| Paper | Title | Page |
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| TUPB03 | Precision Beam Position Monitor for EUROTeV | 57 |
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| For future linear colliders (ILC, CLIC) a new Precision Beam Position Monitor (PBPM) has been designed within the framework of EUROTeV. The design goals are a resolution of 100nm and an overall precision of 10μm, in a circular vacuum chamber of 6mm in diameter. The required bandwidth is 100 kHz-30MHz. The PBPM is based on an inductive type BPM which measures the image current in four electrodes located outside the vacuum tube, from which the position is derived. In this paper, the design of the PBPM is presented together with the first bench measurements, where twoμmovers and a rotational stage, installed on a vibration damped table, have been used to characterize the PBPM. | ||
| TUPB04 | BPM detectors upgrade for the ELETTRA Fast Orbit Feedback | 60 |
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| The project of a fast feedback system to stabilize the closed orbit of the Elettra storage ring is in an advanced stage. All of the existing BPMs have been equipped with new digital detectors in order to provide precise and high-rate position measurements to the feedback system. A new beam position interlock system has also been installed to protect the vacuum chamber from synchrotron radiation produced by insertion devices. This paper presents features and performance of the new orbit measurement system and reports some preliminary results of the feedback commissioning. | ||
| TUPB06 | First Tests with the Sis18 Digital BPM System* | 66 |
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In this paper we describe new approaches for BPM (Beam Position Monitor) measurements, needed in hadron accelerators which have strongly varying beam parameters, such as intensity, accelerating frequency and bunch length. After the data collection and offline evaluation in 2005, first FPGA implementations of algorithms were completed in 2006 and tested at SIS18 and CERN PS. Main aspect of the first tests was the proof of concept in terms of online calculation feasibility. This includes online calculation of the needed integration windows as well as the baseline restoration algorithms. The realization of the hardware and the data handling are discussed. Least squares techniques were used for parametric fitting to gain bunch signal properties which can be used to monitor beam position.
*Founded by EU FP6-Design Studies |
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| TUPB07 | Electric -In-Air-X-Ray- Detectors for high Resolution Vertical Beam Position Measurement at the ESRF | 69 |
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| The tiny fraction of the very hard X-rays that fully penetrate the dipole absorber structure and enter the free air space behind it can be detected in different ways to yield precise information on the vertical characteristics of the electron beam. In addition to a system of imaging detectors to measure the emittance, a 2nd detector type was developed that yields a direct electric signal. It consists of a high-Z blade in conjuction with a small In-Air ionization slot that generates a direct strong electric signal allowing for nanometer resolution measurements of vertical beam motion in a spectrum upto 1KHz. The high resolution performance of this detector type is explained by the fact that it touches the heart and center of the beam whereas other devices (X-BPMs or e-BPMs) have to work on the edges or tails of the beam or feel the beam indirectly by wall-current pick-ups. The results obtained with prototypes will be presented together with the prospects of an installation of 8 units in 2007. The intrinsic advantages of this In-Air detector like costs and simplicity, thanks to a total absence of cooling and UHV requirements, will be emphasized. | ||
| TUPB09 | Digital Beam Trajectory and Orbit System, for the CERN Proton Synchrotron | 75 |
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| A new trajectory and orbit measurement system using fast signal sampling and digital signal processing in an FPGA is proposed for the CERN PS. The system uses a constant sampling frequency while the beam revolution frequency changes during acceleration. Synchronization with the beam is accomplished through a numerical PLL algorithm. This algorithm is also capable of treating RF gymnastics like bunch splitting or batch compression with the help of external timing signals. Baseline correction as well as position calculation is provided in the FPGA code as well. After having implemented the algorithms in C and MatLab and tested them with data from a test run at the PS they have now been implemented in the FPGA for online use. Results of measurements on a single beam position monitor in the CERN PS and the SIS-18 at GSI will be presented. | ||
| TUPB10 | Proposed Beam Position and Phase Measurements for the LANSCE Linac | 78 |
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| There is presently an ongoing effort to develop beam position and phase measurements for the Los Alamos Neutron Science Center (LANSCE) linac associated with an improvement project known as the LANSCE Refurbishment. This non-interceptive measurement’s purpose is to provide both beam measurements of phase for determining rf-cavity phase and amplitude set points, and position measurements for determining the 805-MHz linac input transverse position and trajectories. The measurement components consist of a four-electrode beam position and phase monitor (BPPM), a cable plant that transports the 201.25-MHz signals, electronics capable of detecting phase and amplitude signals, and associated software that communicates with a mature LANSCE control system. This paper describes measurement requirements, proposed beam line device and some initial device bench measurements, initial designs of the associated electronics, and some of the difficulties developing these beam measurements in an operational facility. | ||
| TUPB12 | BPMs for the XFEL Cryo module | 84 |
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| The European XFEL is based on superconducting accelerator technology developed in the context of the TESLA collaboration. The accelerator itself consist of cryo modules each equipped with 8 cavities, followed by a quadrupole/steerer package, a BPM and a HOM absorber. This contribution will present the layout of the BPM system for the cryo modules, describing the monitor itself, its integration into the cryo module. Additionally, the electronics concept will be discussed. Finally the results of beam measurements at FLASH using prototypes of the monitor and the electronics will be presented. | ||
| TUPB15 | Beam Position Monitors Using a Re-entrant Cavity | 93 |
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| Two designs of high resolution beam position monitor, based on a radiofrequency re-entrant cavity, are developed at CEA/Saclay. The main radio-frequency modes excited by the beam in the cavity are monopole and dipole modes. The first monitor is developed in the framework of the European CARE/SRF program. It is designed to work at cryogenic temperature, in a clean environment and to get a high resolution and the possibility to perform bunch to bunch measurements. Two prototypes with a large aperture (78 mm) are installed in the FLASH linac, at DESY. The other design with an aperture of 18 mm and a large frequency separation between monopole and dipole modes, as well as a low loop exposure to the electric fields is developed for the CTF3 probe beam CALIFES at CERN. It is operated in single bunch and multi-bunches. This paper presents the mechanical and signal processing designs of both systems. Simulation and experimental results will be discussed. | ||
| TUPB16 | Optimization of the Linear-cut Beam Position Monitors Based on Finite Element Methods | 96 |
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| This contribution presents simulations of the Beam Position Monitors (BPMs) for the FAIR project that were performed using CST Studio Suite 2006B. The linear-cut BPMs based on a metal-coated ceramics were considered as the only solution that meets the required mechanical stability under cryogenic conditions. The essential BPM features like position sensitivity or linearity of position determination were compared for two geometries. In these geometries, in both cases based on elliptically shaped ceramic pipe, the vertical and horizontal electrode pairs were either mounted subsequently in series or were spirally shaped and combined alternatively within one unit. It is shown that optimization of BPM design increases position sensitivity by more than a factor of two. The frequency dependence of the position sensitivity and an offset of electrical center of BPM in respect to its geometrical center were analyzed in the bandwidth of 200 MHz. In a frequency range up to 100 MHz (i.e. typical for the BPM applications) calculated variations of the displacement sensitivity are smaller than 1%; the careful design of a guard ring configuration allows keeping the offset consistent with zero. | ||
| TUPB18 | Measurement of Electron Beam Charge in the ESRF Accelerator Complex for Absolute and Injection Efficency Measurements Using an FPGA Based Digital BPM Electronics | 102 |
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| A Beam Position Monitor (BPM) using Virtex II pro FPGAs (‘Libera Electron’ from Instrumentation Technologies) has been programmed with an alternative firmware in order to determine the charge by measuring integrated RF amplitude, over an adjustable time window, of signals from 4 strip lines. These strip lines are located on the transfer line from the linac to the booster, on the booster ring, on the transfer line from the booster to the storage ring and on the storage ring. By calibrating the RF loss in all the cables, knowing the geometry of the strip lines and using the crossbar switching before the 4 RF ADCs of the Libera, the charge/current can be compared in order to determine the efficiency of transfer at various locations during injection. Since the current in the storage ring is known to a high accuracy using a parametric current transformer (from Bergoz Instrumentation), the absolute charge can be determined at all locations. | ||
| TUPB19 | Signal Level Calculation for the PETRA-III Beam Position Monitor System | 105 |
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| Starting mid 2007 the PETRA accelerator at DESY in Hamburg (Germany) will be converted into a new high brilliance light source. For measurement and control of the PETRA-III closed orbit with a resolution of better than 1 micrometer (rms) it is planned to install about 220 button type beam position monitors (BPMs). To guarantee a good performance of the BPM electronics, the button signals have to meet several criteria in time and frequency domain. Therefore signal levels for the monitor types included for installation have been estimated. The results of these calculations will be presented together with a comparison of monitor signals from accelerators in operation, and the expected position resolution will be discussed for a certain type of BPM electronics. | ||
| TUPB20 | Large Horizontal Aperture BPM and Precision Bunch Arrival Pickup | 108 |
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| The large horizontal aperture chicane BPM and the precision bunch arrival monitor at FLASH will be important tools to stabilize the arrival-time of the beam at the end of the linac. The pickups for these monitors will be paired with front-ends that sample the zero-crossing of the beam transient through the use of electro-optical modulators and sub-picosecond-long laser pulses delivered by the master-laser oscillator. The design of pickups for this front-end requires the consideration of the beam transient shape as well as the amplitude. Simulations and oscilloscope traces from pickups that use or will use the EOM based phase measurement and the expected limitations and benefits of each pickup are presented. In particular, the design for a 5 um resolution BPM with a 10 cm horizontal aperture is demonstrated in terms of its capability to measure the beam energy and its sensitivity to the shape and orientation of the beam. | ||
| TUPB21 | Experience with Libera Beam Position Monitors at DELTA | 111 |
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| Libera beam posiotion monitor electronics have been installed at the electron storage ring Delta in order to extend the capabilities of the BPM system to turn-by-turn orbit measurements. This report covers the integration of Liberas into the beam diagnostics infrastructure at DELTA and its control system EPICS. Prior to their application in user runs the devices have undergone characterization measurements in a BPM teststand and during machine runs for accelerator physics. Results of these measurements are compared to measurements with DELTAs standard BPM electronics. The necessary clock and trigger signals are provided by a low-cost signal distribution device developed at DELTA. | ||
| TUPB22 | Renewal of BPM Electronics of SPring-8 Storage Ring | 114 |
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| The signal processing electronics of the SPring-8 Storage Ring BPM were replaced during the summer shutdown period of the year 2006. Since then, the new electronics have been put into operation for user experiment runs. The purpose of the renewal was to upgrade the performance of the position measurement system, i.e. the position resolution, speed of the measurement, etc. The position resolution of them in the real operation condition was estimated by using the stored beam in the same condition as the operations for user experiments, in the following way. The closed orbit distortions (COD) were repeatedly measured with the interval of 4 seconds in order to obtain the root mean square (r.m.s.) values of differences between two consecutive measurements. Since the obtained r.m.s. values included the intrinsic resolution of the position measurement system and the effect of the beam motion, the effect of the beam motion was separated from the obtained r.m.s. data by assuming that the effect of the beam motion was proportional to the betatron function values at the BPM locations. As a result, the intrinsic resolution was estimated to be 0.1μmeters. | ||
| TUPB26 | Characterisation of the Systematic Effects of the Insertion Devices with Photon Beam Position Monitors | 126 |
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| The X-ray photon monitors at Swiss Light Source are used for beam-position stabilisation down to sub-micron level. The beam position changes are mainly induced by changing the insertion device (ID) settings. An ID correction scheme involves both digital beam-position monitors (DBPM) located inside the storage ring and analog photon monitors (XBPM) located inside beamline front-ends. However, a beam-position correction scheme optimised for the electron beam is not automatically optimal for the photon beam. A sub-micron stability of the photon beam by changing the ID-settings is possible only if the XBPM readouts are well characterised for each considered ID-setting. We account for some limitations of the XBPM readouts as well as for examples where a sub-micron stability for all considered ID-settings is achieved. | ||
| TUPB31 | The Beam Position System of the CERN Neutrino to Gran Sasso Proton Beam Line | 141 |
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| The CERN Neutrino to Gran Sasso (CNGS) experiment uses 400GeV protons extracted from the SPS, which travel along 825 meters of beam line before reaching the CNGS target. This beam line is equipped with 23 BPMs capable of measuring both the horizontal and vertical position of the beam. The final BPM is linked to the target station and due to radiation constraints has been designed to work in air. This contribution will give an overview of the BPMs used in the tansfer line. It will also provide a detailed explanation of their logarithmic amplifier based acquisition electronics, which consists of an auto-triggered sequencer controlling an integrator, the A/D conversion and the Manchester encoded transmission of the digital data to the surface. At the surface the digital data is aquired using the Digital Acquisition Board (DAB) developed by TRIUMF (Canada) for the LHC BPM system. Results from both laboratory measurements and beam measurements during the 2006 CNGS run will also be presented. | ||
| TUPC09 | Design of the cavity BPM system for FERMI@elettra | 165 |
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| The cavity Beam Position Monitor (BPM) is a fundamental instrument for a seeded FEL, as FERMI@elettra. It allows the measurement of the bunch trajectory non-destructively, on a shot-by shot basis and with sub-micron resolution. The high resolution the cavity BPM is providing relies on the excitation of the dipole mode, originated when the bunch passes off axis in the cavity. Here we present the electromagnetic (EM) design and the cold test of the prototype BPM developed for the FERMI@elettra. The design adopted a C-band cavity with its dipole mode at fDIP=6.5GHz. The prototype is actually fitted with two cavities: one for the position measurement and one for the generation of the reference signal for the demodulator. Furthermore, the design of the prototype electronics for the acquisition and processing of the BPM signals is presented. The adopted scheme consists of a down converter from C-band to the intermediate frequency, followed by an IQ demodulator to generate the base-band signal, proportional to the transverse beam position. The performed simulation session is presented as well which we run before building the hardware for bench tests. | ||
| TUPC13 | The new Diode BPM system for ELETTRA | 177 |
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| A new Beam Position Monitor system has been developed at ELETTRA based on an envelope detector. It is a four channel system reading in parallel the four voltages from a button pick-up that adopts a wide-band Schottky diode. The analogue bandwidth of the currently implemented detector is <1kHz which has been adapted to the present application of the system, i.e. a fast beam position interlock to be installed on the ELETTRA storage ring. The upgrade of the ELETTRA BPM which is based on the Libera detector suggested us to add some redundancy on the fast position interlock in order to protect the vacuum chamber from wrong positions / angles of the beam. The data collection scheme, based on a single board computer for each straight section, is presented. Currently, the system has been installed and tested on all the ELETTRA undulator sections; the first running experience is here presented. | ||
| TUPC19 | Matlab Code for BPM Button Geometry Computation | 186 |
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| Third generation Synchrotron Light Sources with vertical beam sizes down to few microns require beam resolutions on the submicron level. Study of different Beam Position Monitors (BPM) geometries has been done to reach such tight requirements. The used Matlab Graphical User Interface (GUI) is based on the simulation of a charged particle inside a selectable vacuum chamber type, computing the induced signal that it produces on the button feedthroughs. Needed parameters for the computation are the button electrode dimensions, vacuum chamber profile, electron beam current and measurement bandwidth. Output results from the GUI are the induced power on the feedthroughs, BPM sensitivity and intrinsic resolution of the analyzed geometry. As sensitivity and resolution are BPM geometry dependent terms, the Matlab GUI turned out to be an easy and fast way for first step geometry analysis. | ||
| TUPC20 | The SOLEIL BPM and Orbit Feedback Systems | 189 |
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| SOLEIL is a third generation light source built in France, near Paris. Its BPM system is important for machine studies and for delivering stable beams to the users. A beam stable to 1/10th of the dimensions requires submicron stability in the vertical plane. The monitors, anchored either to the girders or to the ground, are fixed points of the vacuum chamber. Bellows avoid transverse drifts due to mechanical stress. The electronics design was driven by combined efforts through an active communication between accelerator labs (SOLEIL at first, later joined by DIAMOND) and Instrumentation Technologies. The result is the “Libera Electron” beam position processor. It combines a 0.2μm rms resolution and micron level stability for beam delivery with accurate turn-by-turn measurements (3μm resolution at 0.8MHz) for machine commissioning and beam physics studies. It also features position interlock, tune measurement, and postmortem capabilities. A Slow Orbit Feedback for correcting low frequency drifts (0 to 0.1Hz) is currently in operation. The Fast Orbit Feedback to be implemented soon will suppress higher frequency perturbations up to 100Hz. | ||
| TUPC23 | Design of a Submicron Resolution Cavity BPM for the ILC Main Linac | 192 |
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| A high resolution Beam Position Monitor (BPM) is necessary for the beam-based alignment and feedback systems of the future international linear collider (ILC). We present the cavity BPM developed at Fermilab within ILC collaboration. This monitor will be operated at cryogenic temperature and rigidly attached to the quad magnet. The same cylindrical cavity is used to obtain the signals from both dipole and monopole modes excited by beam. Such a scheme makes the BPM more compact for placing it inside the magnet space and simplifying the signal processing. The dipole TM110 mode is utilized to measure pulse to pulse beam motion at a theoretical resolution of approximately 50 nm. In order to measure a single bunch trajectory within 300 ns timescale we use a resonant coupling to lower cavity Q-factor. The ceramic windows are brazed inside coupling slots for vacuum isolation and easy cavity cleaning. We will present a BPM detailed numerical study and analyze its tolerance requirements for submicron resolution. | ||
| TUPC26 | Button Beam Position Monitors for FLASH | 201 |
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| Abstract: FLASH (Free Electron Laser in Hamburg) accelerates electron bunches to up to 750 MeV for producing intense, coherent, very short pulses of radiation. Various types of BPMs (beam position monitors) are installed in the facility: cavity and re-entrant-cavity BPMs in the accelerating cryo-modules and button and stripline BPMs in most of the room-temperature sections. The undulator section, where the FEL radiation is produced, is one of the most critical areas of the linac in terms of requirements on the position monitoring. Due to the tight space, button BPMs were chosen for this area. The electronics is based on the AM/PM principle. In the past couple of years these BPMs were commissioned and intensively studied. A few modifications have been made in the electronics, in order to deal with the small signals and the very high frequencies of the ultra-short bunches. In this paper the button-BPMs at FLASH will be presented. The studies made in the RF laboratory and the measurements made on the performance of the BPMs will be discussed. | ||
| WEO3A01 | Low-Latency High-Resolution Single-Shot Beam Position Monitors | 376 |
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| In this paper design aspects of high-resolution, single-shot transverse beam position monitors (BPMs) are discussed. The focus is put on BPMs which can provide (sub-)micrometer precision at measurement speeds of less than a few hundred nanoseconds. Different pickups, analog signal conditioning electronics, and digital post processing schemes are reviewed. Their characteristics and limitations with respect to application in high-resolution, fast BPMs are pointed out. Exemplary implementations of successful BPM realizations found in the literature are reviewed. A specific implementation of a BPM based on a resonant stripline pickup, developed for a fast transverse feedback system for the European X-FEL, is also presented. |