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MOO1A02 High Resolution Transverse Profile Measurement laser, electron, 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.  
 
MOO1A03 Review of Synchrotron Radiation based Diagnostics for Transverse Profile Measurements emittance, radiation, optics, diagnostics 6
 
  • G. Kube
    DESY, Hamburg
  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.  
 
MOD1A03 Electron Beam Diagnostics for the ALBA Light Source booster, diagnostics, linac, radiation 27
 
  • U. Iriso, A. Olmos, F. Peréz
    ALBA, Bellaterra
  This paper presents the diagnostics systems that will be used to monitor the electron beam at ALBA, a 3 GeV 3rd generation synchrotron light source. The electron beam is characterized by measuring its transverse position in the beam pipe, beam current, transverse size and longitudinal structure. We provide a complete picture of all the systems to diagnose the electron beam along ALBA facility, not only in the Storage Ring but also in the injector system (Linac, Booster and transfer lines).  
 
TUO1A02 Feedbacks on Tune and Chromaticity feedback, controls, coupling, resonance 43
 
  • R. J. Steinhagen
    CERN, Geneva
  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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TUPB02 Stripline Transversal Filter Techniques For Sub-Picosecond Bunch Timing Measurements feedback, diagnostics, controls, vacuum 54
 
  • J. D. Fox, T. Mastorides
    SLAC, Menlo Park, California
  Measurement of time of arrival of a particle bunch is a fundamental beam diagnostic. The PEP-II/ALS/BESSY/PLS longitudinal feedback systems use a planar stripline circuit structure to convert a 30 ps beam BPM impulse signal into a 4 cycle tone burst at the 6th harmonic of the accelerator RF frequency (roughly 3 GHz). A phase-detection technique is used to measure the arrival time of these BPM impulses with 180 fs rms single-shot resolution (out of a 330 ps dynamic range). Scaled in frequency, this approach is directly applicable to LCLS, FEL and other sub-fs regime pulse and timing measurements. The transversal circuit structure is applicable to measurement of microbunches or closely spaced bunches (the PEP-II examples make independent measurements at 2 nS bunch spacing) and opens up some new diagnostic and control possibilities. This paper reviews the principles of the technique, and uses data from PEP-II operations to predict the limits of performance of this measurement scheme for arrival phase measurement. These predictions are compared with results in the literature from electro-optic high-resolution sub-picosecond beam timing and phasing diagnostics.

* Briggs, et al, "Prompt Bunch by Bunch Synchrotron Oscillation Detection by a Fast Phase Measurement", Proceedings of the IEEE Particle Accelerator Conference, 5/91, 1404-1406

 
 
TUPB06 First Tests with the Sis18 Digital BPM System* acceleration, pick-up, injection, instrumentation 66
 
  • A. A. Galatis, P. Forck, K. Lang, A. Peters
    GSI, Darmstadt
  In this paper we describe new approaches for BPM (Beam Position Monitor) measurements, needed in hadron accelerators which have strongly varying beam parameters, such as intensity, accelerating frequency and bunch length. After the data collection and offline evaluation in 2005, first FPGA implementations of algorithms were completed in 2006 and tested at SIS18 and CERN PS. Main aspect of the first tests was the proof of concept in terms of online calculation feasibility. This includes online calculation of the needed integration windows as well as the baseline restoration algorithms. The realization of the hardware and the data handling are discussed. Least squares techniques were used for parametric fitting to gain bunch signal properties which can be used to monitor beam position.

*Founded by EU FP6-Design Studies

 
 
TUPB09 Digital Beam Trajectory and Orbit System, for the CERN Proton Synchrotron acceleration, pick-up, target, controls 75
 
  • G. Kasprowicz, J. M. Belleman, U. Raich
    CERN, Geneva
  A new trajectory and orbit measurement system using fast signal sampling and digital signal processing in an FPGA is proposed for the CERN PS. The system uses a constant sampling frequency while the beam revolution frequency changes during acceleration. Synchronization with the beam is accomplished through a numerical PLL algorithm. This algorithm is also capable of treating RF gymnastics like bunch splitting or batch compression with the help of external timing signals. Baseline correction as well as position calculation is provided in the FPGA code as well. After having implemented the algorithms in C and MatLab and tested them with data from a test run at the PS they have now been implemented in the FPGA for online use. Results of measurements on a single beam position monitor in the CERN PS and the SIS-18 at GSI will be presented.  
 
TUPB14 Test of a Silicon Photomultiplier for Ionization Profile Monitor Applications photon, controls, simulation, permanent-magnet 90
 
  • D. A. Liakin, S. V. Barabin, A. Y. Orlov
    ITEP, Moscow
  • P. Forck, T. Giacomini
    GSI, Darmstadt
  A sample of SiPM (silicon photomultiplier) has been tested as an elementary light detector for accelerated beam fast profile evolution observation by using it in residual gas ionization profile monitors. A noise, sensitivity, dynamic range and timing parameters tests of SiPM were performed. A procedure of the data acquisition and following signal reconstruction is discussed. A special attention has been paid to the fine time resolution counting mode with single photon detection. A dedicated signal normalizing and time-to-digit converter design was prototyped and tested. In addition some different modes of operation and optical schemes are discussed in this paper. It is shown that fast optical detectors like SiPMs also could be used for high performance profile measurements with spatial resolution compatible with CCD sensors.  
 
TUPB27 Recent Results from the Electron Beam Profile Monitor at the Swiss Light Source electron, 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.  
 
TUPB30 Applications of IEEE-1394 and GigE Vision Digital Camera in the TLS controls, diagnostics, radiation, emittance 138
 
  • C. H. Kuo, J. Chen, P. C. Chiu, K. T. Hsu, S. Y. Hsu, D. Lee, C. Y. Wu
    NSRRC, Hsinchu
  Digital cameras comply with IEEE-1394 and GigE Vision standard are applied for beam diagnostic applications at NSRRC. These cameras provide low distortion for image transmission over long distance and flexible camera parameters adjustment with remote interface. These digital interfaces include of FireWire and gigabit Ethernet. The wide bandwidth bus can reduce latency time and timing jitter effectively and provides high quality image transportation. It also provides lossless compressed image with high update rate. Experiences accompany with both kind of cameras will be summarized. System integration with control system, analysis and application will also include in the report.  
 
TUPC03 Synchrotron Radiation Monitor for Energy Spectrum Measurements in the Bunch Compressor at FLASH electron, dipole, acceleration, 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.  
 
TUPC06 Coherent Radiation Studies For The FERMI@Elettra Relative Bunch Length Diagnostics radiation, dipole, diagnostics, electron 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.  
 
TUPC16 Ultimate Resolution of Soleil X-Ray Pinhole Camera photon, radiation, coupling, synchrotron-radiation 180
 
  • M.-A. Tordeux, L. Cassinari, O. V. Chubar, J.-C. Denard, D. Pédeau, B. Pottin
    SOLEIL, Gif-sur-Yvette
  During the commissioning of the SOLEIL Storage Ring, beam emittances have been measured with an X-ray pinhole camera system. The evolution of the system and its performances are presented here. As a result of the excellent alignment of the ring magnets, the vertical beam size is smaller than expected, that led us to an effort towards improving the initial resolution of the instrument. A high sensitivity CCD camera allows us to select the harder X-ray part of the radiation which is a key element for resolution improvement. Finally an evaluation of the ultimate pinhole resolution is made for SOLEIL.  
 
WEPB12 Measurement of Bunch Lengthening Effects Using a Streak Camera with Reflective Optics optics, impedance, vacuum, coupling 256
 
  • T. Obina, T. Mitsuhashi
    KEK, Ibaraki
  For the precise measurement of the bunch length, the incident optics of a streak camera must be free from an optical path difference due to chromatic effects. We designed and installed a reflective optics for the streak camera, and measured the bunch length as a function of the beam current. In the KEK Photon Factory, almost one half of the vacuum components were replaced in 2005. We measured the bunch lengthening effects before and after the replacement. The threshold-current of the microwave instabilities showed the impedance of the storage ring was greatly improved. This paper describes the detail of measurement and the calculations of the impedance of vacuum components.  
 
WEPB24 Machine Protection and Interlock Systems at Synchrotron SOLEIL vacuum, storage-ring, diagnostics, booster 286
 
  • Y.-M. Abiven, F. Dohou, R. P. Patrick
    SOLEIL, Gif-sur-Yvette
  SOLEIL is a third generation Synchrotron radiation source located in France near Paris, having the classical accelerator structure consisting of a Linac pre-accelerator, a Booster accelerator and a Storage Ring, which are connected by two transfer lines[1]. Since January, the Storage Ring delivers photon beam to 9 beamlines. In order to protect the very sensitive and essential equipment during machine operation, (vacuum chambers, vacuum valves, mirrors, etc.) an interlock system has been implemented. This system is based on industrial and autonomous PLC (Programmable Logic Controller). This paper describes each level of the interlock chain from the diagnostics and vacuum sensors and processes, up to the backbone of the interlock system which stops the RF system.  
 
WEPB25 Time Domain Measurements at Diamond electron, photon, single-bunch, 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 electron, diagnostics, positron, 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.  
 
WEPC08 Fiberoptics-Based Instrumentation for Storage Ring Beam Diagnostics coupling, diagnostics, photon, synchrotron-radiation 325
 
  • S. De Santis, J. M. Byrd
    LBNL, Berkeley, California
  • Y. Yin
    Y. Y. Labs, Inc., Fremont, California
  We present the results of our experiments at the Advanced Light Source concerning the coupling of synchrotron radiation into optical fibers. Many beam diagnostic devices in today's synchrotron rings make use of the radiation emitted by the circulating particles. Such instruments are placed in close proximity of the accelerator, where in many instances they cannot be easily accessed for safety consideration, or at the end of a beamline, which, because of its cost, can only move the light port a few meters away from the ring. Our method, suitable for all those applications where the longitudinal properties of the beam are measured (i.e. bunch length, phase, etc.), allows placing the diagnostic instruments wherever is more convenient, up to several hundreds of meters away from the tunnel. This would make maintaining and replacing instruments, or switching between them, possible without any access to restricted areas. Additionally, one can use the vast array of optoelectronic devices, developed by the telecommunication industry, for signal analysis.  
 
WEO3A02 Diagnostic Instrumentation for Medical Accelerator Facilities ion, proton, diagnostics, linac 381
 
  • M. Schwickert, A. Peters
    GSI, Darmstadt
  A number of accelerator facilities are presently emerging for the medical treatment of tumour patients using proton and light ion-beams. Both, the development of relatively compact accelerators and extensive studies on ion-therapy carried out at various accelerator laboratories were prerequisites for the layout of dedicated medical accelerator facilities. This paper focuses on the special demands for beam diagnostic devices during the commissioning and routine operation of a medical accelerator. The proton-therapy project PROSCAN at the Paul-Scherrer-Institute in Villigen/Switzerland exemplifies medical treatment in the frame of a research institute. As examples for dedicated ion-therapy projects the beam diagnostic layout is presented for the CNAO project (Centro Nazionale Adroterapia Oncologica) located in Pavia/Italy and the HIT facility (Heidelberger Ionen Therapie) in Heidelberg/Germany. Beam diagnostic devices of HIT are illustrated and the underlying concept for the type and precision of the devices is explained. Additionally, measurement results of the HIT linac and synchrotron commissioning are presented.