IBIC2013 - List of Keywords (longitudinal)

Paper	Title	Other Keywords	Page
MOPC31	Streak Camera Imaging at ELSA	ELSA, feedback, transverse, 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.

MOPC34	Longitudinal Beam Profile Monitor for Investigating the Microbunching Instability at Diamond Light Source	optics, DIAMOND, radiation, storage-ring	143
	W. Shields, R. Bartolini, A.F.D. Morgan, G. Rehm Diamond, Oxfordshire, United Kingdom R. Bartolini, P. Karataev JAI, Oxford, United Kingdom P. Karataev Royal Holloway, University of London, Surrey, United Kingdom
	An investigation into the microbunching instability at Diamond Light Source has recently been conducted. Beyond the instability threshold, the bunch emits bursts of coherent synchrotron radiation with wavelengths comparable to the bunch length or shorter. The operating conditions for producing the instability include both normal optics, and low-alpha optics, where the bunch length can be shortened to a few picoseconds. A Michelson interferometer has been designed and installed utilising a silicon crystal wafer beamsplitter. Large bandwidth, room temperature pyroelectric detectors and low-noise, fast-response Schottky Barrier diode detectors have been employed to generate interferograms. In this paper, we describe the observed spectral content and the resulting calculated bunch length.

MOPC35	A Beam-Synchronous Gated Peak-Detector for the LHC Beam Observation System	LHC, CERN, injection, synchrotron	147
	T.E. Levens, T. Bohl, U. Wehrle CERN, Geneva, Switzerland
	Measurements of the bunch peak amplitude using the longitudinal wideband wall-current monitor are a vital tool used in the Large Hadron Collider (LHC) beam observation system. These peak-detected measurements can be used to diagnose bunch shape oscillations, for example coherent quadrupole oscillations, that occur at injection and during beam manipulations. Peak-detected Schottky diagnostics can also be used to obtain the synchrotron frequency distribution and other parameters from a bunched beam under stable conditions. For the LHC a beam-synchronous gated peak detector has been developed to allow individual bunches to be monitored without the influence of other bunches circulating in the machine. The requirement for the observation of both low intensity pilot bunches and high intensity bunches for physics requires a detector front-end with a high bandwidth and a large dynamic range while the usage for Schottky measurements requires low noise electronics. This paper will present the design of this detector system as well as initial results obtained during the 2012-2013 LHC run.
	Poster MOPC35 [2.792 MB]

MOPC36	Test of a Non-Invasive Bunch Shape Monitor at GSI High Current LINAC	electron, linac, GSI, MCP	151
	P. Forck, C. Dorn, O.K. Kester, P. Kowina, B. Zwicker GSI, Darmstadt, Germany O.K. Kester IAP, Frankfurt am Main, Germany
	Funding: The work is funded by European Union FP7 within CRISP. At the heavy ion LINAC at GSI, a novel scheme of non-invasive Bunch Shape Monitor has been tested with several ion beams at 11.4 MeV/u. The monitor’s principle is based on the analysis of secondary electrons as liberated from the residual gas by the beam impact. These electrons are accelerated by an electrostatic field, transported through a sophisticated electrostatic energy analyzer and an RF-deflector, acting as a time-to-space converter. Finally a MCP amplifies electrons and with a CCD camera the electron distribution is detected. For the applied beam settings this Bunch Shape Monitor is able to obtain longitudinal profiles down to a width of 400 ps with a resolution of 50 ps, corresponding to 2 degree of the 108 MHz accelerating frequency. Systematic parameter studies for the device were performed to demonstrate the applicability and to determine its resolution. The achievements and ongoing improvements for the monitor are discussed.
	Poster MOPC36 [2.665 MB]

MOPC37	Longitudinal Bunch Profile Reconstruction Using Broadband Coherent Radiation at FLASH	radiation, electron, transverse, 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.

MOPC39	Commissioning of a New Streak Camera at TLS for TPS Project	laser, synchrotron, storage-ring, feedback	159
	C.Y. Liao, M.C. Chou, K.T. Hsu, K.H. Hu, C.H. Kuo, C.-C. Kuo, W.K. Lau, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source which is being construction at campus of National Synchrotron Radiation Research Center (NSRRC) in Taiwan. A new streak camera equipped with a 125/250 MHz synchroscan unit, a fast/slow single sweep unit, and a dual-time sweep unit is prepared for beam diagnostics, especially for the TPS. An ultra short femtosecond Ti-Sapphire laser was used to evaluate the sub-picosecond temporal resolution of the streak camera and the first beam measurements of the streak camera using synchrotron light from the existing 1.5 GeV Taiwan Light Source (TLS) were performed. The commissioning results are summarized in this report.

MOPC40	Measurement of Longitudinal Bunch Profile and Twiss Parameters in SNS LINAC	laser, linac, SCL, SNS	163
	A.V. Aleksandrov, C. Huang, Y. Liu, A.P. Shishlo, A.P. Zhukov ORNL, Oak Ridge, Tennessee, USA
	Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. We are reporting on the latest progress in the longitudinal beam profile and emittance diagnostics development at SNS. In order to characterize the longitudinal phase space of the beam in the SNS 1GeV proton LINAC the bunch profile needs to be measured with a few picosecond resolution. The original SNS set of diagnostics included only four interceptive Feschenko-style longitudinal profile monitors in the normal conducting part of the LINAC at 100MeV. Two recently added systems are: a non-interceptive laser scanner in the injector at 2.5MeV and a novel non-interceptive method for longitudinal Twiss parameters measurement using the beam position monitors in the Super Conducting LINAC (SCL) at 300MeV. This paper presents details of these two diagnostics and discusses their performance, resolution limitations and future development plans.
	Poster MOPC40 [8.865 MB]

MOPF25	Cryogenic Current Comparator as Low Intensity Beam Current Monitor in the CERN Antiproton Decelerators	antiproton, CERN, shielding, cryogenics	267
	M.F. Fernandes, J. Tan CERN, Geneva, Switzerland M.F. Fernandes, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom M.F. Fernandes, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the EU within the oPAC project under contract 289485. In the low-energy Antiproton Decelerator (AD) and the future Extra Low ENergy Antiproton (ELENA) rings at CERN, an absolute measurement of the beam intensity is essential to monitor any losses during the deceleration and cooling phases. However, existing DC current transformers can hardly reach the μA level, while at the AD and ELENA currents can be as low as 100 nA. A Cryogenic Current Comparator (CCC) based on a superconducting quantum interference device (SQUID) is currently being designed and shall be installed in the AD and ELENA machines. It should meet the following specifications: A current resolution smaller than 10 nA, a dynamic range covering currents between 100 nA and 1 mA, as well as a bandwidth from DC to 1 kHz. Different design options are being considered, including the use of low or high temperature superconductor materials, different CCC shapes and dimensions, different SQUID characteristics, as well as electromagnetic shielding requirements. In this contribution we present first results from a comparative analysis of different monitor options, taking into consideration the external electromagnetic sources at the foreseen device locations.
	Poster MOPF25 [1.059 MB]

TUPC07	Design and Impedance Optimization of the SIRIUS BPM Button	BPM, vacuum, impedance, storage-ring	365
	H.O.C. Duarte, S.R. Marques, L. Sanfelici LNLS, Campinas, Brazil
	Design of several BPM Buttons is presented with detail impedance, heat transfer and mechanical analysis. Special attention is given to the application of ceramics as materials with low relative permittivity inside of the BPM Button and to the geometric shape of the BPM Button. The heat dissipation is evaluated based on the loss factor calculated for a 2.65mm bunch length. The narrow-band impedance is discussed and its dependence on applied ceramic materials is compared.
	Poster TUPC07 [1.715 MB]

TUPC08	Design and Impedance Optimization of the LNLS-UVX Longitudinal Kicker Cavity	kicker, impedance, feedback, synchrotron	369
	L. Sanfelici, H.O.C. Duarte, S.R. Marques LNLS, Campinas, Brazil
	Performance evolution of parameters achieved during the electromagnetic design of the longitudinal kicker cavity for the LNLS UVX storage ring is presented. The effort on the electromagnetic optimization process of the heavily loaded cavity has been made to reach the required electrodynamic parameters of the kicker. The results for three different geometries are compared and a good compromise between the longitudinal shunt impedance and the effect of the longitudinal Higher Order Modes (HOM’s) on beam stability has been found.
	Poster TUPC08 [1.365 MB]

TUPC14	Development of a Low-Beta Button BPM for PXIE Project	BPM, simulation, pick-up, beam-position	392
	A. Lunin, N. Eddy, T.N. Khabiboulline, V.A. Lebedev, V.P. Yakovlev Fermilab, Batavia, USA
	The button BPM is under development for a low beta section of the Project X Injector Experiment (PXIE) at Fermilab. The presented paper includes an analytical estimation of the BPM performance as well a direct wakefield simulation with CST Particle Studio (on a hexahedral mesh). In addition we present a novel approach of a low beta beam interaction with BPM electrodes realized with ANSYS HFSS TD-solver on unstructured tetrahedral mesh. Both methods show a good agreement of BPM output signals for various beam parameters. Finally we describe the signal processing scheme and the electronics we are going to use.
	Poster TUPC14 [1.051 MB]

TUPC16	Bunch-by-Bunch Feedback and Diagnostics at BESSY II	feedback, beam-losses, injection, kicker	399
	A. Schälicke, F. Falkenstern, R. Müller HZB, Berlin, Germany
	At the light source BESSY II new digital bunch-by-bunch feedback systems have been put into operation in January 2013, replacing the existing analog as well as the obsolete digital systems. From the first days of operation the new system successfully suppresses transverse and longitudinal beam instabilities in wide range of machine parameters. The system offers also many new diagnostics opportunities, these include the analysis of instability modes, measurement of the feedback loop gain, and determination of the transfer function. A method to systematically optimise the output amplifier response function with the help of shaper coefficients for the optimal bunch separation has been developed. In addition the analysis of the input data stream allows a passive determination of machine properties like betatron and synchrotron frequencies as well as the longitudinal phases for every bunch. The integration of external triggers permits the analysis of postmortem data, the characterisation of beam-loss events, and monitoring of the injection process. In this contribution first operational experience, the developed data analysis techniques and experimental data will be presented.
	Poster TUPC16 [56.767 MB]

TUPC18	Development of a Highly Efficient Energy Kicker for Longitudinal Bunch-by-Bunch Feedback	kicker, synchrotron, electron, storage-ring	407
	M. Masaki, T. Fujita, K. Kobayashi, T. Nakamura, H. Ohkuma, M. Oishi, S. Sasaki, M. Shoji JASRI/SPring-8, Hyogo-ken, Japan
	A highly efficient energy kicker has been developed for longitudinal bunch-by-bunch feedback to suppress synchrotron oscillation of a high-current single electron bunch, and to cure possible longitudinal multi-bunch instability if lower beam energy is to be adopted for emittance reduction and electric power saving in a future upgrade plan of SPring-8. Through the performance test using a prototype kicker, a new water-cooled copper kicker was designed and fabricated, and it has been installed in the storage ring. The new kicker consists of three cells with each cavity length of 96 mm, its resonant frequency of 1.65 GHz, which is 3.25 times of RF frequency of the storage ring, and low Q-factor of 4.2. In beam kick test, the synchrotron oscillation amplitude of 0.64 ps was excited by kick voltage with continuous amplitude modulation at synchrotron frequency when the RF input power was 132 W/3cells. The kick voltage evaluated from the experimental result is 920 V/3cells. Shunt impedance of each kicker cell is estimated as 1.1 kΩ. As we intended, the shunt impedance per length is about three times higher than those of widely used waveguide overloaded cavity type kickers.
	Poster TUPC18 [9.117 MB]

TUPC36	First Realization and Performance Study of a Single-Shot Longitudinal Bunch Profile Monitor Utilizing a Transverse Deflecting Structure	FEL, feedback, kicker, electron	456
	M. Yan, C. Behrens, C. Gerth, R. Kammering, A. Langner, F. Obier, V. Rybnikov DESY, Hamburg, Germany J. Wychowaniak TUL-DMCS, Łódź, Poland
	For the control and optimization of electron beam parameters at modern free-electron lasers (FEL), transverse deflecting structures (TDS) in combination with imaging screens have been widely used as robust longitudinal diagnostics with single-shot capability, high resolution and large dynamic range. At the free-electron laser in Hamburg (FLASH), a longitudinal bunch profile monitor utilizing a TDS has been realized. In combined use with a fast kicker magnet and an off-axis imaging screen, selection and measurement of a single bunch out of the bunch train with bunch spacing down to 1us can be achieved without affecting the remaining bunches which continue to generate FEL radiation during user operation. Technical obstacles have been overcome such as suppression of coherent transition radiation from the imaging screen, the continuous image acquisition and processing with the bunch train repetition rate of 10Hz. The monitor, which provides the longitudinal bunch profile and length, has been used routinely at FLASH. In this paper, we present the setup and operation of the longitudinal bunch profile monitor as well as the performance during user operation.

TUPC37	Presentation of the Smith-Purcell Experiment at SOLEIL	radiation, SOLEIL, linac, vacuum	460
	N. Delerue, J. Barros, S. Jenzer, M. Vieille Grosjean LAL, Orsay, France L. Cassinari, M. Labat SOLEIL, Gif-sur-Yvette, France G. Doucas, I.V. Konoplev, A. Reichold JAI, Oxford, United Kingdom A. Faus-Golfe, N. Fuster Martinez, J. Resta-López IFIC, Valencia, Spain
	Funding: Work supported by seed funding from Université Paris-Sud, program 'Attractivité' and by the French ANR under contract ANR-12-JS05-0003-01. The potential of Coherent Smith-Purcell radiation as a longitudinal bunch profile monitor has already been demonstrated and has recently been extended to the sub-picosecond range. As a critical step toward the construction of a single shot bunch profile monitor using Coherent Smith-Purcell radiation it is important to measure very accurately the distribution of such radiation. Optimum background suppression techniques need to be found and relatively cheap detectors suitable for the far infra-red need to be qualified. To perform these tasks a test stand has been installed at the end of the linac of the synchrotron SOLEIL. This test stand and the first results from its commissioning will be presented here.

TUPC38	Longitudinal Profile Monitor Using Smith-Purcell Radiation: Recent Results from the E-203 Collaboration	radiation, electron, SLAC, background	464
	N. Delerue, J. Barros, S. Le Corre, M. Vieille Grosjean LAL, Orsay, France H.L. Andrews LANL, Los Alamos, New Mexico, USA F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S. Stevenson JAI, Oxford, United Kingdom V. Bharadwaj, C.I. Clarke SLAC, Menlo Park, California, USA N. Fuster Martinez IFIC, Valencia, Spain M. Labat SOLEIL, Gif-sur-Yvette, France
	Funding: Financial support from the John Adams Institute, the Fell Fund (University of Oxford), the Université Paris-Sud (programme 'Attractivité') and the French ANR (contract ANR-12-JS05-0003-01). We report on recent measurements made at FACET by the E-203 collaboration to test a longitudinal bunch profile monitor based on Coherent Smith-Purcell radiation. The capacity of this monitor to resolve sub-picosecond bunches will be shown as well as a comparison of profile reconstructed for different beam compression settings. We will also present recent electromagnetic simulations of the interactions between the beam and the grating as well as the expected resolution of such monitor. Comparison between Coherent Smith-Purcell radiation measurement and those made with other techniques will also be discussed. Finally future upgrades of the experiment and steps toward the construction of a single shot longitudinal profile monitor will be presented.

TUPC40	Bunch Length Measurements Using Correlation Theory in Incoherent Optical Transition Radiation	OTR, electron, radiation, laser	471
	B. Smit, F. Frei, R. Ischebeck, G.L. Orlandi, V. Schlott PSI, Villigen PSI, Switzerland
	Funding: Paul Scherrer Institut (PSI) As Free Electron Lasers create ultra-short bunch lengths, the longitudinal diagnostic for such femto-second bunches becomes more difficult. We suggest a bunch length method using the spectral analysis of incoherent Optical Transition Radiation (OTR) in the visible frequency domain. The frequency response of OTR is taken by inserting an aluminium coated silicon wafer into the electron beam. The OTR light is collected with mirror optics into an optical fibre, which is coupled to a spectrometer (334 THz to 1500 THz). The resolution of the spectrometer allows us to measure bunch length lower than 100 fs rms. Bunch length was varied from 100 femto-seconds down to a few femto-seconds. The spectral response of Optical Transition Radiation (OTR) showed an increase of the correlation between neighbouring frequencies as bunch length was reduced.

TUPC41	A Femtosecond Resolution Electro-Optic Diagnostic Using a Nanosecond-Pulse Laser	laser, diagnostics, CLIC, alignment	474
	S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom W.A. Gillespie, D.A. Walsh University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
	Funding: We gratefully acknowledge support under CERN collaboration agreement KE1865/TE Electro-optic longitudinal profile diagnostic systems with intrinsically improved reliability and a time resolution of 20 fs rms are being developed for CLIC. Exploiting the electro-optic effect, the bunch electric field 'pulse carves' an optical replica from a narrow bandwidth nanosecond duration laser probe. All-optical characterisation of the optical replica is via spectrally resolved auto-correlation, providing a sub-20fs resolution capability. An optical parametric amplification stage following the pulse carving, and driven by same nanosecond laser that provides the probe, enables sufficient intensity for single-shot measurement. In basing the optical system on nanosecond Q-switched lasers, bypassing complex femtosecond laser systems, the potential for robust instrumentation development is enhanced. The bandwidth limitations of the electro-optic materials are being addressed through investigations into multiple crystal detectors, and THz induced second harmonic generation on metal surfaces. Experimental results on the optical subsystems, using laser-produced THz as an electron bunch mimic, are presented together with performance projections for the integrated system.

TUPC43	Bunch Length Measurement With Streak Camera At SSRF Storage Ring	electron, storage-ring, synchrotron, diagnostics	478
	J. Chen, Z.C. Chen, Y.B. Leng, K.R. Ye, R.X. Yuan SINAP, Shanghai, People's Republic of China
	A streak camera is installed to measure the bunch length of storage ring at SSRF. The principle, structure, configuration and error analysis of the measurement is introduced. Some result of the measurement are analysed to explain the physical meaning of beam status. The system is used in daily operation and machine study at SSRF.

TUPF07	Covariance and Temporal Causality in the Transition Radiation Emission by an Electron Bunch	electron, radiation, transverse, 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	electron, transverse, 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.

TUPF27	An Ultra Low-Noise AC Beam Transformer and Digital Signal Processing System for CERN’s ELENA Ring	CERN, diagnostics, pick-up, extraction	571
	M.E. Angoletta, C. Carli, F. Caspers, S. Federmann, J.C. Molendijk, F. Pedersen, J. Sanchez-Quesada CERN, Geneva, Switzerland
	CERN’s Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron that will be commissioned in 2016 to further decelerate the antiprotons coming from CERN’s Antiproton Decelerator. Essential longitudinal diagnostics required for commissioning and operation include the intensity measurement for bunched and debunched beams and the measurement of Dp/p for debunched beams to assess the electron cooling performance. The beam phase information is also needed by the low-level RF system. The baseline system for providing the required beam parameters and signals is based upon two ultra-low-noise AC beam transformers and associated digital signal processing. The AC beam transformers cover different frequency regions and are an adaptation to the ELENA layout of those used in the AD. Two AC beam transformers will also be installed in the extraction lines to provide beam intensity and bunch shape measurements. The digital signal processing will be carried out with the leading-edge hardware family used for ELENA’s low-level RF system. The paper provides an overview of the beam transformer and head amplifier, as well as of the associated digital signal processing.

TUPF32	A Cryogenic Current Comparator for FAIR with Improved Resolution	pick-up, cryogenics, DESY, shielding	590
	R. Geithner, W. Vodel HIJ, Jena, Germany R. Geithner, R. Neubert, P. Seidel FSU Jena, Jena, Germany F. Kurian, H. Reeg, M. Schwickert GSI, Darmstadt, Germany
	A Cryogenic Current Comparator is a highly sensitive tool for the non-destructive online monitoring of continuous as well as bunched beams of very low intensities. The noise-limited current resolution of such a device depends on the ferromagnetic material embedded in the pickup coil of the CCC. Therefore, the main focus of research was on the low temperature properties of ferromagnetic core materials. In this contribution we present first results of the completed Cryogenic Current Comparator for FAIR working in a laboratory environment, regarding the improvements in resolution due to the use of suitable ferromagnetic core materials.
	Poster TUPF32 [3.868 MB]

WEBL3	Wake Field Monitors in a Multi Purpose X Band Accelerating Structure	alignment, CERN, dipole, emittance	634
	M.M. Dehler, S. Bettoni, B. Beutner, G. De Michele PSI, Villigen PSI, Switzerland G. De Michele EPFL, Lausanne, Switzerland G. De Michele CERN, Geneva, Switzerland
	In a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a series of four multipurpose X-band accelerating structures has been designed and fabricated. These feature integrated wake field monitors (WFMs), which are used to measure the alignment (offset and tilt) between structure and beam. One structure has recently been installed in the SwissFEL Injector Test facility (SITF) at PSI. The WFM front end electronics will be developed within the EuCard2 framework, so for the measurements described in this paper we used the raw WFM signals. We compare these measurements to the theoretical results obtained via an equivalent circuit model used in the design and numerical calculations. The beam tests show that by minimizing the WFM signals, the emittance dilution given by the transverse wakes, crucial because of the small aperture of the structure, is minimized as well.
	Slides WEBL3 [1.668 MB]

WEPC34	Time Trend Observation of Certain Remarked Bunches using a Streak Camera	synchrotron, injection, damping, KEK	761
	T. Naito, S. Araki, H. Hayano, K. Kubo, S. Kuroda, T.M. Mitsuhashi, T. Okugi, S. Sakanaka, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: This work is supported by Japan-U.S. cooperative program . A streak camera with two dimensional sweep function can measure the trend of the longitudinal beam profile in the ring. In the case of the multi-bunch measurement, the different bunch profile sit on same timing, thus, we can not distinguish the behavior of each bunch. We have developed a trigger circuit to measure the bunch-by-bunch longitudinal beam profile, which uses non integer sweep frequency for the acceleration frequency. The bunch profile of each bunch sit on different position in this measurement. We observed the increment of the synchrotron oscillation amplitude from the first bunch to the 20th bunch in the KEK-ATF Damping Ring by using this system. This paper describes the hardware and the measurement results.

WEPC36	Development of Electron Bunch Compression Monitors for SwissFEL	electron, radiation, synchrotron, transverse	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.

WEPF28	Longitudinal Beam Diagnostic from a Distributed Electrostatic Pick-Up in CERN’s ELENA Ring	CERN, pick-up, antiproton, diagnostics	883
	M.E. Angoletta, F. Caspers, S. Federmann, J.C. Molendijk, P.J. Pascal Jean, F. Pedersen, J. Sanchez-Quesada, L. Søby, M.A. Timmins CERN, Geneva, Switzerland
	The CERN Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron that will be commissioned in 2016 to further decelerate the antiprotons coming from CERN’s Antiproton Decelerator (AD). Required longitudinal diagnostics include the intensity measurement for bunched and debunched beam and the measurement of Dp/p for a debunched beam to assess the electron cooling performance. A novel method for the calculation of these parameters is proposed for ELENA, where signals from the twenty electrostatic pick-ups (PU) used for orbit measurements will be combined to improve the signal-to-noise ratio. This requires that the signals be digitally down-converted, rotated and digitally summed so that the many electrostatic PUs will function as a single, distributed PU from to the processing system viewpoint. This method includes some challenges and will not be used as the baseline longitudinal diagnostics for the initial ELENA operation. This paper gives an overview of the hardware and digital signal processing involved, as well as of the challenges that will have to be faced.

WEPF31	A FESA DAQ for Fast Current Transformer in SIS 18	synchrotron, CERN, SIS, pick-up	894
	O. Chorniy, H. Bräuning, T. Hoffmann, H. Reeg, A. Reiter GSI, Darmstadt, Germany
	This contribution presents the development of the data acquisition (DAQ) system for the readout of fast beam current transformers (FCT) as installed in the GSI synchrotron SIS18 and as foreseen in several FAIR ring accelerators. Fast current transformers are reliable devices that offer a large analogue bandwidth and can therefore monitor bunch structures with high resolution. At appropriate sampling rates continuous measurements throughout repeated machine cycles lead to a large amount of raw data. The analysis of those raw data may range from simple bunch parameter calculations to complex longitudinal phase space reconstructions. Consequently, a new DAQ system must be carefully designed to allow for flexible acquisition modes or to allow for data reduction methods in special applications. The aims of the development are discussed and the status of the new DAQ is presented.
	Poster WEPF31 [2.307 MB]

THBL1	RF Heating from Wake Losses in Diagnostics Structures	resonance, LHC, impedance, simulation	929
	E. Métral CERN, Geneva, Switzerland
	Heating of diagnostics structures (striplines, buttons, screen vessels, wire scanners etc) has been observed at many facilities with higher stored currents. Simulations of wake losses using 3D EM codes are regularly used to estimate the amount of power lost from the bunched beam but on its own this does not tell how much is radiated back into the beam pipe or transmitted into external ports and how much is actually being dissipated in the structure and where. This talk should introduce into the matter, summarise some of the observations at various facilities and illustrate what approaches of detailed simulations have been taken. summarizing a workshop at DLS (see http://tinyurl.com/wakeloss )
	Slides THBL1 [9.078 MB]

Paper

Title

Other Keywords

Page

MOPC31

Streak Camera Imaging at ELSA

ELSA, feedback, transverse, 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.

MOPC34

Longitudinal Beam Profile Monitor for Investigating the Microbunching Instability at Diamond Light Source

optics, DIAMOND, radiation, storage-ring

143

W. Shields, R. Bartolini, A.F.D. Morgan, G. Rehm
Diamond, Oxfordshire, United Kingdom
R. Bartolini, P. Karataev
JAI, Oxford, United Kingdom
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom

An investigation into the microbunching instability at Diamond Light Source has recently been conducted. Beyond the instability threshold, the bunch emits bursts of coherent synchrotron radiation with wavelengths comparable to the bunch length or shorter. The operating conditions for producing the instability include both normal optics, and low-alpha optics, where the bunch length can be shortened to a few picoseconds. A Michelson interferometer has been designed and installed utilising a silicon crystal wafer beamsplitter. Large bandwidth, room temperature pyroelectric detectors and low-noise, fast-response Schottky Barrier diode detectors have been employed to generate interferograms. In this paper, we describe the observed spectral content and the resulting calculated bunch length.

MOPC35

A Beam-Synchronous Gated Peak-Detector for the LHC Beam Observation System

LHC, CERN, injection, synchrotron

147

T.E. Levens, T. Bohl, U. Wehrle
CERN, Geneva, Switzerland

Measurements of the bunch peak amplitude using the longitudinal wideband wall-current monitor are a vital tool used in the Large Hadron Collider (LHC) beam observation system. These peak-detected measurements can be used to diagnose bunch shape oscillations, for example coherent quadrupole oscillations, that occur at injection and during beam manipulations. Peak-detected Schottky diagnostics can also be used to obtain the synchrotron frequency distribution and other parameters from a bunched beam under stable conditions. For the LHC a beam-synchronous gated peak detector has been developed to allow individual bunches to be monitored without the influence of other bunches circulating in the machine. The requirement for the observation of both low intensity pilot bunches and high intensity bunches for physics requires a detector front-end with a high bandwidth and a large dynamic range while the usage for Schottky measurements requires low noise electronics. This paper will present the design of this detector system as well as initial results obtained during the 2012-2013 LHC run.

Poster MOPC35 [2.792 MB]

MOPC36

Test of a Non-Invasive Bunch Shape Monitor at GSI High Current LINAC

electron, linac, GSI, MCP

151

P. Forck, C. Dorn, O.K. Kester, P. Kowina, B. Zwicker
GSI, Darmstadt, Germany
O.K. Kester
IAP, Frankfurt am Main, Germany

Funding: The work is funded by European Union FP7 within CRISP.
At the heavy ion LINAC at GSI, a novel scheme of non-invasive Bunch Shape Monitor has been tested with several ion beams at 11.4 MeV/u. The monitor’s principle is based on the analysis of secondary electrons as liberated from the residual gas by the beam impact. These electrons are accelerated by an electrostatic field, transported through a sophisticated electrostatic energy analyzer and an RF-deflector, acting as a time-to-space converter. Finally a MCP amplifies electrons and with a CCD camera the electron distribution is detected. For the applied beam settings this Bunch Shape Monitor is able to obtain longitudinal profiles down to a width of 400 ps with a resolution of 50 ps, corresponding to 2 degree of the 108 MHz accelerating frequency. Systematic parameter studies for the device were performed to demonstrate the applicability and to determine its resolution. The achievements and ongoing improvements for the monitor are discussed.

Poster MOPC36 [2.665 MB]

MOPC37

Longitudinal Bunch Profile Reconstruction Using Broadband Coherent Radiation at FLASH

radiation, electron, transverse, 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.

MOPC39

Commissioning of a New Streak Camera at TLS for TPS Project

laser, synchrotron, storage-ring, feedback

159

C.Y. Liao, M.C. Chou, K.T. Hsu, K.H. Hu, C.H. Kuo, C.-C. Kuo, W.K. Lau, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) is a 3 GeV synchrotron light source which is being construction at campus of National Synchrotron Radiation Research Center (NSRRC) in Taiwan. A new streak camera equipped with a 125/250 MHz synchroscan unit, a fast/slow single sweep unit, and a dual-time sweep unit is prepared for beam diagnostics, especially for the TPS. An ultra short femtosecond Ti-Sapphire laser was used to evaluate the sub-picosecond temporal resolution of the streak camera and the first beam measurements of the streak camera using synchrotron light from the existing 1.5 GeV Taiwan Light Source (TLS) were performed. The commissioning results are summarized in this report.

MOPC40

Measurement of Longitudinal Bunch Profile and Twiss Parameters in SNS LINAC

laser, linac, SCL, SNS

163

A.V. Aleksandrov, C. Huang, Y. Liu, A.P. Shishlo, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
We are reporting on the latest progress in the longitudinal beam profile and emittance diagnostics development at SNS. In order to characterize the longitudinal phase space of the beam in the SNS 1GeV proton LINAC the bunch profile needs to be measured with a few picosecond resolution. The original SNS set of diagnostics included only four interceptive Feschenko-style longitudinal profile monitors in the normal conducting part of the LINAC at 100MeV. Two recently added systems are: a non-interceptive laser scanner in the injector at 2.5MeV and a novel non-interceptive method for longitudinal Twiss parameters measurement using the beam position monitors in the Super Conducting LINAC (SCL) at 300MeV. This paper presents details of these two diagnostics and discusses their performance, resolution limitations and future development plans.

Poster MOPC40 [8.865 MB]

MOPF25

Cryogenic Current Comparator as Low Intensity Beam Current Monitor in the CERN Antiproton Decelerators

antiproton, CERN, shielding, cryogenics

267

M.F. Fernandes, J. Tan
CERN, Geneva, Switzerland
M.F. Fernandes, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
M.F. Fernandes, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the EU within the oPAC project under contract 289485.
In the low-energy Antiproton Decelerator (AD) and the future Extra Low ENergy Antiproton (ELENA) rings at CERN, an absolute measurement of the beam intensity is essential to monitor any losses during the deceleration and cooling phases. However, existing DC current transformers can hardly reach the μA level, while at the AD and ELENA currents can be as low as 100 nA. A Cryogenic Current Comparator (CCC) based on a superconducting quantum interference device (SQUID) is currently being designed and shall be installed in the AD and ELENA machines. It should meet the following specifications: A current resolution smaller than 10 nA, a dynamic range covering currents between 100 nA and 1 mA, as well as a bandwidth from DC to 1 kHz. Different design options are being considered, including the use of low or high temperature superconductor materials, different CCC shapes and dimensions, different SQUID characteristics, as well as electromagnetic shielding requirements. In this contribution we present first results from a comparative analysis of different monitor options, taking into consideration the external electromagnetic sources at the foreseen device locations.

Poster MOPF25 [1.059 MB]

TUPC07

Design and Impedance Optimization of the SIRIUS BPM Button

BPM, vacuum, impedance, storage-ring

365

H.O.C. Duarte, S.R. Marques, L. Sanfelici
LNLS, Campinas, Brazil

Design of several BPM Buttons is presented with detail impedance, heat transfer and mechanical analysis. Special attention is given to the application of ceramics as materials with low relative permittivity inside of the BPM Button and to the geometric shape of the BPM Button. The heat dissipation is evaluated based on the loss factor calculated for a 2.65mm bunch length. The narrow-band impedance is discussed and its dependence on applied ceramic materials is compared.

Poster TUPC07 [1.715 MB]

TUPC08

Design and Impedance Optimization of the LNLS-UVX Longitudinal Kicker Cavity

kicker, impedance, feedback, synchrotron

369

L. Sanfelici, H.O.C. Duarte, S.R. Marques
LNLS, Campinas, Brazil

Performance evolution of parameters achieved during the electromagnetic design of the longitudinal kicker cavity for the LNLS UVX storage ring is presented. The effort on the electromagnetic optimization process of the heavily loaded cavity has been made to reach the required electrodynamic parameters of the kicker. The results for three different geometries are compared and a good compromise between the longitudinal shunt impedance and the effect of the longitudinal Higher Order Modes (HOM’s) on beam stability has been found.

Poster TUPC08 [1.365 MB]

TUPC14

Development of a Low-Beta Button BPM for PXIE Project

BPM, simulation, pick-up, beam-position

392

A. Lunin, N. Eddy, T.N. Khabiboulline, V.A. Lebedev, V.P. Yakovlev
Fermilab, Batavia, USA

The button BPM is under development for a low beta section of the Project X Injector Experiment (PXIE) at Fermilab. The presented paper includes an analytical estimation of the BPM performance as well a direct wakefield simulation with CST Particle Studio (on a hexahedral mesh). In addition we present a novel approach of a low beta beam interaction with BPM electrodes realized with ANSYS HFSS TD-solver on unstructured tetrahedral mesh. Both methods show a good agreement of BPM output signals for various beam parameters. Finally we describe the signal processing scheme and the electronics we are going to use.

Poster TUPC14 [1.051 MB]

TUPC16

Bunch-by-Bunch Feedback and Diagnostics at BESSY II

feedback, beam-losses, injection, kicker

399

A. Schälicke, F. Falkenstern, R. Müller
HZB, Berlin, Germany

At the light source BESSY II new digital bunch-by-bunch feedback systems have been put into operation in January 2013, replacing the existing analog as well as the obsolete digital systems. From the first days of operation the new system successfully suppresses transverse and longitudinal beam instabilities in wide range of machine parameters. The system offers also many new diagnostics opportunities, these include the analysis of instability modes, measurement of the feedback loop gain, and determination of the transfer function. A method to systematically optimise the output amplifier response function with the help of shaper coefficients for the optimal bunch separation has been developed. In addition the analysis of the input data stream allows a passive determination of machine properties like betatron and synchrotron frequencies as well as the longitudinal phases for every bunch. The integration of external triggers permits the analysis of postmortem data, the characterisation of beam-loss events, and monitoring of the injection process. In this contribution first operational experience, the developed data analysis techniques and experimental data will be presented.

Poster TUPC16 [56.767 MB]

TUPC18

Development of a Highly Efficient Energy Kicker for Longitudinal Bunch-by-Bunch Feedback

kicker, synchrotron, electron, storage-ring

407

M. Masaki, T. Fujita, K. Kobayashi, T. Nakamura, H. Ohkuma, M. Oishi, S. Sasaki, M. Shoji
JASRI/SPring-8, Hyogo-ken, Japan

A highly efficient energy kicker has been developed for longitudinal bunch-by-bunch feedback to suppress synchrotron oscillation of a high-current single electron bunch, and to cure possible longitudinal multi-bunch instability if lower beam energy is to be adopted for emittance reduction and electric power saving in a future upgrade plan of SPring-8. Through the performance test using a prototype kicker, a new water-cooled copper kicker was designed and fabricated, and it has been installed in the storage ring. The new kicker consists of three cells with each cavity length of 96 mm, its resonant frequency of 1.65 GHz, which is 3.25 times of RF frequency of the storage ring, and low Q-factor of 4.2. In beam kick test, the synchrotron oscillation amplitude of 0.64 ps was excited by kick voltage with continuous amplitude modulation at synchrotron frequency when the RF input power was 132 W/3cells. The kick voltage evaluated from the experimental result is 920 V/3cells. Shunt impedance of each kicker cell is estimated as 1.1 kΩ. As we intended, the shunt impedance per length is about three times higher than those of widely used waveguide overloaded cavity type kickers.

Poster TUPC18 [9.117 MB]

TUPC36

First Realization and Performance Study of a Single-Shot Longitudinal Bunch Profile Monitor Utilizing a Transverse Deflecting Structure

FEL, feedback, kicker, electron

456

M. Yan, C. Behrens, C. Gerth, R. Kammering, A. Langner, F. Obier, V. Rybnikov
DESY, Hamburg, Germany
J. Wychowaniak
TUL-DMCS, Łódź, Poland

For the control and optimization of electron beam parameters at modern free-electron lasers (FEL), transverse deflecting structures (TDS) in combination with imaging screens have been widely used as robust longitudinal diagnostics with single-shot capability, high resolution and large dynamic range. At the free-electron laser in Hamburg (FLASH), a longitudinal bunch profile monitor utilizing a TDS has been realized. In combined use with a fast kicker magnet and an off-axis imaging screen, selection and measurement of a single bunch out of the bunch train with bunch spacing down to 1us can be achieved without affecting the remaining bunches which continue to generate FEL radiation during user operation. Technical obstacles have been overcome such as suppression of coherent transition radiation from the imaging screen, the continuous image acquisition and processing with the bunch train repetition rate of 10Hz. The monitor, which provides the longitudinal bunch profile and length, has been used routinely at FLASH. In this paper, we present the setup and operation of the longitudinal bunch profile monitor as well as the performance during user operation.

TUPC37

Presentation of the Smith-Purcell Experiment at SOLEIL

radiation, SOLEIL, linac, vacuum

460

N. Delerue, J. Barros, S. Jenzer, M. Vieille Grosjean
LAL, Orsay, France
L. Cassinari, M. Labat
SOLEIL, Gif-sur-Yvette, France
G. Doucas, I.V. Konoplev, A. Reichold
JAI, Oxford, United Kingdom
A. Faus-Golfe, N. Fuster Martinez, J. Resta-López
IFIC, Valencia, Spain

Funding: Work supported by seed funding from Université Paris-Sud, program 'Attractivité' and by the French ANR under contract ANR-12-JS05-0003-01.
The potential of Coherent Smith-Purcell radiation as a longitudinal bunch profile monitor has already been demonstrated and has recently been extended to the sub-picosecond range. As a critical step toward the construction of a single shot bunch profile monitor using Coherent Smith-Purcell radiation it is important to measure very accurately the distribution of such radiation. Optimum background suppression techniques need to be found and relatively cheap detectors suitable for the far infra-red need to be qualified. To perform these tasks a test stand has been installed at the end of the linac of the synchrotron SOLEIL. This test stand and the first results from its commissioning will be presented here.

TUPC38

Longitudinal Profile Monitor Using Smith-Purcell Radiation: Recent Results from the E-203 Collaboration

radiation, electron, SLAC, background

464

N. Delerue, J. Barros, S. Le Corre, M. Vieille Grosjean
LAL, Orsay, France
H.L. Andrews
LANL, Los Alamos, New Mexico, USA
F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S. Stevenson
JAI, Oxford, United Kingdom
V. Bharadwaj, C.I. Clarke
SLAC, Menlo Park, California, USA
N. Fuster Martinez
IFIC, Valencia, Spain
M. Labat
SOLEIL, Gif-sur-Yvette, France

Funding: Financial support from the John Adams Institute, the Fell Fund (University of Oxford), the Université Paris-Sud (programme 'Attractivité') and the French ANR (contract ANR-12-JS05-0003-01).
We report on recent measurements made at FACET by the E-203 collaboration to test a longitudinal bunch profile monitor based on Coherent Smith-Purcell radiation. The capacity of this monitor to resolve sub-picosecond bunches will be shown as well as a comparison of profile reconstructed for different beam compression settings. We will also present recent electromagnetic simulations of the interactions between the beam and the grating as well as the expected resolution of such monitor. Comparison between Coherent Smith-Purcell radiation measurement and those made with other techniques will also be discussed. Finally future upgrades of the experiment and steps toward the construction of a single shot longitudinal profile monitor will be presented.

TUPC40

Bunch Length Measurements Using Correlation Theory in Incoherent Optical Transition Radiation

OTR, electron, radiation, laser

471

B. Smit, F. Frei, R. Ischebeck, G.L. Orlandi, V. Schlott
PSI, Villigen PSI, Switzerland

Funding: Paul Scherrer Institut (PSI)
As Free Electron Lasers create ultra-short bunch lengths, the longitudinal diagnostic for such femto-second bunches becomes more difficult. We suggest a bunch length method using the spectral analysis of incoherent Optical Transition Radiation (OTR) in the visible frequency domain. The frequency response of OTR is taken by inserting an aluminium coated silicon wafer into the electron beam. The OTR light is collected with mirror optics into an optical fibre, which is coupled to a spectrometer (334 THz to 1500 THz). The resolution of the spectrometer allows us to measure bunch length lower than 100 fs rms. Bunch length was varied from 100 femto-seconds down to a few femto-seconds. The spectral response of Optical Transition Radiation (OTR) showed an increase of the correlation between neighbouring frequencies as bunch length was reduced.

TUPC41

A Femtosecond Resolution Electro-Optic Diagnostic Using a Nanosecond-Pulse Laser

laser, diagnostics, CLIC, alignment

474

S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
W.A. Gillespie, D.A. Walsh
University of Dundee, Nethergate, Dundee, Scotland, United Kingdom

Funding: We gratefully acknowledge support under CERN collaboration agreement KE1865/TE
Electro-optic longitudinal profile diagnostic systems with intrinsically improved reliability and a time resolution of 20 fs rms are being developed for CLIC. Exploiting the electro-optic effect, the bunch electric field 'pulse carves' an optical replica from a narrow bandwidth nanosecond duration laser probe. All-optical characterisation of the optical replica is via spectrally resolved auto-correlation, providing a sub-20fs resolution capability. An optical parametric amplification stage following the pulse carving, and driven by same nanosecond laser that provides the probe, enables sufficient intensity for single-shot measurement. In basing the optical system on nanosecond Q-switched lasers, bypassing complex femtosecond laser systems, the potential for robust instrumentation development is enhanced. The bandwidth limitations of the electro-optic materials are being addressed through investigations into multiple crystal detectors, and THz induced second harmonic generation on metal surfaces. Experimental results on the optical subsystems, using laser-produced THz as an electron bunch mimic, are presented together with performance projections for the integrated system.

TUPC43

Bunch Length Measurement With Streak Camera At SSRF Storage Ring

electron, storage-ring, synchrotron, diagnostics

478

J. Chen, Z.C. Chen, Y.B. Leng, K.R. Ye, R.X. Yuan
SINAP, Shanghai, People's Republic of China

A streak camera is installed to measure the bunch length of storage ring at SSRF. The principle, structure, configuration and error analysis of the measurement is introduced. Some result of the measurement are analysed to explain the physical meaning of beam status. The system is used in daily operation and machine study at SSRF.

TUPF07

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

electron, radiation, transverse, 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

electron, transverse, 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.

TUPF27

An Ultra Low-Noise AC Beam Transformer and Digital Signal Processing System for CERN’s ELENA Ring

CERN, diagnostics, pick-up, extraction

571

M.E. Angoletta, C. Carli, F. Caspers, S. Federmann, J.C. Molendijk, F. Pedersen, J. Sanchez-Quesada
CERN, Geneva, Switzerland

CERN’s Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron that will be commissioned in 2016 to further decelerate the antiprotons coming from CERN’s Antiproton Decelerator. Essential longitudinal diagnostics required for commissioning and operation include the intensity measurement for bunched and debunched beams and the measurement of Dp/p for debunched beams to assess the electron cooling performance. The beam phase information is also needed by the low-level RF system. The baseline system for providing the required beam parameters and signals is based upon two ultra-low-noise AC beam transformers and associated digital signal processing. The AC beam transformers cover different frequency regions and are an adaptation to the ELENA layout of those used in the AD. Two AC beam transformers will also be installed in the extraction lines to provide beam intensity and bunch shape measurements. The digital signal processing will be carried out with the leading-edge hardware family used for ELENA’s low-level RF system. The paper provides an overview of the beam transformer and head amplifier, as well as of the associated digital signal processing.

TUPF32

A Cryogenic Current Comparator for FAIR with Improved Resolution

pick-up, cryogenics, DESY, shielding

590

R. Geithner, W. Vodel
HIJ, Jena, Germany
R. Geithner, R. Neubert, P. Seidel
FSU Jena, Jena, Germany
F. Kurian, H. Reeg, M. Schwickert
GSI, Darmstadt, Germany

A Cryogenic Current Comparator is a highly sensitive tool for the non-destructive online monitoring of continuous as well as bunched beams of very low intensities. The noise-limited current resolution of such a device depends on the ferromagnetic material embedded in the pickup coil of the CCC. Therefore, the main focus of research was on the low temperature properties of ferromagnetic core materials. In this contribution we present first results of the completed Cryogenic Current Comparator for FAIR working in a laboratory environment, regarding the improvements in resolution due to the use of suitable ferromagnetic core materials.

Poster TUPF32 [3.868 MB]

WEBL3

Wake Field Monitors in a Multi Purpose X Band Accelerating Structure

alignment, CERN, dipole, emittance

634

M.M. Dehler, S. Bettoni, B. Beutner, G. De Michele
PSI, Villigen PSI, Switzerland
G. De Michele
EPFL, Lausanne, Switzerland
G. De Michele
CERN, Geneva, Switzerland

In a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a series of four multipurpose X-band accelerating structures has been designed and fabricated. These feature integrated wake field monitors (WFMs), which are used to measure the alignment (offset and tilt) between structure and beam. One structure has recently been installed in the SwissFEL Injector Test facility (SITF) at PSI. The WFM front end electronics will be developed within the EuCard2 framework, so for the measurements described in this paper we used the raw WFM signals. We compare these measurements to the theoretical results obtained via an equivalent circuit model used in the design and numerical calculations. The beam tests show that by minimizing the WFM signals, the emittance dilution given by the transverse wakes, crucial because of the small aperture of the structure, is minimized as well.

Slides WEBL3 [1.668 MB]

WEPC34

Time Trend Observation of Certain Remarked Bunches using a Streak Camera

synchrotron, injection, damping, KEK

761

T. Naito, S. Araki, H. Hayano, K. Kubo, S. Kuroda, T.M. Mitsuhashi, T. Okugi, S. Sakanaka, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: This work is supported by Japan-U.S. cooperative program .
A streak camera with two dimensional sweep function can measure the trend of the longitudinal beam profile in the ring. In the case of the multi-bunch measurement, the different bunch profile sit on same timing, thus, we can not distinguish the behavior of each bunch. We have developed a trigger circuit to measure the bunch-by-bunch longitudinal beam profile, which uses non integer sweep frequency for the acceleration frequency. The bunch profile of each bunch sit on different position in this measurement. We observed the increment of the synchrotron oscillation amplitude from the first bunch to the 20th bunch in the KEK-ATF Damping Ring by using this system. This paper describes the hardware and the measurement results.

WEPC36

Development of Electron Bunch Compression Monitors for SwissFEL

electron, radiation, synchrotron, transverse

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.

WEPF28

Longitudinal Beam Diagnostic from a Distributed Electrostatic Pick-Up in CERN’s ELENA Ring

CERN, pick-up, antiproton, diagnostics

883

M.E. Angoletta, F. Caspers, S. Federmann, J.C. Molendijk, P.J. Pascal Jean, F. Pedersen, J. Sanchez-Quesada, L. Søby, M.A. Timmins
CERN, Geneva, Switzerland

The CERN Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron that will be commissioned in 2016 to further decelerate the antiprotons coming from CERN’s Antiproton Decelerator (AD). Required longitudinal diagnostics include the intensity measurement for bunched and debunched beam and the measurement of Dp/p for a debunched beam to assess the electron cooling performance. A novel method for the calculation of these parameters is proposed for ELENA, where signals from the twenty electrostatic pick-ups (PU) used for orbit measurements will be combined to improve the signal-to-noise ratio. This requires that the signals be digitally down-converted, rotated and digitally summed so that the many electrostatic PUs will function as a single, distributed PU from to the processing system viewpoint. This method includes some challenges and will not be used as the baseline longitudinal diagnostics for the initial ELENA operation. This paper gives an overview of the hardware and digital signal processing involved, as well as of the challenges that will have to be faced.

WEPF31

A FESA DAQ for Fast Current Transformer in SIS 18

synchrotron, CERN, SIS, pick-up

894

O. Chorniy, H. Bräuning, T. Hoffmann, H. Reeg, A. Reiter
GSI, Darmstadt, Germany

This contribution presents the development of the data acquisition (DAQ) system for the readout of fast beam current transformers (FCT) as installed in the GSI synchrotron SIS18 and as foreseen in several FAIR ring accelerators. Fast current transformers are reliable devices that offer a large analogue bandwidth and can therefore monitor bunch structures with high resolution. At appropriate sampling rates continuous measurements throughout repeated machine cycles lead to a large amount of raw data. The analysis of those raw data may range from simple bunch parameter calculations to complex longitudinal phase space reconstructions. Consequently, a new DAQ system must be carefully designed to allow for flexible acquisition modes or to allow for data reduction methods in special applications. The aims of the development are discussed and the status of the new DAQ is presented.

Poster WEPF31 [2.307 MB]

THBL1

RF Heating from Wake Losses in Diagnostics Structures

resonance, LHC, impedance, simulation

929

E. Métral
CERN, Geneva, Switzerland

Heating of diagnostics structures (striplines, buttons, screen vessels, wire scanners etc) has been observed at many facilities with higher stored currents*. Simulations of wake losses using 3D EM codes are regularly used to estimate the amount of power lost from the bunched beam but on its own this does not tell how much is radiated back into the beam pipe or transmitted into external ports and how much is actually being dissipated in the structure and where. This talk should introduce into the matter, summarise some of the observations at various facilities and illustrate what approaches of detailed simulations have been taken.
* summarizing a workshop at DLS (see http://tinyurl.com/wakeloss )

Slides THBL1 [9.078 MB]