DIPAC2011 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOOA02	Beam Instrumentation for X-ray FELs	FEL, feedback, 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]

MOOB04	Bunch Compression, RF Curvature Correction and R₅₅, T₅₅₅ and U₅₅₅₅ Measurements at JLab FEL	FEL, linac, SRF, sextupole	15
	P. Evtushenko, S.V. Benson, D. Douglas JLAB, Newport News, Virginia, USA
	The JLab IR/UV FEL Upgrade operates with the bunch length compressed down to 100-150 fs RMS. An indispensible part of the bunch compression scheme is the correction of the so-called LINAC RF curvature. Unlike other systems – where the RF curvature gets corrected using higher a harmonic LINAC – our system utilizes magnetic elements of the beam transport system to correct and adjust the second and third order correlation terms. These are expressed in terms of the transport matrix elements T₅₆₆ and U₅₆₆₆. The linear correlation term described by M₅₅ is adjusted using the magnetic system as well. The large energy spread induced on the beam by the FEL operation is compressed as a part of the energy recovery process. As in the case of bunch length compression, this energy compression is optimized by properly adjusting high order transport matrix elements. In this contribution we describe the system used for direct measurements of the transport matrix elements M₅₅, T₅₆₆ and U₅₆₆₆ and its impact on the operation and bunch compression. Results of the measurements are presented together with the bunch length measurements including the data showing resolution and accuracy of the system.
	Slides MOOB04 [0.999 MB]

MOOC01	Overview of Recent Trends and Developments for BPM Systems	pick-up, coupling, monitoring, linac	18
	M. Wendt Fermilab, Batavia, USA
	Beam position monitoring (BPM) systems are the workhorse beam diagnostics for almost any kind of charged particle accelerator; linear, circular or transport-lines, operating with leptons, hadrons or heavy ions. The BPMs are essential for beam commissioning, accelerator fault analysis and trouble shooting, machine optics and lattice measurements, and finally for the accelerator optimization to achieve the ultimate beam quality. This presentation summarizes the efforts of the beam instrumentation community on recent developments and advances on BPM technologies, i.e. BPM pickup monitors and front-end electronics (analog and digital). Principles, examples, and state-of-the-art status on various BPM techniques are outlined, serving hadron and heavy ion machines, sync light synchrotron's, as well as electron linacs for FEL or HEP applications.
	Slides MOOC01 [4.123 MB]

MOOC02	Cavity BPM System for ATF2	monitoring, quadrupole, EPICS, extraction	23
	A. Lyapin, R. Ainsworth, S.T. Boogert, G.E. Boorman, F.J. Cullinan, N.Y. Joshi JAI, Egham, Surrey, United Kingdom A.S. Aryshev, Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan J.C. Frisch, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White SLAC, Menlo Park, California, USA A. Heo, E.-S. Kim, H.-S. Kim, Y.I. Kim KNU, Deagu, Republic of Korea M.C. Ross Fermilab, Batavia, USA
	In this paper we summarise our 2-year experience operating the Cavity Beam Position Monitor (CBPM) system at the Accelerator Test Facility (ATF) in KEK. The system currently consists of 41 C and S-band CBPMs and is the main diagnostic tool for the new ATF2 extraction beamline. We concentrate on issues related to the scale of the system and also consider long-term effects, most of which are undetectable or insignificant in smaller experimental prototype systems. We consistently show sub-micron BPM resolutions and week-to-week scale drifts of an order of 1%.
	Slides MOOC02 [2.075 MB]

MOOC03	The Fermi@Elettra Cavity BPM System: Description and Commissioning Results	pick-up, controls, FEL, undulator	26
	M. Ferianis, A.O. Borga, P. Craievich, R. De Monte, G. Gaio, M. Predonzani ELETTRA, Basovizza, Italy M. Dal Forno DIEIT, Trieste, Italy
	The Fermi@elettra cavity BPM (C-BPM) system is based on an original implementation of the C-BPM scheme as the pick-up, operating at 6.5GHz, is coupled to a dedicated, self-calibrating electronics based on a novel concept. The system has been developed in-house; both the E-M and the mechanical design of the pick-up have been carried out, including an original frequency tuning scheme. The detector electronics directly obtains the envelope of the sum and difference signals by means of an RF 180° hybrid; no mixer for the RF signal down conversion is used. The detector is based on 3 blocks: an RF front-end, a baseband analogue transmission module and a digital back-end unit, based on a micro-TCA platform. The digital back-end is equipped with a powerful Virtex 5 FPGA and several real-time tasks have been implemented on it, including intra-pulse calibration. Ten C-BPM stations have been installed so far, fully integrated in the FERMI control System, enabling a real-time control of this key FEL diagnostics. Results on performances with beam are also presented; the scale factor of C-BPMs is obtained with beam, as two-axis micrometer translation stages have been installed.
	Slides MOOC03 [2.733 MB]

MOPD13	Mode Selective Waveguide BPM	coupling, pick-up, simulation, impedance	65
	A. Lyapin JAI, Egham, Surrey, United Kingdom
	I propose a mode-selective waveguide Beam Position Monitor (BPM). It uses waveguide couplers arranged at the beampipe to create boundary conditions similar to those in slot-coupled cavity BPMs. This structure allows to couple to the differential waveguide mode co-propagating with the beam, and reject the usually much stronger monopole component of the field. As the full dynamic range of the processing electronics can be used for position measurements, and a waveguide is a native high-pass filter, such a BPM is expected to outperform stripline and button BPMs in terms of both spacial and time resolution. In this paper I give some details on the basic principle and the first simulation results and discuss possible ways of signal processing.
	Poster MOPD13 [3.052 MB]

MOPD17	Beam-based HOM Study in Third Harmonic SC Cavities for Beam Alignment at FLASH	HOM, dipole, electron, polarization	77
	P. Zhang, R.M. Jones, I.R.R. Shinton UMAN, Manchester, United Kingdom N. Baboi, B. Lorbeer, P. Zhang DESY, Hamburg, Germany H. Ecklebe, T. Flisgen, H.-W. Glock Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by European Commission under the FP7 Research Infrastructures grant agreement No.227579. An electron beam entering an accelerator cavity excites higher order modes (HOM). These are radiated to HOM couplers, subsequently damped, and can also be used to facilitate beam monitoring. The modes which deflect the beam transversely are the focus of this study and are used to monitor the beam position. Results are presented on the first analysis of beam alignment based on HOM signals from the third harmonic cavities at FLASH. The electrical center of each mode is ascertained by moving the beam to minimize the HOM signal detected. A single electron bunch per RF pulse is used.

MOPD19	Button BPM Development for the European XFEL	simulation, vacuum, cryogenics, linac	83
	D. Lipka, B. Lorbeer, D. Nölle, M. Siemens, S. Vilcins DESY, Hamburg, Germany
	Button beam position monitors will be the main BPM type used to measure the electron beam position at the European XFEL. Two different kinds of buttons are necessary: one type will be installed in the acceleration modules of the cold linac and the other in the warm environment. The electro-magnetic design of the feedthrough for both types of buttons will be discussed. A comparison of the designed and measured RF properties will be presented. In addition to the usual RF properties, also the properties at cryogenic level will play a role. HOM power must not heat up the BPM feedthroughs, in order to keep the cryo load of an overall accelerator module low, and also to prevent damage due to large temperature gradients over the ceramics of the feedthrough. First measurements with beam at FLASH show good agreement of the measured signals with the expectation.

MOPD25	Diode Down-mixing of HOM Coupler Signals for Beam Position Determination in 1.3-GHz- and 3.9-GHz-Cavities at FLASH	HOM, polarization, dipole, coupling	101
	H.-W. Glock, H. Ecklebe, T. Flisgen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany N. Baboi, P. Zhang DESY, Hamburg, Germany
	Funding: work supported by BMBF under contract 05K10HRC and by European Commission under the FP7 Research Infrastructures grant agreement No.227579 Beam excited signals available at the HOM coupler ports of superconducting accelerating cavities cover a wide frequency range and carry information about (amongst others) transverse beam position. Down-mixing these signals using detector diodes is a mean to measure with standard and non-specific oscilloscope technology the time dependency of the power leaving the HOM coupler. Experiments undertaken at the accelerator modules ACC1 and ACC39 at FLASH demonstrated the possibility to extract beam position data out of low-frequency signals sampled with such a setup. These experiments as part of an ongoing study are described together with mathematical details of the evaluation scheme.

MOPD28	Loss Factor Measurement using Time Correlated Single Photon Counting of Synchrotron Radiation	photon, storage-ring, synchrotron, vacuum	110
	G. Rehm, C. Bloomer, C.A. Thomas Diamond, Oxfordshire, United Kingdom
	A method to derive the total loss factor from the variation of SR photon arrival times with bunch charge has been developed. A time correlated single photon counting system is used operationally for fill pattern and bunch purity measurements. By fitting the individual peaks in the photon arrival time histogram, their relative timing can be retrieved with ps resolution and reproducibility. For a measurement of the loss factor, a fill pattern comprising a range of different bunch charges is stored and then their timing relative to the RF buckets is charted against charge. Examples of measurements illustrate the variation of loss factor with RF voltage and change in Insertion Device gap.

MOPD32	Bunch Length Measurement from Power Fluctuation at Diamond	synchrotron, radiation, synchrotron-radiation, lattice	119
	C.A. Thomas, I.P.S. Martin, G. Rehm Diamond, Oxfordshire, United Kingdom
	Bunch length can be measured using the visible light power fluctuation statistics of an individual bunch. This method developed at ALS has been implemented at Diamond with further improvement on the detection method and the speed of the measurement. In this paper, we firstly report on the development and implementation of the method. We will show the performance of several detector diodes used and the limits of the method. Validation of the method will be demonstrated against streak camera measurement with picosecond long bunches. Before concluding, we will discuss about the strengths and weaknesses of the method.

MOPD36	Development of a Silicon Detector Monitor for the Superconducting Upgrade of the REX-ISOLDE Heavy-Ion Linac at CERN	linac, ion, diagnostics, rfq	131
	F. Zocca IEM, Madrid, Spain E. Bravin, M.A. Fraser, D. Voulot, F.J.C. Wenander, F. Zocca CERN, Geneva, Switzerland M. Pasini Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Leuven, Belgium
	A silicon detector monitor has been developed and tested in the frame of the beam diagnostics development program for the HIE-ISOLDE superconducting upgrade of the REX-ISOLDE heavy-ion linac at CERN. The monitor is intended for beam energy and timing measurements as well as for phase scanning of the superconducting cavities. Tests have been performed with a stable ion beam, composed of carbon, oxygen and neon ions accelerated to energies from 300 keV/u to 2.85 MeV/u. The silicon detector was placed directly in the beam line and tested with a beam which was strongly attenuated to simulate the single particle detection regime for which the monitor is intended to finally function. The energy measurements performed allowed for beam spectroscopy and ion identification with a resolution of 3%. The principle of cavity phase scanning was also demonstrated with the REX 7-gap resonator thanks to the accurate peak energy identification. The time structure of the beam, characterized by a bunch period of 9.87 ns, was measured with a resolution better than 200 ps. This paper describes the results from all these tests as well as providing details of the detector.

MOPD64	High Quality Measurements of Beam Lifetime, Instant-Partial-Beam Losses and Charge-Accumulation with the New ESRF BPM System	injection, beam-losses, storage-ring, controls	194
	K.B. Scheidt, F. Ewald, B. Joly ESRF, Grenoble, France
	The BPM system of the ESRF Storage Ring, that was entirely replaced by 224 units of the Libera-Brilliance system in 2009, is now also being used for precise and fast measurements of the Beam Lifetime and so-called Instant-Partial-BeamLosses. This is possible by the use of the Sum signal of the four BPM buttons on each of the 224 BPM stations in the Ring. This paper will describe the strong advantages in terms of response time, but also the precautions and the limitations of this particular use. Results will show the ultimate attainable performances and a detailed comparison with that of three independent DC current transformers also installed in the Ring. The same Sum signal is also usable for precise measurement of Accumulated Charge during the injection process and results of this will also be presented.

MOPD78	Synchronous Measurement of Stability of Electron Beam, X-ray Beam, Ground and Cavity Voltage	electron, feedback, 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.

TUPD07	Instrumentation Needs and Solutions for the Development of an SRF Photoelectron Injector at the Energy-Recovery Linac BERLinPro	emittance, gun, SRF, laser	317
	R. Barday, T. Kamps, A. Neumann, J. Rudolph, S.G. Schubert, J. Völker HZB, Berlin, Germany A. Ferrarotto, T. Weis DELTA, Dortmund, Germany
	BERLinPro is an energy-recovery linac for an electron beam with 1 mm mrad normalized emittance and 100 mA average current. The initial beam parameters are determined by the performance of the electron source, an SRF photo-electron injector. Development of this source is a major part of the BERLinPro programme. The instrumentation for the first stage of the programme serves the purpose to have robust and reliable monitors for fundamental beam parameters like emittance, bunch charge, energy and energy spread. The critical issue of the second stage is the generation of an electron beam with 100 mA average current and a normalized emittance of 1 mm mrad. Therefore we plan to setup a dedicated instrumentation beamline with a compact DC gun to measure thermal emittance, current and current lifetime. In parallel an SRF gun with dedicated diagnostics will be build focused on ERL specific aspects like emittance compensation with low-energy beams and reliability of high current operation. This paper collects requirements for each development stage and discusses solutions to specific measurement problems.

TUPD14	Commissioning of the Cavity BPM for the FERMI@Elettra FEL Project	electron, FEL, undulator, polarization	329
	P. Craievich, T. Borden, A.O. Borga, R. De Monte, M. Ferianis, M. Predonzani ELETTRA, Basovizza, Italy M. Dal Forno, R. Vescovo DIEIT, Trieste, Italy
	The cavity Beam Position Monitor (BPM) is a fundamental beam diagnostic device that allows the measurements of the electron beam trajectory in a non-destructively way and with sub-micron resolution. Ten cavity BPM systems have been installed along the undulators chain in the FERMI@Elettra FEL1 project. In this paper we discuss the installation, commissioning and performance of these cavity BPM systems. We have carried out preliminary operations during a pre-beam period, such as the alignment and fine tuning of the RF cavities under vacuum. During the commissioning each BPM has been calibrated by mechanically moving the support on which the BPM is mounted. We have estimated the single shot resolution in presence of beam jitter by reading the beam position synchronously over many electron bunches from three or more BPMs. The algorithms have been subsequently improved, and the results are described.
	Poster TUPD14 [0.460 MB]

TUPD18	Beam Position Monitors for the ACS Section of the J-PARC Linac	impedance, linac, ion, simulation	341
	T. Miyao, Z. Igarashi, T. Toyama KEK, Ibaraki, Japan A. Miura JAEA/J-PARC, Tokai-mura, Japan
	The J-PARC is consisted of Linac, 3GeV-RCS, and 50GeV-MR. We are aiming at the energy upgrade of J-PARC linac from 181MeV to 400MeV. We employed the ACS(Annular Coupled Structure) as the acceleration cavities. To have the energy upgrade, we need to develop beam instruments including beam position monitors (BPMs). Then, we designed them to be able to measure a horizontal and vertical beam position and employed a stripline-type as their electrodes. The BPMs are required to be calibrated to the accuracy of beam orbit within 100μm. To achieve the requirement, we did some calibrations. First, we decided a width of stripuline, whose characteristic impedance can be calibrated to 50 Ω with electric field simulations. Second, we also measured characteristic impedance of 4 different striplines per a BPM corresponding with BPM simulations. Last, we measured an electrical center position of BPMs with a simulated beam signal at 324MHz, 6dBm. A BPM will be installed at each quadrupole magnet in the ACS section to be used for a beam commissioning. Systematic calibration of developed BPMs is described in this paper. In addition, a phase measurement using these BPMs will be considered.

TUPD24	Design Status of Beam Position Monitors for the FAIR Proton Linac	linac, proton, simulation, vacuum	356
	C.S. Simon, F. Senée CEA/DSM/IRFU, France G. Clemente, P. Forck, W. Kaufmann, P. Kowina GSI, Darmstadt, Germany
	Beam Position Monitors (BPM) based on capacitive buttons are designed for the FAIR Proton-LINAC, constructed as an extension of the existing GSI facility. This LINAC is aiming to produce a maximum design current of 70 mA at the 70 MeV energy with an accelerating frequency of 325 MHz. At 14 locations, the BPMs will measure the transverse beam position, the relative beam current and the mean beam energy by time-of-flight method. Depending of the location, the BPM design has to be optimized, taking into account an energy range from 3 MeV to 70 MeV, a short insertion and a beam pipe aperture changes from 30 mm to 50 mm. Some of BPMs will be mounted very close to the CH cavities and special care must be taken to suppress the pickup of the strong rf-field from that cavities. In this contribution, the status of the BPM design will be presented.

TUPD26	Cavity-based Beam Diagnostics at ELSA	electron, extraction, resonance, target	362
	T.R. Pusch, F. Frommberger, W. Hillert, B. Neff ELSA, Bonn, Germany
	Funding: Funded by DFG SFB/TR 16 Online monitoring of the intensity and position of an electron beam of a few hundred pA in the experiment beamlines at the ELSA facility is enabled by a system of resonant cavities. The position signal extracted from the resonators amounts to about 10^-19 W for 0.1 mm displacement at a beam current of 400 pA. It is separated from noise by phase-sensitive detection in a lock-in amplifier. The beam's position is obtained with a precision of one tenth of a millimeter, the signal strength being normalized by a beam current measurement with an uncertainty of a few pA. Via frequency mixing, the cavity signal of 1.5 GHz is converted down to a frequency below 100 kHz in order to be accepted by the amplifier, requiring a local oscillator stabilized by a feedback loop to 10^-6 precision. Details of the measurement system are presented.

TUPD70	Conceptual Design of a High Sensitive Versatile Schottky Sensor for the Collector Ring at FAIR	coupling, antiproton, impedance, storage-ring	470
	M. Hansli, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany W. Kaufmann GSI, Darmstadt, Germany
	Funding: Funded by the Federal Ministry of Education and Research (BMBF): 06DA90351 The FAIR (Facility for Antiproton and Ion Research) accelerator complex includes the Collector Ring CR, i.e. a dedicated storage ring for secondary particles, rare isotopes and antiprotons. The CR features three different modes of operation: pre-cooling of antiprotons at 3 GeV, pre-cooling of rare isotope beams at 740 MeV/u and an isochronous mode for mass measurements. For beam optimizations in all three modes a sensitive Schottky setup is required to monitor very low beam intensities down to single particles. In this paper the conceptual design of a longitudinal Schottky sensor based on a pillbox cavity with adjustable coupling and frequency tuning is presented. The basic measurement principles are depicted and a possible realization is discussed with emphasize on the special requirements of the CR operational modes. Full-wave simulations of the proposed sensor cavity allow for further optimizations.
	Poster TUPD70 [1.247 MB]

TUPD81	The Petra III Multibunch Feedback System	feedback, kicker, 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

FEL, feedback, 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]

MOOB04

Bunch Compression, RF Curvature Correction and R₅₅, T₅₅₅ and U₅₅₅₅ Measurements at JLab FEL

FEL, linac, SRF, sextupole

15

P. Evtushenko, S.V. Benson, D. Douglas
JLAB, Newport News, Virginia, USA

The JLab IR/UV FEL Upgrade operates with the bunch length compressed down to 100-150 fs RMS. An indispensible part of the bunch compression scheme is the correction of the so-called LINAC RF curvature. Unlike other systems – where the RF curvature gets corrected using higher a harmonic LINAC – our system utilizes magnetic elements of the beam transport system to correct and adjust the second and third order correlation terms. These are expressed in terms of the transport matrix elements T₅₆₆ and U₅₆₆₆. The linear correlation term described by M₅₅ is adjusted using the magnetic system as well. The large energy spread induced on the beam by the FEL operation is compressed as a part of the energy recovery process. As in the case of bunch length compression, this energy compression is optimized by properly adjusting high order transport matrix elements. In this contribution we describe the system used for direct measurements of the transport matrix elements M₅₅, T₅₆₆ and U₅₆₆₆ and its impact on the operation and bunch compression. Results of the measurements are presented together with the bunch length measurements including the data showing resolution and accuracy of the system.

Slides MOOB04 [0.999 MB]

MOOC01

Overview of Recent Trends and Developments for BPM Systems

pick-up, coupling, monitoring, linac

18

M. Wendt
Fermilab, Batavia, USA

Beam position monitoring (BPM) systems are the workhorse beam diagnostics for almost any kind of charged particle accelerator; linear, circular or transport-lines, operating with leptons, hadrons or heavy ions. The BPMs are essential for beam commissioning, accelerator fault analysis and trouble shooting, machine optics and lattice measurements, and finally for the accelerator optimization to achieve the ultimate beam quality. This presentation summarizes the efforts of the beam instrumentation community on recent developments and advances on BPM technologies, i.e. BPM pickup monitors and front-end electronics (analog and digital). Principles, examples, and state-of-the-art status on various BPM techniques are outlined, serving hadron and heavy ion machines, sync light synchrotron's, as well as electron linacs for FEL or HEP applications.

Slides MOOC01 [4.123 MB]

MOOC02

Cavity BPM System for ATF2

monitoring, quadrupole, EPICS, extraction

23

A. Lyapin, R. Ainsworth, S.T. Boogert, G.E. Boorman, F.J. Cullinan, N.Y. Joshi
JAI, Egham, Surrey, United Kingdom
A.S. Aryshev, Y. Honda, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
J.C. Frisch, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White
SLAC, Menlo Park, California, USA
A. Heo, E.-S. Kim, H.-S. Kim, Y.I. Kim
KNU, Deagu, Republic of Korea
M.C. Ross
Fermilab, Batavia, USA

In this paper we summarise our 2-year experience operating the Cavity Beam Position Monitor (CBPM) system at the Accelerator Test Facility (ATF) in KEK. The system currently consists of 41 C and S-band CBPMs and is the main diagnostic tool for the new ATF2 extraction beamline. We concentrate on issues related to the scale of the system and also consider long-term effects, most of which are undetectable or insignificant in smaller experimental prototype systems. We consistently show sub-micron BPM resolutions and week-to-week scale drifts of an order of 1%.

Slides MOOC02 [2.075 MB]

MOOC03

The Fermi@Elettra Cavity BPM System: Description and Commissioning Results

pick-up, controls, FEL, undulator

26

M. Ferianis, A.O. Borga, P. Craievich, R. De Monte, G. Gaio, M. Predonzani
ELETTRA, Basovizza, Italy
M. Dal Forno
DIEIT, Trieste, Italy

The Fermi@elettra cavity BPM (C-BPM) system is based on an original implementation of the C-BPM scheme as the pick-up, operating at 6.5GHz, is coupled to a dedicated, self-calibrating electronics based on a novel concept. The system has been developed in-house; both the E-M and the mechanical design of the pick-up have been carried out, including an original frequency tuning scheme. The detector electronics directly obtains the envelope of the sum and difference signals by means of an RF 180° hybrid; no mixer for the RF signal down conversion is used. The detector is based on 3 blocks: an RF front-end, a baseband analogue transmission module and a digital back-end unit, based on a micro-TCA platform. The digital back-end is equipped with a powerful Virtex 5 FPGA and several real-time tasks have been implemented on it, including intra-pulse calibration. Ten C-BPM stations have been installed so far, fully integrated in the FERMI control System, enabling a real-time control of this key FEL diagnostics. Results on performances with beam are also presented; the scale factor of C-BPMs is obtained with beam, as two-axis micrometer translation stages have been installed.

Slides MOOC03 [2.733 MB]

MOPD13

Mode Selective Waveguide BPM

coupling, pick-up, simulation, impedance

65

A. Lyapin
JAI, Egham, Surrey, United Kingdom

I propose a mode-selective waveguide Beam Position Monitor (BPM). It uses waveguide couplers arranged at the beampipe to create boundary conditions similar to those in slot-coupled cavity BPMs. This structure allows to couple to the differential waveguide mode co-propagating with the beam, and reject the usually much stronger monopole component of the field. As the full dynamic range of the processing electronics can be used for position measurements, and a waveguide is a native high-pass filter, such a BPM is expected to outperform stripline and button BPMs in terms of both spacial and time resolution. In this paper I give some details on the basic principle and the first simulation results and discuss possible ways of signal processing.

Poster MOPD13 [3.052 MB]

MOPD17

Beam-based HOM Study in Third Harmonic SC Cavities for Beam Alignment at FLASH

HOM, dipole, electron, polarization

77

P. Zhang, R.M. Jones, I.R.R. Shinton
UMAN, Manchester, United Kingdom
N. Baboi, B. Lorbeer, P. Zhang
DESY, Hamburg, Germany
H. Ecklebe, T. Flisgen, H.-W. Glock
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by European Commission under the FP7 Research Infrastructures grant agreement No.227579.
An electron beam entering an accelerator cavity excites higher order modes (HOM). These are radiated to HOM couplers, subsequently damped, and can also be used to facilitate beam monitoring. The modes which deflect the beam transversely are the focus of this study and are used to monitor the beam position. Results are presented on the first analysis of beam alignment based on HOM signals from the third harmonic cavities at FLASH. The electrical center of each mode is ascertained by moving the beam to minimize the HOM signal detected. A single electron bunch per RF pulse is used.

MOPD19

Button BPM Development for the European XFEL

simulation, vacuum, cryogenics, linac

83

D. Lipka, B. Lorbeer, D. Nölle, M. Siemens, S. Vilcins
DESY, Hamburg, Germany

Button beam position monitors will be the main BPM type used to measure the electron beam position at the European XFEL. Two different kinds of buttons are necessary: one type will be installed in the acceleration modules of the cold linac and the other in the warm environment. The electro-magnetic design of the feedthrough for both types of buttons will be discussed. A comparison of the designed and measured RF properties will be presented. In addition to the usual RF properties, also the properties at cryogenic level will play a role. HOM power must not heat up the BPM feedthroughs, in order to keep the cryo load of an overall accelerator module low, and also to prevent damage due to large temperature gradients over the ceramics of the feedthrough. First measurements with beam at FLASH show good agreement of the measured signals with the expectation.

MOPD25

Diode Down-mixing of HOM Coupler Signals for Beam Position Determination in 1.3-GHz- and 3.9-GHz-Cavities at FLASH

HOM, polarization, dipole, coupling

101

H.-W. Glock, H. Ecklebe, T. Flisgen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
N. Baboi, P. Zhang
DESY, Hamburg, Germany

Funding: work supported by BMBF under contract 05K10HRC and by European Commission under the FP7 Research Infrastructures grant agreement No.227579
Beam excited signals available at the HOM coupler ports of superconducting accelerating cavities cover a wide frequency range and carry information about (amongst others) transverse beam position. Down-mixing these signals using detector diodes is a mean to measure with standard and non-specific oscilloscope technology the time dependency of the power leaving the HOM coupler. Experiments undertaken at the accelerator modules ACC1 and ACC39 at FLASH demonstrated the possibility to extract beam position data out of low-frequency signals sampled with such a setup. These experiments as part of an ongoing study are described together with mathematical details of the evaluation scheme.

MOPD28

Loss Factor Measurement using Time Correlated Single Photon Counting of Synchrotron Radiation

photon, storage-ring, synchrotron, vacuum

110

G. Rehm, C. Bloomer, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

A method to derive the total loss factor from the variation of SR photon arrival times with bunch charge has been developed. A time correlated single photon counting system is used operationally for fill pattern and bunch purity measurements. By fitting the individual peaks in the photon arrival time histogram, their relative timing can be retrieved with ps resolution and reproducibility. For a measurement of the loss factor, a fill pattern comprising a range of different bunch charges is stored and then their timing relative to the RF buckets is charted against charge. Examples of measurements illustrate the variation of loss factor with RF voltage and change in Insertion Device gap.

MOPD32

Bunch Length Measurement from Power Fluctuation at Diamond

synchrotron, radiation, synchrotron-radiation, lattice

119

C.A. Thomas, I.P.S. Martin, G. Rehm
Diamond, Oxfordshire, United Kingdom

Bunch length can be measured using the visible light power fluctuation statistics of an individual bunch. This method developed at ALS has been implemented at Diamond with further improvement on the detection method and the speed of the measurement. In this paper, we firstly report on the development and implementation of the method. We will show the performance of several detector diodes used and the limits of the method. Validation of the method will be demonstrated against streak camera measurement with picosecond long bunches. Before concluding, we will discuss about the strengths and weaknesses of the method.

MOPD36

Development of a Silicon Detector Monitor for the Superconducting Upgrade of the REX-ISOLDE Heavy-Ion Linac at CERN

linac, ion, diagnostics, rfq

131

F. Zocca
IEM, Madrid, Spain
E. Bravin, M.A. Fraser, D. Voulot, F.J.C. Wenander, F. Zocca
CERN, Geneva, Switzerland
M. Pasini
Instituut voor Kern- en Stralingsfysica, K. U. Leuven, Leuven, Belgium

A silicon detector monitor has been developed and tested in the frame of the beam diagnostics development program for the HIE-ISOLDE superconducting upgrade of the REX-ISOLDE heavy-ion linac at CERN. The monitor is intended for beam energy and timing measurements as well as for phase scanning of the superconducting cavities. Tests have been performed with a stable ion beam, composed of carbon, oxygen and neon ions accelerated to energies from 300 keV/u to 2.85 MeV/u. The silicon detector was placed directly in the beam line and tested with a beam which was strongly attenuated to simulate the single particle detection regime for which the monitor is intended to finally function. The energy measurements performed allowed for beam spectroscopy and ion identification with a resolution of 3%. The principle of cavity phase scanning was also demonstrated with the REX 7-gap resonator thanks to the accurate peak energy identification. The time structure of the beam, characterized by a bunch period of 9.87 ns, was measured with a resolution better than 200 ps. This paper describes the results from all these tests as well as providing details of the detector.

MOPD64

High Quality Measurements of Beam Lifetime, Instant-Partial-Beam Losses and Charge-Accumulation with the New ESRF BPM System

injection, beam-losses, storage-ring, controls

194

K.B. Scheidt, F. Ewald, B. Joly
ESRF, Grenoble, France

The BPM system of the ESRF Storage Ring, that was entirely replaced by 224 units of the Libera-Brilliance system in 2009, is now also being used for precise and fast measurements of the Beam Lifetime and so-called Instant-Partial-BeamLosses. This is possible by the use of the Sum signal of the four BPM buttons on each of the 224 BPM stations in the Ring. This paper will describe the strong advantages in terms of response time, but also the precautions and the limitations of this particular use. Results will show the ultimate attainable performances and a detailed comparison with that of three independent DC current transformers also installed in the Ring. The same Sum signal is also usable for precise measurement of Accumulated Charge during the injection process and results of this will also be presented.

MOPD78

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

electron, feedback, 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.

TUPD07

Instrumentation Needs and Solutions for the Development of an SRF Photoelectron Injector at the Energy-Recovery Linac BERLinPro

emittance, gun, SRF, laser

317

R. Barday, T. Kamps, A. Neumann, J. Rudolph, S.G. Schubert, J. Völker
HZB, Berlin, Germany
A. Ferrarotto, T. Weis
DELTA, Dortmund, Germany

BERLinPro is an energy-recovery linac for an electron beam with 1 mm mrad normalized emittance and 100 mA average current. The initial beam parameters are determined by the performance of the electron source, an SRF photo-electron injector. Development of this source is a major part of the BERLinPro programme. The instrumentation for the first stage of the programme serves the purpose to have robust and reliable monitors for fundamental beam parameters like emittance, bunch charge, energy and energy spread. The critical issue of the second stage is the generation of an electron beam with 100 mA average current and a normalized emittance of 1 mm mrad. Therefore we plan to setup a dedicated instrumentation beamline with a compact DC gun to measure thermal emittance, current and current lifetime. In parallel an SRF gun with dedicated diagnostics will be build focused on ERL specific aspects like emittance compensation with low-energy beams and reliability of high current operation. This paper collects requirements for each development stage and discusses solutions to specific measurement problems.

TUPD14

Commissioning of the Cavity BPM for the FERMI@Elettra FEL Project

electron, FEL, undulator, polarization

329

P. Craievich, T. Borden, A.O. Borga, R. De Monte, M. Ferianis, M. Predonzani
ELETTRA, Basovizza, Italy
M. Dal Forno, R. Vescovo
DIEIT, Trieste, Italy

The cavity Beam Position Monitor (BPM) is a fundamental beam diagnostic device that allows the measurements of the electron beam trajectory in a non-destructively way and with sub-micron resolution. Ten cavity BPM systems have been installed along the undulators chain in the FERMI@Elettra FEL1 project. In this paper we discuss the installation, commissioning and performance of these cavity BPM systems. We have carried out preliminary operations during a pre-beam period, such as the alignment and fine tuning of the RF cavities under vacuum. During the commissioning each BPM has been calibrated by mechanically moving the support on which the BPM is mounted. We have estimated the single shot resolution in presence of beam jitter by reading the beam position synchronously over many electron bunches from three or more BPMs. The algorithms have been subsequently improved, and the results are described.

Poster TUPD14 [0.460 MB]

TUPD18

Beam Position Monitors for the ACS Section of the J-PARC Linac

impedance, linac, ion, simulation

341

T. Miyao, Z. Igarashi, T. Toyama
KEK, Ibaraki, Japan
A. Miura
JAEA/J-PARC, Tokai-mura, Japan

The J-PARC is consisted of Linac, 3GeV-RCS, and 50GeV-MR. We are aiming at the energy upgrade of J-PARC linac from 181MeV to 400MeV. We employed the ACS(Annular Coupled Structure) as the acceleration cavities. To have the energy upgrade, we need to develop beam instruments including beam position monitors (BPMs). Then, we designed them to be able to measure a horizontal and vertical beam position and employed a stripline-type as their electrodes. The BPMs are required to be calibrated to the accuracy of beam orbit within 100μm. To achieve the requirement, we did some calibrations. First, we decided a width of stripuline, whose characteristic impedance can be calibrated to 50 Ω with electric field simulations. Second, we also measured characteristic impedance of 4 different striplines per a BPM corresponding with BPM simulations. Last, we measured an electrical center position of BPMs with a simulated beam signal at 324MHz, 6dBm. A BPM will be installed at each quadrupole magnet in the ACS section to be used for a beam commissioning. Systematic calibration of developed BPMs is described in this paper. In addition, a phase measurement using these BPMs will be considered.

TUPD24

Design Status of Beam Position Monitors for the FAIR Proton Linac

linac, proton, simulation, vacuum

356

C.S. Simon, F. Senée
CEA/DSM/IRFU, France
G. Clemente, P. Forck, W. Kaufmann, P. Kowina
GSI, Darmstadt, Germany

Beam Position Monitors (BPM) based on capacitive buttons are designed for the FAIR Proton-LINAC, constructed as an extension of the existing GSI facility. This LINAC is aiming to produce a maximum design current of 70 mA at the 70 MeV energy with an accelerating frequency of 325 MHz. At 14 locations, the BPMs will measure the transverse beam position, the relative beam current and the mean beam energy by time-of-flight method. Depending of the location, the BPM design has to be optimized, taking into account an energy range from 3 MeV to 70 MeV, a short insertion and a beam pipe aperture changes from 30 mm to 50 mm. Some of BPMs will be mounted very close to the CH cavities and special care must be taken to suppress the pickup of the strong rf-field from that cavities. In this contribution, the status of the BPM design will be presented.

TUPD26

Cavity-based Beam Diagnostics at ELSA

electron, extraction, resonance, target

362

T.R. Pusch, F. Frommberger, W. Hillert, B. Neff
ELSA, Bonn, Germany

Funding: Funded by DFG SFB/TR 16
Online monitoring of the intensity and position of an electron beam of a few hundred pA in the experiment beamlines at the ELSA facility is enabled by a system of resonant cavities. The position signal extracted from the resonators amounts to about 10^-19 W for 0.1 mm displacement at a beam current of 400 pA. It is separated from noise by phase-sensitive detection in a lock-in amplifier. The beam's position is obtained with a precision of one tenth of a millimeter, the signal strength being normalized by a beam current measurement with an uncertainty of a few pA. Via frequency mixing, the cavity signal of 1.5 GHz is converted down to a frequency below 100 kHz in order to be accepted by the amplifier, requiring a local oscillator stabilized by a feedback loop to 10^-6 precision. Details of the measurement system are presented.

TUPD70

Conceptual Design of a High Sensitive Versatile Schottky Sensor for the Collector Ring at FAIR

coupling, antiproton, impedance, storage-ring

470

M. Hansli, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
W. Kaufmann
GSI, Darmstadt, Germany

Funding: Funded by the Federal Ministry of Education and Research (BMBF): 06DA90351
The FAIR (Facility for Antiproton and Ion Research) accelerator complex includes the Collector Ring CR, i.e. a dedicated storage ring for secondary particles, rare isotopes and antiprotons. The CR features three different modes of operation: pre-cooling of antiprotons at 3 GeV, pre-cooling of rare isotope beams at 740 MeV/u and an isochronous mode for mass measurements. For beam optimizations in all three modes a sensitive Schottky setup is required to monitor very low beam intensities down to single particles. In this paper the conceptual design of a longitudinal Schottky sensor based on a pillbox cavity with adjustable coupling and frequency tuning is presented. The basic measurement principles are depicted and a possible realization is discussed with emphasize on the special requirements of the CR operational modes. Full-wave simulations of the proposed sensor cavity allow for further optimizations.

Poster TUPD70 [1.247 MB]

TUPD81

The Petra III Multibunch Feedback System

feedback, kicker, 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.