IBIC2014 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOPF16	CERN-SPS Wire Scanner Impedence and Wire Heating Studies	coupling, vacuum, electromagnetic-fields, emittance	88
	E. Piselli, O.E. Berrig, F. Caspers, B. Dehning, J. Emery, M. Hamani, J. Kuczerowski, B. Salvant, R.S. Sautier, R. Veness, C. Vuitton, C. Zannini CERN, Geneva, Switzerland
	This article describes a study performed on one of the SPS vertical rotational wire scanners in order to investigate the breakage of the wire, which occurred on several occasions during the last year of operation. The thermionic emission current of the wire was measured to evaluate temperature changes, and was observed to rise significantly as the wire approached the ultimate LHC beam in the SPS, indicating the possibility of strong coupling between the beam’s electromagnetic field and the wire. Different laboratory measurements, complemented by CST Microwave Studio simulations, have therefore been performed to try and understand the RF modes responsible for this heating. These results are presented here, along with the subsequent modifications adopted on all of the operational SPS wire scanners.
	Poster MOPF16 [0.747 MB]
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MOPF27	Simulation and First Results of the ELBE SRF Gun II	gun, laser, SRF, cavity	106
	P.N. Lu, A. Arnold, U. Lehnert, P. Murcek, J. Teichert, H. Vennekate, R. Xiang HZDR, Dresden, Germany
	In Rossendorf, a 3 and one half cell cavity SRF photo injector has been installed, which promises to accelerate the electron beam to 9 MeV in 0.5 meter. The gun is expected to operate both in the 13 MHz mode with a bunch charge of 77 pC, or in the 500 kHz mode, with a 1 nC charge. The simulation presented in this contribution includes particle tracking in the new cavity itself with the ASTRA code, and in the bunch transport line in the ELBE beam lines with the elegant code. The measured profile and time structure of the UV laser on the cathode are utilized to specify the electron bunch parameters. Then a single bunch of electrons is tracked in the cavity field that was calculated by Superfish, with space charge effects considered. From the exit of the cavity, the electron bunch has a relatively high energy so we ignore the space charge effect there and apply elegant to track the particles through the magnet elements and accelerator modules. The main purpose of this simulation is to find the optimized parameters for different beam transport tasks. As a first experimental result of the photoinjector, energy and phase space measurement will be also presented in the paper. Both the slit mask and the quadrupole scan methods are applied to measure the beam emittance. An obvious progression will be to compare the results from this gun with those from the ELBE SRF gun I.
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MOPD01	RHIC p-Carbon Polarimeter Target Lifetime Issue	target, polarization, proton, detector	124
	H. Huang, E.C. Aschenauer, G. Atoian, A. Bazilevsky, O. Eyser, A. Fernando, D.M. Gassner, D. Kalinkin, J. Kewisch, G.J. Mahler, Y. Makdisi, S. Nemesure, A. Poblaguev, W.B. Schmidke, D. Steski, T. Tsang, K. Yip, A. Zelenski BNL, Upton, Long Island, New York, USA I.G. Alekseev, D. Svirida ITEP, Moscow, Russia
	Funding: Work performed under contract No. DE-AC02-98CH1-886 with the auspices of the DOE of United States RHIC polarized proton operation requires fast and reliable proton polarimeter for polarization monitoring during stores. Polarimeters based on p-Carbon elastic scattering in the Coulomb Nuclear Interference(CNI) region has been used. Two polarimeters are installed in each of the two collider rings and they are capable to provide important polarization profile information. The polarimeter also provides valuable information for polarization loss on the energy ramp. As the intensity increases over years, the carbon target lifetime is getting shorter and target replacement during operation is necessary. Simulations and experiment tests have been done to address the target lifetime issue. This paper summarizes the recent operation and the target test results.
	Poster MOPD01 [10.776 MB]
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MOPD06	Electron Beam Diagnostics for Short Pulse FEL Schemes at CLARA	electron, laser, FEL, diagnostics	147
	S. Spampinati, D. Newton Cockcroft Institute, Warrington, Cheshire, United Kingdom D. Newton The University of Liverpool, Liverpool, United Kingdom
	CLARA (Compact Linear Accelerator for Research and Applications) [1] is a proposed 250 MeV, 100-400 nm FEL test facility at Daresbury Laboratory. The purpose of CLARA is to test and validate new FEL schemes in areas such as ultra-short pulse generation, temporal coherence and pulse-tailoring. Some of the schemes that can be tested at CLARA depend on a manipulation of the electron beam properties with characteristic scales shorter than the electron beam and require a 30 - 50 μm modulation of the beam energy acquired via the interaction with an infrared laser beam in a short undulator. In this article we describe the electron beam diagnostics required to carry on these experiments.
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MOPD25	Time Domain Pickup Signal characterization for Low Charge Arrival-Time Measurements at FLASH	pick-up, laser, operation, electron	209
	A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany M.K. Czwalinna, H. Schlarb, C. Sydlo DESY, Hamburg, Germany T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	For the low charge operation mode at the European XFEL, high bandwidth cone-shaped pickups were developed as a part of the Bunch Arrival-time Monitors (BAMs). The simulation showed that the signal parameters of interest, the signal slope and bandwidth are improved by more than a factor of six compared to the state of the art pickups. The pickups are installed at FLASH for verification. In this paper, time-domain measurements of the cone-shaped pickups at FLASH are presented. The pickup signal is recorded with a high bandwidth sampling oscilloscope. Two channel measurements are conducted with a single and a combined pickup signal in order to analyze the orbit and charge dependence of the pickup signal parameters. The measured time domain pickup signal wave form is compared to the CST PARTICLE STUDIO simulation.
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TUPF02	Proposed Pulse Stretching of BPM Signals for the Position Determination of Very Short and Closely Spaced Bunches	electron, synchrotron-radiation, collider, synchrotron	294
	P. Thieberger, S.J. Brooks, K. Hamdi, R.L. Hulsart, G.J. Mahler, R.J. Michnoff, M.G. Minty, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the U.S. Department of Energy A proposal for a future ultra relativistic polarized electron-proton collider (eRHIC) is based in part on the transport of multiple electron beams of different energies through two FFAG beam transports around the 3834 m long RHIC tunnel circumference in order to recirculate them through an Energy Recovery Linac for their stepwise acceleration and deceleration. For each of these transports, the beams will travel in a common vacuum chamber, horizontally separated from each other by a few mm. Determining the position of the individual bunches is challenging due to their very short length (~12 ps rms) and their temporal proximity (less than 4 ns in some cases). Providing pulses adequate for accurate sampling is further complicated by the less-than-ideal response of long coaxial cables. Here we propose two approaches to produce enhanced, i.e. stretched pulse shapes of limited duration; one based on specially shaped BPM electrodes and the other one on analog integration of more conventional stripline BPM signals. In both cases, signals can be generated which contain relatively flat portions which should be easier to sample with good precision without requiring picoseconds timing accuracy.
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TUPF03	Overview of the Geometrical Non-Linear Effects of Button BPMs and Methodology for Their Efficient Suppression	pick-up, coupling, storage-ring, vacuum	298
	A.A. Nosych, U. Iriso, A. Olmos ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain M. Wendt CERN, Geneva, Switzerland
	This paper describes an overview of the geometric non-linear effects common to beam position monitors (BPMs) installed in the accelerators and a methodology to correct for these effects. A typical characteristic curve of a pick-up is linear within a limited range from the BPM origin. At larger offsets the non-linearity of the curve is more pronounced and gets worse if the button diameter is small with respect to the beam pipe diameter. The general real-time linearization methods usually utilize linear correction combined with a simplistic polynomial, which may lead to inaccuracies in their limited application. We have developed a more rigorous methodology to suppress the non-linear effects of the BPMs through electromagnetic (EM) simulations and 2D fitting approximations. The focus is mainly on standard button pick-ups for the electron (ALBA) and proton machines (LHC).
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TUPF04	Numerical Calculations for the FAIR Proton Linac BPMs	linac, proton, pick-up, vacuum	303
	C.S. Simon CEA/DSM/IRFU, France M.H. Almalki, P. Forck, W. Kaufmann, T. Sieber GSI, Darmstadt, Germany V. Bellego CEA/IRFU, Gif-sur-Yvette, France
	Fourteen Beam Position Monitors (BPMs) will be installed along the FAIR Proton LINAC. These monitors will be used to determine the beam position, the relative beam current and the mean beam energy by time of flight (TOF). A capacitive button type pickup was chosen for its easy mechanical realization and for the short insertion length which is important for the four BPMs locations of the inter-tank sections between the CH-cavities. Depending on the location, the BPM design has to be optimized, taking into account an energy range from 3 MeV to 70 MeV, limited space for installation and a 30 mm or 50 mm beam pipe aperture. This paper reports wake field numerical simulations performed by the code CST PARTICLE STUDIO to design and characterize the BPMs. Time of response of monitors are presented and results of calculations for various pickup-geometries are discussed taking into account different beam velocities.
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TUPF11	Mechanical Design of Cryogenic Vacuum Feedthroughs for X-FEL Button BPMs	cryogenics, vacuum, project-management, operation	332
	S. Vilcins, D. Lipka DESY, Hamburg, Germany
	The European XFEL is a 4th generation synchrotron radiation source, currently under construction in Hamburg. Based on different Free-Electron Laser and spontaneous sources and driven by a superconducting accelerator, it will be able to provide several user stations with photons simultaneously. Due to the superconducting technology in the accelerators modules many components have to operate at liquid helium temperature. This poster will concentrate on high frequency ultra high vacuum feedthrough used for the beam position monitors of the cryogenic accelerator modules. Main emphasis will be put on the design of these feedthroughs, their material composition and the production process. The capability to be used under these very special conditions was investigated with FEM simulations, as well as with a test procedure. The results of these simulations will be presented; the tests and their results will be explained in detail.
	Poster TUPF11 [0.407 MB]
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TUPF14	Newly Developed 6mm Buttons for the BPMs in the ESRF Low-Emittance-Ring	coupling, factory, vacuum, operation	346
	K.B. Scheidt ESRF, Grenoble, France
	For the small beam pipe of the BPMs in the LE-ring a development of 6mm button-UHV-feedthroughs was launched and has resulted in the delivery of a total of 27 prototypes from both the Kyocera and the PMB-ALCEN companies. These buttons are flat, without skirt, with a central pin of Molybdenum ending in a male SMA connector. Among these prototype units are versions with Copper, Steel and Molybdenum material for the button itself, with the aim of assessing possible different heatload issues. All design considerations, that are compatible with a further button reduction to 4mm, will be presented next to issues of costs, mechanical tolerances and feasibility.
	Poster TUPF14 [1.420 MB]
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TUPF25	Characterization of the Laser Beam for HHG Seeding	FEL, electron, laser, undulator	380
	S. Ackermann, B. Faatz DESY, Hamburg, Germany V. Miltchev Uni HH, Hamburg, Germany
	Recently free-electron laser (FEL) facilities around the world have shown that the direct seeding approach can enhance the spectral, temporal and coherence properties of the emitted radiation as well as reducing the fluctuations in arrival time and output energy. To achieve this, a photon pulse of the desired wavelength ("seed") is overlapped transversely and temporally with the electrons in the undulator to start up the FEL process from a defined radiation pulse rather than from noise. To benefit from the advantages of this technique, the energy of the seed has to exceed the energy of the spontaneous emission. The ratio between these two energies is strongly influenced by the seed beam properties. In this contribution, we will present simulations on the achieveable power contrast in dependence on the beam quality of the seed, and compare the results to the experimental data of the seeded FEL experiment ("sFLASH") at DESY, Hamburg. Additionally we show up a way of creating FEL seed pulses for simulation purposes from Hermite-Gaussian generating functions.
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TUPD02	Electron Beam Profiler for the Fermilab Main Injector	electron, proton, gun, ion	398
	R.M. Thurman-Keup, M.L. Alvarez, J. Fitzgerald, C.E. Lundberg, P.S. Prieto Fermilab, Batavia, Illinois, USA W. Blokland ORNL, Oak Ridge, Tennessee, USA
	The long range plan for Fermilab calls for large proton beam intensities in excess of 2 MW for use in the neutrino program. Measuring the transverse profiles of these high intensity beams is challenging and generally relies on non-invasive techniques. One such technique involves measuring the deflection of a beam of electrons with a trajectory perpendicular to the proton beam. A device such as this is already in use at the Spallation Neutron Source at ORNL and a similar device will be installed shortly in the Fermilab Main Injector. The Main Injector device is discussed in detail and some test results and simulations are shown.
	Poster TUPD02 [2.115 MB]
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TUPD13	Experience with and Studies of the SNS Target Imaging System	target, neutron, proton, operation	447
	W. Blokland ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725 The Target Imaging System (TIS) shows the size and position of the proton beam by using a luminescent Cr:Al2O3 coating on the SNS target. The proton beam hitting the coating creates light which is transferred through mirrors and optical fibers to a digital camera outside the high radiation area. The TIS is used during operations to verify that the beam is in the right location and does not exceed the maximum proton beam peak density. This paper describes our operational experience with the TIS and the results of studies on the linearity, uniformity, and luminescence decay of the coating. In the future, tubes with material samples might be placed in front of the target for irradiation studies. The simulations of placing tubes in the front of target coating and its effect on the beam width and position measurements are also discussed.
	Poster TUPD13 [3.216 MB]
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TUPD21	AC Coupling Studies and Circuit Model for Loss Monitor Ring	niobium, background, ion, coupling	455
	Z. Liu, J.L. Crisp, S.M. Lidia FRIB, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University. As a follow-up study to the initial design of FRIB Loss Monitor Ring (previously named Halo Monitor Ring [1]), we present recent results of coupling studies between the FRIB CW beam and the Loss Monitor Ring (LMR). While a ~33 kHz low-pass filter was proposed to attenuate high-frequency AC-coupled signals [1,2], the LMR current signal may still contain low frequency signals induced by the un-intercepted beam, for example, by the 50μs beam notch that repeats every 10ms. We use CST Microwave Studio to simulate the AC response of a Gaussian source signal and benchmarked it to analytical model. A circuit model for beam-notch-induced AC signal is deduced and should put a ~33pA (peak) bipolar pulse on the LMR at 100Hz repetition rate. Although its amplitude falls into our tolerable region, we could consider an extended background integration to eliminate this effect.
	Poster TUPD21 [1.201 MB]
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WECYB1	Development of a Modified Six-Port Discriminator for Precise Beam Position Measurements	pick-up, operation, detector, electronics	495
	A. Penirschke, A. Angelovski, M. Hansli, R. Jakoby, T. Mahn TU Darmstadt, Darmstadt, Germany
	For the European XFEL, new energy beam position monitors based on planar transmission lines were designed for energy measurements in the dispersive section of bunch compressor chicanes. The EBPM consists of transversely mounted stripline pickups in a rectangular beam pipe section and a signal detection scheme which measures the phases of the pulses at the ends of the pickup. It allows simultaneous measurements of the beam energy and arrival-time. This paper presents the development of a RF readout electronic based on a modified six-port discriminator as a low-cost alternative to the readout electronics based on the MTCA.4 platform for the EBPM. Based on the six-port, the beam position can be determined by means of the phase difference between the received signals from both ends of the transmission line pickup. The six-port discriminator is a linear passive component, first developed in the 70s for accurate measurements of complex reflection coefficients in microwave network analysis. It typically consists of two hybrid couplers and two power dividers or one Wilkinson power divider and three -3dB hybrid couplers. For the measurement of the difference of two signals excited from a single source one of the hybrid coupler can be omitted. The advantage of the six port is the fact that accurate phase measurements can be performed at microwave and millimeter wave frequencies only by amplitude measurements. This paper shows the principle of operation, developed prototype, and first test results A. Penirschke et al., Proceedings of IBIC2013, Oxford, United Kingdom (2013). ** G.F. Engen, IEEE MTT, vol.25, no.12, pp.1077-1079, December 1977.
	Slides WECYB1 [2.567 MB]
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WEPF05	Simulation of the Beam Dump for a High Intensity Electron Gun	electron, gun, scattering, collider	536
	A. Jeff, S. Döbert, T. Lefèvre CERN, Geneva, Switzerland A. Jeff The University of Liverpool, Liverpool, United Kingdom K. Pepitone CEA, LE BARP cedex, France
	The CLIC Drive Beam is a high-intensity pulsed electron beam. A test facility for the Drive Beam electron gun will soon be commissioned at CERN. In this contribution we outline the design of a beam dump / Faraday cup capable of resisting the beam’s thermal load. The test facility will operate initially up to 140 keV. At such low energies, the electrons are absorbed very close to the surface of the dump, leading to a large energy deposition density in this thin layer. In order not to damage the dump, the beam must be spread over a large surface. For this reason, a small-angled cone has been chosen. Simulations using geant4 have been performed to estimate the distribution of energy deposition in the dump. The heat transport both within the electron pulse and between pulses has been modelled using finite element methods to check the resistance of the dump at high repetition rates. In addition, the possibility of using a moveable dump to measure the beam profile and emittance is discussed.
	Poster WEPF05 [0.224 MB]
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WEPF07	Optimization of a Short Faraday Cup for Low-Energy Ions Using Numerical Simulations	electron, ion, diagnostics, linac	544
	A.G. Sosa, E. Bravin, E.D. Cantero CERN, Geneva, Switzerland C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: CATHI is a Marie Curie Initial Training Network funded by the European Commission under Grant Agreement Number PITN-GA-2010-264330. ISOLDE, the heavy-ion facility at CERN is undergoing a major upgrade with the installation of a superconducting LINAC that will allow post-acceleration of ion beams up to 10 MeV/u. In this framework, customized beam diagnostics are being developed in order to fulfill the design requirements as well as to fit in the compact diagnostic boxes foreseen. The main detector of this system is a compact Faraday cup that will measure beam intensities in the range of 1 pA to 1 nA. In this contribution, simulation results of electrostatic fields and particle tracking are detailed for different Faraday cup prototypes taking into account the energy spectrum and angle of emission of the ion-induced secondary electrons.
	Poster WEPF07 [1.282 MB]
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WEPF13	The Status of Beam Diagnostics for the Hie-Isolde Linac at Cern	diagnostics, emittance, detector, TRIUMF	565
	E.D. Cantero, W. Andreazza, E. Bravin, A.G. Sosa CERN, Geneva, Switzerland A.G. Sosa Cockcroft Institute, Warrington, Cheshire, United Kingdom A.G. Sosa The University of Liverpool, Liverpool, United Kingdom
	Funding: CATHI is a Marie Curie Initial Training Network funded by the European Commission under Grant Agreement Number PITN-GA-2010-264330. The HIE-ISOLDE project aims at upgrading the CERN ISOLDE radioactive ion beam facility for higher beam intensities and higher beam energies. New beam diagnostic devices have to be developed as part of this upgrade, in particular for the measurement of intensity, energy, transverse and longitudinal profiles, and transverse emittance. The beam energy ranges from 300 keV/u to 10 MeV/u and beam intensities are between 1 pA and 1 nA. Faraday cups will be used for the measurement of the beam intensity while silicon detectors will be used for the energy and longitudinal profile measurements. The transverse profiles will be measured by moving a V-shaped slit in front of a Faraday cup and the beam position will be calculated from the profiles. The transverse emittance can be measured using the existing REX-ISOLDE slit and grid system, or by the combined use of two scanning slits and a Faraday cup. The final design of the mentioned devices will be presented in this contribution, including the results of the experimental validation tests performed on prototypes during the last two years.
	Poster WEPF13 [4.263 MB]
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WEPF25	A Fast Quadrupole Magnet for Machine Studies at Diamond	quadrupole, resonance, photon, storage-ring	605
	A.F.D. Morgan, G. Rehm DLS, Oxfordshire, United Kingdom
	Fast quadrupolar magnets have been demonstrated in various schemes for increasing the coupled bunch instability thresholds, and for measuring the shift of transverse quadrupolar moment oscillation thus probing the transverse quadrupolar impedance. Due to machine upgrades, a ceramic vessel installed in the Diamond storage ring has become temporarily available for use. We decided to take advantage of this situation by designing and installing a simple air core quadrupole magnet which can operate at the fundamental quadrupolar frequencies (~212kHz for the horizontal and ~405kHz for the vertical plane). In the first instance we aim to use it to study the coupled bunch instability thresholds and quadrupolar tune shifts.
	Poster WEPF25 [1.359 MB]
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WEPD21	BPM Data Correction at SOLEIL	electronics, vacuum, storage-ring, synchrotron	684
	N. Hubert, B. Béranger, L.S. Nadolski SOLEIL, Gif-sur-Yvette, France
	In a synchrotron light source like SOLEIL, Beam Position Monitors (BPM) are optimized to have the highest sensitivity for an electron beam passing nearby their mechanical center. Nevertheless, this optimization is done to the detriment of the response linearity when the beam is off-centered for dedicated machine physic studies. To correct the geometric non linearity of the BPM, we have applied an algorithm based on a boundary element method. Moreover the BPM electronics is able to provide position data at a turn by turn rate. Unfortunately the filtering process in this electronics mixes the information from one turn to the neighboring turns. An additional demixing algorithm has been set-up to correct this artefact. The paper reports on performances and limitations of those two algorithms that are used at SOLEIL to correct the BPM data.
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THCXB1	Cross-Calibration of Three Electron Cloud Density Detectors at CesrTA	electron, detector, photon, resonance	722
	J.P. Sikora, J.R. Calvey, J.A. Crittenden Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. Measurements of electron cloud density using three detector types are compared under the same beam conditions at the same location in the Cornell Electron Storage Ring (CESR). Two of the detectors sample the flux of cloud electrons incident on the beam-pipe wall. The Retarding Field Analyzer (RFA) records the time-averaged charge flux and has a retarding grid that can be biased to select high energy electrons. The Shielded Button Electrode (SBE) samples the electron flux without a retarding grid, acquiring signals with sub-nanosecond resolution. The third detector uses resonant microwaves and measures the electron cloud density within the beam-pipe through the cloud-induced shift in resonant frequency. The analysis will include comparison of the output from POSINST and ECLOUD simulations of electron cloud buildup. These time-sliced particle-in-cell 2D modeling codes – simulating photoelectron production, secondary emission and cloud dynamics – have been expanded to include the electron acceptance of the RFA and SBE detectors in order to model the measured signals. The measurements were made at the CESR storage ring, which has been reconfigured as a test accelerator (CesrTA) providing electron or positron beams ranging in energy from 2 GeV to 5 GeV.
	Slides THCXB1 [3.240 MB]
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THCXB2	Performance Evaluation of the Intra-Bunch Feedback System at J-PARC Main Ring	feedback, damping, betatron, experiment	727
	K.G. Nakamura Kyoto University, Kyoto, Japan Y.H. Chin, T. Koseki, H. Kuboki, M. Okada, M. Tobiyama KEK, Ibaraki, Japan Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Intra-bunch feedback system in J-PARC (Japan Proton Accelerator Complex) Main Ring(MR) has been developed for suppression of head-tail motion and reduction of beam loss. This system consists of mainly BPM, signal processing circuit (iGp12), power amplifiers, and stripline kickers. These components were fabricated and installed in April of 2014. This system succeeded in suppressing the internal bunch motion caused by injection kicker error in the 3GeV constant-energy operation, and showed shorter damping time compared to the bunch by bunch feedback system, which is currently working in the normal operation. In this paper, we will report the performance of the system by comparison with simulations.
	Slides THCXB2 [6.430 MB]
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Paper

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MOPF16

CERN-SPS Wire Scanner Impedence and Wire Heating Studies

coupling, vacuum, electromagnetic-fields, emittance

88

E. Piselli, O.E. Berrig, F. Caspers, B. Dehning, J. Emery, M. Hamani, J. Kuczerowski, B. Salvant, R.S. Sautier, R. Veness, C. Vuitton, C. Zannini
CERN, Geneva, Switzerland

This article describes a study performed on one of the SPS vertical rotational wire scanners in order to investigate the breakage of the wire, which occurred on several occasions during the last year of operation. The thermionic emission current of the wire was measured to evaluate temperature changes, and was observed to rise significantly as the wire approached the ultimate LHC beam in the SPS, indicating the possibility of strong coupling between the beam’s electromagnetic field and the wire. Different laboratory measurements, complemented by CST Microwave Studio simulations, have therefore been performed to try and understand the RF modes responsible for this heating. These results are presented here, along with the subsequent modifications adopted on all of the operational SPS wire scanners.

Poster MOPF16 [0.747 MB]

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MOPF27

Simulation and First Results of the ELBE SRF Gun II

gun, laser, SRF, cavity

106

P.N. Lu, A. Arnold, U. Lehnert, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
HZDR, Dresden, Germany

In Rossendorf, a 3 and one half cell cavity SRF photo injector has been installed, which promises to accelerate the electron beam to 9 MeV in 0.5 meter. The gun is expected to operate both in the 13 MHz mode with a bunch charge of 77 pC, or in the 500 kHz mode, with a 1 nC charge. The simulation presented in this contribution includes particle tracking in the new cavity itself with the ASTRA code, and in the bunch transport line in the ELBE beam lines with the elegant code. The measured profile and time structure of the UV laser on the cathode are utilized to specify the electron bunch parameters. Then a single bunch of electrons is tracked in the cavity field that was calculated by Superfish, with space charge effects considered. From the exit of the cavity, the electron bunch has a relatively high energy so we ignore the space charge effect there and apply elegant to track the particles through the magnet elements and accelerator modules. The main purpose of this simulation is to find the optimized parameters for different beam transport tasks. As a first experimental result of the photoinjector, energy and phase space measurement will be also presented in the paper. Both the slit mask and the quadrupole scan methods are applied to measure the beam emittance. An obvious progression will be to compare the results from this gun with those from the ELBE SRF gun I.

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MOPD01

RHIC p-Carbon Polarimeter Target Lifetime Issue

target, polarization, proton, detector

124

H. Huang, E.C. Aschenauer, G. Atoian, A. Bazilevsky, O. Eyser, A. Fernando, D.M. Gassner, D. Kalinkin, J. Kewisch, G.J. Mahler, Y. Makdisi, S. Nemesure, A. Poblaguev, W.B. Schmidke, D. Steski, T. Tsang, K. Yip, A. Zelenski
BNL, Upton, Long Island, New York, USA
I.G. Alekseev, D. Svirida
ITEP, Moscow, Russia

Funding: Work performed under contract No. DE-AC02-98CH1-886 with the auspices of the DOE of United States
RHIC polarized proton operation requires fast and reliable proton polarimeter for polarization monitoring during stores. Polarimeters based on p-Carbon elastic scattering in the Coulomb Nuclear Interference(CNI) region has been used. Two polarimeters are installed in each of the two collider rings and they are capable to provide important polarization profile information. The polarimeter also provides valuable information for polarization loss on the energy ramp. As the intensity increases over years, the carbon target lifetime is getting shorter and target replacement during operation is necessary. Simulations and experiment tests have been done to address the target lifetime issue. This paper summarizes the recent operation and the target test results.

Poster MOPD01 [10.776 MB]

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MOPD06

Electron Beam Diagnostics for Short Pulse FEL Schemes at CLARA

electron, laser, FEL, diagnostics

147

S. Spampinati, D. Newton
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D. Newton
The University of Liverpool, Liverpool, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) [1] is a proposed 250 MeV, 100-400 nm FEL test facility at Daresbury Laboratory. The purpose of CLARA is to test and validate new FEL schemes in areas such as ultra-short pulse generation, temporal coherence and pulse-tailoring. Some of the schemes that can be tested at CLARA depend on a manipulation of the electron beam properties with characteristic scales shorter than the electron beam and require a 30 - 50 μm modulation of the beam energy acquired via the interaction with an infrared laser beam in a short undulator. In this article we describe the electron beam diagnostics required to carry on these experiments.

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MOPD25

Time Domain Pickup Signal characterization for Low Charge Arrival-Time Measurements at FLASH

pick-up, laser, operation, electron

209

A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
M.K. Czwalinna, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

For the low charge operation mode at the European XFEL, high bandwidth cone-shaped pickups were developed as a part of the Bunch Arrival-time Monitors (BAMs). The simulation showed that the signal parameters of interest, the signal slope and bandwidth are improved by more than a factor of six compared to the state of the art pickups. The pickups are installed at FLASH for verification. In this paper, time-domain measurements of the cone-shaped pickups at FLASH are presented. The pickup signal is recorded with a high bandwidth sampling oscilloscope. Two channel measurements are conducted with a single and a combined pickup signal in order to analyze the orbit and charge dependence of the pickup signal parameters. The measured time domain pickup signal wave form is compared to the CST PARTICLE STUDIO simulation.

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TUPF02

Proposed Pulse Stretching of BPM Signals for the Position Determination of Very Short and Closely Spaced Bunches

electron, synchrotron-radiation, collider, synchrotron

294

P. Thieberger, S.J. Brooks, K. Hamdi, R.L. Hulsart, G.J. Mahler, R.J. Michnoff, M.G. Minty, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
A proposal for a future ultra relativistic polarized electron-proton collider (eRHIC) is based in part on the transport of multiple electron beams of different energies through two FFAG beam transports around the 3834 m long RHIC tunnel circumference in order to recirculate them through an Energy Recovery Linac for their stepwise acceleration and deceleration. For each of these transports, the beams will travel in a common vacuum chamber, horizontally separated from each other by a few mm. Determining the position of the individual bunches is challenging due to their very short length (~12 ps rms) and their temporal proximity (less than 4 ns in some cases). Providing pulses adequate for accurate sampling is further complicated by the less-than-ideal response of long coaxial cables. Here we propose two approaches to produce enhanced, i.e. stretched pulse shapes of limited duration; one based on specially shaped BPM electrodes and the other one on analog integration of more conventional stripline BPM signals. In both cases, signals can be generated which contain relatively flat portions which should be easier to sample with good precision without requiring picoseconds timing accuracy.

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TUPF03

Overview of the Geometrical Non-Linear Effects of Button BPMs and Methodology for Their Efficient Suppression

pick-up, coupling, storage-ring, vacuum

298

A.A. Nosych, U. Iriso, A. Olmos
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
M. Wendt
CERN, Geneva, Switzerland

This paper describes an overview of the geometric non-linear effects common to beam position monitors (BPMs) installed in the accelerators and a methodology to correct for these effects. A typical characteristic curve of a pick-up is linear within a limited range from the BPM origin. At larger offsets the non-linearity of the curve is more pronounced and gets worse if the button diameter is small with respect to the beam pipe diameter. The general real-time linearization methods usually utilize linear correction combined with a simplistic polynomial, which may lead to inaccuracies in their limited application. We have developed a more rigorous methodology to suppress the non-linear effects of the BPMs through electromagnetic (EM) simulations and 2D fitting approximations. The focus is mainly on standard button pick-ups for the electron (ALBA) and proton machines (LHC).

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TUPF04

Numerical Calculations for the FAIR Proton Linac BPMs

linac, proton, pick-up, vacuum

303

C.S. Simon
CEA/DSM/IRFU, France
M.H. Almalki, P. Forck, W. Kaufmann, T. Sieber
GSI, Darmstadt, Germany
V. Bellego
CEA/IRFU, Gif-sur-Yvette, France

Fourteen Beam Position Monitors (BPMs) will be installed along the FAIR Proton LINAC. These monitors will be used to determine the beam position, the relative beam current and the mean beam energy by time of flight (TOF). A capacitive button type pickup was chosen for its easy mechanical realization and for the short insertion length which is important for the four BPMs locations of the inter-tank sections between the CH-cavities. Depending on the location, the BPM design has to be optimized, taking into account an energy range from 3 MeV to 70 MeV, limited space for installation and a 30 mm or 50 mm beam pipe aperture. This paper reports wake field numerical simulations performed by the code CST PARTICLE STUDIO to design and characterize the BPMs. Time of response of monitors are presented and results of calculations for various pickup-geometries are discussed taking into account different beam velocities.

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TUPF11

Mechanical Design of Cryogenic Vacuum Feedthroughs for X-FEL Button BPMs

cryogenics, vacuum, project-management, operation

332

S. Vilcins, D. Lipka
DESY, Hamburg, Germany

The European XFEL is a 4th generation synchrotron radiation source, currently under construction in Hamburg. Based on different Free-Electron Laser and spontaneous sources and driven by a superconducting accelerator, it will be able to provide several user stations with photons simultaneously. Due to the superconducting technology in the accelerators modules many components have to operate at liquid helium temperature. This poster will concentrate on high frequency ultra high vacuum feedthrough used for the beam position monitors of the cryogenic accelerator modules. Main emphasis will be put on the design of these feedthroughs, their material composition and the production process. The capability to be used under these very special conditions was investigated with FEM simulations, as well as with a test procedure. The results of these simulations will be presented; the tests and their results will be explained in detail.

Poster TUPF11 [0.407 MB]

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TUPF14

Newly Developed 6mm Buttons for the BPMs in the ESRF Low-Emittance-Ring

coupling, factory, vacuum, operation

346

K.B. Scheidt
ESRF, Grenoble, France

For the small beam pipe of the BPMs in the LE-ring a development of 6mm button-UHV-feedthroughs was launched and has resulted in the delivery of a total of 27 prototypes from both the Kyocera and the PMB-ALCEN companies. These buttons are flat, without skirt, with a central pin of Molybdenum ending in a male SMA connector. Among these prototype units are versions with Copper, Steel and Molybdenum material for the button itself, with the aim of assessing possible different heatload issues. All design considerations, that are compatible with a further button reduction to 4mm, will be presented next to issues of costs, mechanical tolerances and feasibility.

Poster TUPF14 [1.420 MB]

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TUPF25

Characterization of the Laser Beam for HHG Seeding

FEL, electron, laser, undulator

380

S. Ackermann, B. Faatz
DESY, Hamburg, Germany
V. Miltchev
Uni HH, Hamburg, Germany

Recently free-electron laser (FEL) facilities around the world have shown that the direct seeding approach can enhance the spectral, temporal and coherence properties of the emitted radiation as well as reducing the fluctuations in arrival time and output energy. To achieve this, a photon pulse of the desired wavelength ("seed") is overlapped transversely and temporally with the electrons in the undulator to start up the FEL process from a defined radiation pulse rather than from noise. To benefit from the advantages of this technique, the energy of the seed has to exceed the energy of the spontaneous emission. The ratio between these two energies is strongly influenced by the seed beam properties. In this contribution, we will present simulations on the achieveable power contrast in dependence on the beam quality of the seed, and compare the results to the experimental data of the seeded FEL experiment ("sFLASH") at DESY, Hamburg. Additionally we show up a way of creating FEL seed pulses for simulation purposes from Hermite-Gaussian generating functions.

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TUPD02

Electron Beam Profiler for the Fermilab Main Injector

electron, proton, gun, ion

398

R.M. Thurman-Keup, M.L. Alvarez, J. Fitzgerald, C.E. Lundberg, P.S. Prieto
Fermilab, Batavia, Illinois, USA
W. Blokland
ORNL, Oak Ridge, Tennessee, USA

The long range plan for Fermilab calls for large proton beam intensities in excess of 2 MW for use in the neutrino program. Measuring the transverse profiles of these high intensity beams is challenging and generally relies on non-invasive techniques. One such technique involves measuring the deflection of a beam of electrons with a trajectory perpendicular to the proton beam. A device such as this is already in use at the Spallation Neutron Source at ORNL and a similar device will be installed shortly in the Fermilab Main Injector. The Main Injector device is discussed in detail and some test results and simulations are shown.

Poster TUPD02 [2.115 MB]

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TUPD13

Experience with and Studies of the SNS Target Imaging System

target, neutron, proton, operation

447

W. Blokland
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725
The Target Imaging System (TIS) shows the size and position of the proton beam by using a luminescent Cr:Al2O3 coating on the SNS target. The proton beam hitting the coating creates light which is transferred through mirrors and optical fibers to a digital camera outside the high radiation area. The TIS is used during operations to verify that the beam is in the right location and does not exceed the maximum proton beam peak density. This paper describes our operational experience with the TIS and the results of studies on the linearity, uniformity, and luminescence decay of the coating. In the future, tubes with material samples might be placed in front of the target for irradiation studies. The simulations of placing tubes in the front of target coating and its effect on the beam width and position measurements are also discussed.

Poster TUPD13 [3.216 MB]

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TUPD21

AC Coupling Studies and Circuit Model for Loss Monitor Ring

niobium, background, ion, coupling

455

Z. Liu, J.L. Crisp, S.M. Lidia
FRIB, East Lansing, Michigan, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
As a follow-up study to the initial design of FRIB Loss Monitor Ring (previously named Halo Monitor Ring [1]), we present recent results of coupling studies between the FRIB CW beam and the Loss Monitor Ring (LMR). While a ~33 kHz low-pass filter was proposed to attenuate high-frequency AC-coupled signals [1,2], the LMR current signal may still contain low frequency signals induced by the un-intercepted beam, for example, by the 50μs beam notch that repeats every 10ms. We use CST Microwave Studio to simulate the AC response of a Gaussian source signal and benchmarked it to analytical model. A circuit model for beam-notch-induced AC signal is deduced and should put a ~33pA (peak) bipolar pulse on the LMR at 100Hz repetition rate. Although its amplitude falls into our tolerable region, we could consider an extended background integration to eliminate this effect.

Poster TUPD21 [1.201 MB]

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WECYB1

Development of a Modified Six-Port Discriminator for Precise Beam Position Measurements

pick-up, operation, detector, electronics

495

A. Penirschke, A. Angelovski, M. Hansli, R. Jakoby, T. Mahn
TU Darmstadt, Darmstadt, Germany

For the European XFEL, new energy beam position monitors based on planar transmission lines were designed for energy measurements in the dispersive section of bunch compressor chicanes. The EBPM consists of transversely mounted stripline pickups in a rectangular beam pipe section and a signal detection scheme which measures the phases of the pulses at the ends of the pickup*. It allows simultaneous measurements of the beam energy and arrival-time. This paper presents the development of a RF readout electronic based on a modified six-port discriminator as a low-cost alternative to the readout electronics based on the MTCA.4 platform for the EBPM. Based on the six-port, the beam position can be determined by means of the phase difference between the received signals from both ends of the transmission line pickup. The six-port discriminator is a linear passive component, first developed in the 70s for accurate measurements of complex reflection coefficients in microwave network analysis**. It typically consists of two hybrid couplers and two power dividers or one Wilkinson power divider and three -3dB hybrid couplers. For the measurement of the difference of two signals excited from a single source one of the hybrid coupler can be omitted. The advantage of the six port is the fact that accurate phase measurements can be performed at microwave and millimeter wave frequencies only by amplitude measurements. This paper shows the principle of operation, developed prototype, and first test results
* A. Penirschke et al., Proceedings of IBIC2013, Oxford, United Kingdom (2013).
** G.F. Engen, IEEE MTT, vol.25, no.12, pp.1077-1079, December 1977.

Slides WECYB1 [2.567 MB]

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WEPF05

Simulation of the Beam Dump for a High Intensity Electron Gun

electron, gun, scattering, collider

536

A. Jeff, S. Döbert, T. Lefèvre
CERN, Geneva, Switzerland
A. Jeff
The University of Liverpool, Liverpool, United Kingdom
K. Pepitone
CEA, LE BARP cedex, France

The CLIC Drive Beam is a high-intensity pulsed electron beam. A test facility for the Drive Beam electron gun will soon be commissioned at CERN. In this contribution we outline the design of a beam dump / Faraday cup capable of resisting the beam’s thermal load. The test facility will operate initially up to 140 keV. At such low energies, the electrons are absorbed very close to the surface of the dump, leading to a large energy deposition density in this thin layer. In order not to damage the dump, the beam must be spread over a large surface. For this reason, a small-angled cone has been chosen. Simulations using geant4 have been performed to estimate the distribution of energy deposition in the dump. The heat transport both within the electron pulse and between pulses has been modelled using finite element methods to check the resistance of the dump at high repetition rates. In addition, the possibility of using a moveable dump to measure the beam profile and emittance is discussed.

Poster WEPF05 [0.224 MB]

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WEPF07

Optimization of a Short Faraday Cup for Low-Energy Ions Using Numerical Simulations

electron, ion, diagnostics, linac

544

A.G. Sosa, E. Bravin, E.D. Cantero
CERN, Geneva, Switzerland
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: CATHI is a Marie Curie Initial Training Network funded by the European Commission under Grant Agreement Number PITN-GA-2010-264330.
ISOLDE, the heavy-ion facility at CERN is undergoing a major upgrade with the installation of a superconducting LINAC that will allow post-acceleration of ion beams up to 10 MeV/u. In this framework, customized beam diagnostics are being developed in order to fulfill the design requirements as well as to fit in the compact diagnostic boxes foreseen. The main detector of this system is a compact Faraday cup that will measure beam intensities in the range of 1 pA to 1 nA. In this contribution, simulation results of electrostatic fields and particle tracking are detailed for different Faraday cup prototypes taking into account the energy spectrum and angle of emission of the ion-induced secondary electrons.

Poster WEPF07 [1.282 MB]

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WEPF13

The Status of Beam Diagnostics for the Hie-Isolde Linac at Cern

diagnostics, emittance, detector, TRIUMF

565

E.D. Cantero, W. Andreazza, E. Bravin, A.G. Sosa
CERN, Geneva, Switzerland
A.G. Sosa
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A.G. Sosa
The University of Liverpool, Liverpool, United Kingdom

Funding: CATHI is a Marie Curie Initial Training Network funded by the European Commission under Grant Agreement Number PITN-GA-2010-264330.
The HIE-ISOLDE project aims at upgrading the CERN ISOLDE radioactive ion beam facility for higher beam intensities and higher beam energies. New beam diagnostic devices have to be developed as part of this upgrade, in particular for the measurement of intensity, energy, transverse and longitudinal profiles, and transverse emittance. The beam energy ranges from 300 keV/u to 10 MeV/u and beam intensities are between 1 pA and 1 nA. Faraday cups will be used for the measurement of the beam intensity while silicon detectors will be used for the energy and longitudinal profile measurements. The transverse profiles will be measured by moving a V-shaped slit in front of a Faraday cup and the beam position will be calculated from the profiles. The transverse emittance can be measured using the existing REX-ISOLDE slit and grid system, or by the combined use of two scanning slits and a Faraday cup. The final design of the mentioned devices will be presented in this contribution, including the results of the experimental validation tests performed on prototypes during the last two years.

Poster WEPF13 [4.263 MB]

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WEPF25

A Fast Quadrupole Magnet for Machine Studies at Diamond

quadrupole, resonance, photon, storage-ring

605

A.F.D. Morgan, G. Rehm
DLS, Oxfordshire, United Kingdom

Fast quadrupolar magnets have been demonstrated in various schemes for increasing the coupled bunch instability thresholds, and for measuring the shift of transverse quadrupolar moment oscillation thus probing the transverse quadrupolar impedance. Due to machine upgrades, a ceramic vessel installed in the Diamond storage ring has become temporarily available for use. We decided to take advantage of this situation by designing and installing a simple air core quadrupole magnet which can operate at the fundamental quadrupolar frequencies (~212kHz for the horizontal and ~405kHz for the vertical plane). In the first instance we aim to use it to study the coupled bunch instability thresholds and quadrupolar tune shifts.

Poster WEPF25 [1.359 MB]

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WEPD21

BPM Data Correction at SOLEIL

electronics, vacuum, storage-ring, synchrotron

684

N. Hubert, B. Béranger, L.S. Nadolski
SOLEIL, Gif-sur-Yvette, France

In a synchrotron light source like SOLEIL, Beam Position Monitors (BPM) are optimized to have the highest sensitivity for an electron beam passing nearby their mechanical center. Nevertheless, this optimization is done to the detriment of the response linearity when the beam is off-centered for dedicated machine physic studies. To correct the geometric non linearity of the BPM, we have applied an algorithm based on a boundary element method. Moreover the BPM electronics is able to provide position data at a turn by turn rate. Unfortunately the filtering process in this electronics mixes the information from one turn to the neighboring turns. An additional demixing algorithm has been set-up to correct this artefact. The paper reports on performances and limitations of those two algorithms that are used at SOLEIL to correct the BPM data.

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THCXB1

Cross-Calibration of Three Electron Cloud Density Detectors at CesrTA

electron, detector, photon, resonance

722

J.P. Sikora, J.R. Calvey, J.A. Crittenden
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
Measurements of electron cloud density using three detector types are compared under the same beam conditions at the same location in the Cornell Electron Storage Ring (CESR). Two of the detectors sample the flux of cloud electrons incident on the beam-pipe wall. The Retarding Field Analyzer (RFA) records the time-averaged charge flux and has a retarding grid that can be biased to select high energy electrons. The Shielded Button Electrode (SBE) samples the electron flux without a retarding grid, acquiring signals with sub-nanosecond resolution. The third detector uses resonant microwaves and measures the electron cloud density within the beam-pipe through the cloud-induced shift in resonant frequency. The analysis will include comparison of the output from POSINST and ECLOUD simulations of electron cloud buildup. These time-sliced particle-in-cell 2D modeling codes – simulating photoelectron production, secondary emission and cloud dynamics – have been expanded to include the electron acceptance of the RFA and SBE detectors in order to model the measured signals. The measurements were made at the CESR storage ring, which has been reconfigured as a test accelerator (CesrTA) providing electron or positron beams ranging in energy from 2 GeV to 5 GeV.

Slides THCXB1 [3.240 MB]

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THCXB2

Performance Evaluation of the Intra-Bunch Feedback System at J-PARC Main Ring

feedback, damping, betatron, experiment

727

K.G. Nakamura
Kyoto University, Kyoto, Japan
Y.H. Chin, T. Koseki, H. Kuboki, M. Okada, M. Tobiyama
KEK, Ibaraki, Japan
Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Intra-bunch feedback system in J-PARC (Japan Proton Accelerator Complex) Main Ring(MR) has been developed for suppression of head-tail motion and reduction of beam loss. This system consists of mainly BPM, signal processing circuit (iGp12), power amplifiers, and stripline kickers. These components were fabricated and installed in April of 2014. This system succeeded in suppressing the internal bunch motion caused by injection kicker error in the 3GeV constant-energy operation, and showed shorter damping time compared to the bunch by bunch feedback system, which is currently working in the normal operation. In this paper, we will report the performance of the system by comparison with simulations.

Slides THCXB2 [6.430 MB]

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