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| MOO1A03 |
Review of Synchrotron Radiation based Diagnostics for Transverse Profile Measurements
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6 |
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The transverse particle beam emittance is a crucial accelerator parameter because it is directly related to the brilliance of a synchrotron light source or the luminosity of a particle beam collider. Therefore a precise online control of the beam profile is highly desirable from which the corresponding emittance can be calculated. In addition observation of the particle beam shape's time-like evolution allows to study effects as for example injection mismatch and dynamical beta beating which are important for smooth-running accelerator operation. Due to its non-destructive nature synchrotron radiation is a versatile tool for beam profile measurements and is used in nearly every accelerator. While in principle synchrotron radiation from insertion devices or bending magnets can be utilized, in reality most accelerators use bending magnet radiation based profile monitoring because of space limitations. There exist a number of different techniques in order to overcome limitations due to resolution broadening effects which can result in theoretical resolutions down to the sub-micron level. In this talk an overview over the methods presently applied in most accelerators will be given.
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| MOO2A02 |
Electron Beam Diagnostics for the European X-Ray Free-Electron Laser
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17 |
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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.
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| MOO2A03 |
FERMI@elettra Diagnostics
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20 |
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- M. Ferianis
ELETTRA, Basovizza, Trieste
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FERMI@elettra is the fourth generation light source currently under construction at the Sincrotrone Trieste Laboratory. It is a seeded FEL based on the existing 1.0GeV Linac which will be fitted with FEL specific sub-systems like a new photoinjector and two bunch compressors to obtain in front of the undulator chain a stable and high quality beam. Due to the challeging beam parameters, the diagnostics play a key role for the successfull commissioning first, and then for a reliable operation of the new faciltiy. In this paper we give an overview on the FERMI diagnostics operating in the 6-D phase space along with some keynotes on the timing system which is an integral part of the longitudinal diagnostics.
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| MOD1A01 |
Digital EBPMs at Diamond: Operational Experience and Integration into a Fast Global Orbit Feedback
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24 |
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- G. Rehm, M. G. Abbott, J. Rowland, I. Uzun
Diamond, Oxfordshire
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We present out experience with the Libera EBPM during the first months of operation at Diamond. Measurement noise and beam current dependence with beam are compared to earlier lab measurements. Where discrepancies between the performance in the lab and in the application are observed, the causes have been investigated. Furthermore, results of the integration of the EBPMs into a FOFB system are presented, including measurements of orbit motion spectra with and without FOFB.
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| MOO3A02 |
Beam Induced Fluorescence (BIF) Monitor for Transverse Profile Determination of 5 to 750 MeV/u Heavy Ion Beams
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33 |
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- F. Becker, C. A. Andre, P. Forck
GSI, Darmstadt
- D. Hoffmann
TU Darmstadt, Darmstadt
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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.
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Slides
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| MOO3A03 |
First Vibrating Wire Monitor Measurements of a Hard X-ray Undulator Beam at the Advanced Photon Source
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36 |
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- G. Decker
ANL, Argonne, Illinois
- S. G. Arutunian, M. R. Mailian
YerPhI, Yerevan
- G. Rosenbaum
UGA, Athens, Georgia
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The first hard x-ray flux measurements with a vibrating wire monitor (VWM) using the acoustic resonance frequencies of two vertically-offset horizontal stainless steel wires as temperature diagnostics were conducted at APS beamline 19-ID. Due to the high sensitivity of this technique, the studies were performed at extremely low power levels using radiation from a 3.3-cm-period permanent magnet hybrid undulator with a 5-mA electron beam at an energy of 7 GeV. The x-ray beam was filtered by transmission through 7 mm of beryllium placed in the photon beam path, assuring that only hard x-rays were detected. The particle beam was scanned through a range of 400 microradians using an asymmetric closed-orbit angle bump, producing two vertical photon beam profiles. The difference between processed wire signals provides a very sensitive measure of photon beam position. Details of the measurements will be given, along with a discussion of the limitations of the method and possible future research directions.
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Slides
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| TUO1A02 |
Feedbacks on Tune and Chromaticity
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43 |
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- R. J. Steinhagen
CERN, Geneva
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Feedbacks on tune, coupling and chromaticity are becoming an integral part of safe and reliable accelerator operation. Tight tolerances on beam parameters typically constrain the allowed oscillation amplitudes to the micrometre range, leaving only a small margin for the transverse beam and momentum excitations required for tune and chromaticity measurements. This contribution presents an overview of these beam-based feedback systems, their architecture and design choices involved. It discusses performance limitations due to cross-constraints, non-linearities, the coupling between multiple nested loops, and the interdependence of beam parameters.
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Slides
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| TUO1A03 |
Beam Diagnostic Features of the ESRF Multibunch Feedback
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48 |
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- J. M. Koch, F. Epaud, G. A. Naylor, E. Plouviez
ESRF, Grenoble
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The ESRF storage ring is now equiped with a set of multibunch feedback systems. The main goal of the implementation of these systems is to prevent longitudinal and transverse instabilities. However, beside this main function, these systems provide a powerful diagnostic to study the longitudinal and transverse beam dynamic and document operation problems. In this paper we give a short overview of these feedback systems and describe their diagnostics function in more detail.
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| WEO1A02 |
Progress in Ultrafast X-ray Streak Cameras
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209 |
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- J. M. Byrd
LBNL, Berkeley, California
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Streak cameras remain one of the tools for study of ultrafast phenomena. We present progress on modeling of x-ray streak cameras with application to measurement of ultrafast phenomena. Our approach is based on treating the streak camera as a photocathode gun and applying modeling tools for beam optics and electromagnetic fields. We use these models to compare with experimental results from a streak camera developed at the Advanced Light Source. We also show how this model can be used to explore several ideas for achieving sub-100 fsec resolution.
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| WEO1A03 |
Instrumentation for Longitudinal Beam Gymnastics in FEL's and in the CLIC test facility 3
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215 |
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- 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
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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.
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| WEO2A01 |
Beam Diagnostics for the Front End Test Stand at RAL
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218 |
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- S. Jolly, D. A. Lee, P. Savage
Imperial College of Science and Technology, Department of Physics, London
- D. C. Faircloth, J. K. Pozimski
STFC/RAL, Chilton, Didcot, Oxon
- C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
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The Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) is intended to demonstrate the early stages of acceleration (0-3MeV) and beam chopping required for high power proton accelerators, including proton drivers for pulsed neutron spallation sources and neutrino factories. The FETS ion source is required to produce a 60 mA beam in pulses up to 2ms long at up to 50 pps with an RMS emittance of 0.3 π mm mrad. A number of different diagnostic systems are currently under development to provide precise measurements of the H- ion beam. A pepperpot emittance measurement system, which is also capable of high resolution transverse beam density measurements, has been designed for use on the ISIS ion source development rig. This system is capable of sub-microsecond time-resolved measurements at a range of positions along the beam axis. Details are given of the improvements to the current design, including extensive tests on suitable scintillators and emittance and profile measurements are presented. Additionally, the designs of two different novel laser diagnostic systems for FETS are also presented.
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| WEO2A02 |
Single Shot Longitudinal Bunch Profile Measurements by Temporally Resolved Electro-Optical Detection
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221 |
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- 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
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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.
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| WEO2A03 |
Advanced Measurements at the SPARC Photoinjector
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224 |
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- 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
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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
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