DIPAC2011 - List of Keywords (feedback)

Paper	Title	Other Keywords	Page
MOOA02	Beam Instrumentation for X-ray FELs	cavity, FEL, undulator, diagnostics	1
	H. Loos SLAC, Menlo Park, California, USA
	Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC03-76SF00515. The performance of X-ray Free-electron lasers depends strongly on the achieved quality of the high brightness electron beam and its shot by shot stability. The requirements and challenges of the instrumentation needed to tune and optimize such electron beams will be discussed. Of particular interest are measurements of the beam orbit, emittance, energy, and bunch length and the different measurement techniques for these transverse and longitudinal beam parameters and their implementation for routine operation will be addressed in detail, particularly the necessary instrumentation to fulfill different user requirements in terms of beam energy and bunch length. Specific requirements for the initial commissioning, routine optimization and feedback applications will be presented as well.
	Slides MOOA02 [2.114 MB]

MOPD23	Photon BPM Electronics Development at Taiwan Light Source	photon, injection, controls, diagnostics	95
	P.C. Chiu, J. Chen, Y.K. Chen, K.T. Hsu, K.H. Hu, C.H. Kuo NSRRC, Hsinchu, Taiwan
	Photon BPMs are very useful for photon beam position and stability observation. There are several kinds of photon BPMs and electronics with different design installed at beamline front-ends at the Taiwan Light Source. To provide a better integration and efficient usage of the photon BPM, a commercial BPM electronics - Libera Photon was chosen for an integral solution and has showed at least one micron performance for several months of testing. In this report, the installation process and testing results of the photon BPM will be presented.
	Poster MOPD23 [0.595 MB]

MOPD24	A High-resolution Diode-based Orbit Measurement System – Prototype Results from the LHC	pick-up, vacuum, injection, coupling	98
	M. Gasior, J. Olexa, R.J. Steinhagen CERN, Geneva, Switzerland
	The prototype of a high resolution beam position monitor (BPM) electronics based on diode peak detectors was tested with LHC beams. In this technique developed at CERN the short beam pulses from each BPM electrode are converted into slowly varying signals by compensated diode peak detectors. The slow signals can be digitised with a laboratory voltmeter or high resolution ADC. As presented in the paper, this technique allows resolutions in the order of 1 ppm of the BPM aperture to be achieved with a measurement rate in the Hz range. Ongoing developments and future prospects for the technique are also discussed.
	Poster MOPD24 [2.055 MB]

MOPD26	Testing of New Hadron Beam Phase and Position Monitor at CIEMAT Laboratory	instrumentation, controls, pick-up, monitoring	104
	M. Znidarcic, B.B. Baricevic, R. Hrovatin I-Tech, Solkan, Slovenia J.M. Carmona, A. Ibarra, I. Podadera CIEMAT, Madrid, Spain
	The Libera Single Pass H is the new instrumentation intended for phase, position and charge monitoring in hadron and heavy ion LINACs and transfer lines. Initial measurements and verification of the instrumentation performance were conducted in the laboratory at Instrumentation Technologies. Characterization measurements of the same electronics were later carried out at CIEMAT laboratory. The measurements were performed on a CIEMAT wire test bench with the 175 MHz pulsed signal connected to the wire. Different measurements were performed on the test bench; First, by moving the wire over larger displacements and checking the position and, later, by changing the signal phase and performing the phase shift measurement. This article discusses the new Libera Single Pass H electronics, the tests carried out in the test bench and the performance obtained.

MOPD38	1-MHz Line Detector for Intra-bunch-train Multichannel Feedback	laser, radiation, electron, diagnostics	137
	L. Kotynia, D.R. Makowski, A. Mielczarek, A. Napieralski TUL-DMCS, Łódź, Poland C. Gerth, T. Jezynski, H. Schlarb, B. Schmidt, B. Steffen DESY, Hamburg, Germany
	Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285). The measurement and control of the electron bunch length is one of the key diagnostics in linac-based free-electron lasers to reach the required peak current in the electron bunches. In order to use the multi-channel signals from longitudinal bunch shape measurements for intra train feedback for the European XFEL, line readout rates in the MHz range and low latencies are required, which is far more than commercial multichannel radiation detectors (line cameras) can provide. The paper presents a 256 channel detector that allows analyzing optical or infrared radiation with 1 MHz rate and a few microseconds latency using photodiode arrays, as needed for synchrotron light monitors, electro-optical bunch length measurements, or other laser based diagnostics. The proposed architecture aims at high frequency readout with low latency by using a multichannel electronic front-end designed for HEP, combined with Si or InGaAs detector arrays with very fast response time, and a low-latency data acquisition system. Currently the device is at the conceptual design stage.
	Poster MOPD38 [3.262 MB]

MOPD73	Study of Beam Size Blowup due to Transverse Bunch Feedback Noise on e⁺e⁻ Collider	luminosity, simulation, beam-beam-effects, injection	212
	M. Tobiyama, K. Ohmi KEK, Ibaraki, Japan
	Vertical beam size blowup with the gain of the transverse bunch feedback systems has been observed in KEKB B-factory rings. With the numerical simulation, large beam-beam effect enhances small oscillation induced by the broadband noise of the bunch feedback kick. To examine the simulation, beam response, effective beam size and the luminosity change with artificial external noise injected in the transverse feedback system have beem measuredn in KEKB LER ring during collision. The result has been compaired with the simulation including beam-beam effect and showed good agreement.
	Poster MOPD73 [0.296 MB]

MOPD74	The New Fast Orbit Correction System of the ESRF Storage Ring	storage-ring, power-supply, insertion, damping	215
	E. Plouviez, F. Epaud, J.M. Koch, K.B. Scheidt ESRF, Grenoble, France
	The ESRF is upgrading the orbit correction system of its storage ring. The goal of this upgrade is to damp the effect on the orbit stability of the insertion devices during the changes of their settings, as well as the effect of the environmental vibrations and AC main power spurious fields; in order to achieve this goal we aim at a correction bandwith of 200Hz. The final system will use the data of 224 BPMs already equipped with Libera brilliance electronics. The correction will be applied by a set of 96 correctors implemented in the auxillary legs of the sextupolar magnets, driven by newly designed fast power supplies . The power supplies are controlled using a set of 8 FPGA boards connected to the power supplies inputs with serial links; these FPGA will also compute the correctors currents using the BPMs data. All the correctors and BPMs are now installed and interconnected and we have already performed orbit correction tests over 2 of the 32 cells of our storage ring using one single FPGA board controlling 6 correctors. These tests have allowed us to evaluate the final performance of the system. This paper presents this new system and the results of these tests.

MOPD76	The Petra III Fast Orbit Feedback System	instrumentation, controls, injection, brilliance	221
	J. Klute, K. Balewski, H.T. Duhme, H. Tiessen, F. Wierzcholek DESY, Hamburg, Germany
	Orbit stability is a crucial and import issue of 3rd generation light sources. Ambient mechanical and electrical noise cause rather large orbit distortions which have to be counteracted by an orbit feedback. Extensive studies of the orbit distortions in PETRA III have shown that the frequencies of the ambient noise lie within a frequency range from about 0.01Hz to 100Hz. In this paper we describe the main components, their properties and the layout of PETRA III’s orbit feedback. Furthermore experimental results on short and long term stability will be presented. It will be shown that the required orbit stability of ±0.5 μm in the vertical plane can be maintained over 50 h.

MOPD77	Broadband Digital Feedback System for the VEPP-4M Electron-Positron Collider	kicker, electron, betatron, positron	224
	V.V. Oreshonok, V.V. Smaluk BINP SB RAS, Novosibirsk, Russia V.P. Cherepanov, V.V. Oreshonok, D.P. Sukhanov NSU, Novosibirsk, Russia
	To suppress the transverse instability, which is the main reason of beam current limitation at the VEPP-4M electron-positron collider, a digital bunch-by-bunch feedback system has been developed, installed and commissioned. The real-time data processing is performed by a special code running in an FPGA module. This provides high efficiency and flexibility of the system. During the system commissioning, a 3-times increase of the beam current injected into VEPP-4M was reached. The system design and data processing algorithms are described, the commissioning results are presented.

MOPD78	Synchronous Measurement of Stability of Electron Beam, X-ray Beam, Ground and Cavity Voltage	cavity, electron, photon, controls	227
	G. Rehm, M.G. Abbott, C. Bloomer, I. Uzun Diamond, Oxfordshire, United Kingdom
	We have developed hardware and software that allows continuous and synchronous recording of electron and X-Ray beam position as well as cavity voltage and ground vibrations at a rate of about 10kS/s for periods of many days. To this end, additional nodes have been added to our existing fast network that feeds the Fast Orbit Feedback System, namely tungsten vane type front end XBPMs, RF cavity pickups and accelerometers. The synchronous nature of these measurements shows the correlation between electron beam motion through an insertion device and observed X-ray beam motion in the frontend or orbit distortions caused by fluctuations of the RF cavity voltage. While the additional channels currently are only observed, the potential of including these in the fast orbit feedback will be discussed.

MOPD79	An FPGA-based Turn-by-Turn Beam Position Monitoring System for Studying Multiple Bunch Beams in the ATF Damping Ring	injection, extraction, damping, synchrotron	230
	G.B. Christian, D.R. Bett, B. Constance, M.R. Davis JAI, Oxford, United Kingdom R. Apsimon, P. Burrows, A. Gerbershagen, C. Perry Oxford University, Physics Department, Oxford, Oxon, United Kingdom J. Resta-López IFIC, Valencia, Spain
	Instabilities associated with beam-size blow-up have previously been observed with multi-bunch beam in the damping ring (DR) of the KEK Accelerator Test Facility (ATF). A system has been developed to monitor such instabilities, utilising an ATF stripline beam position monitor (BPM) in the DR, and BPM processor hardware designed for the FONT upstream feedback system in the ATF extraction line. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR in single-bunch multi-train mode or the head bunch of up to three trains in multi-bunch mode, with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software were modified to record turn-by-turn data for up to six channels and 1–3 bunches in the DR. The maximum memory configuration on the FPGA allows 131071 bunch-turn-channels of data to be recorded from a particular machine pulse, and the system has the capability to select only certain turns at a regular interval in which to record data, in order to zoom out and cover the entire period of the damping cycle at the ATF. An overview of the system and initial results will be presented.

MOPD80	An FPGA-based Bunch-by-Bunch Position and Angle Feedback System at ATF2	kicker, extraction, linear-collider, collider	233
	G.B. Christian, R. Apsimon, D.R. Bett, B. Constance, M.R. Davis JAI, Oxford, United Kingdom P. Burrows, C. Perry Oxford University, Physics Department, Oxford, Oxon, United Kingdom A. Gerbershagen CERN, Geneva, Switzerland J. Resta-López IFIC, Valencia, Spain
	The FONT5 intra-train feedback system serves as a prototype for an interaction point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider. The system has been tested on the KEK Accelerator Test Facility (ATF) and is deployed to stabilise the beam orbit at the ATF2. The goal of this system is to correct both position and angle jitter in the vertical plane, providing stability of ~1 micron at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. The total latency of the system with coupled position and angle feedback loops operating simultaneously was measured to be approximately 140 ns. The greatest degree of correction observed was down to a jitter of 0.4 microns at one of the feedback BPMs, a factor of six compared to the uncorrected beam jitter, for a very high degree of bunch-to-bunch correlation.

MOPD87	The LHC Beam Presence Flag System	controls, injection, impedance, monitoring	251
	M. Gasior, T.B. Bogey CERN, Geneva, Switzerland
	Before injecting any high intensity bunches into the LHC a circulating low intensity pilot bunch must be present to confirm the correct settings of the main machine parameters. For the 2010 LHC run the detection of this pilot beam was done with the beam current transformer system. To increase redundancy of this important safety function a dedicated beam presence flag system was designed, built and tested with beam to be used operationally in the 2011 run. In this system signals from four electrodes of a beam position monitor (BPM) are processed with separate channels, resulting in a quadruple system redundancy for either beam. Each system channel consists of an analogue front-end converting the BPM signals into two logic states, which are then transmitted optically to the machine protection and interlock systems. For safety reasons the system does not have any remote control or adjustable elements and its only inputs are the beam signals. This paper describes the new LHC beam presence flag system, in particular the analogue front-end based on diode peak detectors.
	Poster MOPD87 [8.200 MB]

TUOA01	Beam Instrumentation in J-PARC	linac, impedance, proton, septum	275
	T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	The talk will summarize the beam instrumentation at J-PARC with a focus on MW class proton beams. The measurements of beam intensities, positions, losses, profiles, and halos at each stage of accelerator, 181 MeV LINAC (to be upgraded to 400MeV), 3 GeV RCS and 50 (30 as phase I) GeV MR will be reported. Present status, including modification and improvement of instrumentations to meet with LINAC energy upgrade and a future plan will be reported with emphasis on high beam power related issues such as radiation hardness (mechanically and electrically), beam coupling impedance, etc..
	Slides TUOA01 [22.777 MB]

TUOB03	Next Generation Electronics based on μTCA for Beam-Diagnostics at FLASH and XFEL	diagnostics, controls, laser, low-level-rf	294
	P. Gessler, M.K. Bock, M. Bousonville, M. Felber, M. Hoffmann, T. Jezynski, T. Lamb, F. Ludwig, G. Petrosyan, L.M. Petrosyan, K. Rehlich, S. Schulz, P. Vetrov, M. Zimmer DESY, Hamburg, Germany C. Bohm, A. Hidvégi Stockholm University, Stockholm, Sweden K. Czuba Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland D.R. Makowski TUL-DMCS, Łódź, Poland
	Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285). Almost all accelerator-related diagnostic and steering systems require front-end electronic hardware and software for digitizing, synchronization, processing, controlling, and providing access to the control system. Increasingly high demands on resolution, bandwidth, stability, redundancy, low latency, real-time processing and distribution create the need for new technologies in order to fulfill those demands. For this reason, at the European XFEL and FLASH, the new, μTCA industry standard will be deployed. Over the last few years, significant achievements have been made in μTCA developments in collaboration with other research institutes and industry. In this paper, we give an overview of the required components of a typical μTCA system for diagnostics applications. The FLASH bunch arrival-time monitor will be used as an example.
	Slides TUOB03 [9.075 MB]

TUPD12	The LHC Beam Position System: Performance during 2010 and Outlook for 2011	pick-up, closed-orbit, injection, vacuum	323
	E. Calvo Giraldo, J.L. Gonzalez, L.K. Jensen, O.R. Jones, T. Lefèvre, J.-J. Savioz, R.J. Steinhagen, J. Wenninger CERN, Geneva, Switzerland
	This paper presents the performance of the LHC Beam Position System during 2010. The system proved to meet most specifications, was highly reliable and continuously provided 25Hz real-time orbit data with micron level resolution to the automatic global orbit feedback system. However, several issues were observed and they will be discussed in detail, such as the dependence on bunch intensity and the effect of surface electronics temperature variations on the measured position.

TUPD21	Frontend Measurements and Optimizations at Libera Brilliance BPM Electronics during Commissioning of the Petra III Synchrotron Light Source	brilliance, controls, instrumentation, synchrotron	350
	F. Schmidt-Föhre, G. Kube, J.M. Maass, K. Wittenburg DESY, Hamburg, Germany
	New 3rd generation synchrotron light sources like Petra III utilize high-accuracy beam position measurement (BPM) systems to achieve the desired precision for beam position measurement and control, as needed for electron/positron beam stability and brilliance of the delivered photon beam. To reach the design goals, specifically adapted and parameterized commercial-of-the-shelf (COTS) Libera Brilliance BPM processor electronics are used within the Petra III BPM system. Quality of the acquired position measurement and orbit control data is highly dependent on the properties and setup of the analog and digital frontend of such BPM electronics. This paper shows influences and optimizations at the BPM system frontend of the Petra III light-source in reference to corresponding measurements done during the accelerator commissioning phase.

TUPD23	New Bunch-by-Bunch Feedback System for the TLS	controls, diagnostics, EPICS, kicker	353
	C.H. Kuo, Y.K. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu NSRRC, Hsinchu, Taiwan
	FPGA based bunch-by-bunch feedback systems were deployed in 2005-2006 by using SPring-8 designed feedback processors for the Taiwan Light Source. To provide spare units and explore integrate with the control system in the EPICS toolkit environment, feedback processors from the Dimtel were setup. The new system can be swap with the existed system by simple cable re-connection and integrated with the EPICS system in seamless way. Rich functionality except the basic feedback function includes excitation of individual bunch or specifies bunches, averaged spectrum, tune measurement by the feedback dip in the averaged spectrum, fill pattern measurement, etc. are explorer. Current stage implementation and features of the system will summary in this report.

TUPD28	Benchmarking the Performance of the Present Bunch Arrival Time Monitors at FLASH	pick-up, FEL, laser, electron	365
	M.K. Bock, M. Bousonville, M. Felber, P. Gessler, T. Lamb, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz DESY, Hamburg, Germany
	Funding: This work is partly supported by IRUVX-PP, an EU co-funded project under FP7 (Grant Agreement 211285) Presently, at FLASH four bunch arrival time monitors (BAM) are installed and in permanent operation. Moreover, they are incorporated in a longitudinal intra-bunch train feedback. In this paper, we present a review of the performance and the limitations of the current BAM design, based on the most recent machine studies. The detection principle of the monitor implements the electro-optical modulation of synchronised laser pulses. The RF and electro-optical front-ends are designed to be operated in a frequency band from DC up to 10 GHz. This allows for measuring the arrival time of each individual electron bunch at femtosecond resolution. The current design of the BAMs has been tested under the influence of disturbances on the arrival time measurement, such as variation of the bunch charge as well as deviation from the reference transverse bunch position. Those results will be incorporated in an upcoming design revision to upgrade the application and robustness of the BAMs.

TUPD35	Development of an Alternative, Photodiode-Based, Femtosecond Stable Detection Principle for the Link Stabilization in the Optical Synchronization Systems at FLASH and XFEL	laser, controls, FEL, status	380
	T. Lamb, M.K. Bock, M. Bousonville, M. Felber, P. Gessler, F. Ludwig, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz DESY, Hamburg, Germany
	Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285). The fs-stable timing information in the optical synchronization system at FLASH and the upcoming European XFEL is based on the distribution of laser pulses in optical fibers. The optical length of the fibers is continuously monitored and drifts in signal propagation time are actively compensated in order to provide a phase stable pulse train at the end of the fiber link. At present, optical cross-correlation is used to measure the optical length changes. To overcome some of the disadvantages of the current scheme, a different approach for the detection of the optical fiber link length variation was developed. This new scheme uses 10GHz photodiodes to measure the amplitude modulation of harmonics created by overlapping two pulse trains. The long-term stability of the prototype of this detector over 33h was demonstrated to be below 5fs (peak-to-peak) with a rms jitter of about 0.86fs. The detection principle itself is practically insensitive to environmental influences and needs only about 10% of the optical power, compared to the optical cross-correlator.

TUPD36	Progress and Status of the Laser-based Synchronization System at FLASH	laser, FEL, electron, status	383
	S. Schulz, M.K. Bock, M. Bousonville, M. Felber, P. Gessler, T. Lamb, F. Ludwig, S. Ruzin, H. Schlarb, B. Schmidt DESY, Hamburg, Germany
	Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285). The free-electron lasers FLASH and European XFEL demand a high timing accuracy between the electron bunches and external laser systems for both exploitation of the short VUV and X-ray pulses in time-resolved pump-probe experiments and seeded operation modes. The required precision can only be achieved with laser-based synchronization schemes. The prototype system installed at FLASH is continuously evolving and subject to improvements. In this paper, we give an overview on the present status, report on the latest developments and extensions, and discuss future challenges. Particularly, the recent move to a new type of master laser oscillator led to a significant enhancement of the robustness and reliability. Consequently, research can focus on the implementation of the electron bunch arrival time feedback, new technologies for timing distribution and integration of Ti:sapphire lasers into the optical synchronization system.

TUPD44	LHC Beam Loss Monitoring System Verification Applications	controls, monitoring, collider, survey	404
	E. Fadakis, B. Dehning, S. Jackson, C. Zamantzas CERN, Geneva, Switzerland
	The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. In addition to protecting the collider, the system also needs to provide a means of diagnosing machine faults and deliver a feedback of losses to the control room as well as to several systems for their setup and analysis. It has to transmit and process signals from almost 4’000 monitors, and has nearly 3 million configurable parameters. The system was designed with reliability and availability in mind. The specified operation and the fail-safety standards must be guaranteed for the system to perform its function in preventing superconductive magnet destruction caused by particle flux. Maintaining the expected reliability requires extensive testing and verification. In this paper we report our most recent additions to the numerous verification applications. The developments have been made using LabVIEW and CERN custom made libraries and allow the user to connect either directly to the front end computer (FEC) or through a dedicated server.

TUPD64	Test Measurements of a 20 m/s Carbon Wire Beam Scanner	vacuum, controls, simulation, acceleration	452
	M. Koujili, J. De Freitas, B. Dehning, J. Emery, J.F. Herranz Alvarez, D. Ramos, M. Sapinski CERN, Geneva, Switzerland Y. Ait Amira UFC, Besançon, France A. Djerdir UTBM, Belfort, France
	This paper presents the design of the actuator for the fast and high accuracy Wire Scanner system. The actuator consists of a rotary brush-less synchronous motor with the permanent magnet rotor installed inside the vacuum chamber and the stator installed outside. The fork, permanent magnet rotor and two angular position sensors are mounted on the same axis and located inside the beam vacuum chamber. The system has to resist a bake-out temperature of 200°C and ionizing radiation up to tenths of kGy/year. Maximum wire travelling speed of 20 m/s and a position measurement accuracy of 4 μm is required. Therefore, the system must avoid generating vibration and electromagnetic interference. A digital feedback controller will allow maximum flexibility for the loop parameters and feeds the 3-phase linear power driver. The performance of the presented design is investigated through simulations and experimental tests.

TUPD69	Operational Experience and Improvements of the LHC Beam Current Transformers	vacuum, luminosity, proton, diagnostics	467
	P. Odier, D. Belohrad, J-J. Gras, M. Ludwig CERN, Geneva, Switzerland
	During the 2010 run the LHC continuously improved its performance. In particular the bunch charge and number of bunches were significantly increased, which revealed certain limitations of the LHC beam current transformers. The DC current transformers (DCCT), used to measure the circulating beam current, exhibited saturation related to bunch intensity, the number of batches in the machine and their spacing. Two major issues were also discovered on the fast beam current transformers (FBCT) used to measure the individual bunch charges: discrepancies in the measured intensities when compared to the DCCTs measurements and a bunch length dependence on the measured intensity. Further analysis showed that both problems are linked to the beam position dependence of the signal acquired from the toroids used in the FBCTs. This paper presents the observed issues, discusses possible solutions and reports on the results from modification made for the 2011 run.

TUPD72	Advancements in the Base-Band-Tune and Chromaticity Instrumentation and Diagnostics Systems during LHC's First Year of Operation	diagnostics, synchrotron, resonance, monitoring	476
	R.J. Steinhagen, M. Gasior, S. Jackson CERN, Geneva, Switzerland
	The Base-Band-Tune (BBQ) system is an integral part of day-to-day LHC operation, used for tune and chromaticity diagnostics and feedback and giving unprecedented precision with good reliability. This contribution summarises the system's overall performance and documents the various improvements of the analogue front-end circuitry, digital post-processing and integration that were necessary in response to issues arising during high-intensity physics operation. The result of beam studies undertaken are presented, which have established a better understanding of the detection principle since its first introduction in 2005.
	Poster TUPD72 [0.794 MB]

TUPD74	The Bunch by Bunch Feedback System in J-PARC Main Ring	injection, kicker, proton, acceleration	482
	Y. Kurimoto, Y.H. Chin, T. Obina, M. Tobiyama, T. Toyama KEK, Ibaraki, Japan Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	We report the current status of the bunch by bunch feedback system for the J-PARC Main Ring. The J-PARC Main Ring is the synchrotron accelerating protons from 3 GeV to 30 GeV. It is normally operating at the intensity of 135 kW. The bunch by bunch feedback system have been developed and used for the normal operation of J-PARC Main Ring. The system aims to reduce the coherent transverse oscillation due to the instabilities or injection errors. It consists of a beam position monitor, a stripline kicker and a signal processing electronics. We've observed the injection error leading to the head-tail oscillation and succeed in damping such kind of oscillations and reducing the beam loss significantly.
	Poster TUPD74 [1.107 MB]

TUPD78	SOLEIL Beam Orbit Stability Improvements	photon, kicker, synchrotron, electron	488
	N. Hubert, L. Cassinari, J.-C. Denard, P. Lebasque, L.S. Nadolski, D. Pédeau SOLEIL, Gif-sur-Yvette, France
	SOLEIL beam orbit stability is being significantly improved. A first effort was set on long term stability for specific beamlines (new 160 m long Nanoscopium and Hard X-rays beamlines). BPM and XBPM steel supports will be replaced for reducing their sensitiveness to temperature drift. Thermal expansion of INVAR and fused Silica stands has been measured. INVAR has been selected for the new BPM supports. A second effort aimed at improving the orbit stability of beamlines based on bending magnets. We plan to use their first XBPM in the global orbit feedback loops (slow and fast). For that purpose new XBPM electronics called Libera photons will be used. Soleil, having contributed to the development, tested extensively the first series. A third effort focused on noise source location. An application developed in-house has identified localized orbit perturbation sources introducing spurious spectrum lines at 46, 50 and 54 Hz on the orbit. They originate from fans rotating close to ceramics chambers of kickers, FCT and shaker. Their suppression decreases the vertical integrated noise down to 300 nm in the DC-500Hz frequency range.

TUPD79	Preliminary Tune Feedback Study in the Taiwan Light Source	insertion, insertion-device, undulator, controls	491
	C.H. Kuo, J. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu NSRRC, Hsinchu, Taiwan
	There are many difference type insertion devices are disturbed in the storage ring of TLS. The traditional feed-forward control to correct orbit change and tune shift that isn’t enough when difference type insertion devices are operated with various condition. There is global orbit feedback to solve global orbit problem. In the tune shift, the tune feedback will be proposed to make up it for various insertion devices operation. The stable tune measurement and compensation will be discussed in this report.

TUPD81	The Petra III Multibunch Feedback System	kicker, cavity, synchrotron, impedance	494
	J. Klute, K. Balewski, A. Delfs, H.T. Duhme, M. Ebert, Ru. Neumann, F. Obier DESY, Hamburg, Germany
	In order to fulfill the demands of a high brilliance synchrotron light source like PETRA III different feedback systems are required. The high brilliance is accomplished by high beam current of 100 mA and very small transverse emittances. The current in PETRA is limited by coupled bunch instabilities to rather low values and powerful longitudinal and transverse feedback systems are necessary to achieve the design current. A careful design of the feedback is required in order to avoid any kind of beam quality degradation such as beam blow up due to noise. Additional requirements on signal processing are: very high dynamic range, adaptive signal adjustment, very high sensitivity to beam oscillations, high resolution and very high bandwidth. This contribution will describe the most important components and their properties. Results of the feedback operation will be presented and discussed. The design current of 100mA has been achieved without the indication of emittance growth and the feedback has been operated reliably during the fast user period.

Paper

Title

Other Keywords

Page

MOOA02

Beam Instrumentation for X-ray FELs

cavity, FEL, undulator, diagnostics

1

H. Loos
SLAC, Menlo Park, California, USA

Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC03-76SF00515.
The performance of X-ray Free-electron lasers depends strongly on the achieved quality of the high brightness electron beam and its shot by shot stability. The requirements and challenges of the instrumentation needed to tune and optimize such electron beams will be discussed. Of particular interest are measurements of the beam orbit, emittance, energy, and bunch length and the different measurement techniques for these transverse and longitudinal beam parameters and their implementation for routine operation will be addressed in detail, particularly the necessary instrumentation to fulfill different user requirements in terms of beam energy and bunch length. Specific requirements for the initial commissioning, routine optimization and feedback applications will be presented as well.

Slides MOOA02 [2.114 MB]

MOPD23

Photon BPM Electronics Development at Taiwan Light Source

photon, injection, controls, diagnostics

95

P.C. Chiu, J. Chen, Y.K. Chen, K.T. Hsu, K.H. Hu, C.H. Kuo
NSRRC, Hsinchu, Taiwan

Photon BPMs are very useful for photon beam position and stability observation. There are several kinds of photon BPMs and electronics with different design installed at beamline front-ends at the Taiwan Light Source. To provide a better integration and efficient usage of the photon BPM, a commercial BPM electronics - Libera Photon was chosen for an integral solution and has showed at least one micron performance for several months of testing. In this report, the installation process and testing results of the photon BPM will be presented.

Poster MOPD23 [0.595 MB]

MOPD24

A High-resolution Diode-based Orbit Measurement System – Prototype Results from the LHC

pick-up, vacuum, injection, coupling

98

M. Gasior, J. Olexa, R.J. Steinhagen
CERN, Geneva, Switzerland

The prototype of a high resolution beam position monitor (BPM) electronics based on diode peak detectors was tested with LHC beams. In this technique developed at CERN the short beam pulses from each BPM electrode are converted into slowly varying signals by compensated diode peak detectors. The slow signals can be digitised with a laboratory voltmeter or high resolution ADC. As presented in the paper, this technique allows resolutions in the order of 1 ppm of the BPM aperture to be achieved with a measurement rate in the Hz range. Ongoing developments and future prospects for the technique are also discussed.

Poster MOPD24 [2.055 MB]

MOPD26

Testing of New Hadron Beam Phase and Position Monitor at CIEMAT Laboratory

instrumentation, controls, pick-up, monitoring

104

M. Znidarcic, B.B. Baricevic, R. Hrovatin
I-Tech, Solkan, Slovenia
J.M. Carmona, A. Ibarra, I. Podadera
CIEMAT, Madrid, Spain

The Libera Single Pass H is the new instrumentation intended for phase, position and charge monitoring in hadron and heavy ion LINACs and transfer lines. Initial measurements and verification of the instrumentation performance were conducted in the laboratory at Instrumentation Technologies. Characterization measurements of the same electronics were later carried out at CIEMAT laboratory. The measurements were performed on a CIEMAT wire test bench with the 175 MHz pulsed signal connected to the wire. Different measurements were performed on the test bench; First, by moving the wire over larger displacements and checking the position and, later, by changing the signal phase and performing the phase shift measurement. This article discusses the new Libera Single Pass H electronics, the tests carried out in the test bench and the performance obtained.

MOPD38

1-MHz Line Detector for Intra-bunch-train Multichannel Feedback

laser, radiation, electron, diagnostics

137

L. Kotynia, D.R. Makowski, A. Mielczarek, A. Napieralski
TUL-DMCS, Łódź, Poland
C. Gerth, T. Jezynski, H. Schlarb, B. Schmidt, B. Steffen
DESY, Hamburg, Germany

Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285).
The measurement and control of the electron bunch length is one of the key diagnostics in linac-based free-electron lasers to reach the required peak current in the electron bunches. In order to use the multi-channel signals from longitudinal bunch shape measurements for intra train feedback for the European XFEL, line readout rates in the MHz range and low latencies are required, which is far more than commercial multichannel radiation detectors (line cameras) can provide. The paper presents a 256 channel detector that allows analyzing optical or infrared radiation with 1 MHz rate and a few microseconds latency using photodiode arrays, as needed for synchrotron light monitors, electro-optical bunch length measurements, or other laser based diagnostics. The proposed architecture aims at high frequency readout with low latency by using a multichannel electronic front-end designed for HEP, combined with Si or InGaAs detector arrays with very fast response time, and a low-latency data acquisition system. Currently the device is at the conceptual design stage.

Poster MOPD38 [3.262 MB]

MOPD73

Study of Beam Size Blowup due to Transverse Bunch Feedback Noise on e⁺e⁻ Collider

luminosity, simulation, beam-beam-effects, injection

212

M. Tobiyama, K. Ohmi
KEK, Ibaraki, Japan

Vertical beam size blowup with the gain of the transverse bunch feedback systems has been observed in KEKB B-factory rings. With the numerical simulation, large beam-beam effect enhances small oscillation induced by the broadband noise of the bunch feedback kick. To examine the simulation, beam response, effective beam size and the luminosity change with artificial external noise injected in the transverse feedback system have beem measuredn in KEKB LER ring during collision. The result has been compaired with the simulation including beam-beam effect and showed good agreement.

Poster MOPD73 [0.296 MB]

MOPD74

The New Fast Orbit Correction System of the ESRF Storage Ring

storage-ring, power-supply, insertion, damping

215

E. Plouviez, F. Epaud, J.M. Koch, K.B. Scheidt
ESRF, Grenoble, France

The ESRF is upgrading the orbit correction system of its storage ring. The goal of this upgrade is to damp the effect on the orbit stability of the insertion devices during the changes of their settings, as well as the effect of the environmental vibrations and AC main power spurious fields; in order to achieve this goal we aim at a correction bandwith of 200Hz. The final system will use the data of 224 BPMs already equipped with Libera brilliance electronics. The correction will be applied by a set of 96 correctors implemented in the auxillary legs of the sextupolar magnets, driven by newly designed fast power supplies . The power supplies are controlled using a set of 8 FPGA boards connected to the power supplies inputs with serial links; these FPGA will also compute the correctors currents using the BPMs data. All the correctors and BPMs are now installed and interconnected and we have already performed orbit correction tests over 2 of the 32 cells of our storage ring using one single FPGA board controlling 6 correctors. These tests have allowed us to evaluate the final performance of the system. This paper presents this new system and the results of these tests.

MOPD76

The Petra III Fast Orbit Feedback System

instrumentation, controls, injection, brilliance

221

J. Klute, K. Balewski, H.T. Duhme, H. Tiessen, F. Wierzcholek
DESY, Hamburg, Germany

Orbit stability is a crucial and import issue of 3rd generation light sources. Ambient mechanical and electrical noise cause rather large orbit distortions which have to be counteracted by an orbit feedback. Extensive studies of the orbit distortions in PETRA III have shown that the frequencies of the ambient noise lie within a frequency range from about 0.01Hz to 100Hz. In this paper we describe the main components, their properties and the layout of PETRA III’s orbit feedback. Furthermore experimental results on short and long term stability will be presented. It will be shown that the required orbit stability of ±0.5 μm in the vertical plane can be maintained over 50 h.

MOPD77

Broadband Digital Feedback System for the VEPP-4M Electron-Positron Collider

kicker, electron, betatron, positron

224

V.V. Oreshonok, V.V. Smaluk
BINP SB RAS, Novosibirsk, Russia
V.P. Cherepanov, V.V. Oreshonok, D.P. Sukhanov
NSU, Novosibirsk, Russia

To suppress the transverse instability, which is the main reason of beam current limitation at the VEPP-4M electron-positron collider, a digital bunch-by-bunch feedback system has been developed, installed and commissioned. The real-time data processing is performed by a special code running in an FPGA module. This provides high efficiency and flexibility of the system. During the system commissioning, a 3-times increase of the beam current injected into VEPP-4M was reached. The system design and data processing algorithms are described, the commissioning results are presented.

MOPD78

Synchronous Measurement of Stability of Electron Beam, X-ray Beam, Ground and Cavity Voltage

cavity, electron, photon, controls

227

G. Rehm, M.G. Abbott, C. Bloomer, I. Uzun
Diamond, Oxfordshire, United Kingdom

We have developed hardware and software that allows continuous and synchronous recording of electron and X-Ray beam position as well as cavity voltage and ground vibrations at a rate of about 10kS/s for periods of many days. To this end, additional nodes have been added to our existing fast network that feeds the Fast Orbit Feedback System, namely tungsten vane type front end XBPMs, RF cavity pickups and accelerometers. The synchronous nature of these measurements shows the correlation between electron beam motion through an insertion device and observed X-ray beam motion in the frontend or orbit distortions caused by fluctuations of the RF cavity voltage. While the additional channels currently are only observed, the potential of including these in the fast orbit feedback will be discussed.

MOPD79

An FPGA-based Turn-by-Turn Beam Position Monitoring System for Studying Multiple Bunch Beams in the ATF Damping Ring

injection, extraction, damping, synchrotron

230

G.B. Christian, D.R. Bett, B. Constance, M.R. Davis
JAI, Oxford, United Kingdom
R. Apsimon, P. Burrows, A. Gerbershagen, C. Perry
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

Instabilities associated with beam-size blow-up have previously been observed with multi-bunch beam in the damping ring (DR) of the KEK Accelerator Test Facility (ATF). A system has been developed to monitor such instabilities, utilising an ATF stripline beam position monitor (BPM) in the DR, and BPM processor hardware designed for the FONT upstream feedback system in the ATF extraction line. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR in single-bunch multi-train mode or the head bunch of up to three trains in multi-bunch mode, with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software were modified to record turn-by-turn data for up to six channels and 1–3 bunches in the DR. The maximum memory configuration on the FPGA allows 131071 bunch-turn-channels of data to be recorded from a particular machine pulse, and the system has the capability to select only certain turns at a regular interval in which to record data, in order to zoom out and cover the entire period of the damping cycle at the ATF. An overview of the system and initial results will be presented.

MOPD80

An FPGA-based Bunch-by-Bunch Position and Angle Feedback System at ATF2

kicker, extraction, linear-collider, collider

233

G.B. Christian, R. Apsimon, D.R. Bett, B. Constance, M.R. Davis
JAI, Oxford, United Kingdom
P. Burrows, C. Perry
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
A. Gerbershagen
CERN, Geneva, Switzerland
J. Resta-López
IFIC, Valencia, Spain

The FONT5 intra-train feedback system serves as a prototype for an interaction point beam-based feedback system for future electron-positron colliders, such as the International Linear Collider. The system has been tested on the KEK Accelerator Test Facility (ATF) and is deployed to stabilise the beam orbit at the ATF2. The goal of this system is to correct both position and angle jitter in the vertical plane, providing stability of ~1 micron at the entrance to the ATF2 final-focus system. The system comprises three stripline beam position monitors (BPMs) and two stripline kickers, custom low-latency analogue front-end BPM processors, a custom FPGA-based digital processing board with fast ADCs, and custom kicker-drive amplifiers. An overview of the hardware, and the latest results from beam tests at ATF2, will be presented. The total latency of the system with coupled position and angle feedback loops operating simultaneously was measured to be approximately 140 ns. The greatest degree of correction observed was down to a jitter of 0.4 microns at one of the feedback BPMs, a factor of six compared to the uncorrected beam jitter, for a very high degree of bunch-to-bunch correlation.

MOPD87

The LHC Beam Presence Flag System

controls, injection, impedance, monitoring

251

M. Gasior, T.B. Bogey
CERN, Geneva, Switzerland

Before injecting any high intensity bunches into the LHC a circulating low intensity pilot bunch must be present to confirm the correct settings of the main machine parameters. For the 2010 LHC run the detection of this pilot beam was done with the beam current transformer system. To increase redundancy of this important safety function a dedicated beam presence flag system was designed, built and tested with beam to be used operationally in the 2011 run. In this system signals from four electrodes of a beam position monitor (BPM) are processed with separate channels, resulting in a quadruple system redundancy for either beam. Each system channel consists of an analogue front-end converting the BPM signals into two logic states, which are then transmitted optically to the machine protection and interlock systems. For safety reasons the system does not have any remote control or adjustable elements and its only inputs are the beam signals. This paper describes the new LHC beam presence flag system, in particular the analogue front-end based on diode peak detectors.

Poster MOPD87 [8.200 MB]

TUOA01

Beam Instrumentation in J-PARC

linac, impedance, proton, septum

275

T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

The talk will summarize the beam instrumentation at J-PARC with a focus on MW class proton beams. The measurements of beam intensities, positions, losses, profiles, and halos at each stage of accelerator, 181 MeV LINAC (to be upgraded to 400MeV), 3 GeV RCS and 50 (30 as phase I) GeV MR will be reported. Present status, including modification and improvement of instrumentations to meet with LINAC energy upgrade and a future plan will be reported with emphasis on high beam power related issues such as radiation hardness (mechanically and electrically), beam coupling impedance, etc..

Slides TUOA01 [22.777 MB]

TUOB03

Next Generation Electronics based on μTCA for Beam-Diagnostics at FLASH and XFEL

diagnostics, controls, laser, low-level-rf

294

P. Gessler, M.K. Bock, M. Bousonville, M. Felber, M. Hoffmann, T. Jezynski, T. Lamb, F. Ludwig, G. Petrosyan, L.M. Petrosyan, K. Rehlich, S. Schulz, P. Vetrov, M. Zimmer
DESY, Hamburg, Germany
C. Bohm, A. Hidvégi
Stockholm University, Stockholm, Sweden
K. Czuba
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
D.R. Makowski
TUL-DMCS, Łódź, Poland

Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285).
Almost all accelerator-related diagnostic and steering systems require front-end electronic hardware and software for digitizing, synchronization, processing, controlling, and providing access to the control system. Increasingly high demands on resolution, bandwidth, stability, redundancy, low latency, real-time processing and distribution create the need for new technologies in order to fulfill those demands. For this reason, at the European XFEL and FLASH, the new, μTCA industry standard will be deployed. Over the last few years, significant achievements have been made in μTCA developments in collaboration with other research institutes and industry. In this paper, we give an overview of the required components of a typical μTCA system for diagnostics applications. The FLASH bunch arrival-time monitor will be used as an example.

Slides TUOB03 [9.075 MB]

TUPD12

The LHC Beam Position System: Performance during 2010 and Outlook for 2011

pick-up, closed-orbit, injection, vacuum

323

E. Calvo Giraldo, J.L. Gonzalez, L.K. Jensen, O.R. Jones, T. Lefèvre, J.-J. Savioz, R.J. Steinhagen, J. Wenninger
CERN, Geneva, Switzerland

This paper presents the performance of the LHC Beam Position System during 2010. The system proved to meet most specifications, was highly reliable and continuously provided 25Hz real-time orbit data with micron level resolution to the automatic global orbit feedback system. However, several issues were observed and they will be discussed in detail, such as the dependence on bunch intensity and the effect of surface electronics temperature variations on the measured position.

TUPD21

Frontend Measurements and Optimizations at Libera Brilliance BPM Electronics during Commissioning of the Petra III Synchrotron Light Source

brilliance, controls, instrumentation, synchrotron

350

F. Schmidt-Föhre, G. Kube, J.M. Maass, K. Wittenburg
DESY, Hamburg, Germany

New 3rd generation synchrotron light sources like Petra III utilize high-accuracy beam position measurement (BPM) systems to achieve the desired precision for beam position measurement and control, as needed for electron/positron beam stability and brilliance of the delivered photon beam. To reach the design goals, specifically adapted and parameterized commercial-of-the-shelf (COTS) Libera Brilliance BPM processor electronics are used within the Petra III BPM system. Quality of the acquired position measurement and orbit control data is highly dependent on the properties and setup of the analog and digital frontend of such BPM electronics. This paper shows influences and optimizations at the BPM system frontend of the Petra III light-source in reference to corresponding measurements done during the accelerator commissioning phase.

TUPD23

New Bunch-by-Bunch Feedback System for the TLS

controls, diagnostics, EPICS, kicker

353

C.H. Kuo, Y.K. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu
NSRRC, Hsinchu, Taiwan

FPGA based bunch-by-bunch feedback systems were deployed in 2005-2006 by using SPring-8 designed feedback processors for the Taiwan Light Source. To provide spare units and explore integrate with the control system in the EPICS toolkit environment, feedback processors from the Dimtel were setup. The new system can be swap with the existed system by simple cable re-connection and integrated with the EPICS system in seamless way. Rich functionality except the basic feedback function includes excitation of individual bunch or specifies bunches, averaged spectrum, tune measurement by the feedback dip in the averaged spectrum, fill pattern measurement, etc. are explorer. Current stage implementation and features of the system will summary in this report.

TUPD28

Benchmarking the Performance of the Present Bunch Arrival Time Monitors at FLASH

pick-up, FEL, laser, electron

365

M.K. Bock, M. Bousonville, M. Felber, P. Gessler, T. Lamb, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz
DESY, Hamburg, Germany

Funding: This work is partly supported by IRUVX-PP, an EU co-funded project under FP7 (Grant Agreement 211285)
Presently, at FLASH four bunch arrival time monitors (BAM) are installed and in permanent operation. Moreover, they are incorporated in a longitudinal intra-bunch train feedback. In this paper, we present a review of the performance and the limitations of the current BAM design, based on the most recent machine studies. The detection principle of the monitor implements the electro-optical modulation of synchronised laser pulses. The RF and electro-optical front-ends are designed to be operated in a frequency band from DC up to 10 GHz. This allows for measuring the arrival time of each individual electron bunch at femtosecond resolution. The current design of the BAMs has been tested under the influence of disturbances on the arrival time measurement, such as variation of the bunch charge as well as deviation from the reference transverse bunch position. Those results will be incorporated in an upcoming design revision to upgrade the application and robustness of the BAMs.

TUPD35

Development of an Alternative, Photodiode-Based, Femtosecond Stable Detection Principle for the Link Stabilization in the Optical Synchronization Systems at FLASH and XFEL

laser, controls, FEL, status

380

T. Lamb, M.K. Bock, M. Bousonville, M. Felber, P. Gessler, F. Ludwig, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz
DESY, Hamburg, Germany

Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285).
The fs-stable timing information in the optical synchronization system at FLASH and the upcoming European XFEL is based on the distribution of laser pulses in optical fibers. The optical length of the fibers is continuously monitored and drifts in signal propagation time are actively compensated in order to provide a phase stable pulse train at the end of the fiber link. At present, optical cross-correlation is used to measure the optical length changes. To overcome some of the disadvantages of the current scheme, a different approach for the detection of the optical fiber link length variation was developed. This new scheme uses 10GHz photodiodes to measure the amplitude modulation of harmonics created by overlapping two pulse trains. The long-term stability of the prototype of this detector over 33h was demonstrated to be below 5fs (peak-to-peak) with a rms jitter of about 0.86fs. The detection principle itself is practically insensitive to environmental influences and needs only about 10% of the optical power, compared to the optical cross-correlator.

TUPD36

Progress and Status of the Laser-based Synchronization System at FLASH

laser, FEL, electron, status

383

S. Schulz, M.K. Bock, M. Bousonville, M. Felber, P. Gessler, T. Lamb, F. Ludwig, S. Ruzin, H. Schlarb, B. Schmidt
DESY, Hamburg, Germany

Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285).
The free-electron lasers FLASH and European XFEL demand a high timing accuracy between the electron bunches and external laser systems for both exploitation of the short VUV and X-ray pulses in time-resolved pump-probe experiments and seeded operation modes. The required precision can only be achieved with laser-based synchronization schemes. The prototype system installed at FLASH is continuously evolving and subject to improvements. In this paper, we give an overview on the present status, report on the latest developments and extensions, and discuss future challenges. Particularly, the recent move to a new type of master laser oscillator led to a significant enhancement of the robustness and reliability. Consequently, research can focus on the implementation of the electron bunch arrival time feedback, new technologies for timing distribution and integration of Ti:sapphire lasers into the optical synchronization system.

TUPD44

LHC Beam Loss Monitoring System Verification Applications

controls, monitoring, collider, survey

404

E. Fadakis, B. Dehning, S. Jackson, C. Zamantzas
CERN, Geneva, Switzerland

The LHC Beam Loss Monitoring (BLM) system is one of the most complex instrumentation systems deployed in the LHC. In addition to protecting the collider, the system also needs to provide a means of diagnosing machine faults and deliver a feedback of losses to the control room as well as to several systems for their setup and analysis. It has to transmit and process signals from almost 4’000 monitors, and has nearly 3 million configurable parameters. The system was designed with reliability and availability in mind. The specified operation and the fail-safety standards must be guaranteed for the system to perform its function in preventing superconductive magnet destruction caused by particle flux. Maintaining the expected reliability requires extensive testing and verification. In this paper we report our most recent additions to the numerous verification applications. The developments have been made using LabVIEW and CERN custom made libraries and allow the user to connect either directly to the front end computer (FEC) or through a dedicated server.

TUPD64

Test Measurements of a 20 m/s Carbon Wire Beam Scanner

vacuum, controls, simulation, acceleration

452

M. Koujili, J. De Freitas, B. Dehning, J. Emery, J.F. Herranz Alvarez, D. Ramos, M. Sapinski
CERN, Geneva, Switzerland
Y. Ait Amira
UFC, Besançon, France
A. Djerdir
UTBM, Belfort, France

This paper presents the design of the actuator for the fast and high accuracy Wire Scanner system. The actuator consists of a rotary brush-less synchronous motor with the permanent magnet rotor installed inside the vacuum chamber and the stator installed outside. The fork, permanent magnet rotor and two angular position sensors are mounted on the same axis and located inside the beam vacuum chamber. The system has to resist a bake-out temperature of 200°C and ionizing radiation up to tenths of kGy/year. Maximum wire travelling speed of 20 m/s and a position measurement accuracy of 4 μm is required. Therefore, the system must avoid generating vibration and electromagnetic interference. A digital feedback controller will allow maximum flexibility for the loop parameters and feeds the 3-phase linear power driver. The performance of the presented design is investigated through simulations and experimental tests.

TUPD69

Operational Experience and Improvements of the LHC Beam Current Transformers

vacuum, luminosity, proton, diagnostics

467

P. Odier, D. Belohrad, J-J. Gras, M. Ludwig
CERN, Geneva, Switzerland

During the 2010 run the LHC continuously improved its performance. In particular the bunch charge and number of bunches were significantly increased, which revealed certain limitations of the LHC beam current transformers. The DC current transformers (DCCT), used to measure the circulating beam current, exhibited saturation related to bunch intensity, the number of batches in the machine and their spacing. Two major issues were also discovered on the fast beam current transformers (FBCT) used to measure the individual bunch charges: discrepancies in the measured intensities when compared to the DCCTs measurements and a bunch length dependence on the measured intensity. Further analysis showed that both problems are linked to the beam position dependence of the signal acquired from the toroids used in the FBCTs. This paper presents the observed issues, discusses possible solutions and reports on the results from modification made for the 2011 run.

TUPD72

Advancements in the Base-Band-Tune and Chromaticity Instrumentation and Diagnostics Systems during LHC's First Year of Operation

diagnostics, synchrotron, resonance, monitoring

476

R.J. Steinhagen, M. Gasior, S. Jackson
CERN, Geneva, Switzerland

The Base-Band-Tune (BBQ) system is an integral part of day-to-day LHC operation, used for tune and chromaticity diagnostics and feedback and giving unprecedented precision with good reliability. This contribution summarises the system's overall performance and documents the various improvements of the analogue front-end circuitry, digital post-processing and integration that were necessary in response to issues arising during high-intensity physics operation. The result of beam studies undertaken are presented, which have established a better understanding of the detection principle since its first introduction in 2005.

Poster TUPD72 [0.794 MB]

TUPD74

The Bunch by Bunch Feedback System in J-PARC Main Ring

injection, kicker, proton, acceleration

482

Y. Kurimoto, Y.H. Chin, T. Obina, M. Tobiyama, T. Toyama
KEK, Ibaraki, Japan
Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

We report the current status of the bunch by bunch feedback system for the J-PARC Main Ring. The J-PARC Main Ring is the synchrotron accelerating protons from 3 GeV to 30 GeV. It is normally operating at the intensity of 135 kW. The bunch by bunch feedback system have been developed and used for the normal operation of J-PARC Main Ring. The system aims to reduce the coherent transverse oscillation due to the instabilities or injection errors. It consists of a beam position monitor, a stripline kicker and a signal processing electronics. We've observed the injection error leading to the head-tail oscillation and succeed in damping such kind of oscillations and reducing the beam loss significantly.

Poster TUPD74 [1.107 MB]

TUPD78

SOLEIL Beam Orbit Stability Improvements

photon, kicker, synchrotron, electron

488

N. Hubert, L. Cassinari, J.-C. Denard, P. Lebasque, L.S. Nadolski, D. Pédeau
SOLEIL, Gif-sur-Yvette, France

SOLEIL beam orbit stability is being significantly improved. A first effort was set on long term stability for specific beamlines (new 160 m long Nanoscopium and Hard X-rays beamlines). BPM and XBPM steel supports will be replaced for reducing their sensitiveness to temperature drift. Thermal expansion of INVAR and fused Silica stands has been measured. INVAR has been selected for the new BPM supports. A second effort aimed at improving the orbit stability of beamlines based on bending magnets. We plan to use their first XBPM in the global orbit feedback loops (slow and fast). For that purpose new XBPM electronics called Libera photons will be used. Soleil, having contributed to the development, tested extensively the first series. A third effort focused on noise source location. An application developed in-house has identified localized orbit perturbation sources introducing spurious spectrum lines at 46, 50 and 54 Hz on the orbit. They originate from fans rotating close to ceramics chambers of kickers, FCT and shaker. Their suppression decreases the vertical integrated noise down to 300 nm in the DC-500Hz frequency range.

TUPD79

Preliminary Tune Feedback Study in the Taiwan Light Source

insertion, insertion-device, undulator, controls

491

C.H. Kuo, J. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu
NSRRC, Hsinchu, Taiwan

There are many difference type insertion devices are disturbed in the storage ring of TLS. The traditional feed-forward control to correct orbit change and tune shift that isn’t enough when difference type insertion devices are operated with various condition. There is global orbit feedback to solve global orbit problem. In the tune shift, the tune feedback will be proposed to make up it for various insertion devices operation. The stable tune measurement and compensation will be discussed in this report.

TUPD81

The Petra III Multibunch Feedback System

kicker, cavity, synchrotron, impedance

494

J. Klute, K. Balewski, A. Delfs, H.T. Duhme, M. Ebert, Ru. Neumann, F. Obier
DESY, Hamburg, Germany

In order to fulfill the demands of a high brilliance synchrotron light source like PETRA III different feedback systems are required. The high brilliance is accomplished by high beam current of 100 mA and very small transverse emittances. The current in PETRA is limited by coupled bunch instabilities to rather low values and powerful longitudinal and transverse feedback systems are necessary to achieve the design current. A careful design of the feedback is required in order to avoid any kind of beam quality degradation such as beam blow up due to noise. Additional requirements on signal processing are: very high dynamic range, adaptive signal adjustment, very high sensitivity to beam oscillations, high resolution and very high bandwidth. This contribution will describe the most important components and their properties. Results of the feedback operation will be presented and discussed. The design current of 100mA has been achieved without the indication of emittance growth and the feedback has been operated reliably during the fast user period.