CERN, Geneva
During the 2008 LHC injection synchronisation tests and the subsequent days with circulating beam, the majority of the LHC beam instrumentation systems were capable of measuring their first beam parameters. This included the two large, distributed, beam position and beam loss systems, as well as the scintillating and OTR screen systems, the fast and DC beam current transformer systems, the tune measurement system and the wire scanner system. The fast timing system was also extensively used to synchronise most of this instrumentation. This presentation will comment on the results to date, some of the issues observed and what remains to be done for the next LHC run.
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.
DESY, Hamburg
The Positron Intensity Accumulator PIA at DESY is used to accumulate the intensity and damp down the emittance of the positrons produced in the Linac II before they are injected into DESY II. Up to 19 shots are collected and damped. During the damping process the (baseband) peak current is increased by about a factor 4. Therefore the signal from the circulating beam can be up to 80 times bigger than the injected beam and hence overload any first turn detectors. The injected beam however is bunched by the 3 GHz RF of the linac. By filtering the 3 GHz component of the antenna signal and subsequent demodulation it is possible to set up a BPM system detecting exclusively the injected beam.
BNL, Upton, Long Island, New York
ANL, Argonne, Illinois
Sub-micron beam stability is a necessary performance requirement for the NSLS II light source, a substantial challenge testing the limits for presently available RF beam position monitoring methods. Direct performance comparisons between commercially available bpms and Advanced Photon Source in-house developed bpm were made at the APS Storage Ring. Noise floor, fill pattern dependence, and intensity dependence were investigated and correlated with photon diagnostics at the beam diagnostic beamline at APS sector 35. Key results will be presented.
ISA, Aarhus
This paper presents an overview of the proposed beam diagnostic for Astrid2, which is the new 580 MeV 3rd generation synchrotron light source to be build in Aarhus, Denmark. Astrid2 will use the present Astrid1 as booster, allowing for full energy injection and thereby top-up-operation. The diagnostics will include viewers, beam current monitors, electronic beam position monitors, striplines, etc. The description will include both the storage ring and the transfer beam line.
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.
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.
CERN, Geneva
A discrete components design of a current digitizer based on the current-to-frequency converter (CFC) principle is currently under development at CERN. The design targets at rather high input current compared to similar designs, with a maximum equal to 200mA and a minimum of 1nA, as required by the ionization chamber that will be employed in the Proton Synchrotron and Booster accelerators as well as in the LINAC. It allows the acquisition of currents of both polarities without requiring any configuration and provides fractional counts through an ADC to increase the resolution. Several architectural choices are being considered for the front-end circuit, including charge balance integrators, dual-integrator input stages, integrators with switchable-capacitor, in both synchronous and asynchronous versions. The signal is processed by an FPGA and transmitted over a VME64x bus. Design, simulations and measurements are discussed in this article.
IMP, Lanzhou
HIRFL-CSR, a new heavy ion cooler-storage ring in China IMP, had been installed and started commission from 2005. We report here the BPM system on the main ring (CSRm) and the experimental ring (CSRe). The BPM structure, the signal processing system and on-line measurement experiments are presented. The measurement results such as turn-by-turn bunch observation, closed-orbit measurement, Schottky noise measurement are also presented in this paper.
ASCo, Clayton, Victoria
The Australian Synchrotron (AS) timing system is based on a hybrid design: an Event Generator-Event Receiver (EVG-EVR) system creates the injection trigger and various clocks, while a network of digital delay generators adjusts pulse delays and widths. This architecture, combined with a storage ring fill pattern monitor, allows the targeting of injection into specific buckets in the storage ring. Nevertheless, more demanding needs from the machine and the beamlines require an upgrade of the system. Delay generators will be removed and replaced by EVRs. This will allow fixed or variable frequency clocks to be made available to beamlines or to trigger diagnostic hardware, orbit interlock distribution, etc., while reducing jitters to below 100 ps. This paper presents the architecture of the new timing system at AS and emphasizes its benefits for diagnostic tools.