IBIC2013 - List of Keywords (transverse)

Paper	Title	Other Keywords	Page
MOBL1	Instrumentation and Results from the SwissFEL Injector Test Facility	radiation, diagnostics, electron, laser	12
	R. Ischebeck, V.R. Arsov, S. Bettoni, B. Beutner, M.M. Dehler, A. Falone, F. Frei, I. Gorgisyan, Ye. Ivanisenko, P.N. Juranic, B. Keil, F. Löhl, G.L. Orlandi, M. Pedrozzi, P. Pollet, E. Prat, T. Schietinger, V. Schlott, B. Smit PSI, Villigen PSI, Switzerland P. Peier DESY, Hamburg, Germany
	The SwissFEL Injector Test Facility (SITF) has been equipped with numerous prototype diagnostics (BPMs, screen monitors, wire scanners, optical synchrotron radiation monitor, compression (THz) monitor, bunch arrival time monitor, EO spectral decoding monitor, charge and loss monitor) specifically designed for the low charge SwissFEL operation modes. The design of the diagnostics systems and recent measurement results will be presented.
	Slides MOBL1 [35.165 MB]

MOCL3	Emittance and Momentum Diagnostics for Beams with Large Momentum Spread	quadrupole, CLIC, emittance, diagnostics	37
	M. Olvegård, V.G. Ziemann Uppsala University, Uppsala, Sweden
	In the drive beam complex of CLIC, but also in plasma wakefield accelerators, the momentum spread can be on the order of tens of percent while conventional diagnostic methods often assume a very small momentum spread. This leads to systematic misinterpretations of the measurements. Spectrometry and emittance measurements based on quadrupole scan rely on measuring the beam size, which depends on the beam envelope. This, in turn, depends on the momentum distribution. We have studied the systematic errors that arise and developed novel algorithms to correctly analyze these measurements for arbitrary momentum distributions. As an application we consider the CLIC drive beam decelerator, where extraction of up to 90% of the kinetic energy leads to a very large momentum spread. We study a measurement of the time-resolved momentum distribution, based on sweeping the beam in a circular pattern and recording the beam size on a screen using optical transition radiation. We present the algorithm to extract the time-resolved momentum distribution, together with simulation results to prove its applicability.
	Slides MOCL3 [2.984 MB]

MOPC03	Overview of the ESS-Bilbao Mobile Diagnostics Test Stand	ESS, rfq, emittance, diagnostics	45
	D. Belver, I. Arredondo, I. Bustinduy, P. Echevarria, J. Feuchtwanger, Z. Izaola, J. Ortega Mintegui, S. Varnasseri ESS Bilbao, Zamudio, Spain
	A MObile diagnostics Test Stand (MOTS) is being designed at ESS-Bilbao in order to characterize the beam at the end of the Radio Frequency Quadrupole (RFQ) at 3 MeV. Injection of the beam from the RFQ to the Drift Tube Linac (DTL) tank and acceleration up to 12 MeV is a sensitive operation in the accelerating chain. The output beam of the RFQ should be fully characterized and tuned to optimize this operation. To perform this characterization the MOTS is being designed with a set of diagnostics devices to measure also beam parameters after the Medium Energy Beam Transport (MEBT), and with minor modifications after the first tank of the DTL. The most important beam parameters that will be measured with the test stand are the beam current, the beam energy and the energy spread. Other important parameters are the beam emittance, the transverse beam position and the profile and bunch length. This contribution describes the beam properties that will be measured and the corresponding instrumentation devices, and presents a general layout of the MOTS.
	Poster MOPC03 [1.146 MB]

MOPC07	Design Considerations for a New Beam Diagnostics for Medical Electron Accelerators	electron, diagnostics, controls, emittance	60
	D. Vlad Siemens AG Healthcare, H CP CV - Components and Vacuum, Erlangen, Germany M. Hänel Siemens Healthcare, Erlangen, Germany
	A new beam diagnostics system is under construction at the Siemens Healthcare Sector facility in Rudolstadt, Germany. The project goal is to develop, commission and operate a beam diagnostics system to characterize the compact medical linear electron accelerators and help improve the quality of their output beam. A brief system description together with the main electron beam parameters is given. The diagnostics will allow the characterization of the compact linear accelerators by measuring beam intensity/charge using a toroid, transverse beam profile using scintillating screens and transverse beam emittance by means of the quadrupole scan method. In the longitudinal plane the energy and energy spread will be determined using a spectrometer magnet.

MOPC29	Realization of Transverse Feedback System for SIS18/100 using FPGA	feedback, BPM, controls, FIR	128
	T. Rueckelt Technische Universität Darmstadt (TU Darmstadt), Signal Processing Group, Darmstadt, Germany M. Alhumaidi, T. Rueckelt, A.M. Zoubir TU Darmstadt, Darmstadt, Germany
	Higher beam intensities in particle accelerator are usually prevented by beam instabilities. To cure these instabilities, additional active system must be used besides passive damping. For this purpose, we have developed a distributed low-latency Transverse Feedback System (TFS) using FPGAs. Data acquisition takes place on multiple BPMs with individual FPGAs and ADCs around the accelerator ring. Acquired data is compressed and sent over broadband fiber optic wires to a central unit. For synchronization, data is tagged using timestamps from a reference time, which is distributed by a specially constrained network time protocol to obtain cycle accuracy. The central unit provides an FIR filter for system bandwidth limitation, and an adaptive IIR filter for stable beam signal rejection. Feedback is given using a linear combination of the pre-processed BPM signals. The system provides substantial flexibility, due to the possibility to configure most parameters online. Filters, feedback sources and parameters, compression rate and more can be adapted via Ethernet interface, which also supplies analysis data. First results are shown.
	Poster MOPC29 [1.842 MB]

MOPC31	Streak Camera Imaging at ELSA	ELSA, feedback, longitudinal, synchrotron	132
	M.T. Switka, W. Hillert, M. Schedler, S. Zander ELSA, Bonn, Germany
	Funding: Funded by the DFG within SFB/TR 16 The Electron Stretcher Facility ELSA provides polarized electrons with energies up to 3.2 GeV for external hadron experiments. In order to suffice the need of stored beam currents towards 200 mA, studies of instabilities and the effect of adequate countermeasures are essential for appropriate machine settings. For this purpose a new diagnostic beamline has been constructed. It is optimized for transverse and longitudinal streak camera measurements with time resolution down to one picosecond. Operation of the diagnostic beamline has recently started and first measurements are presented.

MOPC37	Longitudinal Bunch Profile Reconstruction Using Broadband Coherent Radiation at FLASH	radiation, longitudinal, electron, laser	154
	E. Hass Uni HH, Hamburg, Germany C. Behrens, C. Gerth, B. Schmidt, M. Yan DESY, Hamburg, Germany S. Wesch HZB, Berlin, Germany
	The required high peak current in free-electron lasers is realized by longitudinal compression of the electron bunches to sub-picosecond length. Measurement of the absolute spectral intensity of coherent radiation emitted by an electron bunch allows monitoring and reconstruction of the longitudinal bunch profile. To measure coherent radiation in the teraherz and infrared range a in-vacuum coherent radiation intensity spectrometer was developed for the free-electron laser in Hamburg(FLASH). The spectrometer is equipped with five consecutive dispersion gratings and 120 parallel readout channels: it can be operated either in short (5-44 um) or in long wavelength mode (45-430 um). Fast parallel readout permits the monitoring of coherent radiation from single electron bunches. Large wavelength coverage and superb absolute calibration of the device allows reconstruction of the longitudinal bunch profile using Kramers-Kronig based phase retrieval technique. The device is used as a bunch length monitor and tuning tool during routine operation at FLASH. Comparative measurements with radio-frequency transverse deflecting structure show excellent agreement of both methods.

MOPC42	Novel Pickup for Bunch Arrival Time Monitor	pick-up, LEFT, simulation, laser	170
	A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	For an optical-modulator-based BAM, main parameter of the pickup output signal is slope steepness. We suggest a novel pickup with flat thin electrodes in a transverse gap. Increasing the electrode width makes the steepness greater in the same extent as the signal increases. For a given width, reducing the electrode thickness allows to reach ultimate steepness. Wave processes in the pickup were investigated on a large scale model, using the technique described in . The DESY 40GHz button pickup was used as a reference. It is shown that steepness of the flat electrode pickup can be achieved two times greater. It is also shown that a BAM electrode pickup has a remarkable feature: the steepness does not depend on electrode sizes, if the ratio w/G (a flat electrode pickup, the width and gap length) or d/D (a button pickup, the diameters) is kept constant. This makes pickup bandwidth that is of the order of c over 2G or 2D, a free parameter. For flat electrode pickup, the steepness can be kept as high with transition to a more practical bandwidth 20GHz. The investigation results are the base for a final pickup optimisation using electrodynamic simulation. A. Kalinin, “Pickup Electrode Electrodynamics Investigation”, WEPC26, this conference
	Poster MOPC42 [0.549 MB]

MOPF01	Transverse Beam Size Measurements Using Interferometry at ALBA	vacuum, synchrotron, dipole, radiation	193
	U. Iriso, L. Torino CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain T.M. Mitsuhashi KEK, Ibaraki, Japan
	Double-slit interferometry using visible light has been used for measuring the transverse beam size in different accelerators. The beam size is inferred from the analysis of the spatial coherence of the synchrotron light produced by a bending magnet. At ALBA, this technique has been implemented with moderate success, mainly limited by the present imperfections in the in-vacuum mirror that is used to extract the light out of the vacuum chamber. In this paper, we report the results obtained with the current set-up, and discuss possible improvements.

MOPF10	Off-Axis Undulator Radiation for CLIC Drive Beam Diagnostics	undulator, radiation, CLIC, electron	228
	A. Jeff, T. Lefèvre CERN, Geneva, Switzerland A. Jeff, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom A. Jeff, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	The Compact LInear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 10¹⁵ electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. In this paper we propose the use of relatively inexpensive permanent-magnet undulators to generate off-axis visible Synchrotron Radiation from the CLIC Drive Beam. The field strength and period length of the undulator should be designed such that the on-axis undulator wavelength is in the ultra-violet. A smaller but still useable amount of visible light is then generated in a hollow cone. This light can be reflected out of the beam pipe by a ring-shaped mirror placed downstream and imaged on a camera. In this contribution, results of SRW and ZEMAX simulations using the CLIC Drive Beam parameters are shown.

MOPF14	Scintillation Screen Response to Heavy Ion Impact	ion, GSI, UNILAC, radiation	235
	E. Gütlich, O.K. Kester IAP, Frankfurt am Main, Germany P. Forck, O.K. Kester GSI, Darmstadt, Germany
	For quantitative transverse ion beam profile measurement, imaging properties of scintillation screens have been investigated for the working conditions of the GSI linear accelerator. In the ion energy range between 4.8 and 11.4 MeV/u the imaging properties of the screens are compared with profiles obtained using standard techniques like SEM grids and scraper. Detailed investigations with e.g. Calcium and Argon ion beams on various radiation-hard materials show that the measured beam profiles can differ from those measured with standard methods and depend on several beam and material parameters . For the practical usage of scintillators, it is necessary to have predictions for the response of the scintillator to a given ion beam. An existing model for the light output of scintillators for single particle irradiation has been extended to include the effect of overlapping excitation tracks. To validate the model, dedicated measurements with well-defined Carbon and Titanium ion beams at 11.4 MeV/u have been carried out. To understand the mechanisms, the beam flux and the pulse length has been varied. The measured light yield is compared to the model calculations. E. Gütlich et al., “Scintillation screen studies for high dose ion beam applications”, IEEE Transactions on Nuclear Science, Vol. 59, No. 5, October 2012, pp. 2354 – 2359.
	Poster MOPF14 [0.818 MB]

MOPF16	Sub-Micrometre Resolution Laserwire Transverse Beam Size Measurement System	laser, electron, OTR, photon	243
	L.J. Nevay JAI, Egham, Surrey, United Kingdom A.S. Aryshev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan S.T. Boogert, P. Karataev, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom L. Corner, R. Walczak Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	The laserwire system at the Accelerator Test Facility 2 (ATF2) is a transverse beam profile measurement system capable of measuring a micrometre-size electron beam. We present recent results demonstrating a measured vertical size of 1.16 ± 0.06 μm and a horizontal size of 110.1 ± 3.8 μm. Due to the high aspect ratio of the electron beam, the natural divergence of the tightly focussed laser beam across the electron beam width requires the use of the full overlap integral to deconvolve the scans. For this to be done accurately, the propagation of the 150 mJ, 167 ps long laser pulses was precisely measured at a scaled virtual interaction point.

MOPF22	The Effect of Space Charge Along the Tomography Section at PITZ	space-charge, PITZ, emittance, simulation	255
	G. Kourkafas, M. Khojoyan, M. Krasilnikov, D. Malyutin, B. Marchetti, M. Otevřel, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria
	The Photo Injector Test facility at DESY, Zeuthen site (PITZ) focuses on testing, characterizing and optimizing high brightness electron sources for free electron lasers. Among various diagnostic tools installed at PITZ, the tomography module is used to reconstruct the transverse phase-space distribution of the electron beam by capturing its projections while rotating in the normalized phase space. This technique can resolve the two transverse planes simultaneously with an improved signal-to-noise ratio, allowing measurements of individual bunches within a bunch train with kicker magnets. The low emittance, high charge density and moderate energy of the electron bunch at PITZ contribute to significant space-charge forces which induce mismatches to the reconstruction procedure. This study investigates how the phase-space transformations and thus the reconstruction result are affected when considering linear and non-linear self-fields along the tomography section for the design Twiss parameters. The described analysis proposes a preliminary approach for including the effect of space charge in the tomographic reconstruction at PITZ.
	Poster MOPF22 [1.312 MB]

TUCL3	Gas Electron Multipliers Versus Multi Wire Proportional Chambers	CERN, electron, antiproton, ion	342
	S.C. Duarte Pinto Delft University of Technology, Opto-electronic Section, Delft, The Netherlands J. Spanggaard CERN, Geneva, Switzerland
	Gas Electron Multiplication technology is finding more and more applications in beam instrumentation and at CERN these detectors have recently been adapted for use in transverse profile measurements at several of our facilities. In the experimental areas of CERN’s Antiproton Decelerator, low energy Gas Electron Multipliers successfully replaced all Multi-Wire Proportional Chambers in 2012 and another detector type has now been developed for high energy applications in the experimental areas of the SPS, totalling a potential of more than a hundred profile detectors to be replaced by GEM detectors of different types. This paper aims to describe the historical evolution of GEM technology by covering the many different applications but with specific focus on its potential to replace Multi-Wire Proportional Chambers for standard transverse profile measurement.
	Slides TUCL3 [3.275 MB]

TUPC11	Beam-Based Measurement of ID Taper Impedance at Diamond	impedance, vacuum, simulation, BPM	380
	V.V. Smaluk, R. Bartolini, R.T. Fielder, G. Rehm Diamond, Oxfordshire, United Kingdom
	New insertion devices (IDs) are being designed now for a Diamond upgrade. One of the important topics of the design is the coupling impedance of the ID vacuum chamber movable tapers. To get a complete and reliable information of the impedance, analytical estimations, numerical simulation and beam-based measurement have been performed. The impedance of an existing ID taper geometrically similar to the new one has been measured using the orbit bump method. It turns out that in spite of the small magnitude (a few um) of orbit distortion to be observed in this case, the BPM resolution is sufficient for this measurement. The measurement results in comparison with simulation data are discussed in this paper.

TUPC39	Dispersive Fourier-Transform Electrooptical Sampling for Single-Shot Modulation Measurement in a Proton-Driven Plasma Wakefield Accelerator	proton, plasma, laser, radiation	467
	O. Reimann MPI-P, München, Germany R. Tarkeshian MPI, Muenchen, Germany
	The concept of proton-driven plasma wakefield acceleration has recently been proposed as a means of accelerating a bunch of electrons to high energies with very high gradients, and a demonstration experiment (AWAKE) at CERN is now under development. For this a clear understanding of the temporal and spatial modulation of the proton driver bunches after propagating the plasma channel is essential. A single-shot electrooptical sampling system using dispersive Fourier-transform exploiting transverse coherent transition radiation* is proposed here to determine the bunch modulation and field properties in the frequency domain. Frequencies up to the terahertz region with a resolution of less than 10 GHz are measurable. The system with a closed optical fiber path is based on a semiconductor laser source to achieve easy handling and robustness. The principle idea, estimations of the required sensitivity, and first experimental results are presented. * Pukhov, A. et al. Phys. Rev.ST Accel. Beams 15 (2012)

TUPF07	Covariance and Temporal Causality in the Transition Radiation Emission by an Electron Bunch	electron, radiation, longitudinal, ITY	511
	G.L. Orlandi PSI, Villigen PSI, Switzerland
	A model of the transition radiation emission by a N electron bunch must conform to covariance and causality. The covariance of the charge density must imprint the transition radiation energy spectrum via a proper formulation of the charge form factor. The emission phases of the radiation pulse must be causality correlated with the temporal sequence of the N electron collisions onto the metallic screen. Covariance and temporal causality are the two faces of the same coin: failing in implementing one of the two constraints into the model necessarily implies betraying the other one. The main formal aspects of a covariance and temporal-causality consistent formulation of the transition radiation energy spectrum by an N electron beam are here described. In the case of a transition radiator with a round surface, explicit formal results are presented.

TUPF08	Characterization of Compressed Bunches in the SwissFEL Injector Test Facility	longitudinal, electron, simulation, acceleration	515
	G.L. Orlandi, M. Aiba, F. Baerenbold, S. Bettoni, B. Beutner, H. Brands, P. Craievich, F. Frei, R. Ischebeck, E. Prat, T. Schietinger, V. Schlott PSI, Villigen PSI, Switzerland
	The quality of the beam transverse emittance at the cathode and the uniformity of the longitudinal compression of the electron bunch are essential for the lasing efficiency of a Free Electron Laser. In SwissFEL the longitudinal compression of the electron beam is performed by means of two magnetic chicanes and an off-crest acceleration scheme. The curvature induced on the beam longitudinal phase-space during the compression can be compensated by means of an X-band cavity. The beam longitudinal phase-space can be experimentally characterized by means of a Transverse Deflecting Cavity (TDC) and a profile monitor in a dispersive section. Longitudinal phase-space measurements at the SwissFEL Injector Test Facility under compression with and without X-band linearizer are presented. In addition, energy spread measurements done by monitoring the Synchrotron Radiation (SR) emitted by the electron beam in the dispersive section of the chicane are shown. A comparison with numerical simulations is presented.

TUPF10	A Non-Intercepting Beam Emittance Measurement Device Based on Neutral Beam Fluorescence Method at PKU	emittance, ion, ion-source, dipole	522
	S.X. Peng, J. Chen, Z.Y. Guo, H.T. Ren, Y. Xu, J. Zhao PKU, Beijing, People's Republic of China J.E. Chen, A.L. Zhang Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China L.T. Sun, H.W. Zhao IMP, Lanzhou, People's Republic of China
	A new concept to attain ion beam emmitance through measuring the forward neutral beam without intercepting the beam transportion was proposed at PKU. The forward neutral beam produced by space charge compensation and separated from the transporting ion beam with the help of a deflecting magnetic field, carries the entire emittance information of the original particle beam and becomes a fast and non-interceptive beam diagnostic tool. This idea was tested on PKU ion source test bench and the experimental results show that the neutral beam fluorescence method is feasible. Bases on these qualification results, a formal non-intercepting emittance measurement device was designed. It is a 90 degree full-scale dipole analysis magnet combining with the classical pepper-pot technique. Test and commissioning of the device are in progress. Details of design and comnissioning results will be presented in this paper.

TUPF22	Beam Halo Monitor Based on an HD Digital Micro Mirror Array	controls, laser, monitoring, radiation	557
	B.B.D. Lomberg, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom B.B.D. Lomberg, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work is supported by the European Union under contract PITN-GA-2011-289485 and by STFC under the Cockcroft Institute Core Grant No. ST/G008248/1. A beam halo monitor is an essential device to pursue studies of halo particles produced in any particle accelerator as to investigate the effects of disturbances, such as field kicks, gradient errors, etc. A fast, least intrusive, high dynamic range monitor will allow the detection and potentially control of particles at the tail of a transverse beam distribution. Light generated by a beam of charged particles is routinely used for beam diagnostic purposes. A halo monitor based on a digital micro-mirror device (DMD) used to generate an adaptive optical mask to block light in the core of the emitted light profile and hence limit observation to halo particles has been developed in close collaboration with CERN and University of Maryland. In this contribution an evolution of this monitor is presented. A high definition micro-mirror array with 1920x1080 pixels has been embedded into a MATLAB-based control system, giving access to even higher monitor resolution. A masking algorithm has also been developed that automates mask generation based on user-definable thresholds, converts between CCD and DMD geometries, processes and analyses the beam halo signal and is presented in detail.
	Poster TUPF22 [1.558 MB]

TUPF29	Tune Measurement from Transverse Feedback Signals in LHC	feedback, LHC, damping, CERN	579
	F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch CERN, Geneva, Switzerland P. Albuquerque HES-SO//Geneva, Geneva, Switzerland
	We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.
	Poster TUPF29 [1.052 MB]

WEAL2	Extremely Low Emittance Beam Size Diagnostics with Sub-Micrometer Resolution Using Optical Transition Radiation	OTR, laser, vacuum, electron	615
	K.O. Kruchinin, S.T. Boogert, P. Karataev, L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom A.S. Aryshev, M.V. Shevelev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan B. Bolzon The University of Liverpool, Liverpool, United Kingdom B. Bolzon, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland
	Transverse electron beam diagnostics is crucial for stable and reliable operation of the future electron-positron linear colliders such as CLIC or Higgs Factory. The-state-of-the-art in transverse beam diagnostics is based on the laser-wire technology. However, it requires a high power laser significantly increases the cost of the laser-wire system. Therefore, a simpler and relatively inexpensive method is required. A beam profile monitor based on Optical Transition Radiation (OTR) is very promising. The resolution of conventional OTR monitor is defined by a root-mean-square of the so-called Point Spread Function (PSF). In optical wavelength range the resolution is diffraction limited down to a few micrometers. However, in * we demonstrated that the OTR PSF has a structure which visibility can be used to monitor vertical beam size with sub-micrometer resolution. In this report we shall represent the recent experimental results of a micron-scale beam size measurement. We shall describe the entire method including calibration procedure, new analysis, and calculation of uncertainties. We shall discuss the hardware status and future plans. * P. Karataev et al., Physical Review Letters 107, 174801 (2011).
	Slides WEAL2 [5.120 MB]

WEPC10	Capability Upgrade of the Diamond Transverse Multibunch Feedback	feedback, DIAMOND, controls, FIR	682
	M.G. Abbott, G. Rehm, I.S. Uzun Diamond, Oxfordshire, United Kingdom
	We describe an upgrade to the Transverse Multi-Bunch Feedback processor used at Diamond for control of multi-bunch instabilities and measurement of betatron tunes. The new system will improve both feedback and diagnostic capabilities. Bunch by bunch selectable control over feedback filters, gain and excitation will allow finer control over feedback, allowing for example the single bunch in a hybrid or camshaft fill pattern to be controlled independently from the bunch train. It will also be possible to excite all bunches at a single frequency while simultaneously sweeping the excitation for tune measurement of a few selected bunches. The single frequency excitation can be used for bunch cleaning or continuous measurement of the beta-function. A simple programmable event sequencer will provide support for up to 8 steps of programmable sweeps and changes to feedback and excitation, allowing a variety of complex and precisely timed beam characterisation experiments including grow-damp measurements in unstable conditions.
	Poster WEPC10 [0.427 MB]

WEPC12	Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System	pick-up, SPS, feedback, coupling	690
	G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle CERN, Geneva, Switzerland
	The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.

WEPC15	Development of the Beam Position Monitors System for the LINAC of SPIRAL2	BPM, linac, SPIRAL2, ion	702
	P. Ausset, M. Ben Abdillah, J. Lesrel, E. Marius IPN, Orsay, France T. Ananthkrishnan, S.K. Bharade, G. Joshi, P.D. Motiwala, C.K. Pithawa BARC, Trombay, Mumbai, India V. Nanal, R.G. Pillay TIFR, Mumbai, India
	The SPIRAL 2 facility will deliver stable heavy ion and deuteron beams at very high intensity, producing and accelerating light and heavy rare ion beams. The driver will accelerate between 0.15mA and 5 mA deuteron beam up to 20 MeV/u and q/A=1/3 heavy ions up to 14.5 MeV/u. It is being built on the site of the Grand Accelerator National d’Ions Lourds at CAEN (France) The accurate tuning of the LINAC is essential for the operation of SPIRAL2 and requires from the Beam Position Monitor (BPM) system the measurements of the beam transverse position, the phase of the beam with respect to the radiofrequency voltage and the beam energy. This paper addresses the advancement made during the last twelve months on the realization of the 22 BPM required for the SPIRAL 2 LINAC. The BPM sensors are now completed and tested. The design of the acquisition card for the BPM is given and will be described. The prototype card is now under test and the first results are given. The aim is to verify the main parameters: sensitivity, position and phase measurement and the appropriate behavior of the BPM acquisition card in all cases (pulsed, electrode signal reconstruction, interlock, post mortem)

WEPC26	Pickup Electrode Electrodynamics Investigation	pick-up, LEFT, impedance, vacuum	742
	A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Waves induced in a pickup by beam were investigated on a large scale model, using 10ps step in coaxial line as beam, and a differentiating capacitive probe. The probe signal was observed at 20GHz oscilloscope. In each of the front and rear transverse gaps between pickup electrode and wall (button pickup), a shorter-than-gap bunch excites a ‘plain-wave’ packet which length is of the order of gap length over c. Two packets are spaced by electrode length over c. The packets propagate along the electrode to a coaxial connector. At this low impedance common point each of the packets partially reflects back and partially passes into the opposite gap. The voltage appearing on the impedance excites two TEM-wave packets: one propagates backwards, another one propagates forward through connector. The connector output is sum of two such packets spaced the same as two incident packets. The packets propagating backwards reflect from the electrode open end, come back to the summing point and generate output in similar way. The same processes occur in a pickup with single gap electrodes (stripline pickup). This phenomenological picture can be used as a guide in pickup design and simulation.
	Poster WEPC26 [0.647 MB]

WEPC28	Bunch By Bunch Transverse Beam Position Observation and Analyze During Injection at SSRF	injection, kicker, betatron, storage-ring	746
	Y.B. Leng, Y.B. Yan, Y. Yang, R.X. Yuan, N. Zhang SSRF, Shanghai, People's Republic of China
	Funding: Work supported by National Science Foundation of China (No. 11075198) Top-up operation has been performed at SSRF since Dec. 2012. Orbit disturbance every 10 minutes decreased the quality of synchrotron radiation. In order to minimize this disturbance the tilts and the timing of injection kickers need to be tuning carefully based on real beam information. A set of button type pick-up and a scope based IOC were employed to capture the transient beam movement with bunch by bunch rate during injection. Several sets of observation and analyze will be discussed in this paper.

WEPC36	Development of Electron Bunch Compression Monitors for SwissFEL	electron, radiation, longitudinal, synchrotron	769
	F. Frei, B. Beutner, I. Gorgisyan, R. Ischebeck, G.L. Orlandi, P. Peier, E. Prat, V. Schlott, B. Smit PSI, Villigen PSI, Switzerland P. Peier DESY, Hamburg, Germany
	SwissFEL will be a hard x-ray fourth generation light source to be built at Paul Scherrer Institut (PSI), Switzerland. In SwissFEL the electron bunches will be produced with a length of 3ps and will then be compressed by a factor of more than 1000 down to a few fs in order to generate ultra short x-ray pulses. Therefore reliable, accurate and noninvasive longitudinal diagnostic is essential after each compressing stage. In order to meet the requirements of this machine, new monitors have to be developed. We will present recent results of setups that measure electro-magnetic radiation, namely edge, synchrotron and diffraction radiation, emitted by the electron bunches (far field, spectral domain). These monitors are tested in the SwissFEL Injector Test Facility. A state of the art S-band Transverse Deflecting Cavity together with a Screen Monitor is used for calibration.

WEPF03	Scintillating Screen Monitors for Transverse Electron Beam Profile Diagnostics at the European XFEL	electron, XFEL, OTR, DESY	807
	Ch. Wiebers, M. Holz, G. Kube, D. Nölle, G. Priebe, H.-Ch. Schröder DESY, Hamburg, Germany
	Transverse beam profile diagnostics in modern electron linear accelerators like FELs or injector LINACs are mainly based on optical transition radiation (OTR) as standard technique which is observed in backward direction when a charged particle beam crosses the boundary between two media with different dielectric properties. The experience from modern LINAC based 4th generation light sources shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. As a consequence, for the European XFEL which is currently under construction in Hamburg, transverse beam profile measurements are based on scintillating screen monitors. The LYSO:Ce screens are oriented such that coherent OTR generated at the screen boundaries will be geometrically suppressed. An additional advantage is that the imaging optics operate in Scheimpflug condition thus adjusting the plane of sharp focus with respect to the CCD chip and significantly increasing the apparent depth of field. This report gives an overview of the measuring principle and the monitor setup together with results of laboratory test measurements and a first prototype test at FLASH (DESY, Hamburg).

WEPF09	Profile and Emittance Measurements at the CERN LINAC-4 3 MeV Test Stand	emittance, linac, rfq, CERN	826
	F. Zocca, E. Bravin, M. Duraffourg, G.J. Focker, D. Gerard, U. Raich, F. Roncarolo CERN, Geneva, Switzerland
	A new 160 MeV H⁻ Linac named Linac-4 will be built at CERN to replace the old 50 MeV proton Linac. The ion source, the 3 MeV RFQ and the medium energy transport (MEBT) hosting a chopper, have been commissioned in a dedicated test stand. Wire grids and wire scanners were used to measure the transverse beam profile and a slit/grid emittance meter was installed on a temporary test bench plugged at the RFQ and MEBT exit in different stages. The emittance meter slit was also used as a scanning scraper able to reconstruct the transverse profile by measuring the transmission with a downstream current transformer. On the same measurement bench, a spectrometer in conjunction with a wire grid allowed measuring the energy spread of the particles. This paper summarizes the measurement results that allowed characterizing the 3 MeV beam and discusses the present understanding of monitor performance.

WEPF23	Beam Diagnostics R&D within oPAC	radiation, diagnostics, OTR, simulation	864
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: oPAC is funded by the European Commission under Grant Agreement Number 289485. Optimization of particle accelerators by combining research into beam physics, beam instrumentation, accelerator control systems and numerical simulation studies is the goal of the oPAC project. Supported with 6 Million Euros by the European Union, the network is one of the largest-ever Initial Training Networks. During the project's four year duration 22 fellows will be trained and a very broad international training program, consisting of schools, topical workshops and conferences will be organized by a consortium of currently more than 30 partner institutions. In this contribution, we will give an overview of oPAC's broad beam diagnostics R&D program, comprising absolute beam intensity measurements for low energy beams, beam diagnostics for synchrotron light sources, cyrogenic beam loss monitors, beam halo monitoring and 3D dose measurements as part of intensity modulated radiotherapy treatment. We will also summarize past oPAC events and give an outlook on future events.

Paper

Title

Other Keywords

Page

MOBL1

Instrumentation and Results from the SwissFEL Injector Test Facility

radiation, diagnostics, electron, laser

12

R. Ischebeck, V.R. Arsov, S. Bettoni, B. Beutner, M.M. Dehler, A. Falone, F. Frei, I. Gorgisyan, Ye. Ivanisenko, P.N. Juranic, B. Keil, F. Löhl, G.L. Orlandi, M. Pedrozzi, P. Pollet, E. Prat, T. Schietinger, V. Schlott, B. Smit
PSI, Villigen PSI, Switzerland
P. Peier
DESY, Hamburg, Germany

The SwissFEL Injector Test Facility (SITF) has been equipped with numerous prototype diagnostics (BPMs, screen monitors, wire scanners, optical synchrotron radiation monitor, compression (THz) monitor, bunch arrival time monitor, EO spectral decoding monitor, charge and loss monitor) specifically designed for the low charge SwissFEL operation modes. The design of the diagnostics systems and recent measurement results will be presented.

Slides MOBL1 [35.165 MB]

MOCL3

Emittance and Momentum Diagnostics for Beams with Large Momentum Spread

quadrupole, CLIC, emittance, diagnostics

37

M. Olvegård, V.G. Ziemann
Uppsala University, Uppsala, Sweden

In the drive beam complex of CLIC, but also in plasma wakefield accelerators, the momentum spread can be on the order of tens of percent while conventional diagnostic methods often assume a very small momentum spread. This leads to systematic misinterpretations of the measurements. Spectrometry and emittance measurements based on quadrupole scan rely on measuring the beam size, which depends on the beam envelope. This, in turn, depends on the momentum distribution. We have studied the systematic errors that arise and developed novel algorithms to correctly analyze these measurements for arbitrary momentum distributions. As an application we consider the CLIC drive beam decelerator, where extraction of up to 90% of the kinetic energy leads to a very large momentum spread. We study a measurement of the time-resolved momentum distribution, based on sweeping the beam in a circular pattern and recording the beam size on a screen using optical transition radiation. We present the algorithm to extract the time-resolved momentum distribution, together with simulation results to prove its applicability.

Slides MOCL3 [2.984 MB]

MOPC03

Overview of the ESS-Bilbao Mobile Diagnostics Test Stand

ESS, rfq, emittance, diagnostics

45

D. Belver, I. Arredondo, I. Bustinduy, P. Echevarria, J. Feuchtwanger, Z. Izaola, J. Ortega Mintegui, S. Varnasseri
ESS Bilbao, Zamudio, Spain

A MObile diagnostics Test Stand (MOTS) is being designed at ESS-Bilbao in order to characterize the beam at the end of the Radio Frequency Quadrupole (RFQ) at 3 MeV. Injection of the beam from the RFQ to the Drift Tube Linac (DTL) tank and acceleration up to 12 MeV is a sensitive operation in the accelerating chain. The output beam of the RFQ should be fully characterized and tuned to optimize this operation. To perform this characterization the MOTS is being designed with a set of diagnostics devices to measure also beam parameters after the Medium Energy Beam Transport (MEBT), and with minor modifications after the first tank of the DTL. The most important beam parameters that will be measured with the test stand are the beam current, the beam energy and the energy spread. Other important parameters are the beam emittance, the transverse beam position and the profile and bunch length. This contribution describes the beam properties that will be measured and the corresponding instrumentation devices, and presents a general layout of the MOTS.

Poster MOPC03 [1.146 MB]

MOPC07

Design Considerations for a New Beam Diagnostics for Medical Electron Accelerators

electron, diagnostics, controls, emittance

60

D. Vlad
Siemens AG Healthcare, H CP CV - Components and Vacuum, Erlangen, Germany
M. Hänel
Siemens Healthcare, Erlangen, Germany

A new beam diagnostics system is under construction at the Siemens Healthcare Sector facility in Rudolstadt, Germany. The project goal is to develop, commission and operate a beam diagnostics system to characterize the compact medical linear electron accelerators and help improve the quality of their output beam. A brief system description together with the main electron beam parameters is given. The diagnostics will allow the characterization of the compact linear accelerators by measuring beam intensity/charge using a toroid, transverse beam profile using scintillating screens and transverse beam emittance by means of the quadrupole scan method. In the longitudinal plane the energy and energy spread will be determined using a spectrometer magnet.

MOPC29

Realization of Transverse Feedback System for SIS18/100 using FPGA

feedback, BPM, controls, FIR

128

T. Rueckelt
Technische Universität Darmstadt (TU Darmstadt), Signal Processing Group, Darmstadt, Germany
M. Alhumaidi, T. Rueckelt, A.M. Zoubir
TU Darmstadt, Darmstadt, Germany

Higher beam intensities in particle accelerator are usually prevented by beam instabilities. To cure these instabilities, additional active system must be used besides passive damping. For this purpose, we have developed a distributed low-latency Transverse Feedback System (TFS) using FPGAs. Data acquisition takes place on multiple BPMs with individual FPGAs and ADCs around the accelerator ring. Acquired data is compressed and sent over broadband fiber optic wires to a central unit. For synchronization, data is tagged using timestamps from a reference time, which is distributed by a specially constrained network time protocol to obtain cycle accuracy. The central unit provides an FIR filter for system bandwidth limitation, and an adaptive IIR filter for stable beam signal rejection. Feedback is given using a linear combination of the pre-processed BPM signals. The system provides substantial flexibility, due to the possibility to configure most parameters online. Filters, feedback sources and parameters, compression rate and more can be adapted via Ethernet interface, which also supplies analysis data. First results are shown.

Poster MOPC29 [1.842 MB]

MOPC31

Streak Camera Imaging at ELSA

ELSA, feedback, longitudinal, synchrotron

132

M.T. Switka, W. Hillert, M. Schedler, S. Zander
ELSA, Bonn, Germany

Funding: Funded by the DFG within SFB/TR 16
The Electron Stretcher Facility ELSA provides polarized electrons with energies up to 3.2 GeV for external hadron experiments. In order to suffice the need of stored beam currents towards 200 mA, studies of instabilities and the effect of adequate countermeasures are essential for appropriate machine settings. For this purpose a new diagnostic beamline has been constructed. It is optimized for transverse and longitudinal streak camera measurements with time resolution down to one picosecond. Operation of the diagnostic beamline has recently started and first measurements are presented.

MOPC37

Longitudinal Bunch Profile Reconstruction Using Broadband Coherent Radiation at FLASH

radiation, longitudinal, electron, laser

154

E. Hass
Uni HH, Hamburg, Germany
C. Behrens, C. Gerth, B. Schmidt, M. Yan
DESY, Hamburg, Germany
S. Wesch
HZB, Berlin, Germany

The required high peak current in free-electron lasers is realized by longitudinal compression of the electron bunches to sub-picosecond length. Measurement of the absolute spectral intensity of coherent radiation emitted by an electron bunch allows monitoring and reconstruction of the longitudinal bunch profile. To measure coherent radiation in the teraherz and infrared range a in-vacuum coherent radiation intensity spectrometer was developed for the free-electron laser in Hamburg(FLASH). The spectrometer is equipped with five consecutive dispersion gratings and 120 parallel readout channels: it can be operated either in short (5-44 um) or in long wavelength mode (45-430 um). Fast parallel readout permits the monitoring of coherent radiation from single electron bunches. Large wavelength coverage and superb absolute calibration of the device allows reconstruction of the longitudinal bunch profile using Kramers-Kronig based phase retrieval technique. The device is used as a bunch length monitor and tuning tool during routine operation at FLASH. Comparative measurements with radio-frequency transverse deflecting structure show excellent agreement of both methods.

MOPC42

Novel Pickup for Bunch Arrival Time Monitor

pick-up, LEFT, simulation, laser

170

A. Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

For an optical-modulator-based BAM, main parameter of the pickup output signal is slope steepness. We suggest a novel pickup with flat thin electrodes in a transverse gap. Increasing the electrode width makes the steepness greater in the same extent as the signal increases. For a given width, reducing the electrode thickness allows to reach ultimate steepness. Wave processes in the pickup were investigated on a large scale model, using the technique described in *. The DESY 40GHz button pickup was used as a reference. It is shown that steepness of the flat electrode pickup can be achieved two times greater. It is also shown that a BAM electrode pickup has a remarkable feature: the steepness does not depend on electrode sizes, if the ratio w/G (a flat electrode pickup, the width and gap length) or d/D (a button pickup, the diameters) is kept constant. This makes pickup bandwidth that is of the order of c over 2G or 2D, a free parameter. For flat electrode pickup, the steepness can be kept as high with transition to a more practical bandwidth 20GHz. The investigation results are the base for a final pickup optimisation using electrodynamic simulation.
* A. Kalinin, “Pickup Electrode Electrodynamics Investigation”, WEPC26, this conference

Poster MOPC42 [0.549 MB]

MOPF01

Transverse Beam Size Measurements Using Interferometry at ALBA

vacuum, synchrotron, dipole, radiation

193

U. Iriso, L. Torino
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
T.M. Mitsuhashi
KEK, Ibaraki, Japan

Double-slit interferometry using visible light has been used for measuring the transverse beam size in different accelerators. The beam size is inferred from the analysis of the spatial coherence of the synchrotron light produced by a bending magnet. At ALBA, this technique has been implemented with moderate success, mainly limited by the present imperfections in the in-vacuum mirror that is used to extract the light out of the vacuum chamber. In this paper, we report the results obtained with the current set-up, and discuss possible improvements.

MOPF10

Off-Axis Undulator Radiation for CLIC Drive Beam Diagnostics

undulator, radiation, CLIC, electron

228

A. Jeff, T. Lefèvre
CERN, Geneva, Switzerland
A. Jeff, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Jeff, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

The Compact LInear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 10¹⁵ electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. In this paper we propose the use of relatively inexpensive permanent-magnet undulators to generate off-axis visible Synchrotron Radiation from the CLIC Drive Beam. The field strength and period length of the undulator should be designed such that the on-axis undulator wavelength is in the ultra-violet. A smaller but still useable amount of visible light is then generated in a hollow cone. This light can be reflected out of the beam pipe by a ring-shaped mirror placed downstream and imaged on a camera. In this contribution, results of SRW and ZEMAX simulations using the CLIC Drive Beam parameters are shown.

MOPF14

Scintillation Screen Response to Heavy Ion Impact

ion, GSI, UNILAC, radiation

235

E. Gütlich, O.K. Kester
IAP, Frankfurt am Main, Germany
P. Forck, O.K. Kester
GSI, Darmstadt, Germany

For quantitative transverse ion beam profile measurement, imaging properties of scintillation screens have been investigated for the working conditions of the GSI linear accelerator. In the ion energy range between 4.8 and 11.4 MeV/u the imaging properties of the screens are compared with profiles obtained using standard techniques like SEM grids and scraper. Detailed investigations with e.g. Calcium and Argon ion beams on various radiation-hard materials show that the measured beam profiles can differ from those measured with standard methods and depend on several beam and material parameters *. For the practical usage of scintillators, it is necessary to have predictions for the response of the scintillator to a given ion beam. An existing model for the light output of scintillators for single particle irradiation has been extended to include the effect of overlapping excitation tracks. To validate the model, dedicated measurements with well-defined Carbon and Titanium ion beams at 11.4 MeV/u have been carried out. To understand the mechanisms, the beam flux and the pulse length has been varied. The measured light yield is compared to the model calculations.
* E. Gütlich et al., “Scintillation screen studies for high dose ion beam applications”, IEEE Transactions on Nuclear Science, Vol. 59, No. 5, October 2012, pp. 2354 – 2359.

Poster MOPF14 [0.818 MB]

MOPF16

Sub-Micrometre Resolution Laserwire Transverse Beam Size Measurement System

laser, electron, OTR, photon

243

L.J. Nevay
JAI, Egham, Surrey, United Kingdom
A.S. Aryshev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
S.T. Boogert, P. Karataev, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
L. Corner, R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

The laserwire system at the Accelerator Test Facility 2 (ATF2) is a transverse beam profile measurement system capable of measuring a micrometre-size electron beam. We present recent results demonstrating a measured vertical size of 1.16 ± 0.06 μm and a horizontal size of 110.1 ± 3.8 μm. Due to the high aspect ratio of the electron beam, the natural divergence of the tightly focussed laser beam across the electron beam width requires the use of the full overlap integral to deconvolve the scans. For this to be done accurately, the propagation of the 150 mJ, 167 ps long laser pulses was precisely measured at a scaled virtual interaction point.

MOPF22

The Effect of Space Charge Along the Tomography Section at PITZ

space-charge, PITZ, emittance, simulation

255

G. Kourkafas, M. Khojoyan, M. Krasilnikov, D. Malyutin, B. Marchetti, M. Otevřel, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria

The Photo Injector Test facility at DESY, Zeuthen site (PITZ) focuses on testing, characterizing and optimizing high brightness electron sources for free electron lasers. Among various diagnostic tools installed at PITZ, the tomography module is used to reconstruct the transverse phase-space distribution of the electron beam by capturing its projections while rotating in the normalized phase space. This technique can resolve the two transverse planes simultaneously with an improved signal-to-noise ratio, allowing measurements of individual bunches within a bunch train with kicker magnets. The low emittance, high charge density and moderate energy of the electron bunch at PITZ contribute to significant space-charge forces which induce mismatches to the reconstruction procedure. This study investigates how the phase-space transformations and thus the reconstruction result are affected when considering linear and non-linear self-fields along the tomography section for the design Twiss parameters. The described analysis proposes a preliminary approach for including the effect of space charge in the tomographic reconstruction at PITZ.

Poster MOPF22 [1.312 MB]

TUCL3

Gas Electron Multipliers Versus Multi Wire Proportional Chambers

CERN, electron, antiproton, ion

342

S.C. Duarte Pinto
Delft University of Technology, Opto-electronic Section, Delft, The Netherlands
J. Spanggaard
CERN, Geneva, Switzerland

Gas Electron Multiplication technology is finding more and more applications in beam instrumentation and at CERN these detectors have recently been adapted for use in transverse profile measurements at several of our facilities. In the experimental areas of CERN’s Antiproton Decelerator, low energy Gas Electron Multipliers successfully replaced all Multi-Wire Proportional Chambers in 2012 and another detector type has now been developed for high energy applications in the experimental areas of the SPS, totalling a potential of more than a hundred profile detectors to be replaced by GEM detectors of different types. This paper aims to describe the historical evolution of GEM technology by covering the many different applications but with specific focus on its potential to replace Multi-Wire Proportional Chambers for standard transverse profile measurement.

Slides TUCL3 [3.275 MB]

TUPC11

Beam-Based Measurement of ID Taper Impedance at Diamond

impedance, vacuum, simulation, BPM

380

V.V. Smaluk, R. Bartolini, R.T. Fielder, G. Rehm
Diamond, Oxfordshire, United Kingdom

New insertion devices (IDs) are being designed now for a Diamond upgrade. One of the important topics of the design is the coupling impedance of the ID vacuum chamber movable tapers. To get a complete and reliable information of the impedance, analytical estimations, numerical simulation and beam-based measurement have been performed. The impedance of an existing ID taper geometrically similar to the new one has been measured using the orbit bump method. It turns out that in spite of the small magnitude (a few um) of orbit distortion to be observed in this case, the BPM resolution is sufficient for this measurement. The measurement results in comparison with simulation data are discussed in this paper.

TUPC39

Dispersive Fourier-Transform Electrooptical Sampling for Single-Shot Modulation Measurement in a Proton-Driven Plasma Wakefield Accelerator

proton, plasma, laser, radiation

467

O. Reimann
MPI-P, München, Germany
R. Tarkeshian
MPI, Muenchen, Germany

The concept of proton-driven plasma wakefield acceleration has recently been proposed as a means of accelerating a bunch of electrons to high energies with very high gradients, and a demonstration experiment (AWAKE) at CERN is now under development. For this a clear understanding of the temporal and spatial modulation of the proton driver bunches after propagating the plasma channel is essential. A single-shot electrooptical sampling system using dispersive Fourier-transform exploiting transverse coherent transition radiation* is proposed here to determine the bunch modulation and field properties in the frequency domain. Frequencies up to the terahertz region with a resolution of less than 10 GHz are measurable. The system with a closed optical fiber path is based on a semiconductor laser source to achieve easy handling and robustness. The principle idea, estimations of the required sensitivity, and first experimental results are presented.
* Pukhov, A. et al. Phys. Rev.ST Accel. Beams 15 (2012)

TUPF07

Covariance and Temporal Causality in the Transition Radiation Emission by an Electron Bunch

electron, radiation, longitudinal, ITY

511

G.L. Orlandi
PSI, Villigen PSI, Switzerland

A model of the transition radiation emission by a N electron bunch must conform to covariance and causality. The covariance of the charge density must imprint the transition radiation energy spectrum via a proper formulation of the charge form factor. The emission phases of the radiation pulse must be causality correlated with the temporal sequence of the N electron collisions onto the metallic screen. Covariance and temporal causality are the two faces of the same coin: failing in implementing one of the two constraints into the model necessarily implies betraying the other one. The main formal aspects of a covariance and temporal-causality consistent formulation of the transition radiation energy spectrum by an N electron beam are here described. In the case of a transition radiator with a round surface, explicit formal results are presented.

TUPF08

Characterization of Compressed Bunches in the SwissFEL Injector Test Facility

longitudinal, electron, simulation, acceleration

515

G.L. Orlandi, M. Aiba, F. Baerenbold, S. Bettoni, B. Beutner, H. Brands, P. Craievich, F. Frei, R. Ischebeck, E. Prat, T. Schietinger, V. Schlott
PSI, Villigen PSI, Switzerland

The quality of the beam transverse emittance at the cathode and the uniformity of the longitudinal compression of the electron bunch are essential for the lasing efficiency of a Free Electron Laser. In SwissFEL the longitudinal compression of the electron beam is performed by means of two magnetic chicanes and an off-crest acceleration scheme. The curvature induced on the beam longitudinal phase-space during the compression can be compensated by means of an X-band cavity. The beam longitudinal phase-space can be experimentally characterized by means of a Transverse Deflecting Cavity (TDC) and a profile monitor in a dispersive section. Longitudinal phase-space measurements at the SwissFEL Injector Test Facility under compression with and without X-band linearizer are presented. In addition, energy spread measurements done by monitoring the Synchrotron Radiation (SR) emitted by the electron beam in the dispersive section of the chicane are shown. A comparison with numerical simulations is presented.

TUPF10

A Non-Intercepting Beam Emittance Measurement Device Based on Neutral Beam Fluorescence Method at PKU

emittance, ion, ion-source, dipole

522

S.X. Peng, J. Chen, Z.Y. Guo, H.T. Ren, Y. Xu, J. Zhao
PKU, Beijing, People's Republic of China
J.E. Chen, A.L. Zhang
Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
L.T. Sun, H.W. Zhao
IMP, Lanzhou, People's Republic of China

A new concept to attain ion beam emmitance through measuring the forward neutral beam without intercepting the beam transportion was proposed at PKU. The forward neutral beam produced by space charge compensation and separated from the transporting ion beam with the help of a deflecting magnetic field, carries the entire emittance information of the original particle beam and becomes a fast and non-interceptive beam diagnostic tool. This idea was tested on PKU ion source test bench and the experimental results show that the neutral beam fluorescence method is feasible. Bases on these qualification results, a formal non-intercepting emittance measurement device was designed. It is a 90 degree full-scale dipole analysis magnet combining with the classical pepper-pot technique. Test and commissioning of the device are in progress. Details of design and comnissioning results will be presented in this paper.

TUPF22

Beam Halo Monitor Based on an HD Digital Micro Mirror Array

controls, laser, monitoring, radiation

557

B.B.D. Lomberg, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
B.B.D. Lomberg, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work is supported by the European Union under contract PITN-GA-2011-289485 and by STFC under the Cockcroft Institute Core Grant No. ST/G008248/1.
A beam halo monitor is an essential device to pursue studies of halo particles produced in any particle accelerator as to investigate the effects of disturbances, such as field kicks, gradient errors, etc. A fast, least intrusive, high dynamic range monitor will allow the detection and potentially control of particles at the tail of a transverse beam distribution. Light generated by a beam of charged particles is routinely used for beam diagnostic purposes. A halo monitor based on a digital micro-mirror device (DMD) used to generate an adaptive optical mask to block light in the core of the emitted light profile and hence limit observation to halo particles has been developed in close collaboration with CERN and University of Maryland. In this contribution an evolution of this monitor is presented. A high definition micro-mirror array with 1920x1080 pixels has been embedded into a MATLAB-based control system, giving access to even higher monitor resolution. A masking algorithm has also been developed that automates mask generation based on user-definable thresholds, converts between CCD and DMD geometries, processes and analyses the beam halo signal and is presented in detail.

Poster TUPF22 [1.558 MB]

TUPF29

Tune Measurement from Transverse Feedback Signals in LHC

feedback, LHC, damping, CERN

579

F. Dubouchet, W. Höfle, G. Kotzian, T.E. Levens, D. Valuch
CERN, Geneva, Switzerland
P. Albuquerque
HES-SO//Geneva, Geneva, Switzerland

We show how bunch-by-bunch position data from the LHC transverse feedback system can be used to determine the transverse tunes. Results from machine development experiments are presented and compared with theoretical predictions. In the absence of external beam excitations the tune is visible in the spectra of the position data with the feedback loop as a dip, while with external excitation a peak is visible. Both options, observation with and without excitation, are demonstrated to be complementary. Periodic excitation and observation of the free oscillation can also be used to determine the damping time of the feedback in addition to the coherent tune. Plans are outlined for hardware upgrades of the LHC transverse feedback system that will enable fast online processing of bunch-by-bunch, turn-by-turn data using Graphical Processing Units (GPU). By using GPUs we gain the ability to compute and store the spectrum of all bunches in real-time and the possibility to reconfigure test and deploy algorithms. This data acquisition and analysis architecture also allows changes to be made without disturbing the operation.

Poster TUPF29 [1.052 MB]

WEAL2

Extremely Low Emittance Beam Size Diagnostics with Sub-Micrometer Resolution Using Optical Transition Radiation

OTR, laser, vacuum, electron

615

K.O. Kruchinin, S.T. Boogert, P. Karataev, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
A.S. Aryshev, M.V. Shevelev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
B. Bolzon
The University of Liverpool, Liverpool, United Kingdom
B. Bolzon, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland

Transverse electron beam diagnostics is crucial for stable and reliable operation of the future electron-positron linear colliders such as CLIC or Higgs Factory. The-state-of-the-art in transverse beam diagnostics is based on the laser-wire technology. However, it requires a high power laser significantly increases the cost of the laser-wire system. Therefore, a simpler and relatively inexpensive method is required. A beam profile monitor based on Optical Transition Radiation (OTR) is very promising. The resolution of conventional OTR monitor is defined by a root-mean-square of the so-called Point Spread Function (PSF). In optical wavelength range the resolution is diffraction limited down to a few micrometers. However, in * we demonstrated that the OTR PSF has a structure which visibility can be used to monitor vertical beam size with sub-micrometer resolution. In this report we shall represent the recent experimental results of a micron-scale beam size measurement. We shall describe the entire method including calibration procedure, new analysis, and calculation of uncertainties. We shall discuss the hardware status and future plans.
* P. Karataev et al., Physical Review Letters 107, 174801 (2011).

Slides WEAL2 [5.120 MB]

WEPC10

Capability Upgrade of the Diamond Transverse Multibunch Feedback

feedback, DIAMOND, controls, FIR

682

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

We describe an upgrade to the Transverse Multi-Bunch Feedback processor used at Diamond for control of multi-bunch instabilities and measurement of betatron tunes. The new system will improve both feedback and diagnostic capabilities. Bunch by bunch selectable control over feedback filters, gain and excitation will allow finer control over feedback, allowing for example the single bunch in a hybrid or camshaft fill pattern to be controlled independently from the bunch train. It will also be possible to excite all bunches at a single frequency while simultaneously sweeping the excitation for tune measurement of a few selected bunches. The single frequency excitation can be used for bunch cleaning or continuous measurement of the beta-function. A simple programmable event sequencer will provide support for up to 8 steps of programmable sweeps and changes to feedback and excitation, allowing a variety of complex and precisely timed beam characterisation experiments including grow-damp measurements in unstable conditions.

Poster WEPC10 [0.427 MB]

WEPC12

Evaluation of Strip-line Pick-up System for the SPS Wideband Transverse Feedback System

pick-up, SPS, feedback, coupling

690

G. Kotzian, W. Höfle, R.J. Steinhagen, D. Valuch, U. Wehrle
CERN, Geneva, Switzerland

The proposed SPS Wideband Transverse Feedback system requires a wide-band pick-up system to be able to detect intra-bunch motion within the SPS proton bunches, captured and accelerated in a 200 MHz bucket. We present the electro-magnetic design of transverse beam position pick-up options optimised for installation in the SPS and evaluate their performance reach with respect to direct time domain sampling of the intra-bunch motion. The analysis also discusses the achieved subsystem responses of the associated cabling with new low dispersion smooth wall cables, wide-band generation of intensity and position signals by means of 180 degree RF hybrids as well as passive techniques to electronically suppress the beam offset signal, needed to optimise the dynamic range and position resolution of the planned digital intra-bunch feedback system.

WEPC15

Development of the Beam Position Monitors System for the LINAC of SPIRAL2

BPM, linac, SPIRAL2, ion

702

P. Ausset, M. Ben Abdillah, J. Lesrel, E. Marius
IPN, Orsay, France
T. Ananthkrishnan, S.K. Bharade, G. Joshi, P.D. Motiwala, C.K. Pithawa
BARC, Trombay, Mumbai, India
V. Nanal, R.G. Pillay
TIFR, Mumbai, India

The SPIRAL 2 facility will deliver stable heavy ion and deuteron beams at very high intensity, producing and accelerating light and heavy rare ion beams. The driver will accelerate between 0.15mA and 5 mA deuteron beam up to 20 MeV/u and q/A=1/3 heavy ions up to 14.5 MeV/u. It is being built on the site of the Grand Accelerator National d’Ions Lourds at CAEN (France) The accurate tuning of the LINAC is essential for the operation of SPIRAL2 and requires from the Beam Position Monitor (BPM) system the measurements of the beam transverse position, the phase of the beam with respect to the radiofrequency voltage and the beam energy. This paper addresses the advancement made during the last twelve months on the realization of the 22 BPM required for the SPIRAL 2 LINAC. The BPM sensors are now completed and tested. The design of the acquisition card for the BPM is given and will be described. The prototype card is now under test and the first results are given. The aim is to verify the main parameters: sensitivity, position and phase measurement and the appropriate behavior of the BPM acquisition card in all cases (pulsed, electrode signal reconstruction, interlock, post mortem)

WEPC26

Pickup Electrode Electrodynamics Investigation

pick-up, LEFT, impedance, vacuum

742

A. Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Waves induced in a pickup by beam were investigated on a large scale model, using 10ps step in coaxial line as beam, and a differentiating capacitive probe. The probe signal was observed at 20GHz oscilloscope. In each of the front and rear transverse gaps between pickup electrode and wall (button pickup), a shorter-than-gap bunch excites a ‘plain-wave’ packet which length is of the order of gap length over c. Two packets are spaced by electrode length over c. The packets propagate along the electrode to a coaxial connector. At this low impedance common point each of the packets partially reflects back and partially passes into the opposite gap. The voltage appearing on the impedance excites two TEM-wave packets: one propagates backwards, another one propagates forward through connector. The connector output is sum of two such packets spaced the same as two incident packets. The packets propagating backwards reflect from the electrode open end, come back to the summing point and generate output in similar way. The same processes occur in a pickup with single gap electrodes (stripline pickup). This phenomenological picture can be used as a guide in pickup design and simulation.

Poster WEPC26 [0.647 MB]

WEPC28

Bunch By Bunch Transverse Beam Position Observation and Analyze During Injection at SSRF

injection, kicker, betatron, storage-ring

746

Y.B. Leng, Y.B. Yan, Y. Yang, R.X. Yuan, N. Zhang
SSRF, Shanghai, People's Republic of China

Funding: Work supported by National Science Foundation of China (No. 11075198)
Top-up operation has been performed at SSRF since Dec. 2012. Orbit disturbance every 10 minutes decreased the quality of synchrotron radiation. In order to minimize this disturbance the tilts and the timing of injection kickers need to be tuning carefully based on real beam information. A set of button type pick-up and a scope based IOC were employed to capture the transient beam movement with bunch by bunch rate during injection. Several sets of observation and analyze will be discussed in this paper.

WEPC36

Development of Electron Bunch Compression Monitors for SwissFEL

electron, radiation, longitudinal, synchrotron

769

F. Frei, B. Beutner, I. Gorgisyan, R. Ischebeck, G.L. Orlandi, P. Peier, E. Prat, V. Schlott, B. Smit
PSI, Villigen PSI, Switzerland
P. Peier
DESY, Hamburg, Germany

SwissFEL will be a hard x-ray fourth generation light source to be built at Paul Scherrer Institut (PSI), Switzerland. In SwissFEL the electron bunches will be produced with a length of 3ps and will then be compressed by a factor of more than 1000 down to a few fs in order to generate ultra short x-ray pulses. Therefore reliable, accurate and noninvasive longitudinal diagnostic is essential after each compressing stage. In order to meet the requirements of this machine, new monitors have to be developed. We will present recent results of setups that measure electro-magnetic radiation, namely edge, synchrotron and diffraction radiation, emitted by the electron bunches (far field, spectral domain). These monitors are tested in the SwissFEL Injector Test Facility. A state of the art S-band Transverse Deflecting Cavity together with a Screen Monitor is used for calibration.

WEPF03

Scintillating Screen Monitors for Transverse Electron Beam Profile Diagnostics at the European XFEL

electron, XFEL, OTR, DESY

807

Ch. Wiebers, M. Holz, G. Kube, D. Nölle, G. Priebe, H.-Ch. Schröder
DESY, Hamburg, Germany

Transverse beam profile diagnostics in modern electron linear accelerators like FELs or injector LINACs are mainly based on optical transition radiation (OTR) as standard technique which is observed in backward direction when a charged particle beam crosses the boundary between two media with different dielectric properties. The experience from modern LINAC based 4th generation light sources shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. As a consequence, for the European XFEL which is currently under construction in Hamburg, transverse beam profile measurements are based on scintillating screen monitors. The LYSO:Ce screens are oriented such that coherent OTR generated at the screen boundaries will be geometrically suppressed. An additional advantage is that the imaging optics operate in Scheimpflug condition thus adjusting the plane of sharp focus with respect to the CCD chip and significantly increasing the apparent depth of field. This report gives an overview of the measuring principle and the monitor setup together with results of laboratory test measurements and a first prototype test at FLASH (DESY, Hamburg).

WEPF09

Profile and Emittance Measurements at the CERN LINAC-4 3 MeV Test Stand

emittance, linac, rfq, CERN

826

F. Zocca, E. Bravin, M. Duraffourg, G.J. Focker, D. Gerard, U. Raich, F. Roncarolo
CERN, Geneva, Switzerland

A new 160 MeV H⁻ Linac named Linac-4 will be built at CERN to replace the old 50 MeV proton Linac. The ion source, the 3 MeV RFQ and the medium energy transport (MEBT) hosting a chopper, have been commissioned in a dedicated test stand. Wire grids and wire scanners were used to measure the transverse beam profile and a slit/grid emittance meter was installed on a temporary test bench plugged at the RFQ and MEBT exit in different stages. The emittance meter slit was also used as a scanning scraper able to reconstruct the transverse profile by measuring the transmission with a downstream current transformer. On the same measurement bench, a spectrometer in conjunction with a wire grid allowed measuring the energy spread of the particles. This paper summarizes the measurement results that allowed characterizing the 3 MeV beam and discusses the present understanding of monitor performance.

WEPF23

Beam Diagnostics R&D within oPAC

radiation, diagnostics, OTR, simulation

864

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: oPAC is funded by the European Commission under Grant Agreement Number 289485.
Optimization of particle accelerators by combining research into beam physics, beam instrumentation, accelerator control systems and numerical simulation studies is the goal of the oPAC project. Supported with 6 Million Euros by the European Union, the network is one of the largest-ever Initial Training Networks. During the project's four year duration 22 fellows will be trained and a very broad international training program, consisting of schools, topical workshops and conferences will be organized by a consortium of currently more than 30 partner institutions. In this contribution, we will give an overview of oPAC's broad beam diagnostics R&D program, comprising absolute beam intensity measurements for low energy beams, beam diagnostics for synchrotron light sources, cyrogenic beam loss monitors, beam halo monitoring and 3D dose measurements as part of intensity modulated radiotherapy treatment. We will also summarize past oPAC events and give an outlook on future events.