profiles below 10 μm. However, high-precision wave-optics based calculations of the synchrotron light characteristics need to be performed (SRW-code) to ensure correct interpretation of the measured profiles. The visible-to-UV branch has a few built-in features allowing numerous cross-checks of the SRW-model. Surprisingly, wave-optics based calculations are also applicable, and required, for the X-ray pinhole camera setup. We briefly discuss the advantage of applying two different measuring techniques at the same source point. In total, for standard user operation at the SLS, the beam line has helped to establish a vertical emittance below 10 pmrad.  
 
TUPB29 Experimental Optimization of the Cathode Laser Temporal Profile laser, cathode, emittance, simulation 135
 
  • M. Krasilnikov
    DESY, Hamburg
  • J. W. Bähr, M. Hänel, F. Stephan
    DESY Zeuthen, Zeuthen
  • I. Will
    MBI, Berlin
  Producing a flat-top temporal intensity profile of the cathode laser pulse is a key issue for the XFEL photo injector. The photo injector test facility at DESY in Zeuthen (PITZ) serves as a test bench for FEL photo injectors. The PITZ cathode laser contains a pulse shaper to produce flat-top temporal pulse profiles. Based on birefringent filters the pulse shaper includes four degrees of freedom to achieve a pulse profile with parameters closer to the required XFEL photo injector specifications (20 ps FWHM, 2 ps rise/fall time). A procedure for experimental temporal laser profile optimization is presented in this paper. The laser profile is measured using a streak camera. The four parameters - pulse length (FWHM), rise and fall time as well as modulation of the flat-top which are obtained from a flat-top fit of the measured profile - are used in the profile evaluation. Utilizing results of beam dynamics simulations for various cathode laser profiles a single value of the goal function – the expected emittance growth due to measured imperfections of the profile - can be obtained. The procedure of the goal function minimization has been implemented and tested at PITZ.  
 
TUPB32 An RF Deflector for the Longitudinal and Transverse Beam Phase Space Analysis at PITZ emittance, diagnostics, single-bunch, electromagnetic-fields 144
 
  • S. A. Korepanov, M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen
  • D. Alesini
    INFN/LNF, Frascati (Roma)
  • L. Ficcadenti
    Rome University La Sapienza, Roma
  A detailed characterization of the longitudinal and transverse phase space of the electron beam provided by the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is required to optimize photo injectors for Free-Electron Laser (FEL) applications. By means of a RF deflector the transverse slice emittance and the longitudinal phase space can be analysed. In this paper we present the status of the RF deflector design. The analysis of the prospect diagnostics shows the possibility to achieve a time resolution of about 0.5 ps, and a longitudinal momentum resolution of 10-4. The influence of the deflector on the beam longitudinal and transverse phase space is analysed.  
 
TUPC02 Photo Injector Cathode Laser Beam Intensity and Pointing Position Diagnostics at PITZ laser, cathode, diagnostics, monitoring 147
 
  • Ye. Ivanisenko, G. Asova, J. W. Bähr, S. A. Korepanov, M. Krasilnikov, B. Petrosyan, F. Stephan
    DESY Zeuthen, Zeuthen
  • O. Kalekin
    Erlangen University, Erlangen
  A photo cathode laser with unique parameters is used at the Photo Injector Test facility at DESY in Zeuthen, PITZ. It is cabable of producing laser pulse trains consisting of up to 800 pulses with a repetition rate of 1 MHz where each laser pulse has a flat-top temporal profile. The knowledge of the laser stability is very important for the emittance measurements procedure. Therefore, a system for monitoring the laser beam intensity and pointing position stability was created at PITZ. It is capable of measuring the laser spot position and pulse intensity for each of the laser pulses in the train using a quadrant diode and a photomultiplier tube, respectively. Taking into account the laser beam spot transverse intensity distribution measured by a CCD camera allows to study the position of the laser spot on the photo cathode with a resolution of 8.3 um. Laser intensity measurements can be done for a wide dynamical range of intensities due to the tunable photo multiplier tube gain. The first experiments with the new system show very small laser spot position jitter on the cathode surface of about 20 um and laser intensity fluctuations of about 14 %.  
 
TUPC03 Synchrotron Radiation Monitor for Energy Spectrum Measurements in the Bunch Compressor at FLASH dipole, acceleration, synchrotron, synchrotron-radiation 150
 
  • C. Gerth
    DESY, Hamburg
  Longitudinal bunch compression in magnetic chicanes is used at the Free-electron LASer in Hamburg FLASH for the generation of ultra-short electron bunches. A Synchrotron Radiation (SR) monitor has been installed behind the third dipole of the first bunch compressor to measure the energy and energy profile of the dispersed bunches. An intensified CCD camera records the emitted SR in the visible and enables one to select single bunches out of a bunch train. The performance of the system has been tested for different accelerator settings. The setup serves as a test bed for the European XFEL.  
 
TUPC05 Screen studies at PITZ emittance, simulation, scattering, diagnostics 153
 
  • R. Spesyvtsev, J. W. Bähr, S. Khodyachykh, L. Staykov
    DESY Zeuthen, Zeuthen
  The Photo Injector Test facility at DESY in Zeuthen (PITZ) has been built to test and to optimize electron sources that fulfill the requirements of SASE FEL's such as FLASH and XFEL. Basic properties of the electron beam such as mean momentum, momentum spread, transverse emittance etc. are determined using measurement of the beam size on YAG or OTR screens. Detailed knowledge of the uncertainties and systematic errors associated with these measurements are important to understand the underlying beam physics. The screen stations consist of a screen set-up, an optical transmission line to a CCD camera, and the video data acquisition system. In this paper we make a detailed description of the screen based beam size measurement systems that we use at PITZ and discuss the systematic errors of uncertainties associated with each single element of a system.  
 
TUPC06 Coherent Radiation Studies For The FERMI@Elettra Relative Bunch Length Diagnostics radiation, dipole, diagnostics, synchrotron 156
 
  • M. Veronese, S. Di Mitri, M. Ferianis
    ELETTRA, Basovizza, Trieste
  Bunch compressors are key components of the seeded FEL FERMI@elettra. Assuring their stable operation requires multiple non-destructive diagnostics to provide error signals to the feedback systems. Both the energy and the peak current of the electron bunch have to be stabilized by the feedback systems. The peak current stabilization implies charge and bunch length stabilization. The latter will be achieved by a redundant diagnostics based on Coherent Synchrotron Radiation (CSR) and Coherent Diffraction Radiation (CDR). In this paper we describe a study of Coherent Radiation emission downstream bunch compressors as the source of a relative bunch length measurement diagnostics. The study evaluates the most critical parameters in the design of such a diagnostic using numerical integration to calculate the spectral angular properties of the radiation for both CSR and CDR.  
 
TUPC07 Design and Construction of the Multipurpose Dispersive Section at PITZ dipole, quadrupole, emittance, diagnostics 159
 
  • S. Khodyachykh, J. W. Bähr, M. Krasilnikov, A. Oppelt, L. Staykov, F. Stephan
    DESY Zeuthen, Zeuthen
  • T. Garvey
    LAL, Orsay
  • J. Rönsch
    Uni HH, Hamburg
  For the characterization of rf photo-electron guns a full set of beam parameters has to be measured. For this purpose a new high energy dispersive arm will be used at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) in addition to the existing beam diagnostics. The multipurpose dispersive arm (HEDA1) is designed [1] for an electron energy range up to 40 MeV and will be put into operation in autumn 2007. It combines the functionality of (i) an electron spectrometer, (ii) a device for the characterization of the longitudinal phase space, and (iii) a transverse slice emittance measuring system. HEDA1 consists of a 180 degree dipole magnet followed by a slit, a quadrupole magnet, and two screen stations. One of the screen stations will be equipped with an optical read-out for a streak camera. We report about the detailed design of individual components and the construction progress.

[1] S. Khodyachykh, et al., Proccedings of the 28th International FEL Conference, Berlin (2006).

 
 
TUPC10 A transverse RF deflecting cavity for the FERMI@elettra project emittance, linac, optics, diagnostics 168
 
  • P. Craievich, S. Di Mitri, M. Ferianis, M. Veronese
    ELETTRA, Basovizza, Trieste
  • D. Alesini
    INFN/LNF, Frascati (Roma)
  • M. Petronio
    DEEI, Trieste
  The layout of FERMI@elettra includes a high energy transfer line (TL) which brings the accelerated electron bunch to the FEL undulator chains. The TL optics has been designed according to several space constraints and with the purpose of including diagnostics for the complete characterization of the electron bunch just before the FEL process starts. Basing on such optics, this paper reports the study of the electron bunch deflection at nominal energy of 1.2 GeV for the measurement of the bunch length, of the transverse slice emittance and of the slice energy spread, coupled to a downstream dipole. The effect of the cavity on the electron beam was simulated by tracking code and the specification on the deflecting voltage was thus confirmed. Furthermore the RF design and electromagnetic simulations are also presented here.  
 
TUPC18 New Type Photocathode for X-Ray Streak Camera of the 10-Fs Resolution radiation, monitoring, vacuum, space-charge 183
 
  • A. M. Tron
    LPI, Moscow
  • T. V. Gorlov
    MEPhI, Moscow
  High current streak camera with new principle of operation* allowing to get resolution of the order of 10 fs in the frequency range both of visible light and x-ray is described. One of the key units of the camera is photocathode of spherical configuration with its surface radius of 10…100 micrometers. For creating the photocathode new technologies, developed and realized, are described. The results of the photocathode fabrication and investigations of its main features are presented and discussed.

* A. M. Tron, I. G. Merinov, T. Gorlov. New generation streak camera design and investigation. Proc. of EPAC 2006, p. 1175.

 
 
TUPC25 Design and Calibration of an Emittance Monitor for the PSI XFEL Project emittance, laser, acceleration, gun 198
 
  • V. Schlott, Å. Andersson, M. Dach, S. C. Leemann, M. Rohrer, A. Streun
    PSI, Villigen
  Paul Scherrer Institute (PSI) intends to realize a compact X-ray Free Electron Laser (XFEL) by developing a high brightness, high current electron source. Field emitter arrays (FEA) in combination with high gradient acceleration promise a substantial reduction of transverse emittances by up to one order of magnitude compared to existing electron sources for XFELs. A flexible, high resolution emittance monitor based on the "pepperpot measurement techique" has been designed for this "low emittance gun" project at PSI. The realization and the calibration procedure of the monitor will be described in this presentation.  
 
TUPC26 Button Beam Position Monitors for FLASH undulator, pick-up, radiation, linac 201
 
  • J. Lund-Nielsen, N. Baboi
    DESY, Hamburg
  • W. Riesch
    DESY Zeuthen, Zeuthen
  Abstract: FLASH (Free Electron Laser in Hamburg) accelerates electron bunches to up to 750 MeV for producing intense, coherent, very short pulses of radiation. Various types of BPMs (beam position monitors) are installed in the facility: cavity and re-entrant-cavity BPMs in the accelerating cryo-modules and button and stripline BPMs in most of the room-temperature sections. The undulator section, where the FEL radiation is produced, is one of the most critical areas of the linac in terms of requirements on the position monitoring. Due to the tight space, button BPMs were chosen for this area. The electronics is based on the AM/PM principle. In the past couple of years these BPMs were commissioned and intensively studied. A few modifications have been made in the electronics, in order to deal with the small signals and the very high frequencies of the ultra-short bunches. In this paper the button-BPMs at FLASH will be presented. The studies made in the RF laboratory and the measurements made on the performance of the BPMs will be discussed.  
 
WEO1A01 Sub-ps Timing and Synchronization Systems for Longitudinal Electron Bunch Profile Measurements laser, radiation, undulator, diagnostics 204
 
  • A. Winter
    DESY, Hamburg
  Precise timing and synchronization systems have become an increasingly important topic for next generation light sources. Particularly free electron lasers can emit X-ray pulses with pulse durations down to the few-tens of femtoseconds level. In order to utilize this potential temporal resolution for pump-probe experiments, a precise synchronization of the experimental laser to the X-ray pulse and stabilization of the electron beam arrival time at the undulators are mandatory. This requires a timing and synchronization system which can supply ultra-stable phase references over long distances, thus enabling the temporal stabilization of the electron beam to a sub-100 fs level. Furthermore, a precise timing and synchronization system renders possible extremely accurate measurements of the longitudinal electron bunch profile. This talk will give an overview of the status of existing sub-ps timing and synchronization systems and of systems currently under construction.  
 
WEO1A03 Instrumentation for Longitudinal Beam Gymnastics in FEL's and in the CLIC test facility 3 linac, diagnostics, radiation, pick-up 215
 
  • T. Lefèvre, H.-H. Braun, E. Bravin, S. Burger, R. Corsini, S. Döbert, L. Søby, F. Tecker, P. Urschütz, C. P. Welsch
    CERN, Geneva
  • D. Alesini, C. Biscari, B. Buonomo, O. Coiro, A. Ghigo, F. Marcellini, B. Preger
    INFN/LNF, Frascati (Roma)
  • P. Craievich, M. Ferianis, M. Veronese
    ELETTRA, Basovizza, Trieste
  • A. E. Dabrowski, M. Velasco
    NU, Evanston
  • A. Ferrari
    UU/ISV, Uppsala
  Built at CERN by an international collaboration, the CLIC Test Facility 3 (CTF3) aims at demonstrating the feasibility of a high luminosity 3TeV e+-e- collider by the year 2010. One of the main issues to be demonstrated is the generation of a high average current (30A) high frequency (12GHz) bunched beam by means of RF manipulation. At the same time, Free Electron Lasers (FEL) are developed in several places all over the world with the aim of providing high brilliance photon sources. These machines all rely on the production of high peak current electron bunches. The required performances put high demands on the diagnostic equipment and innovative longitudinal monitors have been developed during the past years. This paper gives an overview of the longitudinal instrumentation developed at ELETTRA and CTF3, where a special effort was made in order to implement at the same time non-intercepting devices for online monitoring, and destructive diagnostics which have the advantage of providing more detailed information.  
 
WEO2A02 Single Shot Longitudinal Bunch Profile Measurements by Temporally Resolved Electro-Optical Detection laser, resonance, diagnostics, linac 221
 
  • P. J. Phillips, A. MacLeod
    UAD, Dundee
  • G. Berden, A. F.G. van der Meer
    FOM Rijnhuizen, Nieuwegein
  • W. A. Gillespie
    University of Dundee, Nethergate, Dundee, Scotland
  • S. P. Jamison
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • E.-A. Knabbe, B. Schmidt, P. Schmüser, B. Steffen
    DESY, Hamburg
  For the high-gain operation of a SASE FEL, extremly short electron bunches are essential to generate sufficiently high peak currents. At the superconducting linac of FLASH at DESY, we have installed an electro-optic experiment to probe the time structure of the electric field of single sub 200fs e-bunches. In this technique, the field-induced birefringence in an electro-optic crystal is encoded on a chirped ps laser pulse. The longitudinal electric field profile of the electron bunch is then obtained from the encoded optical pulse by a single-shot cross correlation with a 30 fs laser pulse using a second-harmonic crystal (temporal decoding). In the temporal decoding measurements an electro-optic signal of 180 fs FWHM was observed, and is close to the limit due to the material properties of the particular electro-optic crystal used. The measured electro-optical signals are compared to bunch shapes simultaneously measured with a transversly deflecting cavity.  
 
WEO2A03 Advanced Measurements at the SPARC Photoinjector emittance, simulation, laser, space-charge 224
 
  • A. Cianchi, L. Catani
    INFN-Roma II, Roma
  • D. Alesini, M. Bellaveglia, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, M. Incurvati, C. Ligi, E. Pace, L. Pellegrino, R. Ricci, C. Ronsivalle, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, F. Tazzioli, S. Tomassini, C. Vaccarezza, M. Vescovi, C. Vicario
    INFN/LNF, Frascati (Roma)
  • A. Bacci, S. Cialdi, A. R. Rossi, L. Serafini
    INFN-Milano, Milano
  • A. M. Cook, M. P. Dunning, P. Frigola, P. Musumeci, J. B. Rosenzweig
    UCLA, Los Angeles, California
  • L. Giannessi, M. Quattromini
    ENEA C. R. Frascati, Frascati (Roma)
  • M. Migliorati, A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma
  • M. Petrarca
    INFN-Roma, Roma
  The objective of the first stage of the SPARC commissioning was the optimization of the RF-gun setting that best matches the design working point and a detailed study of the emittance compensation process providing the optimal value of emittance at the end of the linac. For this purpose an innovative beam diagnostic, the emittance-meter, consisting of a movable emittance measurement system, was conceived and built. More than a simple improvement over conventional, though non-trivial, beam diagnostic tools this device defines a new strategy for the characterization of new high performance photo-injectors. The emittance meter allows to measure at different location along the beamline the evolution of important beam parameters both in longitudinal and in the transverse phase space such as beam sizes, energy spread and rms transverse emittances in a region where the space-charge effect dominate the electron dynamics. The quality and the amount of the data allowed a clear reconstruction of the phase space evolution. We report also the first experimental observation of the double emittance minima effect on which is based the optimized matching with the SPARC linac  
 
WEPB01 Design of an Electron Beam Energy Control Loop Using Transverse Dispersion controls, dipole, optics, target 229
 
  • M. Justus, U. Lehnert, P. Michel
    FZD, Dresden
  • P. Evtushenko
    Jefferson Lab, Newport News, Virginia
  Stability in mean electron beam energy is of highest interest for a number of experiments performed at the ELBE accelerator. Energy drifts affect parameters of the generated Bremsstrahlung spectra, X-rays or infrared light, as well as the beam trajectory at the production targets or through the FEL waveguide, respectively. In practise, we observe a slow drifting of the effective accelerating field during the first hours after a machine power-up or after switching to different nominal beam energies. Initially, this effect was compensated manually. A first order automation solution has been developed that corrects the resulting energy drift continuously, using a non-intrusive beam position monitor placed in a transversely dispersive part of the beam guide. This paper describes the beam line setup and the simplified dynamic model of the control loop derived from it. Calculation of controller parameters using standard a standard method is shown. The user interface of the control system and working conditions for the loop are explained. Operational performance and conclusions towards improvements close this contribution.  
 
WEPB02 Design of an Intra-Bunch-Train Feedback System for the European X-Ray FEL feedback, kicker, pick-up, dipole 232
 
  • B. Keil, G. J. Behrmann, M. Dehler, R. Kramert, G. Marinkovic, P. Pollet, M. Roggli, M. Rohrer, T. Schilcher, V. Schlott, D. M. Treyer
    PSI, Villigen
  • J. Lund-Nielsen, D. Nölle, M. Siemens, S. Vilcins
    DESY, Hamburg
  After joining the preparatory phase of the European X-ray FEL project, the Paul Scherrer Institute agreed in taking over responsibility for electron beam stabilization by developing a fast intra-bunch-train feedback (IBFB) system, which will be tested in its prototype version at the FLASH linac of the collaboration partner DESY. The proposed IBFB topology consists of two beam position monitors ("upstream BPMs") followed by two kicker magnets for each transverse plane and two more BPMs ("downstream BPMs"). By measuring the position of each bunch at the upstream BPMs and applying suitable transverse kicks individually to the following bunches, the architecture of the FPGA-based digital IBFB electronics (with a latency preferably below the bunch spacing of 200 ns and 1000 ns for the XFEL and FLASH) allows to damp beam motions up to hundreds of kHz. In addition to the FPGA-based feedback, DSPs enable adaptive feed-forward correction of repetitive beam motions as well as feedback parameter optimisation using the downstream BPMs. This paper gives an overview of the architecture and status of the IBFB subsystems being developed, like stripline BPMs, digital electronics and kicker magnets.  
 
WEPB03 Femtosecond Yb-Doped Fiber Laser System at 1 um of Wavelength with 100-nm Bandwidth and Variable Pulse Structure for Accelerator Diagnostics laser, radiation, diagnostics, polarization 235
 
  • A. Winter, B. Steffen
    DESY, Hamburg
  • F. O. Ilday
    Bilkent University, Bilkent, Ankara
  Laser-based diagnostic systems play an increasingly important role in accelerator diagnostics in, for instance, measurements of the electron bunch length. To date, the laser system of choice for electro-optic experiments has been the Ti:Sa laser. These offer nJ pulse energies at fixed repetition rate between 50-100 MHz, which is not well suited to the bunch structure of facilities such as FLASH (several hundred pulses with 1 MHz spacing at 1-5 Hz repetition rate).The limited robustness, stability and operability of Ti:Sa systems make them less than an ideal candidate for a continuously running measurement system requiring minimal maintenance. Fiber lasers represent a promising alternative, since gating and subsequent amplification is simple and of low cost, hence a pulse pattern corresponding exactly to the linac bunch pattern can be generated. Furthermore, these lasers offer superior robustness at a fraction of the cost of a Ti:Sa laser and have been shown to work without maintenance for several months and longer. Here, we present an ytterbium-doped fiber laser system with 80 nm bandwidth and multi-nJ pulse energy with adjustable bunch pattern for use in electro-optic experiments.  
 
WEPB05 Streak Camera Measurements of the SOLEIL Bunch Length single-bunch, impedance, vacuum, radiation 241
 
  • M. Labat, L. Cassinari, M.-E. Couprie, R. Nagaoka, D. Pédeau
    SOLEIL, Gif-sur-Yvette
  A double sweep streak camera (C5680, Hamamatsu) has been installed on the French third generation light source SOLEIL. The visible radiation of the diagnostics beam-line is used to study the longitudinal profile of the stored electron bunches. We report on the commissioning of the streak camera, as well as on its first uses. Measurements of single-bunch length as a function of various machine parameters such as RF cavity voltage and frequency, and beam current with a few picoseconds resolution are reported, and interpreted in terms of vacuum chamber impedance and beam stability.  
 
WEPB06 Direct Comparison of the Methods of Beam Energy Spread Determination in the VEPP-4M Collider collider, betatron, diagnostics, photon 244
 
  • O. I. Meshkov, V. A. Kiselev, N. Yu. Muchnoi, S. V. Sinyatkin, V. V. Smaluk, V. N. Zhilich, A. N. Zhuravlev
    BINP SB RAS, Novosibirsk
  The VEPP-4M electron-positron collider is now operating with the KEDR detector for the experiment of precise measurement of tau-lepton mass. The nearest experimental program of the accelerator includes scan of the energy area below J/psi meson to search narrow resonances. The monitoring of beam energy spread is important to know the energy spread contribution into the total systematic error. In this report we discuss the application of several diagnostics for beam energy spread measurement. The data obtained with Compton BackScattering (CBS) technique* are compared with the value of the spread derived from the betatron motion of the beam**. The measurements by all the methods were done at the same accelerator run, i.e. the different diagnostics can be compared directly. The value of the energy spread was determined for a set of collider operating modes, covering the energy area from 1200 MeV up to 1843 MeV. Width of the J/psi and psi' resonance measured with the KEDR detector is used as a reference.

References*N. Muchnoi et al. //Proceed. of EPAC 2006, Edinburg, Scotland, TUPCH074**T. Nakamura et al. // Proceed. of the 2001 Particle Accelerator Conference, Chicago, p. 1972-1974.

 
 
WEPB07 Time Domain Diagnostics for the ISAC-II Superconducting Heavy Ion Linac linac, ion, emittance, laser 247
 
  • V. A. Verzilov, R. E. Laxdal, M. Marchetto, W. R. Rawnsley
    TRIUMF, Vancouver
  The medium beta section of the ISAC-II superconducting linac has 20 bulk niobium quarter wave resonators and adds up to 20 MV of energy to the 1.5Mev/u and A/q<=6 ion beam injected from the ISAC-I accelerators. The commissioning of this new linac started April 2006 and the first radioactive beam was delivered to an experiment in January 2007. A standard array of ISAC diagnostics were added to the ISAC-II section to commission and tune the transport beamline and linac optics. In addition two new devices were developed: an ion implanted silicon detector measuring beam particles scattered from a gold foil and time of flight (TOF) monitors based on micro-channel plates. These are used both to tune the LINAC and to characterize the accelerated beams in the longitudinal phase space. The TOF monitors have the time resolution below 100ps, energy resolution of 0.1% and dynamic range spanning 6 orders of magnitude. Data acquisition and analysis is highly automatic and integrated into the EPICS based ISAC control system. Design of the monitors and first measurements will be presented.  
 
WEPB13 Focusing of Optical Transition and Diffraction Radiation by a Spherical Target target, radiation, focusing, diagnostics 259
 
  • L. G. Sukhikh, G. A. Naumenko, A. Potylitsyn
    TPU, Tomsk
  • A. S. Aryshev, J. Urakawa
    KEK, Ibaraki
  • S. T. Boogert, V. Karataev
    JAI, Egham, Surrey
  During the last few years Transition Radiation (TR) and Diffraction Radiation (DR) have been intensively studied for different applications such as diagnostics of electron beam size, emittance, length, energy spread, etc. For extremely high-energy electrons the broadening of TR (DR) spatial distribution due to “pre-wave” zone effect [*] leads to distortion of the radiation characteristics and decreasing of photon concentration per unit square detector. In papers [**,***] it was shown that using a spherical target one can make TR (DR) distribution in the pre-wave zone identical to a far-field one. To verify our approach we carried out an experiment at KEK-ATF extraction line with electron beam energy of 1.28 GeV using a spherical target to focus optical TR (DR) at the distance of L=440 mm which corresponds to an extreme pre-wave zone. We also measured OTR (ODR) characteristics from a flat target in order to compare them with OTR (ODR) characteristics from the spherical one. We clearly observed that OTR (ODR) angular distribution from the spherical target is narrower than from a flat one and it’s very similar to a far-field zone distribution as it was predicted by the theory.

* V. A.Verzilov, PLA 273(2000)135** P. V.Karataev, PLA 345(2005)428*** A. P. Potylitsyn and R. O. Rezaev, NIMB 252(2006)44

 
 
WEPB15 A Sub-50 Femtosecond bunch arrival time monitor system for FLASH laser, pick-up, feedback, polarization 262
 
  • F. Löhl, K. E. Hacker, H. Schlarb
    DESY, Hamburg
  A bunch arrival time monitor system using the future laser based synchronization system at FLASH has been developed. The signal of a beam pick-up with several GHz bandwidth is sampled by a sub-ps laser pulse using a broadband electro-optical modulator. Bunch arrival time deviations are converted into amplitude modulations of the sampling laser pulses which are then detected by a photo-detector. A resolution of 30 fs could be reached, with the capability towards sub-10 fs level. In this paper we describe the design of the optical system and we present recent results.  
 
WEPB16 First prototype of an optical cross-correlation based fiber-link stabilization for the FLASH synchronization system laser, polarization, feedback, free-electron-laser 265
 
  • F. Löhl, H. Schlarb
    DESY, Hamburg
  • J. Chen, F. X. Kaertner, J. Kim
    MIT, Cambridge, Massachusetts
  A drift free synchronization distribution system with femtosecond accuracy is of great interest for free-electron-lasers such as FLASH or the European XFEL. Stability at that level can be reached by distributing laser pulses from a mode-locked erbium-doped fiber laser master oscillator over actively optical-length stabilized fiber-links. In this paper we present a prototype of a fiber-link stabilization system based on balanced optical cross-correlation. The optical cross-correlation offers drift-free timing jitter detection. With this approach we were able to reduce the timing jitter added by a 400 m long fiber-link installed in a noisy accelerator environment to below 10 fs (rms) over 12 hours.  
 
WEPB18 Electron Beam Temperature Measurements at the Fermilab Medium Energy Electron Cooler radiation, antiproton, optics, diagnostics 268
 
  • A. Warner, K. Carlson, G. M. Kazakevich, L. R. Prost, M. Sutherland
    Fermilab, Batavia, Illinois
  The Fermilab Recycler ring employs an electron cooler to store and cool 8.9-GeV antiprotons. The cooler is based on an electrostatic accelerator (Pelletron) working in an energy-recovery regime. Several techniques for determining the characteristics of the beam dynamics have been investigated. Beam temperature measurements using OTR in conjunction with a Pepper-pot have been made at several settings of the upstream optics of the machine. Without temperature the pepper-pot hole images would have sharp boundaries. A finite temperature makes these boundaries broader. Thus, comparison of the ratios of the hole image boundaries and intensities is a measure of the beam temperature. In this paper we report the results so far obtained using this technique.  
 
WEPB20 Optical System for Measuring Electron Bunch Length and Longitudinal Phase Space at Pitz: Extension and Methodical Investigations optics, booster, gun, photon 274
 
  • J. W. Bähr, H. L. Luedecke
    DESY Zeuthen, Zeuthen
  • J. Rönsch
    Uni HH, Hamburg
  An extended optical system* for the measurement of the electron bunch length and the longitudinal phase space** using a streak camera is installed at PITZ. This system will be extended by two new branches in 2007, one in the straight section behind the booster cavity and another one in the first magnet spectrometer behind the booster cavity. The physics design of the chambers containing the radiators and of the optical system are presented. The results of optical calculations of the whole system will be given. Results of methodical investigations will be shown as well, especially concerning transversal optical resolution and time dispersion.

* J. Baehr et al., DIPAC ‘03, Mainz, Germany 2003** J. Roensch et al. FEL ’05, SLAC, Stanford, USA, 2005

 
 
WEPB22 Touschek Lifetime Measurement with a Spurious Bunch in UVSOR-II Electron Storage Ring single-bunch, scattering, vacuum, storage-ring 280
 
  • A. Mochihashi, M. Katoh, M. Shimada
    UVSOR, Okazaki
  • Y. Hori
    KEK, Ibaraki
  • M. Hosaka, Y. Takashima
    Nagoya University, Nagoya
  We have developed a method to measure the Touschek beam lifetime of an electron storage ring using spurious bunches in single-bunch operation by measuring change in the single-bunch impurity over time. To measure a spurious bunch and the main bunch simultaneously, we use a photon counting method with sufficient dynamic range and response time. We demonstrated the method by measuring the Touschek beam lifetime in the UVSOR-II electron storage ring. We find that the Touschek beam lifetime dominates the total beam lifetime in UVSOR-II in usual vacuum condition. The Touschek beam lifetime measurement in multibunch operation with the method will be discussed in the presentation.

A. Mochihashi, M. Katoh, M. Hosaka, Y. Takashima, Y. Hori, NIM-A 572 (2007) 1033-1041.

 
 
WEPB23 Beam Diagnostics Development for the Cryogenic Storage Ring CSR ion, diagnostics, pick-up, cryogenics 283
 
  • T. Sieber, H. Fadil, M. Grieser, A. Wolf, R. von Hahn
    MPI-K, Heidelberg
  A cryogenic storage ring is under construction at the MPI-K Heidelberg. It consists of electrostatic elements and has a circumference of ~35m. The CSR shall be used for storage of rotationally non-excited molecules and highly charged ions, therefore extremely low temperatures (<4K) and gas pressures (10-15 mbar) are required. The ring shall also be operational at room temperature and bakeable to at least 300°C. The maximum energy of singly charged ions is 300keV, intensities will be in the range 1nA – 1uA. For the mass range, A<100 is taken as reasonable design value, in later stages of CSR operation experiments with heavier ions are foreseen. Due to the exceptional boundary conditions we are working on new or further developments for most of the diagnostics devices. For example our RGMs have to produce their own local pressure bumps. The MCPs have to work at temperatures around 4K. The beam position pickups shall be operated in resonant mode for increased sensitivity. Our beam profiler will use secondary electrons from a stopper plate, which allows beam imaging in the intensity range 102 to 1012 pps. For intensity measurements a SQUID CCC system is under discussion.  
 
WEPB25 Time Domain Measurements at Diamond photon, single-bunch, synchrotron, diagnostics 289
 
  • C. A. Thomas, G. Rehm
    Diamond, Oxfordshire
  We present a set of four complementary measurements of the synchrotron visible light to characterise the stored electron beam at Diamond in the time domain. The electron bunch profiles and its evolution is measured with picosecond accuracy using a dual sweep streak camera. The beam dynamics are also given by a fast photodiode connected to a fast oscilloscope. The fill pattern is measured using a time correlated single photon counting system which has a high dynamic range for bunch purity measurement, and a fast averaging card which gives the fill structure with high accuracy within a short integration time. We describe our set of instruments, discuss their performance and show first results from measurements of Diamond's properties.  
 
WEPB29 Bunch-by-Bunch Longitudinal Diagnostics at DAΦNE by IR Light diagnostics, positron, synchrotron, single-bunch 298
 
  • A. Bocci, M. C.G. Cestelli Guidi, A. Clozza, A. Drago, A. G. Grilli, A. Marcelli, A. R. Raco, R. S. Sorchetti
    INFN/LNF, Frascati (Roma)
  • E. P. Emanuele
    Università degli Studi di Firenze, Firenze
  • M. P. Piccinini
    Università Roma Tre, Roma
  • J. P. Piotrowski
    Vigo System Sa, Warsaw
  Compact uncooled HgCdTe semiconductor detectors optimized in the mid-IR range have been used to record time resolved single bunch synchrotron radiation (SR) emissions from the DAΦNE e- main ring. These devices allow a low cost bunch-by-bunch longitudinal diagnostics. Indeed, the detectors make possible to record a train of 2.7 ns long bunches per turn. A comparison with synchrotron light signals coming from the e+ ring is stimulating but at DAΦNE only two SR beamlines are operational and because of the lack of apertures in the main wall no easy alternatives exist for the e+ ring. To solve the problem, a compact SR port has been considered and is going to be implemented on the positron ring. A small dedicated vacuum chamber with a ZnSe infrared window and remote controlled mirrors will be installed to focus the light on the IR detectors. The source characteristics have been simulated and the optical system with the complete acquisition system will be described. When ready, the real time comparison between data collected on the two beams will be performed improving accelerator diagnostics and as a major tool to increase the stored currents in the e+ ring and the collider luminosity.  
 
WEPB30 Current Status of the SQUID Based Cryogenic Current Comparator for Absolute Measurements of the Dark Current of Superconducting RF Accelerator Cavities pick-up, cryogenics, shielding, controls 301
 
  • K. Knaack, K. Wittenburg
    DESY, Hamburg
  • R. Neubert, S. Nietzsche, F. Schiller, W. Vodel
    FSU Jena, Jena
  • A. Peters
    HIT, Heidelberg
  This contribution gives an overview on the current status of a LTS-SQUID based Cryogenic Current Comparator (CCC) for detecting dark currents, generated for example by superconducting cavities for the upcoming X-FEL project. To achieve the maximum possible energy the gradients of the superconducting RF accelerator cavities should be pushed close to the physical limit of 50 MV/m. The so-called dark current of the superconducting RF cavities at strong electric fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value classify the cavities. The main component of the CCC is a LTS-DC SQUID system which allows us to measure extremely low magnetic fields, caused by extracted dark currents of RF cavities under test. For this reason the SQUID input coil is connected across a toroidal superconducting pick-up coil (inner diameter: about 100 mm) for the passing electron beam. A noise limited current resolution of 40 pA/sqrt(Hz) with a measurement bandwidth of up to 70 kHz was achieved. Design issues and the application for the CHECHIA cavity test stand at DESY as well as experimental results will be discussed.  
 
WEPC01 Beam Based Measurements of RF Phase and Amplitude Stability at FLASH gun, laser, acceleration, feedback 307
 
  • H. Schlarb, C. Gerth, W. Koprek, F. Löhl, E. Vogel
    DESY, Hamburg
  Beam based techniques to determine the phase and amplitude stability of the photo-cathode laser, the RF gun and superconducting acceleration modules become key tools for the understanding and quality control for FEL operation critical acceleration sub-system. The measurements are used to identify the sources of instabilities, to determine response functions and to optimize RF feedback parameters and algorithm. In this paper, an overview on the measurement techniques and their limitation is given, together with some important results on the currently achieved RF and laser stability.  
 
WEPC03 Secondary Electron Emission Beam Loss Monitor for LHC proton, simulation, beam-losses, radiation 313
 
  • D. K. Kramer, B. Dehning, G. Ferioli, E. B. Holzer
    CERN, Geneva
  Beam Loss Monitoring (BLM) system is a vital part of the active protection of the LHC accelerators’ elements. It should provide the number of particles lost from the primary hadron beam by measuring the radiation field induced by their interaction with matter surrounding the beam pipe. The LHC BLM system will use ionization chambers as standard detectors but in the areas where very high dose rates are expected, the Secondary Emission Monitor (SEM) chambers will be employed because of their high linearity, low sensitivity and fast response. The SEM needs a high vacuum for proper operation and has to be functional for up to 20 years, therefore all the components were designed according to the UHV requirements and a getter pump was included. The SEM electrodes are made of Ti because of its Secondary Emission Yield (SEY) stability. The sensitivity of the SEM was modeled in Geant4 via the Photo-Absorption Ionization module together with custom parameterization of the very low energy secondary electron production. The prototypes were calibrated by proton beams in CERN PS Booster dump line, SPS transfer line and in PSI Optis line. The results were compared to the simulations.  
 
WEPC13 Jitter Reduced Pump-Probe Experiments laser, diagnostics, target, photon 337
 
  • A. Azima, S. Düsterer, J. Feldhaus, P. Radcliffe, H. Redlin, H. Schlarb
    DESY, Hamburg
  • M. Meyer
    LIXAM, Orsay
  For two-colour pump-probe experiments carried out at the free electron laser FLASH@DESY, the FEL laser pulses in the XUV have to be synchronized with femtosecond precision to optical laser pulses (Ti:Sapphire). An electro-optical sampling diagnostic measures the arrival time jitter of the infrared pump-probe laser pulse in respect to the electron bunch of the FEL. Here, the electron arrival time is encoded spatially into the laser pulse profile and readout by an intensified camera. In this paper we report about the improvement of the temporal resolution of pump-probe experiments on gaseous and solid targets using the arrival time data acquired by the described EO-diagnostic.  
 
WEPC14 Segmented Beam Dump for Time Resolved Spectrometry on a High Current Electron Beam radiation, simulation, scattering, linac 340
 
  • T. Lefèvre, H.-H. Braun, E. Bravin, C. Dutriat, C. P. Welsch
    CERN, Geneva
  In the CLIC Test Facility 3, the strong coupling between the beam and the accelerating cavities induces transient effects such that the head of the pulse is accelerated twice as much as the rest of the pulse. Three spectrometer lines are installed along the linac with the aim of measuring energy spread versus time with a 20ns resolution. The major difficulty is due to the high power carried by the beam which imposes extreme constraints of thermal and radiation resistances for the detector. This paper presents the design and the performances of a simple and easy-to-maintain device, called ‘segmented dump’. In this device, the particles are stopped inside metallic plates and the deposited charge is measured in the same way as in faraday cups. Simulations were carried out with the Monte Carlo code ‘FLUKA’ in order to evaluate the problems coming from the energy deposition and find ways to prevent or reduce them. The detector resolution has been optimized by choosing the adequate material and thickness for the plates. The overall layout of the monitor is described with a special emphasis on its mechanical assembly. Finally, limitations arising at high beam energies are discussed.  
 
WEPC17 Fast Orbit Feeback System Upgrade with New Digital Bpm and Power Supply in the Tls feedback, power-supply, controls, vacuum 346
 
  • C. H. Kuo, J. Chen, P. C. Chiu, K. T. Hsu, K. H. Hu, K.-B. Liu
    NSRRC, Hsinchu
  • A. Bardorfer
    Instrumentation Technologies, Solkan
  The BPMs of orbit feedback loop use analogy type in the TLS that is more than 10 years. The analogy type BPM provides high resolution position detection after signal processing. The new generation digital beam position monitor (DBPM) was performed recently. The BPM electronics are commercial available by using direct RF sampling technology, FPGA, and embedded control environment running GNU/Linux. The programmable nature of DBPM system is beneficial for multi-mode high precision beam diagnostics purposes. Sub-micron resolution is achieved for averaged beam position measurement with high update rate. The DBPM are seamless integrated with existed control system and is compatible with old BPM in the orbit feedback loop. In the same time, the corrector power-supply is also upgraded for wide bandwidth control. The integration of old and new BPM, power-supply control for fast orbit feedback will be discussed in this report.  
 
WEPC19 Toroid Protection System for FLASH simulation, linac, beam-losses, single-bunch 349
 
  • A. Hamdi, F. Ballester, M. Luong, J. Novo
    CEA, Gif-sur-Yvette
  • L. Froehlich, M. Görler, S. Magnus, M. Staack, M. Werner
    DESY, Hamburg
  The FLASH fast machine protection includes a beam loss interlock using toroids to measure the beam charge. This system monitors the beam losses across the whole linac while other protection systems are specifically dedicated to critical components. Four protection modes are used to handle different scenarios of losses: charge validation, single bunch, slice and integration modes. This system is based on 4 ADC’s to sample the top and bottom of upstream and downstream toroid signals. A microcontroller drives 2 programmable delay generators to adjust the top and bottom ADC trigger during the calibration phase. The samples are then collected by a 200Kgates FPGA to process the various protection modes. At first, a VHDL testbench was developed to generate test vectors at the FPGA design inputs. Then, an electronic testbench simulates the linac signals to validate the global hardware functions. Finally, the toroid protection was tested on FLASH with long bunch train at 1 MHz repetition rate.  
 
WEPC20 A Real-Time Beam Monitor for Hadrontherapy Applications Based on Thin Foil Secondary Electron Emission and a Back-Thinned Monolithic Pixel Sensor proton, focusing, cyclotron, monitoring 352
 
  • L. Badano, L. Badano
    ELETTRA, Basovizza, Trieste
  • K. Abbas, P. N. Gibson, U. Holzwarth
    JRC, Ispra
  • M. Caccia, C. Cappellini, V. Chmill, M. Jastrzab
    Univ. Insubria and INFN Milano, Como
  • O. Ferrando
    Ente Ospedaliero Ospedali Galliera, Genova
  • G. Molinari
    CERN, Geneva
  A novel, non-disruptive beam profile monitor for low intensity light-ion beams has been constructed and tested. The system is designed for use in medical hadrontherapy centers where real-time monitoring of the beam intensity profile is of great importance for optimization of the accelerator operation, patient safety and dose delivery. The beam monitor is based on the detection of secondary electrons emitted from a submicron thick Al2O3/Al foil placed in the beam at an angle of 45 degrees. The present paper reports the latest results achieved with a customized monolithic active pixel array, which provides the beam intensity and position with a precision of better than 1 mm at a 10 kHz frame rate. The sensor chip is back-thinned to achieve the required sensitivity to short-range secondary electrons focused onto the sensor surface. The monitor performance has been tested with a patterned beam, produced with a multi-hole collimator, with the results indicating that the system performs according to its design specifications.  
 
WEPC21 Diagnostics of the Waveform of Picosecond Electron Bunches Using the Angular Distribution of Coherent Sub-mmTransition and Diffraction Radiation radiation, target, linac, vacuum 355
 
  • A. G. Shkvarunets, R. B. Fiorito
    UMD, College Park, Maryland
  • F. Mueller, V. Schlott
    PSI, Villigen
  The spectra of sub-mm wavelength coherent transition radiation (TR) and diffraction radiation (DR) have previously been used to measure the bunch length of picosecond electron beam pulses. However, both the spectral and angular distributions of the radiation from a finite target or aperture with size r, are strong functions of the wavelength, when λ ≈ 2πr/γ where γ is the relativistic factor of the beam. This dependence must be taken into account in the determination of the bunch form factor and bunch shape. Also the spectral density of the bunch is a strong function of wavelength when λ ≈ d, the characteristic length of the bunch. When both the above conditions are fulfilled, i.e. λ ≈ 2πr/γ ≈ d, the spectral and angular distribution (AD) of the radiation are very sensitive to the longitudinal distribution of the bunch. We are investigating the use of the AD of TR or DR, to diagnose the bunch length and shape. Here we present a comparison of measured and calculated angular distributions from two targets: a solid disk and a rectangular slit, which we have used to determine the waveform of the beam bunch produced at PSI’s SLS pre-injector LINAC.  
 
WEPC24 A Self Calibrating Real Time Multi-Channel Profile Monitor for the Isis Proton Synchrotron ion, proton, controls, acceleration 364
 
  • S. J. Payne, P. G. Barnes, G. M. Cross, A. Pertica, S. A. Whitehead
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  A (+ion) gas ionisation profile monitor (GIPM) has been developed at the Rutherford Appleton Laboratory to capture 'real time' beam profile data within the accelerating ring of the 800MeV ISIS proton sychrotron. The GIPM uses an array of 40 Channeltron detectors, operating at a gain of ~104, to measure the transverse beam profile in the horizontal plane. The data obtained is an average of two rotations of the beam bunch, a limitation due soley to the speed of the +ions. Fast electronics and a multi-channel PXI / LabView data acquisition system are used to simultaneously process and display the 40 channels of beam profile information. Variations in the Channeltrons gain are dealt with using an independent motor driven +ion detector. The beam profiles obtained from this single detector are stored and used as a calibration file to correct data from the new multi-channel profile monitor.  
 
WEPC28 Timing and Synchronization at the LCLS laser, klystron, linac, controls 373
 
  • P. Krejcik, R. Akre, S. Allison, J. Browne, L. R. Dalesio, J. E. Dusatko, J. C. Frisch, R. Fuller, A. E. Gromme, K. D. Kotturi, S. N. Norum, D. Rogind, W. E. White, S. Zelazny
    SLAC, Menlo Park, California
  Timing and synchronization in the LCLS is a three tier process: At level 1 an event generator broadcasts timing fiducials to event receivers over a fiber network. Hardware and software triggers are created in the event receiver according to the digital pattern broadcast at 360 Hz by the event generator. Beam synchronous data acquisition driven by these triggers allows time-stamped acquisition of all diagnostic devices simultaneously on every pulse. Timing fiducials are phase synchronized to the low level RF reference system with 10 ps precision. Level 2 synchronization ensures that individual klystrons powering gun and accelerating sections remain within a few tenths of a degree S-band to the phase reference distribution scheme. The gun laser system is also phase locked to this reference to within 0.5 ps. Level 3 provides synchronization at the 10 fs level between the electron beam and pump-probe laser systems in the end station experiments. This will be achieved with electro-optic sampling of the electron bunch and by synchronizing the laser systems over a stabilized fiber distribution system. A fiber stabilization scheme is currently under test at Lawrence Berkeley Laboratory.