| Paper |
Title |
Other Keywords |
Page |
| MOD1A01 |
Digital EBPMs at Diamond: Operational Experience and Integration into a Fast Global Orbit Feedback
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feedback, storage-ring, power-supply, pick-up |
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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| TUO1A02 |
Feedbacks on Tune and Chromaticity
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feedback, coupling, resonance, synchrotron |
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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feedback, kicker, diagnostics, pick-up |
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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| TUPB01 |
A Fiber Profile Monitor for low Beam Intensities.
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vacuum, secondary-beams, target, background |
51 |
| |
- G. R. Tassotto, H. Nguyen, D. P. Schoo, G. W. Sellberg
Fermilab, Batavia, Illinois
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A scintillating Fiber Profile Monitor (FPM) has been prototyped, built and tested for the new low intensity Meson Test (M-Test) beamline at Fermilab. The beamline has the following beam parameters: E = 1-120 GeV, I from a few hundreds to 700,000 particles/spill, and the spill length is 4.5 seconds. Segmented Wire Ion Chambers (SWICs) and Proportional Wire Chambers (PWCs) do not display the beam profile accurately below about 10,000 particles. For the prototype FPM detector a modified SWIC vacuum can was used. An (x, y) array of fibers replaced the chamber containing windows, gas, and AuW wires soldered on a ceramic substrate. The fibers were purchased from Saint Gobain and are of the type BCF-12 MC, 420 nm wavelength They have a diameter of 0.75 mm and are coated with black EMA for optical isolation. The 64 channel fibers are positioned and then epoxied in a vacuum feed-thru “cookie” to match a Burle 64 channel multianode microchannel plate PMT of the type Planacon # 85011-501. The gain of the Planacon PMT is 800,000 at –2400 Volts. Unlike SWICs or PWCs, this device will allow for vacuum continuity. Comparative data with PWCs will be presented.
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| TUPB02 |
Stripline Transversal Filter Techniques For Sub-Picosecond Bunch Timing Measurements
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feedback, diagnostics, synchrotron, vacuum |
54 |
| |
- J. D. Fox, T. Mastorides
SLAC, Menlo Park, California
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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
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| TUPB04 |
BPM detectors upgrade for the ELETTRA Fast Orbit Feedback
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feedback, electron, closed-orbit, diagnostics |
60 |
| |
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| TUPB08 |
Measurement of Vertical Emittance with a system of Six -In-Air-X-Ray- Projection Monitors at the ESRF
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emittance, electron, photon, shielding |
72 |
| |
- K. B. Scheidt
ESRF, Grenoble
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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.
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| TUPB09 |
Digital Beam Trajectory and Orbit System, for the CERN Proton Synchrotron
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acceleration, pick-up, target, synchrotron |
75 |
| |
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| TUPB14 |
Test of a Silicon Photomultiplier for Ionization Profile Monitor Applications
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photon, synchrotron, simulation, permanent-magnet |
90 |
| |
- D. A. Liakin, S. V. Barabin, A. Y. Orlov
ITEP, Moscow
- P. Forck, T. Giacomini
GSI, Darmstadt
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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.
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| TUPB18 |
Measurement of Electron Beam Charge in the ESRF Accelerator Complex for Absolute and Injection Efficency Measurements Using an FPGA Based Digital BPM Electronics
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booster, storage-ring, injection, electron |
102 |
| |
- G. A. Naylor, B. Joly
ESRF, Grenoble
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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.
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| TUPB19 |
Signal Level Calculation for the PETRA-III Beam Position Monitor System
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insertion, pick-up, vacuum, insertion-device |
105 |
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- G. Kube, M. Werner
DESY, Hamburg
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Starting mid 2007 the PETRA accelerator at DESY in Hamburg (Germany) will be converted into a new high brilliance light source. For measurement and control of the PETRA-III closed orbit with a resolution of better than 1 micrometer (rms) it is planned to install about 220 button type beam position monitors (BPMs). To guarantee a good performance of the BPM electronics, the button signals have to meet several criteria in time and frequency domain. Therefore signal levels for the monitor types included for installation have been estimated. The results of these calculations will be presented together with a comparison of monitor signals from accelerators in operation, and the expected position resolution will be discussed for a certain type of BPM electronics.
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| TUPB22 |
Renewal of BPM Electronics of SPring-8 Storage Ring
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storage-ring, betatron, closed-orbit, emittance |
114 |
| |
- S. Sasaki, T. Fujita, M. Shoji, T. Takashima
JASRI/SPring-8, Hyogo-ken
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The signal processing electronics of the SPring-8 Storage Ring BPM were replaced during the summer shutdown period of the year 2006. Since then, the new electronics have been put into operation for user experiment runs. The purpose of the renewal was to upgrade the performance of the position measurement system, i.e. the position resolution, speed of the measurement, etc. The position resolution of them in the real operation condition was estimated by using the stored beam in the same condition as the operations for user experiments, in the following way. The closed orbit distortions (COD) were repeatedly measured with the interval of 4 seconds in order to obtain the root mean square (r.m.s.) values of differences between two consecutive measurements. Since the obtained r.m.s. values included the intrinsic resolution of the position measurement system and the effect of the beam motion, the effect of the beam motion was separated from the obtained r.m.s. data by assuming that the effect of the beam motion was proportional to the betatron function values at the BPM locations. As a result, the intrinsic resolution was estimated to be 0.1μmeters.
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| TUPB24 |
First Results from the LEIR Ionisation Profile Monitors
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ion, vacuum, electron, accumulation |
120 |
| |
- G. Tranquille, C. B. Bal, V. Prieto, R. S. Sautier
CERN, Geneva
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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.
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| TUPB25 |
Beam Profile Measurement with Optical Fiber Sensors at FLASH
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undulator, beam-losses, radiation, monitoring |
123 |
| |
- W. Goettmann, F. Wulf
HMI, Berlin
- M. Körfer
DESY, Hamburg
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The measurement setup is based on wire scanners, optical fibers mounted symmetrically around the beam line over the full length (30 m) of the undulator section, a signal conditioning unit and a data acquisition system. The fiber sensors along the beam line allow the measurement of the spatial distribution of the scattered beam caused by the wire scanner. At each increment of the wire scanner, the generated Cherenkov light in the fiber sensors - which is proportional to the intensity of the scattered electron shower - is measured. As an improvement, the shower is not only measured at a singular location but over the entire length of the undulator section. Each integral of the generated Cherenkov light along the beam line gives one point of the transversal beam profile. Accomplishing an x-y-scan leads to a two dimensional profile of the beam. The synchronisation with the beam trigger allows the characterization of each bunch. The measured data are visualized in real time and stored in a log file for extended evaluation. The high sensitivity of the system allows an accurate monitoring of the beam profile as well as HALO measurement.
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| TUPB28 |
A Large Scintillating Screen for the LHC Dump Line
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proton, radiation, kicker, photon |
132 |
| |
- T. Lefèvre, C. B. Bal, E. Bravin, S. Burger, B. Goddard, S. C. Hutchins, T. Renaglia
CERN, Geneva
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7 TeV proton beam from the LHC is ejected through a long transfer line to a beam dump block. Approximately 100 m downstream of the ejection septa, a series of dilution kicker magnets provide a sweeping deflection spreading the extracted beam over a 40 cm diameter area on the face of the beam dump core. During normal operation, the quality of each dump event must be recorded and verified. The so called “Post-Mortem” data-set will include information from the beam dumping system as well as from the beam diagnostics along the extraction line. For this purpose, a profile monitor in front of the dump block is permanently available during machine operation. With more than 1014 protons stored in LHC, the thermal properties of the screen have to be considered as beam energy deposition becomes an issue. This paper presents the design of this device, which is original due to its very large size. We introduce the different technical considerations involved in the design of the system and present the complete layout of its installation with a special emphasis on the mechanical design, the screen assembly and the choice of the radiation-hard video camera used to capture the image.
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| TUPB30 |
Applications of IEEE-1394 and GigE Vision Digital Camera in the TLS
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diagnostics, radiation, emittance, synchrotron |
138 |
| |
- C. H. Kuo, J. Chen, P. C. Chiu, K. T. Hsu, S. Y. Hsu, D. Lee, C. Y. Wu
NSRRC, Hsinchu
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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.
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| TUPB31 |
The Beam Position System of the CERN Neutrino to Gran Sasso Proton Beam Line
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pick-up, target, radiation, proton |
141 |
| |
- T. Bogey, O. R. Jones
CERN, Geneva
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The CERN Neutrino to Gran Sasso (CNGS) experiment uses 400GeV protons extracted from the SPS, which travel along 825 meters of beam line before reaching the CNGS target. This beam line is equipped with 23 BPMs capable of measuring both the horizontal and vertical position of the beam. The final BPM is linked to the target station and due to radiation constraints has been designed to work in air. This contribution will give an overview of the BPMs used in the tansfer line. It will also provide a detailed explanation of their logarithmic amplifier based acquisition electronics, which consists of an auto-triggered sequencer controlling an integrator, the A/D conversion and the Manchester encoded transmission of the digital data to the surface. At the surface the digital data is aquired using the Digital Acquisition Board (DAB) developed by TRIUMF (Canada) for the LHC BPM system. Results from both laboratory measurements and beam measurements during the 2006 CNGS run will also be presented.
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| TUPC12 |
FPGA based Frame Grabber for Video Beam Diagnostics
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radiation, diagnostics, injection, proton |
174 |
| |
- I. Krouptchenkov, K. Wittenburg
DESY, Hamburg
| |
TV-based accelerator diagnostics are widely used for machine operation and beam diagnostics. It is planned to renew the video memory modules of the TV monitor data acquisition systems for the injection and transfer lines at DESY. New FPGA based Frame Grabber (FG) modules were developed within this project. The modules are required to be able to work with different analog signal formats, to capture video frames on trigger and to provide live mode operation. The main feature of this FG is the possibility of reprogramming. This allows us to optimize its functionality, for example to operate with non-standard or corrupted video signals. This has proved especially useful for grabbing images from CCD-cameras suffering from radiation damage.
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| TUPC13 |
The new Diode BPM system for ELETTRA
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vacuum, undulator, storage-ring, pick-up |
177 |
| |
- R. De Monte
ELETTRA, Basovizza, Trieste
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A new Beam Position Monitor system has been developed at ELETTRA based on an envelope detector. It is a four channel system reading in parallel the four voltages from a button pick-up that adopts a wide-band Schottky diode. The analogue bandwidth of the currently implemented detector is <1kHz which has been adapted to the present application of the system, i.e. a fast beam position interlock to be installed on the ELETTRA storage ring. The upgrade of the ELETTRA BPM which is based on the Libera detector suggested us to add some redundancy on the fast position interlock in order to protect the vacuum chamber from wrong positions / angles of the beam. The data collection scheme, based on a single board computer for each straight section, is presented. Currently, the system has been installed and tested on all the ELETTRA undulator sections; the first running experience is here presented.
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| TUPC19 |
Matlab Code for BPM Button Geometry Computation
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vacuum, storage-ring, booster, linac |
186 |
| |
- A. Olmos, F. Pérez
ALBA, Bellaterra
- G. Rehm
Diamond, Oxfordshire
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Third generation Synchrotron Light Sources with vertical beam sizes down to few microns require beam resolutions on the submicron level. Study of different Beam Position Monitors (BPM) geometries has been done to reach such tight requirements. The used Matlab Graphical User Interface (GUI) is based on the simulation of a charged particle inside a selectable vacuum chamber type, computing the induced signal that it produces on the button feedthroughs. Needed parameters for the computation are the button electrode dimensions, vacuum chamber profile, electron beam current and measurement bandwidth. Output results from the GUI are the induced power on the feedthroughs, BPM sensitivity and intrinsic resolution of the analyzed geometry. As sensitivity and resolution are BPM geometry dependent terms, the Matlab GUI turned out to be an easy and fast way for first step geometry analysis.
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| TUPC20 |
The SOLEIL BPM and Orbit Feedback Systems
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feedback, storage-ring, vacuum, instrumentation |
189 |
| |
- N. Hubert, L. Cassinari, J.-C. Denard, N. L. Leclercq, A. Nadji, L. S. Nadolski, D. Pédeau
SOLEIL, Gif-sur-Yvette
| |
SOLEIL is a third generation light source built in France, near Paris. Its BPM system is important for machine studies and for delivering stable beams to the users. A beam stable to 1/10th of the dimensions requires submicron stability in the vertical plane. The monitors, anchored either to the girders or to the ground, are fixed points of the vacuum chamber. Bellows avoid transverse drifts due to mechanical stress. The electronics design was driven by combined efforts through an active communication between accelerator labs (SOLEIL at first, later joined by DIAMOND) and Instrumentation Technologies. The result is the “Libera Electron” beam position processor. It combines a 0.2μm rms resolution and micron level stability for beam delivery with accurate turn-by-turn measurements (3μm resolution at 0.8MHz) for machine commissioning and beam physics studies. It also features position interlock, tune measurement, and postmortem capabilities. A Slow Orbit Feedback for correcting low frequency drifts (0 to 0.1Hz) is currently in operation. The Fast Orbit Feedback to be implemented soon will suppress higher frequency perturbations up to 100Hz.
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| WEPB01 |
Design of an Electron Beam Energy Control Loop Using Transverse Dispersion
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dipole, electron, optics, target |
229 |
| |
- M. Justus, U. Lehnert, P. Michel
FZD, Dresden
- P. Evtushenko
Jefferson Lab, Newport News, Virginia
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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.
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| WEPB30 |
Current Status of the SQUID Based Cryogenic Current Comparator for Absolute Measurements of the Dark Current of Superconducting RF Accelerator Cavities
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pick-up, cryogenics, electron, shielding |
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.
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| WEPC02 |
Developments at Elettra of the Electronics for the Bunch-Arrival Monitor
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pick-up, monitoring, coupling, laser |
310 |
| |
- L. Pavlovič, T. Korošec, M. Vidmar
Uni LJ, Ljubljana
- M. Ferianis, F. Rossi
ELETTRA, Basovizza, Trieste
- K. E. Hacker, F. Löhl, H. Schlarb
DESY, Hamburg
| |
Within the framework of the EUROFEL project, a task has been started in 2006 for a joint development of a Bunch Arrival Monitor (BAM), based on the original idea from DESY. ELETTRA is responsible for the development of the VME-controlled clock-delay board of the BAM system. A variable clock-delay circuit (a phase shifter) is required to adjust the acquisition sampling point of the pick-up-modulated optical pulses of the master-laser oscillator. Since the optical pulses have a repetition rate of 40.625MHz (54MHz in the future) and the acquisition sampling frequency is double of this value, the clock-delay module operates in the 80-120MHz frequency range. The clock timing jitter of the acquisition system greatly affects the measurements of the system: the output timing jitter from the clock-delay board should be less than 0.5ps-rms. Therefore, due to the very strict additive timing-jitter requirements, three phase shifter versions were designed, built and phase-noise evaluated. Low-pass-filter implementation achieved 563fs (at 283fs source jitter) of total-system timing jitter, integrated IQ multiplier 365fs (at 188fs of source) and passive IQ modulator 265fs (at 208fs of source).
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| WEPC10 |
Tune, Coupling, and Chromaticity Measurement and Feedback During RHIC Run 7
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feedback, injection, coupling, betatron |
331 |
| |
- P. Cameron, J. Cupolo, W. C. Dawson, C. Degen, A. J. Della Penna, L. T. Hoff, Y. Luo, A. Marusic, R. Schroeder, C. Schultheiss, S. Tepikian
BNL, Upton, Long Island, New York
| |
Tune feedback was first implemented in RHIC in 2002, as a specialist activity. The transition to full operational status was impeded by dynamic range problems, as well as by overall loop instabilities driven by large coupling. The dynamic range problem was solved by the CERN development of the Direct Diode Detection Analog Front End[1]. Continuous measurement of all projections of the betatron eigenmodes made possible the world's first implementation of coupling feedback during beam acceleration, resolving the problem of overall loop instabilites[2,3]. Simultaneous tune and coupling feedbacks were utilized as specialist activities for ramp development during the 2006 RHIC run. At the beginning of the 2007 RHIC run there remained two obstacles to making these feedbacks fully operational in RHIC - chromaticity measurement and control, and the presence of strong harmonics of the power line frequency in the betatron spectrum. Preliminary investigations of power line harmonics were presented earlier[4]. We report here on progress in tune, coupling, and chromaticity measurement and feedback, and discuss the relevance of our results to the LHC commissioning effort.
[1] M. Gasior and R. Jones, DIPAC 2005, Lyon, p.312.[2] P. Cameron et. al., PRST-AB, Dec 2006. [3] R. Jones et. al., DIPAC 2005, Lyon, p.298.[4] P. Cameron et. al., DIPAC 2005, Lyon, p.33.
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| WEPC17 |
Fast Orbit Feeback System Upgrade with New Digital Bpm and Power Supply in the Tls
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feedback, power-supply, electron, 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.
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| WEPC22 |
Synchronization of a 3GHz Repetition Rate Harmonically Mode-Locked Fiber Laser for Optical Timing Applications
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laser, feedback, polarization, linac |
358 |
| |
- L. Banchi, M. Ferianis, F. Rossi
ELETTRA, Basovizza, Trieste
- A. Bogoni, P. Ghelfi, L. Poti'
CNIT, Pisa
| |
We have successfully stabilized a 3GHz Harmonically Mode-Locked fiber ring laser by a PLL feedback control of the cavity length to reduce the pulses RMS timing jitter. The laser cavity is composed of all PM fibers and components to eliminate polarization instabilities and to reduce the vibration sensitivity. The laser stability in terms of timing jitter was around 9ps in the range 10Hz-10MHz. Using a PLL scheme we synchronized the laser repetition rate to an ultra stable RF generator. The noise characteristics of the laser output were measured by observing the SSB noise spectra of the 1st harmonic, from 10Hz to the Nyquist frequency (1.5GHz). We have obtained a global reduction of fiber laser timing jitter value down to less than 100fs in the range 10Hz-10MHz; a complete overlapping between the laser and the RF generator spectral profiles in the loop bandwidth has been observed. An extended investigation has been performed to estimate the phase noise spectra and timing jitter up to 1.5GHz. By doing so, the contribution of the laser supermodes to the phase noise has been taken into account as well, to quantify the true value of the total RMS timing jitter of the optical pulses.
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| WEPC23 |
Progress of the Diagnostics at the Proscan Beam Lines
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diagnostics, quadrupole, emittance, kicker |
361 |
| |
- R. Dölling
PSI, Villigen
| |
PROSCAN, the dedicated new medical facility at PSI using proton beams for the treatment of deep seated tumours and eye melanoma, has entered the operational phase. Air and N2 filled ionisation chambers and secondary emission monitors in several configurations are used as current monitors, profile monitors, halo, position and loss monitors at the PROSCAN beam lines. The operation experience and improvements of these diagnostics as well as of the multi-leaf- and the standard faraday-cups and of the profile-evaluation technique are reported. Additional variants of ionisation chamber position monitors adapted to local requirements are now under construction. Criteria for interlocks which control beam parameters and the correct operation of diagnostics are discussed as well as dedicated procedures for checking the function of the built-in diagnostics. The fast exchange of beam-line components and spare parts are briefly mentioned.
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| WEPC24 |
A Self Calibrating Real Time Multi-Channel Profile Monitor for the Isis Proton Synchrotron
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electron, ion, proton, acceleration |
364 |
| |
- S. J. Payne, P. G. Barnes, G. M. Cross, A. Pertica, S. A. Whitehead
STFC/RAL/ISIS, Chilton, Didcot, Oxon
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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.
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| WEPC28 |
Timing and Synchronization at the LCLS
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laser, electron, klystron, linac |
373 |
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