CERN, Geneva
At present more than 15000 particle accelerators exist worldwide, being built and optimised to handle a large variety of particle beams for basic research and applications in industry and medicine. Diagnostic tools have been developed and optimised according to the special requirements of these machines and to meet the demands of their users. Storage rings for ultra cooled heavy ion beams, third generation synchrotrons for the production of high brilliant radiation, super conducting protons machines working at the energy frontier and finally linear electron accelerators for FEL applications or high energy physics are just the most prominent representatives of the large variety of accelerators and each of them needs highly sophisticated tools to measure and optimise the corresponding beam parameters. Accordingly the issue addressed here is not to cover in full detail the different diagnostic devices but rather to concentrate on the aspects and needs as seen by the accelerator physicists and machine designers.
CERN, Geneva
The CERN Proton Synchrotron has been fitted with a new trajectory measurement system (TMS). Analogue signals from the forty beam position monitors are digitized at 125MS/s, and then further treated entirely in the digital domain to derive the positions of all individual particle bunches on the fly. Large FPGAs handle all digital processing. The system fits in fourteen plug-in modules distributed over three half-width cPCI crates. Data are stored in circular buffers of large enough size to keep a few seconds-worth of position data. Multiple clients can then request selected portions of the data, possibly representing many thousands of consecutive turns, for display on operator consoles. The system uses digital phase-locked loops to derive its beam-locked timing reference. Programmable state machines, driven by accelerator timing pulses and information from the accelerator control system, direct the order of operations. The cPCI crates are connected to a standard Linux computer by means of a private Gigabit ethernet segment. Dedicated server software, running under Linux, knits the system into a coherent whole.
ESRF, Grenoble
The ESRF Storage Ring has, in the period of the last 3 winter months, been fully equiped with new electronics for its BPM system while causing a minimum disturbance to its large community of X-ray beam-line users. The Libera-Brillance is now actively doing the treatment of the weak RF signals on all of the 224 BPM stations, and has replaced the old RF-Multiplexing system that had served reliably for nearly 17 years. This paper will describe the precautions that had been taken to make the whole transition as smooth and fluid as possible, with regards to both the reliability for the SR operation and the positional stability of the X-ray beams for the users of more than 40 beamlines. Information will be given on the structure of the network and computer control, based on the Tango distributed control system and its associated device-servers and tools. Results obtained will be presented to demonstrate the strongly improved performance and functionality in every field of application, and that will make this new BPM system the key component in the near future’s upgraded orbit stabilization system.
CERN, Geneva
A convenient way of having beam bunch intensity information available all around the LHC ring is to use the beam position monitor (BPM) system. The principle is to add the BPM signals, process them and make the result compatible with the time-modulation method used for transmitting the position over a fibre-optic link. In this way the same acquisition system can make both position and intensity data available. This paper describes the technique developed and presents the first intensity measurements performed on the CERN-SPS and LHC.
DELTA, Dortmund
The beam orbit of the 1.5GeV electron storage ring DELTA showed a variety of beam distortions with a pronounced frequency spectrum mostly caused by girder movements and ripples of the magnet power supplies. In order to enhance the orbit stability at least up to 300 Hz bandwidth a global fast orbit feedback is under consideration. As a prototype an FPGA based local fast orbit feedback at a 10 kHz data acquisition rate has been developed. The digitized orbit data are distributed from I-Tech Libera and Bergoz MX-BPMs to an FPGA board via a fibre interconnected network based on the Diamond Communication Controller [*]. The correction algorithm is written in VHDL and the corrections are applied with digital power supplies connected to the FPGA board through RS485 links. The first operational tests of the system achieved an effective damping of orbit distortions up to 350 Hz. The paper will give an overview on the layout of the FPGA based local orbit feedback system, will report on the results of the measured uncorrected orbit distortions at DELTA and the stability enhancements that could be achieved by the local feedback system.
* I. S. Uzun et al., "Initial Design of the Fast Orbit Feedback System for
Diamond Light Source", Proc. 10th ICALEPCS
Fermilab, Batavia
KEK, Ibaraki
To achieve a low vertical beam emittance at the KEK Accelerator Test Facility (ATF) damping ring, the BPM read-out system is currently upgraded with new high resolution electronics. Based on analog and digital down-conversion techniques, the upgrade includes an automatic gain calibration system to correct for slow drift effects and ensure high reproducable beam position readings. The concept and its technical realization, as well as preliminary beam study results are presented.
DESY, Hamburg
The new synchrotron light source PETRA III is powered by a chain of pre-accelerators including Linac II, PIA, transfer lines, and DESY II. The whole chain is equipped with upgraded versions of diagnostic systems that were installed during the 2008 shutdown. This paper presents the upgrade of the beam position monitor (BPM) systems at PIA together with the transfer lines and DESY II. All systems rely on the ‘Delay Multiplex Single Path Technology’ (DMSPT). It is demonstrated that the self-triggered design of the BPM electronics is specifically suited to the different needs of such a heterogeneous pre-accelerator chain. Structures and dependencies of the BPM systems will be described in detail.
GANIL, Caen
LPC, Caen
The SPIRAL2 project is based on a multi-beam driver facility in order to allow both ISOL and low-energy in-flight techniques to produce intense radioactive ion beams (RIB) in a new Facility. A superconducting linac capable of accelerating 5-mA deuterons up to 40 MeV is used to bombard both thick and thin targets. These primary beams will be used for the RIB production by several reaction mechanisms (fusion, fission, etc.) The production of high intensity RIB will be based on fission of uranium target induced by neutrons. These exotic particles will be produced, ionized, selected in a dedicated production building and transported to the existing CIME cyclotron for post acceleration. After this, they will be used in the present experimental area of GANIL. The construction phase of SPIRAL2 was officially started in 2005. The beam diagnostics for the production facility allow a pre-tuning with a stable beam followed by an extrapolation to the radioactive beam. Some diagnostic devices may also provide for equipment protections and for the safety systems. An overview is presented of the diagnostics which will allow tuning and control of the RIB in this new production facility.
BESSY GmbH, Berlin
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
BunchView is a system for the direct measurement of the current from each bunch circulating in a storage ring based on the analysis of the RF-signals delivered by a set of striplines. This paper describes the development, achievements, operation, and results of this fast and accurate bunch current monitor built for the BESSY and MLS storage rings. Using a combination of a 14/16Bit ADC, a high-speed FIFO, ECL technique, and FPGAs, a real-time measurement of the fill-pattern with high accuracy and bunch-by-bunch resolution was achieved. The results are identical to the fill-pattern determined by time correlated single photon counting based on synchrotron radiation detected with an avalanche photo diode. BunchView is fully integrated into the EPICS control system. The data provided by the BunchView monitor give accurate bucket position in the ring and bunch current over a wide range of currents. The smallest measured single bunch current is less than 100nA. In the future the system will be used in the top-up mode of operation in order to inject beam into the emptiest buckets and thus keep the fill-pattern stable over longer periods of time.
YerPhI, Yerevan
BERGOZ Instrumentation, Saint Genis Pouilly
ANL, Argonne, Illinois
YSU, Yerevan
The Vibrating Wire Monitor (VWM) was developed for precise transversal profiling/monitoring of charged particle/photon beams. The extremely high sensitivity of VWM is achieved by sensitivity of wire natural oscillation frequency to wire temperature. Due to the rigidity of the wire support structure, the VWM is also sensitive to the environmental parameters. In this paper, it is shown that the main parameter of influence is the ambient temperature. The magnitude and character of this influence is investigated along with the effect of electromagnetic interference on the VWM electronics in an accelerator environment.
GSI, Darmstadt
At the GSI Linac and transfer lines several Beam Induced Fluorescence Monitors (BIF) for transverse profile determination are installed. The non-intercepting measurement principle is based on the excitation of residual gas molecules by the beam and the detection of the fluorescence photons with image intensified cameras. This allows simultaneous profile determination at multiple positions without beam disturbance. The software ProfileView is a data acquisition system to visualize and record the profiles of several BIF monitors along the beamline. One BIF monitor comprises two image intensified cameras with remote irises, timing interface, gas pressure control and remote reset functionality. The basic functions needed for daily operation are combined in an easy-to-use graphical user interface. Beside this 'operator mode' an 'expert mode' can be called by advanced users to control every hard- or software parameter of the whole system separately. This contribution describes the software design and its realization for communication and data display.
CERN, Geneva
The fast beam intensity measurements for the LHC are provided by eight Fast Beam Current Transformers (FBCT). Four FBCTs installed in the LHC rings are capable of providing both bunch-by-bunch and total turn-by-turn beam intensity information. A further four FBCTs, two in each of the LHC dump lines, are used to measure the total extracted beam intensity. In addition to providing intensity information the ring FBCTs also send signals to the machine protection system. This increases the complexity of both the RF front-end and the digital acquisition parts of the signal processing chain. The aim of this paper is to discuss the implemented hardware solution for the FBCT system, in particular with respect to the signal distribution, FPGA signal processing, calibration, and interaction of the FBCTs with the machine protection chain.
INFN/LNF, Frascati (Roma)
The experimental setup implemented in the SPARC linac control system used to monitor the laser beam energy and to measure the beam charge by means of a Faraday Cup will be illustrated and discussed. The experimental setup makes use of National Instruments 2 GS/s 8-Bit digitizer board. This tool has been shown to be useful in order to monitor the laser beam energy stability and to evaluate the quantum efficiency of the cathode.
CERN, Geneva
The LHC circulating beam current measurement is provided by 8 current transformers, i.e. 2 DC current transformers (DCCT) and 2 fast beam current transformers (FBCT) per ring. This paper presents the DCCT, designed and built at CERN, including the sensor, the electronics and the front-end instrumentation software. The more challenging requirements are the needed resolution, of the order of 1μA rms at 1s average, and the wide dynamic range of the circulating beam intensity from the pilot bunch (8μA) to the ultimate beam (860mA). Another demanding condition is the high level of reliability and availability requested for the operation and machine protection of this highly complex accelerator. The measurement of the first RF captured beam in ring 2 is close to meet the specifications in term of resolution (1.3μA rms at 1s average) and stability over a period of a few hours (drift less than 3μA). Finally elements intended to be installed in the near future are presented.
ORNL, Oak Ridge, Tennessee
BINP SB RAS, Novosibirsk
An electron Scanner has been commissioned to non-destructively measure the transverse profiles in the Spallation Neutron Source (SNS) Ring. The SNS Ring is designed to accumulate in the order of 1.6·1014 protons with a typical peak current of over 50 Amps. Because of this high intensity no other profile measuring devices such as wire scanners were installed. The electron scanner is based on measuring the deflection of 50-75kV electrons by the electric field of the proton beam. Two electron guns, one for each plane, with dipole correctors, quadrupoles and deflectors to shape the electron beam have been installed. This paper describes the system and the initial results.
GSI, Darmstadt
LBNL, Berkeley, California
TU Darmstadt, Darmstadt
As conventional intercepting diagnostics will not withstand high intensity ion beams, Beam Induced Fluorescence (BIF) profile monitors constitute a pre-eminent alternative for online profile measurements. At present two BIF monitors are installed at the GSI UNILAC and several locations are planned for the FAIR high energy beam transport lines. For further optimizations accuracy issues like gas dynamics have to be investigated systematically. Especially the determination of focused beams in front of targets or beam intensities near the space charge limit rely on a careful selection of proper working gas transitions to keep profile distortions as low as possible. With an imaging spectrograph beam induced fluorescence spectra in the range of 300-800 nm were investigated. Wavelength-selective beam profiles were obtained for 5 MeV/u sulphur and tantalum beams in nitrogen, xenon, krypton, argon and helium gas at pressures below 10-3 mbar. In the calibrated BIF spectra the specific gas transitions were identified. The measurement results are compared with particle tracking simulations and discussed for typical applications at the present setup and the future FAIR facility.
CERN, Geneva
During the 2008/2009 shutdown the electronics for the Fast Wire-scanners for the CERN PSB and PS machines will be renovated with new movement and acquisition electronics. A new test bench was produced that allows measuring the movement of wires at speeds up to 20 m/s. This poster will present the calibration system with its related software.
GANIL, Caen
The SPIRAL2 project is based on a multi-beam driver in order to allow both ISOL and low-energy in-flight techniques to produce Radioactive Ion beams (RIB). A superconducting light/heavy-ion LINAC capable of accelerating 5 mA deuterons up to 40 MeV and 1 mA ions up to 14.5 MeV/u is used to bombard both thick and thin targets. These beams could be used for the production of intense RIB by several reaction mechanisms (fusion, fission, transfer, etc.). In order to visualize the SPIRAL2 beam dynamics, several beam profile monitors are under development. Multiwire beam profile monitors (SEM) will be used on the driver and RIB lines, a non interceptive beam profile monitor (RGM) should be mounted on the LINAC diagnostics box and before the experiment facility, and a low intensity beam profile monitor (EFM) on the RIB lines. Signal acquisition from these monitors will be accomplished through new associated electronics which digitize 94 channels in a parallel system. Each channel integrates the current of the associated wire or strip and performs a current-voltage conversion. The dedicated GANIL data display software has been adapted for these new monitors.
CERN, Geneva
UFC, Besançon
UTBM, Belfort
Scanning of a high intensity particle beam imposes challenging requirements on Wire Scanner system. It is expected to reach scanning speed of 20 m/s with position accuracy of the order of 1 μm. In addition a timing accuracy better than 1 millisecond is needed. The adopted solution consists of a wire holding fork rotating by maximal of 200°. Fork, rotor and angular position sensor are mounted on the same axis and located in a chamber connected to the beam vacuum. The requirements imply the design of a system with extremely low vibration, vacuum compatibility, radiation, and temperature tolerance. The adopted solution consists of a rotary brushless synchronous motor with the permanent magnet rotor installed inside of the vacuum chamber and the stator installed outside. The accurate position sensor will be mounted on the rotary shaft inside of vacuum chamber and has to resist bake-out temperature of 200°C and ionizing radiation up to tenth of kGy/years. A digital feedback controller allows maximum flexibility for the loop parameters and feeds the 3 phases input for the linear power driver. The paper will present a detail discussion of chosen concept and the selected components.
FZJ, Jülich
UniDo/IBS, Dortmund
GSI, Darmstadt
ITEP, Moscow
The advanced ionization beam profile monitor is being developed at GSI for the future FAIR facility in collaboration with ITEP and FZ-Jülich. In January 2009 the IPM prototype was installed in COSY-Jülich. After successful hardware test the beam tests followed. The prototype was operated without magnetic field, thus only residual gas ions were detected. An arrangement consisting of an MCP stack, a phosphor screen, and a CCD camera was used to detect ions. We report the first profile measurements of the proton beam up to 2.8 GeV at COSY.
Fermilab, Batavia
Abstract The Fermilab Recycler ring employs an electron cooler to store and cool 8.9-GeV antiprotons. The cooler is based on a 4.3MV, 0.1A, DC electrostatic accelerator (Pelletron) for which current losses have to remain low (~10-5) in order to operate reliably. The Machine Protection System (MPS) has been designed to interrupt the beam in a matter of 1-2 μs when losses higher than a safe limit are detected, either in the accelerator itself or in the beam lines. This paper highlights the various diagnostics, electronics and logic that the MPS relies upon to successfully ensure that no damage be sustained to the cooler or the Recycler ring.
DESY, Hamburg
For current and future accelerators, in particular light sources, high availability is an important topic. Therefore the causes of beam losses must be diagnosed and eliminated as fast as possible. This paper presents a concept using the following signals and data from diagnostic instruments and other sources:
- software alarms transmitted by the control system,
- hardware alarms received and timestamped by the machine protection system, and
- Post-Mortem-Analysis.
MPI-K, Heidelberg
The University of Liverpool, Liverpool
The majority of particles in a beam are located close to the beam axis, called the beam core. However, particles in the tail distribution of the transverse beam profile can never be completely avoided and are commonly referred to as beam halo. The light originating from or generated by the particle beam is often used for non- or least destructive beam profile measurements. Synchrotron radiation, optical transition, or diffraction radiation are examples of such measurements. The huge difference in particle density between the beam core and its halo, and therefore the huge intensity ratio of the emitted light is a major challenge in beam halo monitoring. In this contribution, results from test measurements using a flexible core masking technique are presented indicating way to overcome present limitations. This technique is well-known in e.g. astronomy, but since particle beams are not of constant shape in contrast to astronomical objects, a quickly adjustable mask generation process is required. The flexible core masking technique presented in this paper uses aμmirror array to generate a mask based on an automated algorithm.
CERN, Geneva
The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. As well as protecting the machine, the system is also used as a means of diagnosing machine faults, and providing feedback of losses to the control room and several systems such as the Collimation, the Beam Dump and the Post-Mortem. The system has to transmit and process signals from over 4'000 monitors, and has approaching 3 million configurable parameters. This paper describes the types of configuration data needed, the means used to store and deploy all the parameters in such a distributed system and how operators are able to alter the operating parameters of the system, particularly with regard to the loss threshold values. The various security mechanisms put in place, both at the hardware and software level, to avoid accidental or malicious modification of these BLM parameters are also shown for each case.
DESY, Hamburg
PETRA III, a new high-brilliance synchrotron radiation source, is under commissioning at DESY. Its beam position measurement system is based on the Libera Brilliance electronics. BPM system is used for machine starting up and development. The system will also be used for the beam observation and orbit feedback. This paper presents the infrastructure, features of the BPM system and experience with the commissioning of the BPM electronics.
ESRF, Grenoble
Until 2008, the suppression of the closed orbit distortion on the storage ring of the ESRF was obtained using two separate systems: A slow system using 224 BPM and 96 correctors performing a correction every 30 seconds, and a fast system, using only 32 BPMs and 32 correctors but working at 4.4KHz, damping the orbit distortion from 50mHz up to 150Hz; the 15mHz to 50mHz frequency span was left uncorrected. This separation of the frequency ranges of the two systems avoided cross talks between them, but prevented the efficient cancellation of the very low frequency orbit distortions caused by the frequent modification of the insertion device settings during the beamlines operation. We now coordinate the operation of the slow and fast systems and suppress this dead frequency span. This paper describes the principle and the beneficial effect of this new scheme, and its limitations. To overcome these limitations, we are now developing a single new orbit correction system which will damp the orbit distortion from DC to 150Hz; this system will use the Libera Brillance BPM electronics recently implemented at ESRF, and new fast correctors. This new scheme is also briefly presented.
DELTA, Dortmund
TU Dortmund University, Dortmund
Orbit stability at the 1.5 GeV electron storage ring DELTA is currently achieved via a global slow orbit feedback system at a data acquisition rate of 10 Hz. The system is based on analog Bergoz MX-BPMs and I-Tech Libera digital BPMs. In order to enhance the precision of the slow position measurement and in preparation for a global fast orbit feedback at a 10 kHz data acquisition rate we developed an FPGA based digital frontend for the MX-BPMs. The prototype module is taking orbit data from 4 Bergoz MX-BPMs, clocked to 40 kHz, at a rate of 10 kHz while averaging over 4 samples per clock cycle. The digitized data is distributed via the Diamond Communication Controller [*] formerly only available for Libera BPMs. Precision, fault tolerance and easy maintenance are the key aspects of this system. First operational tests in the storage ring showed that the system reveals the desired capabilities. The paper will give an overview on the layout of the FPGA-based system, will report on the results with beam and will show prospects for the further use at DELTA.
*I. S. Uzun et al., "Initial Design of the Fast Orbit Feedback System for Diamond Light Source", Proc. 10th ICALEPCS
NSRRC, Hsinchu
The BPM electronics of the Taiwan Light Source (TLS) have been upgraded to the Libera Brilliance in August 2008 to improve performance and functionality. Orbit feedback system is also migrated into fast orbit feedback system to enhance orbit stability. Infrastructure of the orbit acquisition system and orbit feedback system has been reconstructed to accommodate with new BPM electronics and satisfy requirements of fast orbit feedback loops. Gigabit Ethernet grouping was adopted for the data transfer rate of 10 kHz between BPM and the orbit feedback system. A summary of the efforts and performance of this upgrade will be presented in this report.
CERN, Geneva
Many beam instrumentation signals of large circular accelerators are in the kHz range and can thus be digitised with powerful high resolution ADCs. A particularly large dynamic range can be achieved if the signals are analysed in the frequency domain. This report presents a system employing audio ADCs and FPGA-based spectral analysis, initially developed for tune measurement applications. Technical choices allowing frequency domain dynamic ranges beyond 140 dB are summarised.
CERN, Geneva
KEK, Ibaraki
UW-Madison/PD, Madison, Wisconsin
For the LHC beam loss measurement system the high voltage supply of the ionisation chambers and the secondary emission detectors is used to test their connectivity. A harmonic modulation of 0.03 Hz results in a current signal of about 100 pA measured by the beam loss acquisition electronics. The signal is analyzed and the measured amplitude and phase are compared with individual channel limits for the 4000 channels. It is foreseen to execute an automatic procedure for all channels every 12 hours which takes about 20 minutes. The paper will present the design of the system, the circuit simulations, measurements of systematic dependencies of different channels and the reproducibility of the amplitude and phase measurements.
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin
DESY, Hamburg
Local beam losses and beam profiles at particle accelerators are determined by measuring the ionizing radiation outside the vacuum chamber. Four different fiber optic radiation sensor systems will be presented. Two are based on the increase of radiation-induced attenuation of (Ge+P)-doped multimode graded index fibers, whereas with the third system detects the Cerenkov light generated by relativistic electrons in radiation hard fibers. The used fiber is an undoped multimode step-index fiber with 300 um core diameter. Dosimetry at high dose levels uses the radiation induced Bragg wavelength shift of Fiber Bragg Gratings. The selection of a suitable fiber for the individual application is an important requirement and depends on the type, doping, used wavelength and annealing behavior. In addition, the dose range, dose rate and temperature must be considered. At six accelerators all systems are used for in-situ beam optimization and dose measurement. This paper summarizes the basic of this measurement technology and the experience at linear accelerators and at storage rings.