| Paper | Title | Page |
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| TUPC001 | Optics Calculation and Emittance Measurement toward Automatic Beam Tuning of Linac | 1035 |
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| The SPring-8 1-GeV linac has a total of 13 sets of 80MW klystron units. In usual operation, two klystron units are driven as the standby unit. If there's any problem with an arbitrary klystron unit, the beam operation is able to restart immediately by using the standby unit. In that case, the optimization of beam optics has carried out using beam screen monitors. This beam tuning spend about one hour. In order to reduce the beam tuning time, we are promoting the development of the automatic beam optics tuning system. Since the complete understanding of the beam envelope is important, the particles tracking simulation of the linac was carried out by using PARMELA and SAD. Five sets of beam size monitors were installed in the end of the linac for measurement of the real beam envelope. In a beam study applying the simulation results, the beam waist was actually formed at the 10-m long drift space after the 1-GeV chicane section as predicted by SAD. The values of the measured beam emittance were smaller than the simulation results. | ||
| TUPC002 | Design of a Tomography Module for the PITZ Facility | 1038 |
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| The goal of the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is to develop sources of high phase-space density electron beams that are required for the successful operation of SASE FELs. This requires detailed characterization of the sources and therefore the development of suitable advanced diagnostics. As part of the ongoing upgrade towards higher beam energies, new diagnostics components are being installed. An example is a tomography module for transverse phase space reconstruction which is designed to operate in the energy range between 15 and 40 MeV. The module consists of four observation screens with three FODO cells between them. A number of upstream quadrupoles are used to match the beam envelope parameters to the optics of the FODO lattice. This contribution presents the final design of the tomography module. Data from numerical simulations are used to illustrate the expected performance and to compare it to a simplified setup of two quadrupoles. The quality of the reconstruction is revised with the help of different algorithms. | ||
| TUPC003 | Libera Grouping: Reducing the Data Encapsulation Overhead | 1041 |
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| Libera Brilliance is a precision digital Beam Position Monitor, a building block for modern fast orbit feedback systems. Gigabit Ethernet and UDP/IP protocol are used as a standard data link for real-time beam position signal transmission to the central fast feedback CPU engines. While the UDP/IP over Gigabit Ethernet provides a standardized and proven solution that enables the utilization of COTS components, the UDP and IP protocols are subject to a large data encapsulation overhead, since the beam position data payload is relatively small. To overcome this, several Libera Brilliance units (up to 16) have been grouped together in a redundant private network via the LC optical links and/or copper “Molex” cables. The purpose of the private network is to exchange the data among the Libera Brilliance units without the protocol overhead and send the gathered data via Gigabit Ethernet. Any of the Libera Brilliance units in a group can act as a Gigabit Ethernet group transmitter. The private network is redundant and can survive a single cable failure. The data encapsulation overhead has been significantly reduced. Libera Grouping is being tested at NSRRC, Taiwan. | ||
| TUPC004 | The Diagnostic Line of Elettra Booster 100MeV Pre-injector | 1044 |
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| In order to fully characterize the beam of the new 100MeV linac pre-injector for the Elettra Booster, a standard diagnostic set-up has been designed which includes strip line BPMs, scintillating screens and current transformers. During the initial tuning of the pre-injector, a thermo-ionic gun followed by a 500MHz pre bunching cavity, an S-band bunching structure and two LIL accelerating sections, some extra diagnostics have been used to get a deeper understanding of the pre-injector operating point. In particular some prototypes of the FERMI@elettra diagnostics, installed on the same booster pre-injector, have been used to better characterize the beam transverse and longitudinal beam axis. An improved resolution screen system, equipped with a YAG screen, has been used as well as a wideband longitudinal pick-up. The measurement results as well as the tuning procedure are here presented. | ||
| TUPC005 | Simulation Study of Laser-wires as a Post-linac Diagnostic for CLIC and ILC | 1047 |
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| Realistic CLIC and ILC bunch trains are simulated in the linac, including intra-train collective effects, and then analysed via a realistic simulation of a laser-wire system, including effects of laser-wire signal extraction, detection and deconvolution. Implications are drawn for the use of laser-wires as a post-linac machine diagnostic. | ||
| TUPC006 | A CompactRIO-based Beam Loss Monitor for the SNS RF Test Cave | 1050 |
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| An RF Test Cave has been built at the Spallation Neutron Source (SNS) to be able to test RF cavities without interfering the SNS accelerator operations. In addition to using thick concrete wall to minimize radiation exposure, a Beam Loss Monitor (BLM) must abort the operation within 100 μsec when the integrated radiation within the cave exceeds a threshold. We choose the CompactRIO platform to implement the BLM based on its performance, cost-effectiveness, and rapid development. Each in/output module is connected through an FPGA to provide point-by-point processing. Every 10 μsec the data is acquired analyzed and compared to the threshold. Data from the FPGA is transferred using DMA to the real-time controller, which communicates to a gateway PC to talk to the SNS control system. The system includes diagnostics to test the hardware and integrates the losses in real-time. In this paper we describe our design, implementation, and results. | ||
| TUPC007 | Numerical and Experimental Investigation of the Contamination of X-ray Beam Position Monitors by Bending Magnet Edge Radiation | 1053 |
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| The details of an investigation into bending magnet edge radiation at Diamond are discussed, reviewing the effects of this radiation on X-ray Beam Position Monitoring (XBPM) equipment. For some time it has been recognized that there are difficulties using XBPMs for determining the centre of mass position of an undulator beam due to contamination from bending magnet radiation. While the geometry of the XBPM blades is designed to help reduce background dipole interference, this radiation is known to account for approximately 1% of the signal received, skewing the calculated beam position by several micrometres. We made detailed models of the bending magnet edge radiation using the SRW program and used Matlab to analyse the data. We present this model and compare our prediction to experimental results obtained at Diamond. | ||
| TUPC008 | Beam Diagnostics with IR Light Emitted by Positron at DAΦNE | 1056 |
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Real-time beam diagnostics is mandatory in accelerators and represents one of the most challenging issues of modern storage rings and future FEL's. Recently, compact mid-IR fast uncooled photo-detectors have been used at DAΦNE to monitor single e- bunches using the SINBAD IR beamline installed on the e- ring*. Electron bunches have a FWHM of 150-300 ps and are separated by 2.7 ns**. Detectors performances are then suitable for a compact and low cost bunch-by-bunch longitudinal diagnostic device. To improve the DAΦNE diagnostic a bending magnet SR port on the e+ ring has been set-up with a HV chamber, a gold-coated plane mirror and a ZnSe window. To collect the SR light and focus radiation on IR detectors allowing the diagnostic of e+ a compact optical system has been installed in air after the window. Here we will present the status of the apparatus, the source characteristics, the optical setup and the complete acquisition system. This IR port will allow comparison in the ns time domain between data collected on both rings, and could be also used to improve DAΦNE diagnostics, i.e., identify and characterize bunch instabilities and/or increase the current in the e+ ring.
*M. Cestelli Guidi et al. J. Opt. Soc. Amer. A 22, 2810 (2005). |
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| TUPC009 | Vertical Beam Profile Measurement and Analysis with X-ray Pinhole | 1059 |
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| Imaging the electron beam profile at a synchrotron light source is commonly performed in the x-ray regime using a pinhole camera system. However, with machines pushing down the vertical emittance, including errors in source point optical parameters, pinhole manufacturing limitations and error analysis difficulties associated with diffraction and image capture, the pinhole imaging system has large errors, up to 50% for an emittance of a few picometre. An analysis has been done at the Australian Synchrotron (AS) looking at the effects of errors in determining the x-ray pinhole source point parameters. | ||
| TUPC010 | Single Bunch Studies at the Australian Synchrotron | 1062 |
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| Studies using a single high charge electron bunch have been conducted at the Australian Synchrotron to characterise the impedance of the machine at various stages of commissioning and insertion device configuration. This paper will present the results of these studies and show the time evolution of machine impedance with increasing number of insertion devices. | ||
| TUPC011 | Micron Size Laser-wire System at the ATF Extraction Line | 1065 |
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| The ATF extraction line laser-wire system has recently been upgraded allowing the measurement of micron scale transverse size electron beams. We report on the hardware upgrades, including focusing lens, laser and mechanical systems. First measurements using the new system from recent operation at the ATF in KEK are presented. | ||
| TUPC012 | MICE: The International Muon Ionization Cooling Experiment: Diagnostic Systems | 1068 |
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The Muon Ionization Cooling Experiment will make detailed measurements of muon ionization cooling using a new constructed low-energy muon beam at the Rutherford Appleton Laboratory. The experiment is a single-particle experiment and utilizes many detector techniques from High-Energy Physics experiments. To characterize and monitor the muon beam line, newly developed scintillating fiber profile monitors will employed. In order to monitor the purity of the beam and tag the arrival time of individual muons, a dual Aerogel Cerenkov system and a plastic scintillator time-of-flight system will be used. The 4-momenta of the muons will be measured by two identical spectrometer systems (one before and one after the cooling apparatus) which employ a fiber tracker that utilizes 350 micron diameter scintillator fiber. An additional time-of-flight system and electron and muon calorimeters are used to tag outgoing muons. We will discuss the design of the MICE diagnostic systems, the operation and give the first results from beam measurements in the MICE experimental hall.
A. Bross on behalf of the MICE collaboration. |
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| TUPC013 | A Compact and Versatile Diagnostic Tool for CNAO Injection Line | 1071 |
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| CNAO, the first Italian center for deep hadrontherapy, is presently in its final step of construction. It will provide treatments with active scanning both with proton and carbon ion beams. Commissioning of the injection lines will be started by the time of the presentation of this report. CNAO beams are generated by two ECR sources, which are both able to produce both particle species. The beam energy in the Low Energy Beam Transfer (LEBT) line is 8 keV/u. A compact and versatile tank has been designed that contains a complete set of diagnostic tools. It is only 390mm long; it houses two horizontal and two vertical plates to suppress beam halo, measure emittance and eventually to limit beam size. It also comprises two wire scanners, for vertical and horizontal beam transverse profile, as well as a Faraday Cup for current measurement. Synchronous profile and intensity measurements and phase space distribution reconstruction can be performed with one tank monitors. Five identical tanks are installed in the LEBT, as consequence of a standardization strategy to facilitate monitoring and make maintenance easier. Expected performances and preliminary beam measurements are presented. | ||
| TUPC014 | SSRF Injector Diagnostics Commissioning Results | 1074 |
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| This paper presents Injector beam diagnostics layout of the Shanghai Synchrotron Radiation Facility(SSRF) which includes the 150MeV LINAC, booster(3.5GeV) and beam transport lines. The different beam diagnostics monitors for beam current, beam position and beam profile are briefly described. The beam diagnostics data acquisition architecture is introduced. Commissioning Results of the 150Mev LINAC are presented, as well as the commissioning status of the booster . | ||
| TUPC015 | Data Acquisition and Analysis in SSRF BPM System | 1077 |
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| The beam position monitor (BPM) system in Shanghai Synchrotron Radiation Facility (SSRF) is fully (Linac, transfer line, booster and storage ring) equipped with Libera Electron BPM Processors. Primary data acquisition and position calculation has been done in Libera FPGA. EPICS support package developed by Diamond Light Source has been adapted to link BPM system with accelerator control system. Two dedicated soft IOCs are introduced to collect beam position data from all Libera IOCs and calculate RMS noise, histogram, spectrum and phase space, etc. online. Other BPM based analysis is completed via MATLAB scripts. The initial results during booster and storage ring commissioning will be described in this paper. | ||
| TUPC017 | Beam Instrumentation System Development and Commissioning in SSRF | 1080 |
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| In recent months the first beams have been stored in the Storage Ring of the Shanghai Synchrotron Radiation Facility (SSRF). The brief introduction will be given of the beam diagnostics system development. The initial commissioning results including beam profile monitors, beam position monitors (BPMs), DC current monitors (DCCT), and synchrotron radiation monitor (SRM) will be reported in this paper. | ||
| TUPC018 | New Experimental Results with Optical Diffraction Radiation Diagnostics | 1083 |
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| The characterization of the transverse phase space for high charge density and high energy electron beams is demanding for the successful development of the next generation light sources and linear colliders. The interest in a non-invasive and non-intercepting beam diagnostics is increasingly high due to the stringent features of such beams. Optical Diffraction Radiation (ODR) is considered as one of the most promising candidates to measure the transverse beam size and angular divergence, i.e. the transverse emittance. An experiment, based on the detection of the ODR angular distribution, has been set up at DESY FLASH Facility to measure the electron beam transverse parameters. In this paper we report the recent results on the incoherent diffraction radiation produced by a 1 GeV energy electron beam going through a rectangular slit. | ||
| TUPC019 | A Retarding Field Detector to Measure the Actual Energy of Electrons Participating in E-cloud Formation in Accelerators | 1086 |
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| Electron cloud related phenomena can cause potentially detrimental effects on beam stability in many planned and under construction accelerators. The possibility to reduce such unwanted phenomena lies on the observation that, machine commissioning does reduce Secondary Electron Yield (SEY). Such SEY reduction (scrubbing) is due to the fact that electrons produced during e-cloud formation hit the accelerator wall, modifying their surface properties. ‘Scrubbing” has been studied only as a function of impinging electron dose but never as a function of the e-cloud electron energy. Simulations predict that the e-cloud is formed by electrons with very low energies (<50 eV). Given the potentially lower scrubbing efficiency for equal dose of very low energy electrons compared to medium energy one, it would be important to measure the actual energy of the electrons forming the cloud in real accelerators. For this reason we decided to construct an optimized retarding Field energy electrometer to be installed in accelerators. Here we will describe what solutions have been adopted during the design phase of such “home made” detector and some laboratory test will be showed and discussed. | ||
| TUPC020 | Development of Non-destructive Beam Current Measurement for the iThemba LABS Cyclotrons | 1089 |
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| The 200 MeV separated-sector cyclotron and its two 8 MeV solid-pole injector cyclotrons at iThemba LABS deliver beams of light and heavy ions, as well as polarized protons, with variable energy for nuclear physics research, a low-intensity proton 200 MeV beam for proton therapy and a high-intensity 66 MeV proton beam for neutron therapy and the production of radioisotopes. The intensity of the 66 MeV proton beam has recently been increased to 250 μA. This necessitated development of non-destructive beam diagnostic equipment, amongst others, for beam current measurement at various positions in the different beamlines. It was decided to determine the beam current by digitizing and analyzing the signals from capacitive phase probes on-line, instead of using more costly DC beam-current transformers. It was also important to design the phase probes with as low as possible inductance in their support to the diagnostic vacuum chambers to eliminate ringing in the probe signals. The design of the probes, the analyses of the probe signals and the results that were obtained with the equipment will be presented. | ||
| TUPC021 | High Bandwidth Wall Current Monitor for CTF3 | 1092 |
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| Wall Current Monitors (WCM) are commonly used to observe the time profile and spectra of a particle beam by detecting its image current. For the 3rd CLIC Test Facility (CTF3), a WCM having a very large bandwidth (100kHz-20GHz) is in principle required. This very stringent request was critically reviewed because the low cut-off frequency of 100 kHz is quite outstanding. It was initially chosen because of the bunch train length but, in reality, because of the high frequency cut-off of 20GHz, the low frequency cut-off should rather be related to the maximum expected Missing Bunch Ratio (MBR). The solution that we propose has a low frequency cut-off of 2GHz corresponding to an MBR of 1/6 for 83ps bunch spacing. If needed, it could be lowered to 400MHz (MBR equal to 1/30). That solution has been fully characterized both from an electromagnetic and from a mechanical point of view. The first tests of a prototype are foreseen in February 2008. | ||
| TUPC022 | Non-destructive Beam Position and Profile Measurements Using Light Emitted by Residual Gas in a Cyclotron Beam Line | 1095 |
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| Non-destructive beam position and profile measurements were made in the transfer beam line between an 8 MeV solid-pole injector cyclotron and a 200 MeV separated-sector cyclotron that is used for nuclear physics research, radioisotope production and proton and neutron therapy. Light emitted from the beam induced ionization of residual gas particles was measured using a multi-cathode photomultiplier tube (PMT). The PMT was mounted outside the vacuum system on a diagnostic chamber and light passing through a glas window was focused on the photocathode array by means of a lens. The anode currents of the PMT were measured with computer-controlled electronic equipment recently developed for measuring the currents of multi-wire beam profile monitors. Software was developed to control the measurement processes, remove offset values and further process the data digitally. The measured beam positions and profiles were compared with those determined with a multi-wire beam profile monitor for a 3.14 MeV proton beam. It was necessary to shield the PMT from gamma rays generated on nearby slits. The design of the measuring equipment is discussed and the results of the measurements are presented. | ||
| TUPC023 | Design of the Transverse C-band Deflecting Structure for Measurement of Bunch Length in X-FEL | 1098 |
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| In SPring-8, the 8 GeV X-FEL with a short length of about 700 m is under construction. An electron beam with a bunch length in duration of less than 200 fs is indispensable for stable and brilliant X-ray radiation. We planned to measure the short bunch length with a transverse RF deflector. A bunch measuring system including the deflector must be located within 15 m of a bunch compressor at a beam energy of 1.45 GeV. To install the system in the restricted space, we need a deflector generating a transverse deflecting voltage over 40 MV. Therefore a new C-band deflecting structure was designed. It is a periodic disk-loaded structure with a racetrack-shaped iris in the center of each disk. The deflecting resonant mode is the HEM11-5π/6 mode of a backward traveling-wave and its transverse shunt impedance is more than 12 MΩ/m. The racetrack-shaped iris serves both as a cell-to-cell coupler and a beam passing hole, prevents rotation of the deflection plane of the HEM11 mode and makes the deflecting mode resonant stably. We represent the details and merits of the C-band structure with the demanded performance in this paper. | ||
| TUPC024 | Video Profile Monitors Development for the CTF3 Probe Beam Linac | 1101 |
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| The innovative CLIC concept is currently under study in the CLIC Test Facility (CTF3) at CERN where the acceleration of a probe beam will be demonstrated. This probe beam, delivered by a linac called CALIFES, is composed of short bunches (0.75 ps, 0.6 nC) at 170 MeV with normalized emittance lower than 20 mm.mrad. Measurements of longitudinal charges distribution, transverse emittance and energy spectrum rely on Video Profile Monitors (VPM) after appropriate manipulations of the beam (deflecting cavity, quad scan and analysis dipole). We report the design, development and tests of these new VPMs based on selectable YAG/OTR screens, optical line and CCD camera. Two selectable magnifications (1.75 and 0.33) are available via motorized lens mounts to comply both with resolution (20 μm) and field of view (10x10mm2). Study of optical line characteristics have been realised with Apilux software and Modulation Transfer Function (MTF) were measured. A grid pattern can be inserted at the screens position to check optical characteristics during operations. Tilt of the CCD plan in order to compensate the screen tilt of 15° has not proven to improve the depth of field and was not implemented. | ||
| TUPC026 | Simulating a UMER Beam Position Monitor | 1104 |
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We have investigated numerically and experimentally a beam position monitor (BPM), using the WARP code* to study image charge effects for an off-axis beam. In order to apply the theory of image charge, we calibrated the BPM response for the University of Maryland Electron Ring**. We studied the BPM linearity using several WARP simulations with different transverse offsets. The simulations were also compared with offsets measured employing a phosphor screen. In this paper we report the methodology used and results of this work.
* D. P. Grote et. all "New Developments in WARP Progress Toward End-to-End Simulation", Fus. Eng. & Des. 32-33 (1996) 193. |
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| TUPC027 | Spatial Autocorrelation for Transverse Beam Quality Characterization | 1107 |
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| Low emittance beams are required for high brightness beams applications. Contributions to emittance degradations come from electromagnetic fields’ non-linearities which can be reduced using a transversally and longitudinally uniform beam. For these reasons the evaluation of the beam quality is a very important task. Concerning the transverse analysis the spatial correlation parameter has been introduced: it gives an evaluation of how beam non-uniformity is distributed. The paper describes the spatial autocorrelation concept and applies it to the evaluation of a laser beam for high brightness beam applications. Moreover the paper shows the spatial autocorrelation evolution along a photo-injector as an additional tool for beam dynamics studies. | ||
| TUPC028 | Design and Construction of an Inductive Pick-up for Beam Position Monitoring in the TBL Line of the CTF3 | 1110 |
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| In order to determine the beam position respect to the vacuum chamber, the IPU senses the azimuthal distribution of the beam image current flowing along its inner wall when a high frequency bunched beam passes through. The inner wall of the pick-up is divided into four electrodes, each of which forms the primary winding of a toroidal transformer. Therefore the beam image current component flowing through each electrode is transformed to a secondary winding connected to a pick-up output. The closer the beam is to the transformer electrode, the greater is the induced signal in its secondary winding. This basic sensing mechanism will allow to determine the beam position through the four transformers distributed orthogonally around the vacuum pipe. The bandwidth of the IPU and the amplifier is set above 200 MHz to let pass, with low distortion, the 20-140 ns pulse train signal induced from the beam. Also, its expected resolution at maximum current is 5μm. This paper reports on the design, construction as well as testing and calibration processes of two IPU prototypes. They will be installed in the Test Beam Line (TBL) of the 3rd CLIC Test Facility (CTF3) at CERN by Spring 2008. | ||
| TUPC030 | Transverse Electron Beam Size Effect on the Bunch Profile Determination with Coherent Radiation Diagnostics | 1113 |
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| Longitudinal diagnostics of electron bunches can be done by measurement of coherent radiation (e.g., in the form of transition radiation) and subsequent extraction of the form factor. By measuring short wavelengths, fine structures in the bunch can be resolved. However, the form factor depends on the three-dimensional charge density distribution, and the usual practice of considering only a one-dimensional line charge in interpreting the radiation spectra is questionable, as the finite transverse extend of the electron bunch can reduce the form factor magnitude at short wavelengths. An experimental study of this issue using a two stage single shot spectrometer has been carried out at the FLASH free-electron laser at DESY, Hamburg. The coherent transition radiation spectra for two beam optics settings were recorded and compared. In one setting the transverse beam size at the transition radiation target screen has been blown up by a factor of about 3.5 compared to the second setting. The ratio of these two spectra shows a suppression of radiation intensity at short wavelengths, as expected from a theoretical calculation. In this paper the result of this study is presented. | ||
| TUPC031 | Longitudinal Beam Diagnostics Application of Synchrotron Radiation at FLASH | 1116 |
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For the operation of the FLASH free electron laser at DESY, Hamburg, tools to measure the longitudinal charge distribution and especially its stability over time are important for efficient machine running. Several techniques using both coherent far-infrared and incoherent visible synchrotron radiation from the two bunch compressor chicanes are summarized and compared in this paper. The experimental setups used are
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| TUPC032 | Phase Space Tomography Using the Cornell ERL DC Gun | 1119 |
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| The brightness and quality of electron beams in linac-based light sources are ultimately limited by the properties of the beam in the injector. It is thus important to have knowledge of the phase space distribution in addition to the rms emittance to provide an insight into high beam brightness formation mechanisms. A tomography technique has been used to reconstruct the transverse phase space of the electron beam delivered from the Cornell University ERL DC gun. The tomography diagnostic utilised three solenoid magnets directly after the DC gun and a view-screen. The injector was operated at 250keV in the emittance dominated regime, and the results showed good agreement to the phase space measured using a slit-screen method and that generated from simulation with the particle tracking code ASTRA. Comparison of various reconstruction methods is provided. | ||
| TUPC033 | IP BPM Position Error at CLIC due to Secondary Emission from Beam-beam Backgrounds | 1122 |
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| Beam-beam background impacts on the IP BPM are studied for the CLIC machine. The large number of coherent pairs ( 1.8×108 charges per BPM strip per bunch crossing) for the CLIC-G default parameter set, potentially leads to a large secondary emission in the BPM strips. Detailed GuineaPig++ and Geant studies reveal, however, that the coherent pairs travel down the extraction line without significant secondary showering. Geant studies of the CLIC incoherent pairs show a flux of secondary emission two orders of magnitude less than that expected for the ILC 1 TeV high luminosity scheme. Since previous studies showed that FONT IP BPM signal distortion for the ILC was of no concern, then it can also be neglected at CLIC. | ||
| TUPC034 | Beam Instrumentations for the J-PARC RCS Commissioning | 1125 |
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| A 3-GeV Rapid-Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) has been commissioned recently. During its beam commissioning, various beam diagnostic instrumentation has been used. The multi-wire profile monitor (MWPM) is used to establish injection and H0 dump line, which transports un-stripped H- or H0 beam to the dump. The electron catcher confirms that the beam hits a charge exchange carbon foil and the specified current monitor limits the beam current to the H0 dump. Single pass BPMs which detect linac frequency (324MHz) and ionization profile monitors (IPM) help to check the one pass orbit without circulation of the beam. The beam position monitor (BPM) can measure both COD and turn-by-turn position. Tune monitor system consists of exciter and its own BPM. The exciter shakes the beam and coherent oscillation is measured at BPM. Dedicated BPMs, Fast CT (FCT) and Wall Current Monitor (WCM) are used for RF feedback or feedforward control. It will describe the performance of each instruments and how they are contributed to the successful beam commissioning. | ||
| TUPC035 | The Beam Position Monitor System of the J-PARC RCS | 1128 |
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| The Beam Position Monitor (BPM) system of the J-PARC RCS has been fabricated, installed and operated successfully during the beam commissioning. There are 54 BPMs around the ring and most of them are placed inside steering magnets. The BPM is electro static type and it has four electrodes. A pair of electrode gives a linear response with diagonal cut shape and they were calibrated before their installation. The signal processing unit, which is equipped with 14-bit 14MSPS ADC and 600MHz DSP, has been developed for the system. In order to measure small signal, especially during the initial phase of the commissioning, careful design also done for cabling. The paper presents the current performance of the system. | ||
| TUPC036 | Multi-wire Profile Monitor for J-PARC 3GeV RCS | 1131 |
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| A set of six multi-wire profile monitors (MWPMs) has been installed in the injection line and the successive H0 dump line of the RCS (Rapid-Cycling Synchrotron), and contributed to the initial RCS commissioning for establishing an optimum injection orbit. The Au coated W wires (0.1 mm dia.) for the H- beam detection are fixed to a ceramic wind frame for two directions (horizontal and vertical with 17.7 o tilt, typically 51 wires with 2.9 mm or 9.5 mm distance), and the frame can be scanned for horizontal or vertical direction by using a stepping-motor driven actuator. A combination of the 17.7 o tilt wires and the precise scan function provides two step measurements, i.e. a rough profile is obtained only at one shot, and a detailed profile is measured for typically 101 shots (10 mm scan at 0.1 mm interval) thereafter. The beam induced charge signals are amplified by the instrumentation pre-amps located in a basement sub-tunnel at distances of 30-40 m from the frame through the shielded twisted pair cables. The signals are further transferred to the sample, hold and multiplex circuits at the ground floor. The digitized profile data are processed to the Gaussian fitting. | ||
| TUPC037 | Development, Production and Testing of 4500 Beam Loss Monitors | 1134 |
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| Beam-loss monitoring (BLM) is a key element in the LHC machine protection. 4250 nitrogen filled ionization chambers (IC) and 350 secondary emission monitors (SEM) have been manufactured at the Institute for High Energy Physics (IHEP) in Protvino, Russia, following their development at CERN. Signal speed and robustness against ageing were the main design criteria. Each monitor is permanently sealed inside a stainless-steel cylinder. The quality of the welding was a critical aspect during production. The SEMs are requested to hold a vacuum of 1·10-7 bar. Impurity levels from thermal and radiation-induced desorption should remain in the range of parts per million in the ICs. The difference in sensitivity is about 3·104. To avoid radiation aging (up to 2·108 Gy in 20 years) production of the chambers followed strict UHV requirements. IHEP designed and built the UHV production stand. Due to the required dynamic range of 1·109, the leakage current of the monitors has to stay below 1 pA. Several tests during and after production were performed at IHEP and CERN. A consistently high quality during the whole production period was achieved and the tight production schedule kept at the same time. | ||
| TUPC038 | Filling Pattern Measurement for the Taiwan Light Source | 1137 |
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| Filling pattern will affect various operation performance of a synchrotron light source. Measurement of the filling pattern correctly is important. The dedicated filling pattern measurement system has been implemented in 2004 for multi-bunch operation in top-up operation mode. Measurement the purity of an isolated bunch by using time correlated single photon counting method is also addressed. Results are presented in this report. | ||
| TUPC039 | p-Carbon CNI Polarimetry in the AGS and RHIC | 1140 |
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| Polarimetry based on proton carbon elastic scattering in the Coulomb Nuclear Interference (CNI) region has been utilized for Relativistic Heavy Ion Collider (RHIC). They have been critical tools for polarized proton acceleration setup and provided polarization values for RHIC experiments. This paper summarizes the recent modifications to the hardware and electronics. The performance of the polarimeters is also discussed. | ||
| TUPC040 | Measurements of Beam-beam Kick using a Gated Beam-position Monitor under Crabbing Collision at KEKB | 1143 |
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| KEKB is a double-ring electron/positron collider with a horizontal crossing-angle. The crab cavities installed in 2007 achieved an effective head-on collision and gained a higher specific luminosity. A gated beam-position monitor is a tool to measure the beam-beam effects. A beam-beam kick curve was measured by comparing the beam position between colliding and non-colliding bunches, while shifting the beam orbit at the interaction point (IP). An effective horizontal beam size at the IP was obtained from a linear part of the beam-beam kick around the central orbit. The estimated beam size agreed with a calculated value including the dynamic effects. It was confirmed that the effective horizontal beam size was reduced by the crabbing collision, as expected from a calculation with a rigid Gaussian model. When a horizontal orbit offset was larger than a beam size, however, we found that the measured beam-beam kick curve deviated from calculated values using the Gaussian model. The result suggests that the beam profile might enlarge horizontally in the peripheral part. | ||
| TUPC041 | Design of Cold BPM Feedthrough | 1146 |
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| We have designed many BPM feedthrough used metallized ceramic components. We select the best material of ceramic and metal ajusted for magnetism and the material of chamber. The request for accelerator application that low temperature and RF property has increased in recent years. In this presentation,we report on the design of the BPM feedthrough for low temperature and for the RF up to 20GHz. We appreciated the bonding strength for ceramic and metal in low temperature 4K,77K. Mo/Mn metallised ceramic is brazed between Fe-Ni-Co Alloy metal components using Ag-Cu brazing material. Ceramic is 99% Alumina which is commonly used for UHV application. The tensile strength in low temperature is lower than in R. T.approximately 10%, but the dispersion affected by brazing flow condition is bigger than this temperature effect. The influence of low temperature is less than brazing flow condition, therefore the bonding strength of metallised ceramic is enough for UHV application at 4K. | ||
| TUPC042 | Limitations of Electro-optic Longitudinal Electron Bunch Length Measurements | 1149 |
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| Electro-optic (EO) techniques are becoming increasingly important in ultrafast electron bunch longitudinal diagnostics and have been implemented at various accelerator labs. A crucial aspect of any implementation is a robust assessment of its resolution capabilities. However the assessments of the temporal limitations often differ between groups and the assumptions employed in deriving these limitations are frequently not addressed. With EO measurements of intense CTR pulses and ultrafast Coulomb fields, it may also be necessary to reconsider the validity of the usual interpretation of the EO effect as a phase retardation proportional to the Coulomb field. From a generic analysis of various sources of the temporal limitations we present a summary of the capability of various EO techniques which can be applied to specific implementations with differing laser and bunch parameters. As well as specifying the quantitative limitations and their scaling with experimental parameters, the qualitative effects of distortion in the measured profile are also summarised. Additional limitations, which arise from a breakdown of the phase-retardation interpretation of the EO effect, are discussed. | ||
| TUPC043 | Towards Sub-micrometer Resolution of Single Bunch Strip Line BPM | 1152 |
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| A high resolution single bunch BPM set-up is designed based on a strip line pickup. One of the BPM modifications developed is a Difference-Sum BPM. In this BPM, each strip line signal is converted into a three 600MHz square wave burst in a cascaded irregular strip line coupler. The Difference and Sum bursts produced by a hybrid junction are detected in a pair of synchronous detectors. The synchronous detector reference signals, and single-sample ADC triggers are manufactured from the Sum burst. The set-up and features of this BPM are presented. The BPM resolution was measured using a KEK ATF beam. For a bunch intensity above 109 electrons the resolution is about 1 μm (for BPM effective aperture 1/5). With appropriate ADCs, this BPM can measure individual bunches at a rate of up to 50 MHz. The BPM latency to the ADC inputs is as low as 10 ns. High resolution and low latency together, make this BPM suitable for beam-based fast feedback/feed-forward systems. | ||
| TUPC044 | Towards Routine Operation of the Digital Tune Monitor in the Tevatron | 1155 |
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| The digital tune monitor (DTM) was designed to measure bunch-by-bunch tunes in the Tevatron collider. It uses a standard BPM as a pickup. The vertical proton monitor is installed and allows us to gain valuable operational experience. A major upgrade is underway to implement an automatic bunch-by-bunch gain and offset adjustment to maintain the highest possible sensitivity under real operational conditions. Once the system is shown to be able to cope with orbit changes and different bunch intensities in an automatic manner while reliably delivering data it will be expanded to measure horizontal proton as well as antiproton tunes. The motivation and the technical description of the DTM as well as the latest experimental results are presented. Major challenges from the design and operation point of view are discussed. | ||
| TUPC045 | Setup and Commissioning of the Diagnostics Beamline for the SRF Photoinjector Project at Rossendorf | 1158 |
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| A superconducting radio frequency photo electron injector (SRF injector) has been developed by a collaboration of BESSY, DESY, FZD and MBI and is in operation since late 2007. After the initial commissioning in late 2007 with a Copper photocathode a Caesium-Telluride cathode was installed early 2008 to allow for high charge production. The longitudinal and transverse electron beam parameters are measured in a compact diagnostics beamline. This paper describes results from beam commissioning of the main diagnostic tools. Special emphasis is given on the bunch length measurement system for the 15 ps FWHM electron bunches. The system is based on the conversion of the electron pulses into radiation pulses by Cherenkov radiation. These radiation pulses are transported in a novel fully-reflective, relay imaging optical beamline to a streak camera, where the temporal properties of the pulses are measured. Results from beam measurements at 2pC (Copper cathode) and 1nC (Cesium-Telluride cathode) bunch charge are presented and discussed. | ||
| TUPC046 | Study on Longitudinal Phase-space of High-brightness Electron Beams at ISIR, Osaka University | 1161 |
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| The performance of the free-electron laser based on self-amplified spontaneous emission strongly depends on characteristics of the electron beam, such as its transverse, longitudinal, and energy profiles as well as bunch charge. The longitudinal phase-space for the electron beam consists of the longitudinal position and energy of electrons, and several methods are extensively under study to evaluate the phase-space profile of the electron beam. We are developing a measurement system consisting of a profile monitor, a bending magnet and a streak camera. We first considered an optical transition radiation monitor as the profile monitor, but we could not get the efficient number of photons to obtain the phase-space images since the angular distribution of the transition radiation is too large to concentrate in the electron energy region of 10 – 20 MeV. In order to increase the number of photons, we have changed to a Cherenkov radiator using a hydrophobic silica aerogel. The Cherenkov radiator was installed in the beam transport line from the linac to the FEL system. We will present an outline of the phase-space measurement system and preliminary experimental results. | ||
| TUPC047 | Optical Transition Radiation Interferometry for the A0 Photoinjector | 1164 |
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| OTR interferometry (OTRI) is a promising diagnostic technique and was successfully developed and used for investigation of relativistic beams. For mid-energy accelerators the technique is traditionally based on thin polymer films (the first one is transparent for visible light) providing the beam multiple scattering of about 1 mrad or less. The disadvantage of these films is the unacceptable vacuum properties for photoinjectors and accelerators using superconducting cavities. We studied the application of thin mica sheets for OTRI diagnostics at the A0 Photoinjector in comparison with 2.5 μm thick Mylar films. This diagnostic is also applicable for the ILCTA-NML accelerator test facility that is planned at Fermilab. The experimental setups of the OTR interferometer for the A0 Photoinjector are described in the report. Results of simulations and measurements and comparison of the results obtained using Mylar and Mica-based interferometers are presented and discussed. | ||
| TUPC048 | Application of a 5 GSPS Analogue Ring Sampling Chip for Low-cost Single-shot BPM Systems | 1167 |
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In contrast to storage ring BPMs with continuously sampling ADCs, BPMs of single-bunch linear accelerators with typical repetition rates of 10-100Hz may also use waveform digitisers that sample just during a short interval when the bunch is passing the pickup. At PSI a 12-channel analogue sampling chip called "DRS" has been developed (*) that samples input signals in an array of 1024 capacitors per channel at up to 5GSPS. The acquisition can be stopped by a trigger signal and then the capacitor voltages of all 12 channels can be digitised with a single commercial external ADC at 33MSPS, achieving ~11 bit effective DC resolution and 450MHz max. bandwidth. The DRS chip was originally developed for low-cost digitization of 3000 detector signals of a particle physics experiment, using the PSI "VPC" VME64x FPGA board as digital back-end equipped with two PMC mezzanine modules with two DRS chips each. However, such DRS-based systems are also an attractive solution for inexpensive direct sampling and FPGA-based post-processing of suitable BPM pickup signals. This paper discusses BPM-related properties, limitations, possible improvements and measurement results of DRS-based electronics.
*S. Ritt. The DRS chip: Cheap waveform digitizing in the GHz range, Nucl. Instrum. Meth. A518: 470-471, 2004. |
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| TUPC050 | A Complete Solution for Beam Loss Monitoring | 1170 |
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| In particle accelerator facilities knowing the beam loss is crucial for the machine to be running at optimal efficiency. Beam loss can be monitored on different time scales. Time scale of seconds is used at normal operation to detect any irregularities such as changes in the beta function or vacuum drop. Time scale of 1 ms is used to optimize injection, and 1 μs timescale in case of severe problems when the beam does not live for more than a couple of turns. The presented beam loss system (microIOC-BLM) uses Bergoz BLM sensors, Beam loss Signal Conditioner (BSC) for data acquisition and microIOC-CosyIcon as the central processing unit. The system is cost effective, portable and can be expanded with additional measuring points. Selectable counting interval from 100 μs to 10 s covers a large part of the required time scales. The minimum and maximum count rates are limited by the sensor between 1/s to 10 M./s. Trigger and gate signals are supported as is summing over a number of measurements. | ||
| TUPC052 | Beam Phase and RF Fields Monitoring System Using Lock-In Amplifier for RIBF | 1173 |
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| The accelerator complex of the RIKEN RI Beam Factory (RIBF) consists of two injectors - heavy ion linac (RILAC and CSM) and K78 MeV AVF cyclotron - and four cyclotrons from the upstream, RRC (K540 MeV), fRC (K570 MeV), IRC (K980 MeV), and SRC (K2600 MeV). In such a multi-stage acceleration system, one of the most important factors for stable operation is to maintain the matching of beam-phases between accelerators. However, drifts of beam-phases have been frequently observed, reasons of which might be the fluctuation of RF-fields, variation of magnetic field, and so on. Hence, it is important to monitor beam-phases constantly, and we have developed a monitoring system using the commercial RF lock-in amplifier model SR844 manufactured by Stanford Research Systems. In addition, the system for monitoring the RF-fields has also been developed to investigate its stability and the correlation with beam-phases. The beam-phases at eleven phase probes installed in the beam transport lines and RF-fields of 25 cavities are monitored in a uranium acceleration. In addition, lock-in amplifiers are also used to obtain good isochronous magnetic fields of three cyclotrons in the RIBF. | ||
| TUPC054 | Pulse-by-pulse Photon Beam Monitor with Microstripline Structure in NSRRC | 1176 |
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| In order to diagnostic pulse-by-pulse beam movement of photon beam, NSRRC(Taiwan) and SPring-8 (Japan) have worked together to develop a front end beam monitor with microstripline structure, which is designed to have specific impedance of 50 ohm. The detector head is composed of a metal line (copper), ceramic plates (aluminum nitride) and a cooling base (copper tungsten). The metal line functions as a photocathode. The metal line is directly connected to SMA feed-through connectors to have fast response time. The detector head has been fabricated in SPring-8, and mounted on the monitor chamber and installed in NSRRC Superconducting Wiggler (SW) front end. The beam monitor can be used to examine not only pulse-by-pulse photon beam, but also the storage ring intensity and the pulse timing. Unique feature of the monitor is to produce unipolar short pulses. The design, fabrication and the measurement will be presented in this paper. | ||
| TUPC055 | Operating MCP Detectors at Cryogenic Temperatures | 1179 |
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| At present, a low energy electrostatic storage ring operating at cryogenic temperatures down to 2 K is being build up at the MPI-K in Heidelberg. Both, beam diagnostics and experiments rely on the use of position sensitive micro-channel plate (MCP) detectors equipped with phosphor screens or delay line anodes. Since little is known about the performance of these detector types in a cryogenic environment a test chamber was built to investigate their properties. A delay line MCP detector was successfully tested at temperatures as low as 25 K. In this contribution the detailed results of theses tests as well as possible applications of the detector are presented. | ||
| TUPC056 | A Novel Beam Profile Monitor Based on a Supersonic Gas Jet | 1182 |
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| At very low residual gas pressure below 10-12 mbar, as foreseen in future low-energy storage rings currently under development at the MPI-K and FAIR, conventional residual gas beam profile monitors cease to work with reasonable count rates. One possible way to overcome this restriction is the use of a supersonic gas jet as a profile monitor. Such a jet could be shaped as a thin curtain, thus providing a uniform target with a variable target density extended over the whole beam. A possible setup of such a device taking into account vacuum considerations, expected count rates and an envisioned detection scheme are presented in this contribution. | ||
| TUPC057 | Improving the ISIS Emittance Scanner Software | 1185 |
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| The software to drive the slit-slit emittance scanners at ISIS is re-written in C#. The scanner driver routine is enhanced to improve accuracy, and to allow real-time monitoring of the scanning procedure. A multiple document interface allows quick comparison with other measurements and with data from particle tracking codes. Integrated data processing and emittance calculation removes the need to transfer data between multiple software packages, making experimental work more efficient. A user-friendly and robust interface allows easy scanning and generates publication quality emittance plots for presentations. | ||
| TUPC058 | Laser-based Ion Beam Diagnostics for the Front End Test Stand at RAL | 1188 |
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| The RAL Front End Test Stand is being constructed to demonstrate that a chopped H- beam of 60 mA at 3 MeV with 50 pps and sufficiently high beam quality as required for future high-power proton accelerators can be produced. Because of the high beam power and a preference for online beam monitoring non-intrusive, non-destructive beam diagnostics are desirable. Two novel instruments, based on the photo-detachment of the outer electron of the H- ions with a laser, are being developed to precisely determine the transverse beam density distribution and the beam emittance at full beam power. This paper discusses the proposed experimental layout of the devices and the progress that has been made towards realizing them. The design of the optical system is presented along with measurements of the laser beam propagation for the beam density distribution experiment. Investigations of the influence of laser beam misalignment along with measurements of the positioning accuracy of movable stages that will be used are given in light of the total expected errors. | ||
| TUPC059 | An Emittance Evaluation Toolbox | 1191 |
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| A long-time experience in emittance measurements and result evaluation at GSI were transformed into the set of the numerical instruments to perform basic and advanced data analysis for the data obtained in various emittance measurement devices. The common problems and differences between slit-grid-, pepper-pot- and longitudinal emittance data analysis are discussed. Some aspects of non-linear algorithms particularly for the case of non-zero slits or pepper-pot holes are presented. | ||
| TUPC060 | A Counting Module for an Advanced Ionization Profile Monitor | 1194 |
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| A new multi-channel counting module has been developed for advanced Ionization Profile Monitor applications. The module's maximal performance concerning time resolution is about 10 beam profile measurements per microsecond at the cost of a slightly reduced spatial resolution with 80% accuracy (or better). Module architecture, basic modes of operation and the user interface are discussed. The results of the first test in laboratory and first beam profile measurements are also presented. | ||
| TUPC061 | Laser Wire Beam Profile Monitor at Spallation Neutron Source (SNS) | 1197 |
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| We report the first measurement of a hydrogen ion beam profile in the superconducting linear accelerator (SCL) at the Spallation Neutron Source (SNS) with a laser wire beam profile monitor. The advantage of the laser beam profile monitor includes non-invasive measurement, longitudinal beam scan and multiple station measurement capabilities. A Q-switched Nd:YAG laser at 1.06 μm is used to detach electrons from hydrogen ions. The laser has a repetition rate of 30 Hz and a pulse width of 7 ns. Typical pulse energies are 50 - 200 mJ. The laser is physically located outside the SCL tunnel and the ion beam profiles are measured at 9 different locations covering the entire SCL region (~ 200 m). At SNS the beam structure consists of 50 ps long micropulses separation by ~ 2.5 ns and gated into macropulses of up to 1 ms long. The firing of the laser flashlamps is synchronized to the macropulse timing. The collection magnet bends the photodetached electrons out of the beam and into a Faraday cup. Both horizontal and vertical beam profiles (typical width: 2 - 4 mm) can be measured with a resolution of 4 um. Transverse beam scans can be performed throughout the macropulse. | ||
| TUPC064 | Design and Commissioning of a Quadrant BPM for the LNLS Beamlines | 1200 |
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| We have recently designed and installed the first quadrant beam position monitor in the MX2 beamline. The whole monitor, including its electronics, was installed in vacuum to reduce errors from current leakage and noise coupled outside the vacuum chamber. Aspects of the mechanical and electronic design of this fluorescence-based beam position monitor, as well as the commissioning results are presented. | ||
| TUPC065 | Luminosity Measurement at DAΦNE for Crab Waist Scheme | 1203 |
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| Since the beginning of 2008 the DAΦNE complex started to test the "crabbed scheme" to improve the luminosity performance of the accelerator. In order to ensure a fast, accurate and absolute measurement of the luminosity and to fully understand the background conditions, the new interaction region has been equipped with three different luminosity monitors: a Bhabha calorimeter, a Bhabha GEM tracker and a gamma bremsstrahlung proportional counter. The detectors design, construction, and performance, as well as the first measurements performed at DAΦNE during the crab waist commissioning are here presented. Data are also compared with the Monte Carlo simulations of the full setup. First results acquired during the SIDDHARTA run are supposed to be presented. | ||
| TUPC066 | Temporal Spot Size Evolution of the DARHT First Axis Radiographic Source | 1206 |
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| DARHT is the Dual Axis Radiographic Hydrodynamic Test Facility at Los Alamos National Laboratory. The radiographic spot size is a critical parameter in the performance of the facility to produce quality radiographs. Time resolved images of the radiographic spot of the First Axis of the DARHT facility have been acquired and correlated with the radiation pulse. Analysis of these time resolved images illustrates the effect of beam target interaction on the temporal evolution of the spot size. An explanation of the experimental setup and analysis of the data will be presented. | ||
| TUPC067 | Development of the Methods of Beam Energy Spread Determination in the VEPP-4M Collider | 1209 |
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| The nearest experimental program of the VEPP-4M electron-positron collider and the KEDR detector includes a scan of the energy area below J/psi meson to search narrow resonances. The monitoring of beam energy spread is important for that. In this report we discuss the application of several diagnostics for beam energy spread measurement. The data obtained with Compton Back-Scattering (CBS) technique are compared with the value of the spread derived from the betatron motion of the beam. Similar experiments were carried out before. They demonstrated the necessity to improve the algorithm of beam energy spread derivation using CBS technique. New set of experiments was aimed on the examination of the improved algorithm. The measurements by all the methods were done at the same accelerator run, i.e., the different diagnostics are compared directly. The value of the energy spread was determined for a fixed collider energy E= 1855 MeV. The beam energy spread was changed by the wiggler current variation. | ||
| TUPC071 | Computer-assisted Electron Beam Centroid Characterization at AIRIX Facility | 1212 |
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AIRIX is a high current accelerator designed for flash X-ray radiography. The electron beam produced into a vacuum diode (2 kA, 3.5 to 3.8 MV, 60 ns) is extracted from a velvet cold cathode. For a beam characterisation we have seen* how to calculate the mean beam divergence (X'(0),Y'(0)), the RMS beam size (XRMS(0), YRMS(0)) as well as the 2D transverse beam emittance (ex(0),ey(0)). To have a complete initial characterization of the beam, we have to further calculate the centroid initial position (xc, yc) and its initial divergence (xc', yc'). In this aim, we use experimental results at BPM's located downstream the initial position of the cathode, and we also use the TRAJENV code coupled with the MINUIT minimization library. In this paper, we propose to describe both experimental and theoretical approaches leading to the full beam characterization (beam size, centroid position and divergence) at the diode output.
*O. Mouton & al. "Computer assisted Electron Beam Characterization at AIRIX Facility," PAC'07, Albuquerque (USA). |
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| TUPC072 | Design and Fabrication of an X-band Traveling Wave Deflection Mode Cavity for Longitudinal Characterization of Ultra-short Electron Beam Pulses | 1215 |
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| An X-band Traveling wave Deflector mode cavity (XTD) has been developed at Radiabeam Technologies to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. An XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. RF design, fabrication procedure, and commissioning plans are presented. An experimental program at ATF to utilize the deflector for compressed beam characterization is discussed, including proposed measurements of the phase space filamentation due to non-linear processes in a chicane compressor. | ||
| TUPC073 | A Real-time Bunch Length Terahertz Interferometer | 1218 |
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| With the recent development of advanced photoinjectors and next generation light sources, the progression towards high-current, ultra-short beams is very important. The measurement of these short pulses, with sub-picosecond resolution is essential for successful beam operation and optimization. This paper describes the development of a real-time, shot-to-shot bunch length diagnostic utilizing a novel beam auto-correlation technique. | ||
| TUPC074 | Beam Transverse Size Effects on the Transition Radiation Energy Spectrum | 1221 |
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| A theoretical model for the transition radiation emission by a relativistic electron bunch is here presented. Such a model, based on an extension of the virtual quanta method to the case of high density charged beams, predicts the existence of beam transverse size effects on the short wavelength part of the transition radiation energy spectrum. The relevance of such effects to the transition radiation based beam diagnostics of an electron linear accelerator is discussed. The physical consistency of the proposed theoretical model for the transition radiation emission is demonstrated on the basis of the constraints imposed by the temporal causality and Huygens-Fresnel principles. Further arguments in favour of such a thesis, which concern the relativistic nature of the radiative mechanism, are discussed. A possible experiment, devoted to a crosscheck of the theoretical results in an electron linear accelerator, is also proposed. | ||
| TUPC075 | Development Status of a Beam Diagnostic System with a Spatial Resolution of Ten Micron-meters for XFEL | 1224 |
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| Aroud 10 micron-meter stability of an electron beam is required along the undulator section of XFEL to stably generate an X ray laser, and comparable resolution is also required for beam position and size measurements. At SPring-8, the construction of an 8 GeV linac with undulators is now in progress to realize the X ray laser driven by such highly qualified electron beams. To obtain these beams, measurements of the spatial and temporal beam structures are very important. We are developing a beam diagnostic system with a measurement resolution of less than 10 micron-meters. The system comprises a cavity type beam position monitor, an optical transition radiation profile monitor, a beam current monitor, an rf beam deflector to diagnose femto-second order temporal structure, and beam slits to shape appropriately beam spatial structure. The arrangement of these instruments were decided by requirements of the beam position and size measurements based on beam optics design. This paper describes the development status of the beam diagnostic system. The test results and design of the instruments showed sufficient performance to realize the above mentioned measurement resolution. | ||
| TUPC076 | TTF HOM Data Analysis with Curve Fitting Method | 1227 |
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| To investigate the possibility of using HOM signal induced in SC cavities as beam and cavity diagnostics, experiments and analyses based on SVD have been done, which are very successful. In this paper, we described one new method based on curve fitting to analyze the HOM signal data, some results have been obtained. The new method can be used to extract the HOM mode frequency, Q and relative phase from the data. On the other hand, this method can also be used to find the HOM mode center, polarization axis, mode axis along the cavity, while careful handling of beam timing information need to be considered in analysis. Comparing with SVD, this method is more physical, and can also be used in the beam diagnostic data analysis to obtain the beam position and beam trajectory angle. | ||
| TUPC077 | The 100-MeV Beam Diagnostic Station for the FERMI Linac | 1230 |
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| In order to transversally match the beam coming out from the injector to the FERMI@Elettra linac lattice, a beam diagnostic station will be placed at 100 MeV. It is equipped with quadrupoles and Optical Transition Radiation (OTR) screens to measure and correct the beam Twiss parameters and to evaluate the transverse emittances through a three-screen technique. Moreover, the second OTR screen is placed close to the laser heater undulator to guarantee that the eletron/photon interaction is achieved at the beam waist. Design optimization studies and simulation results are presented in this paper. | ||
| TUPC078 | The Gun Spectrometer Design for the FERMI@Elettra Project | 1233 |
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| In the FERMI linac layout the first spectrometer has been located close to the exit of the photoinjector gun at about 5 MeV. The main purpose of this equipment is measuring the energy and energy spread of the beam. Combining the spectrometer with Yag screens and Cerenkov radiators allows the investigation and characterization of eventual deterioration of the longitudinal profile due to the space charge forces and microbunching instabilities. The design specification of the magnet and multi-particle tracking code simulation results are presented in this paper. | ||
| TUPC079 | Beam Emittance Measurement for the New Full Energy Injector at ELETTRA | 1236 |
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| An emittance measurement station was set up and operated with the quadrupole scan technique to characterize the electron beam transverse phase space at the Elettra laboratory. The diagnostic station, based on a YAG:Ce scintillation screen imaged by a CCD digital camera, was installed at the end of the 100 MeV booster pre-injector together with a beam longitudinal structure monitor. This equipment plays an important role for the bunching system optimization and for the optical matching of the injection transfer line to the booster ring. Experimental results and comparison with multi-particle tracking codes simulation are presented in this paper. | ||
| TUPC080 | Fermi Low-energy Transverse RF Deflector Cavity | 1239 |
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| The layout of FERMI@Elettra will include a transverse S-band RF deflector that will be located after the first bunch compressor (BC1) at 250 MeV. The deflector will operate in a vertical deflecting mode and coupled to a downstream dipole will be used to measure the electron bunch length and in particular to allow time-resolved beam quality measurements such as horizontal slice emittance and slice energy spread. In this paper we discuss the electron bunch deflection at 250 MeV taking into account the principal elements that dominate the selection of the transverse peak voltage specification: the finite transverse emittance, the resolution of OTR screens and the desired number of the slice divisions along the bunch that we wish to observe. The RF deflector proposed here is a frequency scaled version of the 5-cell standing wave SPARC structure. | ||
| TUPC081 | Single-shot Longitudinal Bunch Profile Measurements at FLASH Using Electro-optic Detection Techniques | 1242 |
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| At the superconducting linac of FLASH at DESY, we have installed an electro-optic experiment for single-shot, non destructive measurements of the longitudinal electric charge distribution of individual electron bunches. The profile of the electron bunch field is electro-optically encoded onto a streched Ti:Sa laser pulse. In the decoding step, the profile is retrieved from a spectral measurement of the encoded pulse or from a cross-correlation of the encoded pulse with a 35 fs laser pulse , obtained from the same laser. At FLASH, sub-100 fs electron bunches have been measured during FEL operation with a resolution of better than 50 fs. The electro-optic measurements have been validated with a tranverse deflecting cavity measurements. | ||
| TUPC082 | Research and Development Program on Beam Position Monitors for NSLS-II Project | 1245 |
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| The NSLS-II Light Source which is planned to be built at Brookhaven National Laboratory is designed for horizontal emittances below 1 nm and will provide users with ultra-bright synchrotron radiation sources. In order to utilize fully the very small emittances and electron beam sizes, submicron stability of the electron orbit in the storage ring needs to be provided. This can only be achieved with high stability beam position monitors. The research program presently carried is aimed for characterization of commercially available RF BPM receivers and on the development of high stability mechanical supports for BPM modules. The details of the program and preliminary results are presented. | ||
| TUPC083 | A Diagnostics Plate for the IFMIF-EVEDA Accelerator | 1248 |
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| The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA cw deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. It is essential then to implement the necessary instrumentation for the commissioning, operation and correct characterization of the beam properties of the accelerator prototype. To achieve this goal, a complete set of instrumentation will be installed in the last part of the accelerator, just before the beam dump, in the so-called Diagnostics Plate (DP). It must allow the measurement of the main parameters of the beam: current, phase, position, transverse profile, energy, transverse halo, transverse emittance and longitudinal profile. The main challenges of such a measurement are the high damage power of the low-energy cw 125 mA beam, which precludes the use of interceptive instrumentation. In addition, the DP will not only be used during operation but also during the commissioning of the different accelerating structures at 5 and 9 MeV. In this contribution, the requirements imposed to the instrumentation, the type of techniques that will be used and a first conceptual design will be presented. | ||
| TUPC084 | Combating Multi-bunch Instabilities with the Libera Bunch-by-bunch Unit | 1251 |
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| Libera Bunch by Bunch is the digital processing unit for a bunch by bunch feedback system. The upgraded unit has a DSP core application featuring a 16 tap filter for each bunch. DSP processing is organized in 4 chains, following the HW implementation of A/D conversion. Besides setting of FIR filter coefficients in each processing chain, one bunch per chain can have different FIR filter coefficients and provides an option for 4 single bunch processing. All FIR filter coefficients are double buffered. Delays maximally equal to a revolution period are implemented before and after the FIR block. As an additional feature, a phase shift block is introduced that precisely shifts the phase of the output signal in the vicinity of a determined frequency. The core application is accompanied with a Matlab GUI, with an additional window for data acquisition. This system accompanied by a Front End unit provides a complete solution for combating multi bunch beam instabilities. A detailed description and results are presented. | ||
| TUPC086 | Pinhole Camera Resolution and Emittance Measurement | 1254 |
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| Third generation synchrotron light source are characterised by a low emittance and a low emittance coupling. Some light sources are already proposing to operate with extremely low coupling close to 0.1% and thus vertical emittance approaching 1pm. We derive the limits for the emittance coupling measurement due to the resolution of the X-ray pinhole camera. We also show that it is possible to design a pinhole camera in order to push the limit resolution beyond 0.1% emittance coupling. We then illustrate our calculations with the example of Diamond and compare them with experimental data. | ||
| TUPC087 | 4D Emittance Measurements Using Multiple Wire and Waist Scan Methods in the ATF Extraction Line | 1257 |
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| Emittance measurements performed in the diagnostic section of the ATF extraction line since 1998 lead to vertical emittances three times larger than the expected ones, with a strong dependence on intensity. An experimental program is pursued to investigate potential sources of emittance growth and find possible remedies. This requires efficient and reliable emittance measurement techniques. In the past, several phase-space reconstruction methods developed at SLAC and KEK have been used to estimate the vertical emittance, based on multiple location beam-size measurements and dedicated quadrupole scans. These methods have been shown to be very sensitive to measurement errors and other fluctuations in beam conditions. In this context new emittance measurements have been performed revisiting these methods and newly developed ones with a systematic approach to compare and characterise their performance in the ATF EXT line. | ||
| TUPC088 | Statistical Weighting of the MICE Beam | 1260 |
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| Conventionally only average properties such as means and variances of charged particle beams are measured. Such a technique is limited in that it is challenging to measure moments beyond the second and certain correlations are difficult to measure. In the Muon Ionisation Cooling Experiment (MICE), the beam rate is sufficiently low that particles pass singly through the accelerator and measurements can be made of the position, time (relative to RF phase) and momentum of individual particles. This makes a number of new analysis tools available. In this paper two particular tools are studied: the analysis of third and higher beam moments and the ability to select an input beam based on such moments. | ||
| TUPC089 | Robust Emittance Evaluation from Complex Transverse Phase Spaces | 1263 |
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| We present a novel procedure to analyze the transverse phase space of low energy electron bunches, close to a beam waist, in order to retrieve a sound estimate of its emittance. The procedure consist in a genetic code and a non linear fit applied in cascade, the first feeding the parameters starting values of the former. This allows us to cleanse the phase space from noise, separate the core charge from the halos and distinguish between bunch components undergoing different dynamics, such as cross over or the double emittance minima effect. Our procedure performs a rough longitudinal beam tomography, based on dynamical considerations, using transverse data. The application of the procedure to some experimental data is shown. | ||
| TUPC090 | Ionisation Profile Monitor to Determine Spatial and Angular Stability of FEL Radiation of FLASH | 1266 |
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| An Ionization Profile Monitor (IPM) is used to detect lateral position changes of an FEL beam. By its help, beam position stability can be measured via the parasitic ionization of the residual gas in the beamline. We give an outline on operation, calibration and maintenance of the two IPM that have been developed at DESY Zeuthen and that have recently been built into FLASH at DESY Hamburg. | ||
| TUPC091 | Measurement of Quadrupolar Tune Shifts under Multibunch Operations of the Photon Factory Storage Ring | 1269 |
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| The quadrupolar tune shifts were observed under a single-bunch operation of the Photon Factory storage ring at KEK, which indicated that a quadrupolar component of wakefields affected the motion of an electron bunch. We recently measured the quadrupolar tune shifts under a multibunch operation of the Photon Factory storage ring. To detect the transverse quadrupole-mode oscillations of electron bunches, we used an avalanche photo diode (APD) which can detect visible synchrotron light with short rise-time of less than 1 ns. As a result, we observed that the quadrupolar tunes depended on the total beam current by 0.0082 1/A (in horizontal) and -0.0082 1/A (in vertical), respectively. These tune shifts can be caused by a quadrupolar component of long-range wakefield. | ||
| TUPC092 | An Application for Beam Profile Reconstruction with Multi-wire Profile Monitors at J-PARC RCS | 1272 |
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| J-PARC RCS is commissioned since October 2007. In the early stage of RCS commissioning, Multi-Wire Profile Monitors (MWPM's) are most important beam monitors to measure positions and profiles of beam orbit in the injection line from LINAC. A MWPM consists of either a horizontal or a vertical wire plane. Each wire plane consists of several wires which has a tilt angle, and a wire scatters H- or proton beams and induced current in the wire is detected. A wire plane moves at a small step in the perpendicular direction to the wires and scans a beam profile. A complex analysis procedure and geometrical description is developed to reconstruct a beam profile from a MWPM. Beam profiles have been measured at MWPM's in the injection line and the H0 beam dump line. | ||
| TUPC093 | Beam Profile Monitor of the J-PARC 3GeV Rapid Cycling Synchrotron | 1275 |
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| To obtain high intensity (1MW) and large emittance (214 π mm mrad) beam profiles of the 3GeV Rapid Cycling Synchrotron (RCS) of the J-PARC, we have developed the ionization profile monitors (IPMs) with wide active aperture and high dynamic range. It has three Microchannel Plates (MCPs) with active area of 81*41mm for signal multiplication and read out devices, and magnet system to generate guiding fields to collect electrons. The wide active aperture of ±116mm is obtained by arranging the three MCPs perpendicular to the beam axis. Furthermore, the dynamic range of 104 level can be obtained by adjusting each bias voltage of the MCPs. The IPMs are now collecting ions without the guiding fields. The beam commissioning of the RCS has been in progress since last year. The horizontal and vertical profiles are of great help, particularly to check injection errors. At the conference, the present status of the IPM system and the latest beam profiles will be reported. | ||
| TUPC094 | Longitudinal Bunch Profile Monitoring via Single Shot Diagnostic with Linear Response | 1278 |
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| A new approach of electro-optic (EO) spectral encoding allows for the non-invasive characterization of the longitudinal electron bunch distribution at the ELYSE laser triggered ps pulse radiolysis facility: the transverse electric field of the relativistic bunch is encoded to the temporally dispersed spectrum of a supercontinuum whose wavelength dependent polarisation state is then analyzed with balanced detection. This method combines the spectral bandwidth of the probe that corresponds to a Fourier transform limit < 5 fs with a direct signal response of the detection scheme. As a result, the field amplitude within the EO crystal can be determined in an absolute, undistorted manner with a time window several times longer than the electron pulse. For a time window easily tunable between 0.5 to 100 ps the possible time resolution is ~ 70 fs respectively 1 ps. The diagnostic allows bunch monitoring at the 100 pC level even for low beam energy and brightness. The influence of the accelerator conditions on the charge profile and its stability was able to be studied for the 8 MeV bunches at ELYSE with a 0.5 mm thick ZnTe crystal in a distance of 4 mm to the beam centre. | ||
| TUPC095 | Beam Diagnostics for Commissioning the HEBT and Gantry Sections of the HIT Medical Accelerator | 1281 |
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| The HIT medical accelerator at Heidelberg, Germany, is the first dedicated heavy-ion cancer therapy facility in Europe, consisting of a two-stage injector Linac followed by a compact synchrotron. It features three treatment places: two horizontal beam lines, where treatment will be carried out from 2008 using proton and carbon beams, and the first 360° rotating heavy-ion Gantry structure. The accelerator sections of this facility were designed and constructed by GSI, which thereafter was in charge of the commissioning. By now, the required medical beam quality has been achieved in both horizontal beam lines, and beam commissioning of the Gantry structure has started. In this contribution we describe the technical layout of beam diagnostic devices and present measurement data taken in high-energy beam transport lines and patient treatment places. | ||
| TUPC096 | Development of Beam Loss Monitor for the SPring-8 Storage Ring | 1284 |
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| A beam loss monitor using PIN photodiodes has been developed. To check its performance, we installed it at an in-vacuum insertion device and at the injection section in the SPring-8 storage ring. Information on the beam loss at these points will be useful for examining demagnetization of permanent magnets of insertion devices and for studying a mechanism of beam loss. A noise level at these points is however high due to stray synchrotron radiation, an induction voltage generated by pulsed injection magnets, etc. The beam loss signal is then picked up under a high noise condition. Experimental results with its countermeasure will be reported. | ||
| TUPC097 | Beam Diagnostics for the Prototype of the Cryogenic Storage Ring CSR | 1287 |
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| The Cryogenic Storage Ring CSR at the MPI-K Heidelberg will be a 35m circumference, electrostatic ring, which is mainly dedicated to Molecular- and Atomic Physics experiments. To reach the low pressures (10-15 mbar), which are necessary to achieve the required long liftetimes of the stored ions, the complete ring has to be operated at a temperature below 4K (2K in sections), which means, that it will be installed inside a large cryostat. To prove the novel cryogenics and vacuum concept of the CSR, we have built up a prototype, which is basically a segment of the CSR, housing an electrostatic ion trap. The ion trap is in the first instance used for vacuum measurements and equipment tests in the XHV range, in a later stage, it shall be an experimental facility of its own. Test operation of the Prototype is currently starting. Since the boundary conditions in the CSR are highly demanding for the beam diagnostics system, we have to perform some tests of the CSR diagnostics devices in our Prototype setup. The Poster will describe these devices and present first experimental results. | ||
| TUPC098 | Results of the LHC Prototype Chromaticity Measurement System Studies in the CERN-SPS | 1290 |
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| Tune and chromaticity control is an integral part of safe and reliable LHC operation. Tight tolerances on the maximum transverse beam excursions allow oscillation amplitudes of less than 30 um. This leaves only a small margin for transverse beam and momentum excitations required for measuring tune and chromaticity. This contribution discusses the baseline LHC continuous chromaticity measurement with results from tests at the CERN-SPS. The system is based on continuous tracking of the tune using a phase-locked-loop (PLL) while modulating the beam momentum. The high PLL tune resolution achieved ( ~1·10-6 ) made it possible to detect chromaticity changes well below the nominally required 1 unit for relative momentum modulations of only 2·10-5. The sensitive tune measurement front-end employed allowed the PLL excitation and radial amplitudes to be kept below a few tens of micrometers. These results show that this type of measurement can be considered as practically non-perturbative permitting its use even during nominal LHC operation. | ||
| TUPC099 | Wire Scanner for Transverse Beam Parameter Measurements in BEPCII | 1293 |
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| The wire scanner has been installed in the linac injector of BEPCII (Beijing Electron-Positron Collider II) to provide the transverse beam parameters. In the several fellowing months, some experiments will be done. The result will be presented and the reason will be analysed. | ||
| TUPC102 | Cooled Beam Diagnostics on LEIR | 1296 |
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| Electron cooling is central in the preparation of dense bunches of lead beams for the LHC. Ion beam pulses from the LINAC3 are transformed into short high-brightness bunches using multi-turn injection, cooling and accumulation in the Low Energy Ion Ring, LEIR. The cooling process must therefore be continuously monitored in order to guarantee that the lead ions have the required characteristics in terms of beam size and momentum spread. In LEIR a number of systems have been developed to perform these measurements. These include Schottky diagnostics, ionisation profile monitors and scrapers. Along with their associated acquisition and analysis software packages these instruments have proved to be invaluable for the optimisation of the electron cooler. | ||
| TUPC103 | Digital Generation of Noise-signals with Arbitrary Constant or Time-varying Spectra | 1299 |
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| Noise sources in the RF system of an accelerator produce longitudinal emittance increase or loss. This noise is inherent, from the beam-control system electronics, external sources or high power components, or can be purposely injected for a specific need such as bunch distribution modification or controlled emittance increase. Simulations to study these effects on the beam require precise reproduction either of the total noise measured on the hardware, or of the noise spectrum to be injected and optimized to produce the desired changes. In the latter case the 'optimized' noise source has also to be created in real-time to actually excite the beam via the RF system. This paper describes a new algorithm to create noise spectra of arbitrary spectral density varying with cycle time. It has very good statistical properties and effectively infinite period length, important for long simulation runs. It is spectrally clean and avoids undesired mirror spectra. Coded in C++, it is flexible and fast. Used extensively in simulations it has also successfully created controlled emittance increase in the SPS by the injection of artificial real-time RF noise. | ||
| TUPC104 | On Application of Cherenkov Radiation in Presence of Dispersive Anisotropic Materials to Diagnostics of Ultrarelativistic Beams | 1302 |
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One of the main methods of diagnostics of charge particles and beams is based on application of Cherenkov radiation. The attractive idea is application of modern metamaterials for these goals. It has been noted that anisotropic dispersive materials can give some important preferences*. However imperfection of Cherenkov diagnostics is low sensibility with respect to energies of ultra-relativistic particles having large Lorentz factor. In this work, it will be shown that this limitation can be overcome with help of using special anisotropic dispersive media (they can be produced in the form of artificial metamaterials). Properties of Cherenkov radiation in the presence of such material will be analyzed. The case of unbounded material and the case of waveguide loaded with such material will be considered. It will be shown that the convenient method of determination of Lorentz factor can be based on measurement of frequencies of harmonics generated in the waveguide. This technique allows obtaining good sensibility for very large magnitudes of Lorentz factor. Other possibilities of application of anisotropic and left-handed metamaterials to beam diagnostics will be discussed as well.
*A. V. Tyukhtin, S. P. Antipov, A. Kanareykin, P. Schoessow. Proc. of PAC07, Albuquerque, NM, USA, p.4156 (2007). |
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| TUPC105 | Slice Emittance Measurements at SPARC Photoinjector with a RF Deflector | 1305 |
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| The SPARC photoinjector is a R&D facility performing beam dynamics studies and driving a SASE-FEL. The RF deflector, completely designed and built by the SPARC team, allows measurements of the longitudinal properties of the beam bunch. Using it and the well know technique of the quadrupoles scan, the slice emittance has been measured in different conditions and benchmarked with the simulations. | ||
| TUPC106 | Optimization of Electron Linac Operating Conditions for Photonuclear Isotope Production | 1308 |
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| The communication describes the method for optimizing the high-power Linac regime (electron energy, pulsed current and beam size, pulse repetition rate) and the composition of output devices to provide the maximum photonuclear yield of isotope product with the maintenance of thermal stability of structural elements. To exemplify, the results of accelerator KUT-30 (45 MeV, 10 kW) optimization at conditions of medical isotope Cu-67 production are reported. Simulation based on a modified PENELOPE/2006 code was employed to compute the Cu-67 generation rate in the Zn target, and also the absorbed radiation power in output device elements for different operating conditions of the accelerator with due regard for its loading characteristic. The simulation results were used to calculate the target and the converter (Ta) temperature at various thicknesses of the latter and at real cooling parameters. Conditions have been established for the maximum Cu-67 yield with keeping thermal stability of the target device. | ||
| TUPC107 | Feed-free Monitoring of Intense High-energy Bremsstrahlung | 1311 |
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| High-intensity (>103 W/cm2) bremsstrahlung sources produced on the basis of electron linacs of energy E0 up to 100 MeV find use in accelerator-driven subcritical assemblies, in photonuclear isotope production, activation analysis, etc. These processes, as a rule, call for maintaining a stable bremsstrahlung flow for one or more days. Therefore the diagnostic means of the radiation must function reliably under conditions of high-absorbed doses (≥108 Gy). To solve the problem, it is proposed to use a direct charge detector (DCD). It consists of two vacuum gap-spaced metal plates of different thickness. The simulation method based on the software PENELOPE/2006 was used to investigate the conditions of equilibrium e, X-radiation formation in the area of detector location, the dependence of detector sensitivity in its standard geometry on the atomic number Z of the plate material and the gammas energy at E0 ranging from 20 to 100 MeV. The realization of the method has been demonstrated by experiment with the use of the DCD prototype. The proposed detector requires no external power supply, is easy to operate and has a high radiation resistance. | ||
| TUPC108 | DITANET–A European Training Network on Novel Diagnostic Techniques for Future Particle Accelerators | 1314 |
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| Beam diagnostics systems are essential constituents of any particle accelerator; they reveal the properties of a beam and how it behaves in a machine. Without an appropriate set of diagnostic elements, it would simply be impossible to operate any accelerator complex let alone optimize its performance. Future accelerator projects will require innovative approaches in particle detection and imaging techniques to provide a full set of information about the beam characteristics. The European Training Network DITANET covers the development of advanced beam diagnostic methods for a wide range of existing or future accelerators, both for electrons and ions. The developments in profile, current, and position measurement techniques stretch beyond present technology and will mark the future state of the art. This contribution presents the scientific challenges that will be addressed within the next four years, together with the networks' structure. | ||
| TUPC109 | Analysis of Measurement Errors in Residual Gas Ionisation Profile Monitors in a High Intensity Proton Beam | 1317 |
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| ISIS is the pulsed neutron and muon source based at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss-limited 50 Hz proton synchrotron which accelerates ~3·1013 protons per pulse from 70 MeV to 800 MeV, corresponding to a mean beam power of 0.2 MW. Beam profile measurements are a key component of both ISIS operational running and R&D beam studies. Understanding and quantifying limitations in these monitors is essential, and has become more important as work to optimise and study the beam in more detail has progressed. This paper presents 3D field and ion trajectory modelling of the ISIS residual gas ionization profile monitors, including the effects of non-uniformity in longitudinal and transverse drift fields, and beam space charge. The simulation model allows comparison between the input beam profile, and that deduced from ion currents. The resulting behaviour, corrections and errors are then compared with experimental data from the ISIS synchrotron. | ||
| TUPC110 | Bunch Diagnostics with Coherent Infrared Undulator Radiation at FLASH | 1320 |
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| The operation of the FLASH free electron laser at DESY, Hamburg, requires a high electron beam quality, one important parameter being the longitudinal charge distribution. As a new tool for investigations using coherent radiation techniques, FLASH has been equipped with an electromagnetic undulator. The device is tunable up to a maximum K-Value of 44, corresponding to 200 um wavelength at an electron energy of 500 MeV. The emitted radiation has been characterized in a first measurement campaign using a dispersive spectrometer based on reflective blazed gratings and a pyroelectric detector, operated in a Nitrogen-purged atmosphere. This paper will summarize the measurements and the results obtained from a longitudinal diagnostics analysis. | ||
| TUPC111 | Overview of the Diagnostics Systems of PETRA III | 1323 |
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| Since mid-2007, the existing storage ring PETRA at DESY is reconstructed towards a dedicated third generation hard x-ray light source operating at 6 GeV with 100 mA stored current. The reconstruction includes the total rebuilding of one-eights of the storage ring. In this part the FODO lattice of the arcs is replaced by double-bend achromat cells, resulting in straight sections for 14 insertion device beamlines. Damping wigglers with a total length of 80 m are installed to reduce the emittance down to the design value of 1 nm rad. In order to fully benefit from this low emittance, beam stability is a crucial issue. For the achievement of the required performance and to allow a safe machine operation a number of beam instrumentation is required. Here the diagnostics system for the electron beam is presented with special emphasis on the essential instruments, i.e. the high resolution BPM system, profile monitors, feedback systems, and the machine protection system. | ||
| TUPC112 | Equipment for Electrons Energy Measurement in HLS | 1326 |
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| The parameters necessary to dimension an equipment for the measurement of the beam energy of a storage ring via the resonance depolarisation are collected for HLS . The electron beam polarizes naturally due to the Sokolov-Ternv effect. For Hefei light source(HLS), the polarisation time is approx 4.346 h at 800MeV. The calculated value 4.346h is only for reference. The radial field will be applied to the beam by a pair of striplines mounted in the storage ring vacuum chamber. When input power is 12.5w, with OPRA program, intergrated field is calculated on axial. Different input power V. S integral field is also calculated. Which the depolarization time V. S input power can calculated by the below. The beam loss system for the electron storage ring of HLS can be used to measure the relative change of Touschek lifetime. It is expected that the relative change of Touschek lifetime due to beam depolarization will be measured in the future. | ||
| TUPC113 | Beam Energy Compensation by RF Amplitude Control for Thermionic RF Gun and Linac Based Mid-infrared FEL | 1329 |
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| Institute of Advanced Energy, Kyoto University has constructed a mid-infrared FEL facility which consists of a thermionic RF gun, a traveling-wave type accelerating tube and a halbach type undulator. The electron beam quality is critical for lasing FEL. However, we found that the beam energy after the accelerator tube decreased from 25 to 23.5 MeV (around 6%) during macro-pulse duration (~4μsec), because.the beam current increases from 65 to 120 mA during the macro-pulse due to the backbombardment effect in the RF gun. To compensate the energy drop and to minimize the energy spread over the macro-pulse, the amplitude of RF power fed to the tube was controlled. Since a precise micro-bunch interval required to build up the FEL, the RF phase was also controlled. As the result, the energy spread of the electron beam was greatly reduced from 6 to 0.8% in FWHM which was same with micro-pulse energy spread (~0.8%). The phase stability during macro-pulse was also improved from 10 to less than 2 degree. | ||
| TUPC114 | Results from the Optical Replica Experiments in FLASH | 1332 |
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| We present experimental results from the optical replica synthesizer, a novel device to diagnose sub-ps electron bunches by creating a coherent optical pulse in the infrared that has the envelope of the electron bunch and analyzing the latter by frequency resolved optical gating methods. Such a device was recently installed in FLASH at DESY. During an experiment period the spatial and temporal overlap of a several ps long electron bunch and a 200 fs laser pulse were achieved within an undulator. Coherent transition radiation due to the induced micro-bunching was observed on a silver-coated silicon screen and varying the timing between electrons and laser pulse produced two-dimensional images of the slices as a function of the longitudinal position within the electron bunch. In a second experiment the strongly compressed electron bunch is modulated by a laser pulse lengthened to about 2 ps and replica pulses that are emitted from a second undulator are observed and diagnosed by frequency resolved optical gating methods. | ||
| TUPC115 | Vibration Stabilization for a Cantilever Magnet Prototype at the Subnanometer Scale | 1335 |
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| In the future linear colliders, the size of the beams is in the nanometer range, which requires stabilization of the final magnets before the interaction point. In order to guarantee the desired luminosity, an absolute displacement lower than 1/3 of the beam size, above a few hertz, has to be obtained. This paper describes an adapted instrumentation, the developed feedback loops dedicated to the active compensation and an adapted modelling able to simulate the behaviour of the structure. The obtained results at the subnanometer scale at the free end of a cantilever magnet prototype with a combination of the developed active compensation method and a commercial active isolation system are described. | ||
| TUPC116 | Field Characterization of XFEL Quadrupole Magnets | 1338 |
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The European X-ray free electron laser (XFEL) will be one of the most advanced light source facilities in Europe and produce high intensity laser light of wavelengths down to 0.1 nm*. The laser light is produced and amplified by electrons moving through long undulator systems, each consisting of several 5 m long segments. After each undulator segment an adjustable quadrupole magnet is placed to focus the electron beam. For optimum control of the laser light the centre of the quadrupoles need to be positioned along a straight line with an accuracy of 0.001 mm which only can be reached by beam based alignment (BBA). Prior to the BBA procedure the magnets need to be aligned along the beam path, therefore the centre position of the magnet has to be determined relative to fiducials placed on the magnet body with an accuracy of approximately 0.01 mm. A rotating coil system has been set up at the Manne Siegbahn Laboratory to characterize the magnetic field between the four magnetic poles and to measure the stability of the magnetic centre. The accuracy of this instrument and procedures of how to fiducialize the magnetic centre are presented.
*European XFEL technical design report, edited by M. Altarelli et. al., DESY 2006. |
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| TUPC117 | Beam Based Alignment of Quadrupole Triplets by Use of MATLAB Based Modeling | 1341 |
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| A new beam based method is introduced to measure the transversal shifts of quadrupole magnets in relation to each other within triplet structures. The displacements of the quadrupole magnets can be calculated by quadrupole strength variation in combination with a simulation of the orbit distortions utilizing a MATLAB based model for beam optics. A local smoothing of the quadrupole alignment can be achieved with accuracy better than those of geodetic surveys. Results are presented and compared with data from geodetic surveys. | ||
| TUPC118 | First Data from the Linear Collider Alignment and Survey Project (LiCAS) | 1344 |
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| The LiCAS project has developed a prototype robotic survey system for rapid and highly accurate surveying of long linear accelerator tunnel networks. It is aimed at the survey of the reference network for the International Linear Collider (ILC). This Rapid Tunnel Reference Surveyor (RTRS) is designed to be an R\&D instrument for evaluating the potential performance of the RTRS concept and its survey technology. The prototype has been commissioned in a test tunnel at DESY with initial calibrations and measurements ongoing. We will report on the results obtained so far and present conclusions for the design of an RTRS suitable for the ILC. | ||
| TUPC119 | Corrector Based Determination of Quadrupole Centres | 1347 |
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| A corrector magnet based method to determine the quadrupole magnet centres for storage rings has been tested on the MAX III synchrotron light source. The required corrector magnet strengths for the corrected beam orbit are used to determine the quadrupole magnet centre positions. This method is the most effective for an optimal distribution of beam position monitors and corrector magnets in the storage ring and will be used as a basis for the MAX IV storage rings. | ||
| TUPC121 | Nanometre Precision Interferometric Stability Monitoring Systems for Key Accelerator Components | 1350 |
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| The MONALISA group develops novel, accurate, nanometre resolution, interferometric systems to monitor relative motions between key accelerator components. We use cost-effective technology developed for the telecommunications market, providing readily scalable, adaptable solutions. Key magnets and diagnostics in the beam-delivery section of the International Linear Collider (ILC) will need to maintain stable relative positions. In particular, the final focus quadrupole magnets require nanometre level stability. Even greater stability requirements will be placed on components for the Compact Linear Accelerator (CLIC). Interferometers provide the only means of monitoring relative positions over long timescales, at the nanometre and sub-nanometre level. We are working to improve our measurement resolution using an optical frequency reference obtained by locking the second harmonic of an ultra-narrow linewidth 1560 nm fibre laser to a D2 transition in Rubidium-87. The latest results from this system tested on novel design, fibre-coupled, evacuated interferometers will be presented. | ||
| TUPC122 | Feedback Corrections for Ground Motion Effects at ATF2 | 1353 |
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| Ground motion will over time produce beam misalignments and size increases at the IP of the ATF2 beam line. The spatial and temporal characteristics of the vibrations measured on the site have been studied and model parameters have been fitted to allow reliably simulating the effects induced on the beam. A feedback loop to minimise the residual beam motion at the IP is considered, based on optimising the coefficients of a PID controller on both short and long time-scales. | ||
| TUPC123 | An Electro-Optic Deflector for a Fast Laser-Wire Scanner | 1356 |
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| A large aperture electro-optic deflector has been designed, realized and tested for application on a laser-wire scanner for particle accelerators. Results on the important parameters such as deflection strenght, speed and mode quality preservation are shown and discussed. | ||
| TUPC124 | Development of a High Power Fibre Laser for Laser Based Electron Beam Diagnostics | 1359 |
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| We present the latest results on the development of a high power fibre laser system for the laserwire project on ILC-like laser based electron beam diagnostics. The laser consists of a solid state oscillator which can be synchronised to an external frequency reference, and two amplification stages in double clad doped fibre, giving 1uJ pulses in a burst mode suitable for the ATF2 laserwire project. This output is amplified in large mode area photonic crystal fibre to generate the high pulse energy necessary for Compton scattering without any deleterious nonlinear effects, whilst maintaining the high spatial mode quality and beam pointing stability of a fibre laser. These properties are essential for producing the sub-micron spot sizes required for the measurement of small particle beam sizes. | ||
| TUPC125 | Status of the Spallation Neutron Source Superconducting RF Facility | 1362 |
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| The Spallation Neutron Source (SNS) project was completed without on-site superconducting RF (SRF) facilities. Installation of the infrastructure necessary to maintain and repair the superconducting Linac and to support power upgrade research and development (R&D) is well underway. Installation of a Class10/100/10,000 cleanroom and outfitting of the test cave with RF, vacuum, controls, personnel protection and cryogenics systems is now complete. These systems were recently operated satisfactorily to test a cryomodule that had been removed from the accelerator and repaired in the cleanroom. A horizontal cryostat has been fabricated and will be soon commissioned. Equipment for cryomodule assembly and disassembly has been installed and used for cryomodule disassembly. Cavity processing equipment, specifically an ultra-pure water system, high pressure rinse system, and vertical test area is being designed and installed. This effort is providing both high-power test capability as well as long-term maintenance capabilities. This paper presents the current status and the future plans for the SNS SRF test facility. | ||
| TUPC127 | Utility Design for the 3GeV TPS Electron Storage Ring | 1365 |
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| Having been running the Taiwan Light Source (TLS) for fourteen years since its opening in 1993, National Synchrotron Radiation Research Center (NSRRC), Taiwan, has been approved to build a photon source (TPS) last year. TPS is preliminarily designed with 3.0 GeV in energy, 518.4m in circumference and 24 Double-Bend Achromat (DBA). The utility system, including the electrical power, cooling water and air conditioning system of the TPS were designed to meet requirements of high reliability and stability. Because the power consumption of the TPS is estimated about three times that of TLS, energy saving is another consideration. This paper therefore discusses utility design concepts and presents partial design results, including capacity requirements, equipment and piping layouts. | ||
| TUPC128 | Air Temperature Analysis and Control Improvement for the EPU 5.6 at TLS | 1368 |
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| This paper presents the air temperature analysis and control improvement for area of the elliptically polarizing undulator EPU 5.6 in the Taiwan Light Source (TLS). To enhance uniformity of ambient air temperature, we applied mini environmental controls and installed five cross flow fans in this area. Eight temperature sensors were installed around the EPU to monitor temperature variation. We also simulated the flow field and temperature distribution in this area by using a computational fluid dynamics (CFD) code. The simulation results were validated by comparing to measured data. The temperature variation along time and spatial temperature differences were controlled within 0.1 degree C and 0.5 degree C, respectively. | ||
| TUPC129 | LHC Access System: from Design to Operation | 1371 |
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| The paper describes the LHC access control and safety system project, the system's architecture and the experience gathered of commissioning it. This system is made of two parts: the LHC Access Control System and the LHC Access Safety System. Using state of the art redundant, fail-safe PLC's and a supplementary, cabled control loop the LHC Access Safety System guarantees the safety of the personnel in all events. Using industrial components, the LHC Access Control System, regulates the access to the tunnels and experimental areas by identifying the users and checking their authorisations. It allows a remote or automatic operation of the access control equipment and restricts the number of users working simultaneously in the interlocked areas. A first implementation of the architecture is now in production and ensures that only authorized personnel can enter the controlled areas of the LHC complex and this only after permission has been given by the CERN Control Centre. The design, procurement and installation of the entire system took more than 4 years and the commissioning phase lasted about 12 months. | ||
| TUPC130 | Integration of CATIA/SMARTEAM into CERN's Corporate Engineering Data Management System | 1374 |
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| The document presents a short overview of the strategy defined to integrate the 3D CAD system CATIA/Smarteam into CERN’s corporate Engineering and Equipment Data Management System (EDMS). EDMS is used to manage the information about the Laboratory’s installations and technical infrastructure. A brief description of the existing EDMS architecture is given, describing the project life cycle management features available. The integration of CATIA/Smarteam into this backbone will offer the Organization an EDMS which can handle all technical information about a facility from its inception to its dismantling seamlessly. An overview of the Design Office requirements on the new CAD system is also presented. | ||
| TUPC131 | Micado - The Data Import Engine of the CERN Engineering and Equipment Data Management System | 1377 |
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| The CERN Engineering and Equipment Data Management System (EDMS) is one of the largest and most complex data management systems of its kind. For the last 10 years, it has received huge quantities of data generated in the different LHC project phases. Capturing all this information would not have been possible without a robust, failsafe, yet flexible and user-friendly data import engine. For this purpose the Micado toolkit was developed at CERN using XML standards, providing multi-level data verifications, an advanced queuing mechanism and batch processing of large amounts of import requests. Whereas Micado originally was developed to facilitate the capturing of LHC manufacturing data, its modular architecture has allowed a cost-effective extension to also cater for the LHC installation and hardware commissioning data import processes. Recently Micado has broadened its scope even further, including also imports of safety inspections, and at the same time the next generation of the tool providing Web Services is already being developed. | ||
| TUPC132 | The Strategy between Optimal Control and Energy Saving about Utility System Operation | 1380 |
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| Previously, the Taiwan Light Source (TLS) at NSRRC has proven the good beam line quality depend on the utility system stability. Subsequently, several studies including the temperature control of cooling water and air conditioner was in progress for improving the system stability. Due to the importance of energy saving issue, the heavy power consumption of utility system are also discussed and intended to reduce extensively. The paper addresses some experience between optimal control and energy saving about operation of utility system in TLS. This provides a strategy between stability control and power reduction, including the flow balance, inverter usage, facility operation, control philosophy and so on. | ||
| TUPC134 | Results from Commissioning of the Energy Extraction Facilities of the LHC Machine | 1383 |
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| The risk of damage to the superconducting magnets, busbars and current leads of the LHC machine in case of a resistive transition (quench) is being minimized by adequate protection. The protection is based on early quench detection, bypassing the quenching magnets by cold diodes, energy density dilution in the quenching magnets using heaters and, eventually, energy extraction. For two hundred and twenty-six LHC circuits (600 A and 13 kA) extraction of the stored magnetic energy to external dump resistors was required. All these systems are now installed in the machine and the final hardware commissioning has been undertaken. After a short description of the topology and definitive features, layouts and parameters of these systems the paper will focus on the results from their successful commissioning and an analysis of the system performance. | ||
| TUPC135 | Experimental Determination of the Timing Stability of the Optical Synchronization System at FLASH | 1386 |
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| An optical, drift free synchronization system with a stability of better than 10 fs is presently being installed at the free electron laser FLASH. A periodic laser pulse train from a mode-locked, erbium doped fiber laser is distributed via length stabilized fiber links. In this paper, we present measurements of the timing stability of the optical distribution system. Two arrival time monitors (BAM) are used to measure the electron bunch arrival times at two positions in the linac separated by 60 m. Each BAM is supplied with fiber-laser pulses by its own fiber link. By correlating the measured arrival times of the same electron bunches, the overall performance of the optical distribution system and the BAMs can be evaluated. A resolution and timing stability of better than 30 fs has beed reached. | ||
| TUPC138 | Development of a New Low-Level RF-Control-System for the S-DALINAC | 1389 |
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| The Superconducting DArmstadt electron LINear ACcelerator S-DALINAC has a maximum energy of 130 MeV and beam currents of up to 60 μA. To reach this energy conveniently in cw, superconducting cavities with a high Q at a frequency of 3 GHz are used. In order to achieve minimal energy spread, the amplitude and phase the cavities have to be controlled strictly in order to compensat the impact of microphonic perturbations. The existing analog rf control system based on a self-exited loop, converts the 3 GHz signals down to the base band. This concept will also be followed by the new digital system currently under design. It is based on an FPGA in the low frequency part, giving a great flexibility in the control algorithm and providing additional diagnostics. For example it is possible to change the operational mode between self-exited loop and generator driven resonator within a second. We will report on the design concept, the status and the latest results measured with a prototype, including different control algorithms as well as beam loading effects. | ||
| TUPC139 | LLRF Electronics for the CNAO Synchrotron | 1392 |
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| The Italian National Centre for Oncological hAdrontherapy (CNAO) is undergoing its final construction phase in Pavia and will use proton and carbon ion beams to treat patients affected by solid tumours. At the hearth of CNAO is a 78 meters circumference synchrotron, capable of accelerating particle up to 400 MeV/u with a repetition rate of 0.4 Hz. Particle acceleration is done by a unique VITROVAC load RF cavity operating at a frequency between 0.3 and 3MHz and up to 3kV peak amplitude. In order to control this cavity a digital LLRF system has been designed at LPSC. It is based mainly upon Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGA) and Direct Digital Synthesizers (DDS). The LLRF system implement both cavity control and beam control capabilities in a compact, remotely programmable and configurable, Ethernet controlled electronic module. It also allows an easy regulation loop tuning, thanks to an embedded acquisition system that stores all input and output signals during a given acceleration cycle. This paper describes the electronics architecture, lab measurements and test results obtained with the system coupled with the CNAO cavity. | ||
| TUPC140 | The Spallation Neutron Source Cryomodule Test Stand RF System | 1395 |
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| The Spallation Neutron Source (SNS) has recently commissioned a cryomodule test facility for the repair and testing of the super-conducting cryogenic cavities. This facility utilizes the original 402.5/805 MHz Radio Frequency (RF) Klystron Test Stand as its power source along with dual Low Level RF (LLRF) control systems. One control system is based on the standard SNS Linac LLRF controls with a second system for open-loop only control. The system is designed to allow simultaneous testing of devices in the test cave and other devices which can be tested outside of the enclosure. Initial tests have shown good results; some improvements are yet to be implemented. This paper will provide an overview of the RF systems, safety systems, and interlocks. | ||
| TUPC141 | Concept and Implementation of the SC Cavity Resonance Frequency Monitor for the Digital RF Field Controller | 1398 |
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| New generations of digital control systems offer large number of computation resources together with precise ADCs (analog to digital converters) and DACs (digital to analog converters) which can be used to generate almost any klystron driving signal. This gives the possibility to implement such features as digital SEL (self excited loop) and frequency sweep mode. They can be used to monitor resonance frequency of SC cavities. This information can be used by tuning system to adjust cavity tuner settings. Such functionality is valuable especially during the first RF station start up when the cavities may be detuned even by a large frequency. The paper presents the concept of such system and summarizes implementation and tests performed at FLASH facility (DESY, Hamburg). | ||
| TUPC142 | Performance of 24 Cavity Vector Sum Controller with Distributed Architecture | 1401 |
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| The paper presents the test results of the digital vector sum control applied for 24 superconducting cavities driven by 1 klystron. The controller is based on FPGA chips and consists of multiple processing boards which communicate via optical fiber links. Flexible and scalable distributed architecture was designed and implemented to provide framework for the control algorithms. The tests were performed at FLASH (DESY, Hamburg) facility using ACC4, ACC5 and ACC6 modules. Results were compared to the existing DSP based system. | ||
| TUPC143 | Precise RF Control System of the SCSS Test Accelerator | 1404 |
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| We present the development and performance of the low level rf control system of SCSS test accelerator (VUV-FEL facility). The FEL radiation in the wavelength region of 50-60 nm reached saturation in fall 2007. Since then, the FEL intensity fluctuation has been suppressed within 10%. This performance was achieved by stabilizing the rf phase and amplitude of the accelerator. For example, the rf phase stability of the 238 MHz cavity is achieved to be 0.03 degree rms corresponding to 350 fs. Those of other cavities such as C-band (5712MHz) accelerator are also obtained to be several 100 fs. To control the rf phase and amplitude precisely, we have developed an IQ modulator / demodulator system. To treat the baseband signal of the system, we have also developed VME high speed DAC / ADC boards. The phase skew of the IQ system is ± 1.0 degree without correction and ± 0.1 degree after correction. To suppress the slow drift of rf components, we applied a PID feedback control loop to the rf source and cavity system. We also improved temperature stabilization for the acceleration structures. | ||
| TUPC144 | Digital Low Level RF System for SOLEIL | 1407 |
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| In the SOLEIL storage ring, two cryomodules, each containing a pair of 352 MHz superconducting cavities, will provide the maximum power of 560, required at the nominal energy of 2.75 GeV with the full beam current of 500 mA. Presently, an analogue Low Level RF system is successfully operating to control the amplitude and phase of the accelerating voltage. A fast digital FPGA based I-Q feedback is currently under development. The digital I-Q loop is realised with a HERON IO2 FPGA module using a Virtex II with 1M gates. The performance of the digital LLRF system has been evaluated using a Matlab-Simulink based simulation tool taking into account different features (loop delays, bandwidth limitation, extra power budget). The hardware design is described and the first experimental results are reported. | ||
| TUPC145 | FPGA Implementation of Multichannel Detuning Computation for SC Linacs | 1410 |
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| The paper presents a multi-cavity system for active compensation of SC cavities' deformations in linear accelerators like Free Electron Laser. Described system consists of digital controller, analog amplifiers and mechanical actuators. The previously developed control algorithms were implemented in SIMCON 3.1 board and allow online calculations of Lorentz force detuning only for one cavity. The recent development in the field is based on serial pipelined computations which allow a real time detuning measurements of 8 and more cavities. Moreover, the SIMCON DSP board was used for 10 ns latency computations. The new approach enables integrating the algorithm dedicated for cavity shape control with the LLRF control system using optical transmission. Furthermore the 8-channels amplifiers have been successfully added to the compensation system for driving the piezoelectric actuators. The system is tested in FLASH at DESY. The accelerating modules ACC 3, 5 and 6 with high operating gradients cavities have been taken into account. The multilayer piezostacks from PI and NOLIAC are used for the compensation purpose of cavities' deformations. | ||
| TUPC146 | Real Time, Distributed, Hardware-software Simulation of Multicavity RF Station for LLRF System Development in FLASH and XFEL | 1413 |
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| The paper describes the implementation of distributed (FPGA, DSP, GPP) system for simulation of multiple TESLA cavities together with high power distribution chain. The applied models simulate the system behavior with the performance close to the response time of the real RF station and cryomodules. Parametrized architecture of the simulator allows to find compromise between the features of the model and the available resources it can be implemented in. The results of driving the simulator using the FLASH LLRF system are presented and compared with the real measurements. Proposed solution is the important tool for LLRF system development and testing, and can be, in many cases, a replacement for the tests in the real superconducting test facilities reducing the development costs and time. | ||
| TUPC147 | Analogue LLRF for the ALBA Booster | 1416 |
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| ALBA Booster will inject up to 2 mA of current, at 3 Hz, in the 3 GeV 3rd generation Synchrotron Light Source ALBA, that is in the construction phase in Cerdanyola, Spain. The Booster will ramp the beam energy from 100 MeV to 3 GeV, the RF voltage will be ramped as well from <100 kV to 1 MV to improve injection efficiency and maintain the beam stable. The Booster RF System will have to provide up to 1 MV of accelerating voltage and have a high dynamic range. An Analogue LLRF prototype has been developed for the Booster 5 cell RF Cavity. The prototype is based on the IQ modulation/demodulation technique and it has been designed completely in house. The prototype has been installed in the high power RF lab of CELLS and tested to control up to 80 kW on the real Booster Cavity. The test results of the control loops (amplitude, phase and tuning) will be presented, as well as the hardware structure and the system interface. | ||
| TUPC148 | Digital LLRF for ALBA Storage Ring | 1419 |
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| ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. A Digital LLRF prototype has been developed for the Storage Ring RF Cavity. The prototype is based on the IQ modulation/demodulation technique and it has been implemented using a commercial FPGA cPCI board. The prototype has been installed in the high power RF lab of CELLS and tested to control up to 80 kW on the real Storage Ring Cavity. The test results of the control loops (amplitude, phase and tuning) will be presented, as well as the hardware structure (digital boards, analogue front ends, timing, etc.) and the system interface. | ||
| TUPC150 | Ensemble Cavity Control System Simulation Using Pulse-to-pulse Calibration | 1422 |
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| For cost reasons one klystron will supply RF power to multiple cavities in recent projects. Individual cavity field stability and optimal drive needs to be achieved considering beam propagation, cavity tuning, cavity coupling, and cable lengths. External environmental factors continuously modify physical properties of the accelerating structures and waveguides. Therefore a calibration system has been designed to adapt individual drive signals and vector-sum alignment in a pulse-to-pulse basis. An eight-cavity model and a calibration system have been tested in simulation using the hardware-software simulation tool developed at LBNL. | ||
| TUPC151 | Universal DOOCS Server Based on the Scripting Language | 1425 |
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This document describes the design and implementation of the universal DOOCS* server based on the script language for the FLASH accelerator in DESY (Hamburg, Germany). Server works with the DOOCS, which is used in FLASH for machine control. The typical usage of this application is to communicate with the measurement equipment and control small facilities of the accelerator. The aim of the project is to provide a tool which can make the server creation easy for non-programmer users (typically physicists). The heart of the server is the script language parser which has been done using well known UNIX tools: bison and flex. The complexity of designed language is comparable with complexity of the Matlab language. Application has additional features like possibility of attaching external dynamic libraries or possibility of defining the state machines (more sequencer like). Server has been tested at FLASH and currently is used by people who wish to control their equipment via DOOCS, with the minimal effort of software development.
*Distributed Object Oriented Control System. |
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| TUPC153 | Hardware-software Simulation for LLRF Control System Development | 1428 |
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| Field Programmable Gate Arrays (FPGA) have been used in accelerator controls for a long time. Stricter performance requirements in new accelerator designs force LLRF control systems to continuously improve, and the increasing density of available FPGAs enables such progress. The increased complexity in FPGA design is not always followed by new RF systems availability for development and testing. Therefore, a hardware-software simulation tool has been developed to model RF systems by a software simulator. It simulates the interaction of HDL code that is to be synthesized with both RF systems and communication ports to external controls software, reproducing realistic working conditions of the FPGA. The hardware-software interaction for LLRF control system design is discussed here. | ||
| TUPC154 | CERN PSB Beam Tests of CNAO Synchrotron's Digital LLRF | 1431 |
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| The Italian National Centre for Oncological hAdrontherapy (CNAO), in its final construction phase, uses proton and carbon ion beams to treat patients affected by solid tumours. At the heart of CNAO is a 78-meter circumference synchrotron that accelerates particles to up to 400 MeV/u. The synchrotron relies on a digital LLRF system based upon Digital Signal Processors (DSPs) and Field Programmable Gate Array (FPGA). This system implements cavity servoing and beam control capabilities, such as phase and radial loops. Beam tests of the CNAO synchrotron LLRF system were carried out at CERN’s Proton Synchrotron Booster (PSB) in autumn 2007, to verify the combined DSP/FPGA architecture and the beam control capabilities. For this, a prototype version of CNAO’s LLRF system was adapted to the PSB requirements. This paper outlines the prototype system layout and describes the tests carried out and their results. In particular, system architecture and beam control capabilities were successfully proven by comparison with the PSB operational beam control system and with the help of several existing beam diagnostic systems. |