Keyword: simulation
Paper Title Other Keywords Page
MOOB03 Diamond-based Beam Halo Monitor Equipped with RF Fingers for SACLA wakefield, electron, vacuum, radiation 12
 
  • H. Aoyagi, T. Aoki, T. Bizen, K. Fukami, N. Nariyama, S. Suzuki
    JASRI/SPring-8, Hyogo-ken, Japan
  • Y. Asano, T. Itoga, H. Kitamura, T. Tanaka
    RIKEN/SPring-8, Hyogo, Japan
  
  Funding: This work is partly supported by Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (c) 21604017.
The diamond-based beam halo monitor has been developed for SPring-8 Angstrom Compact free electron LAser (SACLA). This monitor is an interlock sensor to protect the undulator magnets against radiation damage. Pulse-mode measurement is adopted to suppress the background noise efficiently. The diamond detectors are dipped into the beam duct in order that the intensity of the beam halo can be measured directly. However, it is important issue to avoid degradation in quality of electron beam for SPring-8 XFEL. We designed new RF fingers with aluminum windows in order to reduce the impedance to the beam. The RF fingers are made of beryllium copper, and having the aluminum windows, which is low-Z material, in front of active areas of the diamond detectors. Therefore, the influence of secondary electrons and bremsstrahlung from the finger material can be suppressed. To evaluate influence on the output signal of the diamond detector by changing the finger material, both the simulation study and the experimental measurement have been carried out. Feasibility tests of this monitor, which is equipped with the RF fingers, have also been demonstrated at the SCSS test accelerator. 		 
slides icon Slides MOOB03 [1.353 MB]  
 
MOPD08 Beam Diagnostics in the J-PARC Linac for ACS Upgrade linac, diagnostics, pick-up, acceleration 50
 
  • A. Miura, S. Sato
    JAEA/J-PARC, Tokai-mura, Japan
  • Z. Igarashi, M. Ikegami, T. Miyao, T. Toyama
    KEK, Ibaraki, Japan
  • T. Tomisawa
    JAEA/LINAC, Ibaraki-ken, Japan
  
  J-PARC had developed the beam diagnostic devices for the current J-PARC linac and has used them since the operation start. J-PARC linac began the energy upgrade project since 2009 and 21 ACS cavities will be installed. In this project, many cavities and related devices are newly installed in the ACS section and its downstream part. Because the beam parameters are updated, new beam diagnostic devices are fabricated and current diagnostic devices are developed. Beam position monitors (BPM) are newly designed and fabricated, based on the computer simulation and bench test. Because the gas proportional BLMs as the current BLM are sensitive to background noise of X-ray emitted from RF cavities, it is difficult to recognize real beam loss. We need to subtract an X-ray noise from the signal from BLM, another candidate BLMs have been tried to measure the beam loss. In addition, the bunch shape monitor for the longitudinal tuning has been developed in the corroboration with the institute for nuclear research, Russia. In this paper, we describe the new developed devices and their development process, especially for beam loss monitor and the developing bunch shape monitor.  
 
MOPD13 Mode Selective Waveguide BPM coupling, cavity, pick-up, impedance 65
 
  • A. Lyapin
    JAI, Egham, Surrey, United Kingdom
  
  I propose a mode-selective waveguide Beam Position Monitor (BPM). It uses waveguide couplers arranged at the beampipe to create boundary conditions similar to those in slot-coupled cavity BPMs. This structure allows to couple to the differential waveguide mode co-propagating with the beam, and reject the usually much stronger monopole component of the field. As the full dynamic range of the processing electronics can be used for position measurements, and a waveguide is a native high-pass filter, such a BPM is expected to outperform stripline and button BPMs in terms of both spacial and time resolution. In this paper I give some details on the basic principle and the first simulation results and discuss possible ways of signal processing.  
poster icon Poster MOPD13 [3.052 MB]  
 
MOPD15 Electromagnetic Simulations of an Embedded BPM in Collimator Jaws pick-up, collimation, alignment, proton 71
 
  • A.A. Nosych, C.B. Boccard, M. Gasior
    CERN, Geneva, Switzerland
  
  Next generation of the LHC collimators will be equipped with button beam position monitors (BPMs) embedded into the collimator jaws. Such a solution will improve the accuracy of the jaw alignment with respect to the beam and reduce the beam time necessary for the collimator setup. This paper describes results of electromagnetic simulations of the jaw BPMs performed with the CST Particle Studio suite, aimed at characterisation of the BPMs as well as the simulation software itself. The results are compared to the measurements obtained with beam on a prototype system installed in the CERN SPS.  
poster icon Poster MOPD15 [6.439 MB]  
 
MOPD19 Button BPM Development for the European XFEL vacuum, cryogenics, linac, cavity 83
 
  • D. Lipka, B. Lorbeer, D. Nölle, M. Siemens, S. Vilcins
    DESY, Hamburg, Germany
  
  Button beam position monitors will be the main BPM type used to measure the electron beam position at the European XFEL. Two different kinds of buttons are necessary: one type will be installed in the acceleration modules of the cold linac and the other in the warm environment. The electro-magnetic design of the feedthrough for both types of buttons will be discussed. A comparison of the designed and measured RF properties will be presented. In addition to the usual RF properties, also the properties at cryogenic level will play a role. HOM power must not heat up the BPM feedthroughs, in order to keep the cryo load of an overall accelerator module low, and also to prevent damage due to large temperature gradients over the ceramics of the feedthrough. First measurements with beam at FLASH show good agreement of the measured signals with the expectation.  
 
MOPD22 Beam Based Gain Calibration of Beam Position Monitors at J-PARC MR ion, pick-up, synchrotron 92
 
  • M. Tejima, T. Toyama
    KEK, Ibaraki, Japan
  • S. Hatakeyama
    JAEA/J-PARC, Tokai-mura, Japan
  
  The output data from a beam position monitor (BPM) system usually was calibrated on the test bench and so on. The gain of the output data may drift due to unpredictable imbalance among output signals from the pickup electrodes, because they must travel through separate paths,cables, connectors, attenuators, switches, and then are measured by detectors. The gain calibration has been tried to apply for the BPM system in J-PARC Main Ring. This paper reports the result of beam based gain callibration to estimate the imbalance, which was performed measuring the response from four output data of a BPM head.  
 
MOPD33 Pickup Design for a High Resolution Bunch Arrival Time Monitor for FLASH and XFEL pick-up, electron, vacuum, laser 122
 
  • A. Angelovski, R. Jakoby, A. Kuhl, A. Penirschke, S. Schnepp
    TU Darmstadt, Darmstadt, Germany
  • M.K. Bock, M. Bousonville, P. Gessler, H. Schlarb
    DESY, Hamburg, Germany
  • J. Rönsch-Schulenburg, J. Roßbach
    Uni HH, Hamburg, Germany
  • T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors"
The Free Electron Laser in Hamburg (FLASH) is currently equipped with four Bunch Arrival time Monitors (BAM’s) which are part of the optical synchronization system [1-2]. FLASH usually works with bunch charges of 0.2 to 1 nC, but for a variety of future experiments, the system needs to operate with bunch charges in the range of 10 to 20 pC. Below 0.2 nC the sensitivity of such a BAM scales approximately linearly with the bunch charge and therefore the system no longer fulfills the time resolution requirements for these low charges. For the low bunch charge regime operation, the bandwidth has to be increased substantially. This paper shows a new design of a high frequency button pickup that can operate in a frequency band from DC up to 40 GHz. The design criteria of the pickup are the voltage slope steepness at the zero-crossing, the maximum amplitude and the ringing of the picked-up voltage. The performance of the designed model is analyzed for fabrication tolerances and orbit variations. Some manufacturing and practical issues are discussed and solutions are offered for improving the results. A full wave simulation with CST PARTICLE STUDIO is performed in order to prove the concept.
[1] F. Loehl et. al.,“A Sub 100 fs Electron Bunch Arrival-time Monitor System for FLASH”, THOBFI01, EPAC 2006
[2] F. Loehl et. al.,“A Sub-50 Femtosecond bunch arrival time monitor system for FLASH”, WEPB15, DIPAC 2007
 		 
poster icon Poster MOPD33 [27.661 MB]  
 
MOPD34 Analysis of New Pickup Designs for the FLASH and XFEL Bunch Arrival Time Monitor System pick-up, laser, electron, vacuum 125
 
  • A. Kuhl, A. Angelovski, R. Jakoby, A. Penirschke, S. Schnepp
    TU Darmstadt, Darmstadt, Germany
  • M.K. Bock, M. Bousonville, P. Gessler, H. Schlarb
    DESY, Hamburg, Germany
  • J. Rönsch-Schulenburg, J. Roßbach
    Uni HH, Hamburg, Germany
  • T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors"
The Free Electron Laser in Hamburg (FLASH) is equipped with Bunch Arrival time Monitors (BAM)[1], which provide for a time resolution of less than 10 fs for bunch charges higher than 0.2 nC. Future experiments, however, will aim at generating FEL light pulses from bunch charges of 10-20 pC. The sensitivity of the measurement system is defined by the slope of the pickup signal at the zero crossing and scales close to linear with the bunch charge. The requirements on the time resolution will no longer be fulfilled when operating at decreased bunch charges. Several designs have been developed in CST PARTICLE STUDIO®, each having an increased bandwidth larger than 40 GHz for meeting the requirements when operating at low bunch charges. Furthermore, new post-processing functions for the automatic evaluation of the signal slope and the ringing in the detected voltage signal have been developed and implemented within the CST software for defining optimization goals of the built-in optimizer for determining free design parameters. Results of the new designs are presented and compared with the current BAM pickup.
[1] M.K. Bock et.al., "Recent Developments of the Beam Arrival Time Monitor with Femtosecond Resolution at FLASH", WEOCMH02, IPAC 2010 		 
poster icon Poster MOPD34 [3.112 MB]  
 
MOPD37 Simulations of the Coherent Gap Radiation for the Bunch Length Monitor of FERMI@Elettra radiation, vacuum, resonance, electromagnetic-fields 134
 
  • R. Appio, P. Craievich, M. Ferianis, M. Veronese
    ELETTRA, Basovizza, Italy
  
  Non-destructive bunch length measurements after the magnetic compression is performed in Fermi@Elettra via the so-called Bunch Length Monitor (BLM) diagnostics. The BLM system is based on the diffraction radiation from a ceramic gap, captured by three millimeter-waves diodes, and the edge radiation from the last bending magnet of the bunch compressors, captured by a pyrodetector. In this paper we report on the study of the coherent radiation from a gap which we performed both applying the analytical theory and by means of simulations of the radiated electromagnetic field (CST Particle Studio). The study started from a simple gap in vacuum; time and frequency domain results were then investigated and compared with analytical theory. Finally in order to study a more realistic system, we investigated the effect of the dielectric and metallic holed shield used to assure the electric continuity.  
 
MOPD43 Beam Loss Detected by Scintillation Monitor hadron, linac, background, quadrupole 149
 
  • A. Miura, T. Maruta
    JAEA/J-PARC, Tokai-mura, Japan
  • K. Hasegawa, N. Ouchi, H. Sako
    JAEA, Ibaraki-ken, Japan
  • Z. Igarashi, M. Ikegami, T. Miyao
    KEK, Ibaraki, Japan
  
  Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. After all signals passed through the filter circuit and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.  
 
MOPD73 Study of Beam Size Blowup due to Transverse Bunch Feedback Noise on e+e− Collider luminosity, feedback, beam-beam-effects, injection 212
 
  • M. Tobiyama, K. Ohmi
    KEK, Ibaraki, Japan
  
  Vertical beam size blowup with the gain of the transverse bunch feedback systems has been observed in KEKB B-factory rings. With the numerical simulation, large beam-beam effect enhances small oscillation induced by the broadband noise of the bunch feedback kick. To examine the simulation, beam response, effective beam size and the luminosity change with artificial external noise injected in the transverse feedback system have beem measuredn in KEKB LER ring during collision. The result has been compaired with the simulation including beam-beam effect and showed good agreement.  
poster icon Poster MOPD73 [0.296 MB]  
 
MOPD82 Installation for Measurements of Secondary Emission Yield and Electron Cloud Lifetime in Magnetic Field electron, cryogenics, cathode, vacuum 236
 
  • A.A. Krasnov, V.V. Anashin, V.K. Ovchar, V.V. Smaluk, D.P. Sukhanov
    BINP SB RAS, Novosibirsk, Russia
  
  An experimental setup for investigations of electron-surface interaction and electron cloud behavior is under commissioning at BINP. The proposed method provides direct measurements of secondary emission yield and electron clouds lifetime in the presence of strong magnetic field. In principle, the experiments can be performed at cryogenic temperatures. The experimental data will help to figure out the process of reflection of low energy electrons from a metal surface and can be useful for improvement of computer codes developed for simulation of electron clouds behavior in a cold beam pipe of particle accelerators. The structure and performance capabilities of the setup are described, first experimental results are presented.  
 
MOPD96 The Mirror Mounting of a Fast Switching Mirror Unit at FLASH laser, site, target, synchrotron 269
 
  • F. Perlick, A. Donat, R. Heller, J. Nagler, M. Sachwitz, L.V. Vu
    DESY Zeuthen, Zeuthen, Germany
  
  To provide different beam lines with laser light from one source, a fast switching mirror unit that allows permanent switching with a frequency of up to 2.5 Hz was developed. One part of the study deals with the mirror and the design of its mounting in the chamber. The challenge lies in achieving a firm mounting of the mirror without significant mirror deformation, since the users demand only very few divergence of the laser beam at the test sites. The newest design of the mounting brought considerable improvement with regard to the pitching and the torsion of the mirror, which have an important impact on the beam divergence.  
 
MOPD97 Beam Position Monitor System for the CERN Linac4 linac, pick-up, DTL, resonance 272
 
  • J. Tan, L. Søby, M. Sordet
    CERN, Geneva, Switzerland
  
  The new LINAC4 will provide 160 MeV H¯ ion beams for charge-exchange and proton injection into the CERN accelerator complex. Among a wide variety of beam diagnostics devices, shorted stripline pick-ups will measure the absolute beam position, the relative and absolute beam current, and the average beam energy via the time-of-flight between two monitors. This paper describes the beam position monitor (BPM) with its electronic acquisition chain to be implemented on the movable test bench for beam characterization up to 12 MeV.  
 
TUPD03 Beam Profile Measurement during Top-up Injection with a Pulsed Sextupole Magnet injection, kicker, quadrupole, dipole 305
 
  • R. Takai, K. Harada, T. Honda, Y. Kobayashi, S. Nagahashi, N. Nakamura, T. Obina, A. Ueda
    KEK, Ibaraki, Japan
  • H. Takaki
    ISSP/SRL, Chiba, Japan
  
  A beam injection scheme using a pulsed multipole magnet is suitable for the top-up injection because a disturbance to the stored beam is much smaller than that of the conventional scheme using several kicker magnets. At the Photon Factory storage ring, the top-up injection with a pulsed sextupole magnet (PSM) has been used for the user operation since January 2011. In order to ascertain the effect of the PSM injection, we measured turn-by-turn stored beam profiles following the injection kick by using a fast-gated camera. As a result, it was demonstrated that the PSM injection dramatically decreases not only the coherent dipole oscillation but also the beam profile modulation, as expected from the beam tracking simulation.  
 
TUPD11 Developments for IFMIF/EVEDA LIPAc Beam Position Monitors: The Sensors at the MEBT and the Wire Test Bench pick-up, controls, linac, quadrupole 320
 
  • I. Podadera, J.M. Carmona, A. Guirao, A. Ibarra, L.M. Martinez Fresno, E. Mirones, R. Unamuno, J.G.S. de la Gama
    CIEMAT, Madrid, Spain
  
  Funding: This work has been partially supported by the Spanish Ministry of Science and Innovation under Project ENE2009-11230
The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. In the Medium Energy Beam Transport line (MEBT) connecting the RFQ and the MEBT, non-interceptive Beam Position Monitors pickups (MBPMs) will measure the transverse position and phase in order to maximize the transport efficiency of the beamline. The response of the MBPMs must be optimized for a beam current for 5 MeV, and a peak beam current of 125 mA. Due to the lack of space in the MEBT, the MBPMs will be located inside the magnets. The MBPMs will have to fit inside the magnets without perturbing the magnetic field. In this contribution, the electromagnetic and mechanical design of the MBPM will be presented. In addition, in order to validate and characterize all the BPMs type of IFMIF/EVEDA once they are manufactured, a wire test bench has been constructed and verified at CIEMAT. The design and validation results of the test bench will be discussed. 		 
 
TUPD16 High Frequency Measurements of the Beam Position Monitors for the TBL Line of the CTF3 at CERN impedance, bunching, pick-up, monitoring 335
 
  • J.J. García-Garrigós, C. Blanch Gutierrez, J.V. Civera-Navarrete, A. Faus-Golfe
    IFIC, Valencia, Spain
  • B. Gimeno
    UVEG, Burjasot (Valencia), Spain
  
  Funding: Funding Agency: FPA2010-21456-C02-00
A series of Inductive Pick-Ups (IPU) for Beam Position Monitoring (BPM) with its associated electronics were designed, constructed and tested at IFIC. A full set of 16 BPMs, so called BPS units, were successfully installed in the Test Beam Line (TBL) of the 3rd CLIC Test Facility (CTF3) at CERN. Two different characterization tests, at low and high frequencies, were carried out on the BPS units: The low frequency test, in the beam pulse time scale (until 10ns/100MHz), determined the BPSs parameters directly related to the beam position monitoring and the high frequency test, reaching the microwave X-Ku bands around the beam bunching time scale (83ps/12GHz). In this paper we describe the results and methods used to obtain the longitudinal impedance in the frequency range of interest. This test is based on the S-parameters measurements of the propagating TEM mode in a matched coaxial waveguide, specifically designed for the BPS, which is able to emulate an ultra-relativistic electron beam. 		 
poster icon Poster TUPD16 [1.069 MB]  
 
TUPD17 Spatial Resolution Test of a BPMS for DESIREE Beam Line Diagnostics ion, electron, rfq, diagnostics 338
 
  • S. Das, A. Källberg
    MSL, Stockholm, Sweden
  • J. Harasimowicz
    The University of Liverpool, Liverpool, United Kingdom
  
  Funding: Two of us (S.Das and J. Harasimowicz) acknowledge the financial support received from the European Commission within FP7 Marie Curie Initial Training Network DITANET
Spatial resolution of a beam profile monitoring system (BPMS) was tested. It will be a part of the DESIREE [1] diagnostics to monitor and cover the wide range of beam intensities and energies. The BPMS consists of an aluminum (Al) plate, a grid placed in front of Al, a microchannel plate (MCP), a fluorescent screen (F.S.), a PC, and a CCD camera [2]. A beam collimator containing a set of circular holes of different diameter and separation between them was built to check the spatial resolution of the system [3]. Two holes of diameter 1 mm, separated by 2 mm, in the collimator were used for this purpose. A proton beam was used for the measurements. It was observed that these holes create two beams of approximately same intensity of areas each of 1 mm in diameter with 2 mm separation between the beam centers on the screen, suggesting a resolution of 2 mm of the system. The resolution was tested for different beam energy (0.5-40 keV), and voltages applied on the Al and MCP plates. The experimental results will be compared with the simulations.
[1] www.msl.se;www.atom.physto.se/Cederquist/desiree_web_hc.html
[2] K. Kruglov et al, NIM A, 441, 595 (2002);Nucl. Phys. A, 701, 193c (2002)
[3] S. Das et al, Proceedíngs of DITANET workshop, Nov. 23-25, 2009 		 
 
TUPD18 Beam Position Monitors for the ACS Section of the J-PARC Linac impedance, linac, cavity, ion 341
 
  • T. Miyao, Z. Igarashi, T. Toyama
    KEK, Ibaraki, Japan
  • A. Miura
    JAEA/J-PARC, Tokai-mura, Japan
  
  The J-PARC is consisted of Linac, 3GeV-RCS, and 50GeV-MR. We are aiming at the energy upgrade of J-PARC linac from 181MeV to 400MeV. We employed the ACS(Annular Coupled Structure) as the acceleration cavities. To have the energy upgrade, we need to develop beam instruments including beam position monitors (BPMs). Then, we designed them to be able to measure a horizontal and vertical beam position and employed a stripline-type as their electrodes. The BPMs are required to be calibrated to the accuracy of beam orbit within 100μm. To achieve the requirement, we did some calibrations. First, we decided a width of stripuline, whose characteristic impedance can be calibrated to 50 Ω with electric field simulations. Second, we also measured characteristic impedance of 4 different striplines per a BPM corresponding with BPM simulations. Last, we measured an electrical center position of BPMs with a simulated beam signal at 324MHz, 6dBm. A BPM will be installed at each quadrupole magnet in the ACS section to be used for a beam commissioning. Systematic calibration of developed BPMs is described in this paper. In addition, a phase measurement using these BPMs will be considered.  
 
TUPD24 Design Status of Beam Position Monitors for the FAIR Proton Linac linac, proton, cavity, vacuum 356
 
  • C.S. Simon, F. Senée
    CEA/DSM/IRFU, France
  • G. Clemente, P. Forck, W. Kaufmann, P. Kowina
    GSI, Darmstadt, Germany
  
  Beam Position Monitors (BPM) based on capacitive buttons are designed for the FAIR Proton-LINAC, constructed as an extension of the existing GSI facility. This LINAC is aiming to produce a maximum design current of 70 mA at the 70 MeV energy with an accelerating frequency of 325 MHz. At 14 locations, the BPMs will measure the transverse beam position, the relative beam current and the mean beam energy by time-of-flight method. Depending of the location, the BPM design has to be optimized, taking into account an energy range from 3 MeV to 70 MeV, a short insertion and a beam pipe aperture changes from 30 mm to 50 mm. Some of BPMs will be mounted very close to the CH cavities and special care must be taken to suppress the pickup of the strong rf-field from that cavities. In this contribution, the status of the BPM design will be presented.  
 
TUPD25 Design of Magnetic BPM and Error Corrections electron, shielding, vacuum, instrumentation 359
 
  • M. Shafiee, E. Ebrahimi, S.A.H. Feghhi
    Shahid Beheshti University, Evin, Tehran, Iran
  
  For beam position monitoring (BPM) purposes, two prominent approaches as a physical effect have been applied including electrostatic and magnetic. In electrostatic types, secondary emission from the electrodes can be a problem when strong beam loss occurs, in such a situation, a magnetic BPM may be chosen. For this purpose we made a magnetic BPM including a square shape of ferromagnetic core with winding on each side. In this case study we used it for detecting the position of wire which is including a pulsed current (as an electron bunch) produced by a PROTEK G305 pulse generator. A Tektronix 2235A oscilloscope was calibrated and used to measure the induced voltage of magnetic BPM. Measurement results have been compared with simulation using CST software and performed error corrections which are presented, with this regard we could measure the wire position with high resolution furthermore we deduced the wire position hasn’t linear relation with induced voltage and needs more physical and mathematical analyzing. This way propose us that we can use magnetic BPMs in this approach and calibrate them before installing on accelerators.  
poster icon Poster TUPD25 [0.120 MB]  
 
TUPD32 THz Radiation Diagnostics for Monitoring the Bunch Compression at the SwissFEL Injector Test Facility radiation, electron, vacuum, FEL 374
 
  • C. Gerth, B. Schmidt, S. Wesch
    DESY, Hamburg, Germany
  • R. Ischebeck, G.L. Orlandi, P. Peier, V. Schlott
    PSI, Villigen, Switzerland
  
  At the SwissFEL Injector Test Facility, installation of a magnetic chicane for longitudinal bunch compression is foreseen for the first half of 2011. Bunch compression will be accomplished by operating two S-band accelerating structures on-crest and two S-band structures at off-crest RF phases. An X-band structure for the linearization of the longitudinal phase space will be installed at a later stage. The detection of coherent synchrotron radiation or coherent diffraction radiation in the THz range can be used to monitor the bunch compression process and stabilize the RF phases by a beam-based feedback. In this paper, we study the source characteristics of the edge radiation emitted at the 4th dipole of the bunch compressor as well as the diffraction radiation generated by a metallic foil with a hole. Particle tracking simulations were used to model the bunch compression process for different operation modes. The performance of a bunch compression monitor consisting of focusing mirrors and band pass filters has been evaluated by simulating the THz radiation transport of the optical components.  
 
TUPD38 Design of a Single-Shot Prism Spectrometer in the Near- and Mid-Infrared Wavelength Range for Ultra-Short Bunch Length Diagnostics electron, radiation, diagnostics, optics 386
 
  • C. Behrens
    DESY, Hamburg, Germany
  • A.S. Fisher, J.C. Frisch, A. Gilevich, H. Loos, J. Loos
    SLAC, Menlo Park, California, USA
  
  The successful operation of high-gain free-electron lasers (FEL) relies on the understanding, manipulation, and control of the parameters of the driving electron bunch. Present and future FEL facilities have the tendency to push the parameters for even shorter bunches with lengths below 10 fs and charges well below 100 pC. This is also the order of magnitude at laser-driven plasma-based electron accelerators. Devices to diagnose such ultra-short bunches even need longitudinal resolutions smaller than the bunch lengths, i.e. in the range of a few femtoseconds. This resolution is currently out of reach with time-domain diagnostics like RF-based deflectors, and approaches in the frequency-domain have to be considered to overcome this limitation. Our approach is to extract the information on the longitudinal bunch profile by means of infrared spectroscopy using a prism as dispersive element. In this paper, we present the design considerations on a broadband single-shot spectrometer in the near- and mid-infrared wavelength range (0.8 - 39.0 μm).  
 
TUPD49 Performance of Parabolic and Diffusive OTR Screens at the CLIC Test Facility 3 dipole, linac, diagnostics, alignment 413
 
  • M. Olvegård, B. Bolzon, E. Bravin, S. Burger, A.E. Dabrowski, T. Lefèvre
    CERN, Geneva, Switzerland
  • C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  
  At the CLIC Test Facility 3, OTR screens are commonly used in beam imaging systems for energy and energy spread characterization in dedicated spectrometer lines. In these lines the horizontal beam size is typically of the order of one centimeter. Already in 2005 a limitation was observed resulting from a strong dependence of the intensity of the light captured by the camera, on the position on the screen (vignetting). The severity of this effect increases with the electron energy, as the aperture of the optical system is finite and the OTR photons are emitted in a small cone of 1/γ angle. To mitigate this effect, different shapes and surface polishing of the screens were investigated. Parabolic and diffusive OTR radiators were tested in several spectrometer lines all along the CTF3 complex. The results are presented in this paper.  
 
TUPD50 Slice-Emittance Measurements at ELBE / SRF-Injector emittance, electron, SRF, quadrupole 416
 
  • J. Rudolph, M. Abo-Bakr, T. Kamps
    HZB, Berlin, Germany
  • J. Teichert
    HZDR, Dresden, Germany
  
  Funding: Supported by the European Community-Research Infrastructure Activity under the FP7 program (EuCARD, contract number 227579)
The linear accelerator ELBE delivers high-brightness electron bunches to multiple user stations, including an IR-FEL. The current thermionic injector is being replaced by a superconducting rf photoinjector (SRF-injector) which promises higher beam quality. Using a transfer chicane, beam from the SRF-injector can be injected into the ELBE linac. Detailed characterization of the electron beam is achieved by measuring the vertical slice emittance of the beam. To perform this measurement a combination of rf zero-phasing, spectrometer dipole and quadrupole scan is used. The electron beam is accelerated by the first cavity of the ELBE accelerator module and send through a second cavity which is operated at zero-crossing of the rf. In doing so a linear energy-time correlation is induced to the beam. The chirped beam is send through a spectrometer dipole and the longitudinal distribution can be made visible on a scintillator screen. Performing a quadrupole scan allows the determination of the emittance for different slices. This paper explains the working principle of the method and the experimental setup and shows results of performed simulations as well as first measurement results. 		 
 
TUPD58 Non-interceptive Profile Measurements using an Optical-based Tomography Technique diagnostics, laser, ion, vacuum 437
 
  • C.M. Mateo, G. Adroit, G. Ferrand, A. France, R. Gobin, S. Nyckees, Y. Sauce, F. Senée, O. Tuske
    CEA/IRFU, Gif-sur-Yvette, France
  
  Funding: This work is supported by the DITANET Marie Curie European network
Most of the charged particle beam shapes do not possess symmetry. In such cases, diagnostic measurement obtained in one direction is not enough to reconstruct the spatial distribution of the beam. The use of intense beams which demands for non-interceptive diagnostic devices posed another challenge in measuring the beam’s spatial distribution. At CEA Saclay and within the DITANET framework, the use of tomography combined with optical diagnostics to develop a non-interceptive transverse profile monitor is under development. This profile monitor is presently tested on the BETSI test bench. In this contribution, a tomography algorithm suited for beam profile measurements is presented. This algorithm is based on the formulation of iterative Algebraic Reconstruction Technique (ART) problem and the Maximum-Likelihood Expectation Maximization (MLEM) for the iteration step. The algorithm is optimized within the limit of using 6 projections only. Several beam shapes are generated and then reconstructed computationally. Actual measurements in the BETSI test bench are also done to verify the tomographic reconstruction process. 		 
 
TUPD59 Suppression of Coherent Optical Transition Radiation in Transverse Beam Diagnostics by Utilising a Scintillation Screen with a Fast Gated CCD Camera electron, laser, FEL, linac 440
 
  • M. Yan
    Uni HH, Hamburg, Germany
  • C. Behrens, C. Gerth, G. Kube, B. Schmidt, S. Wesch
    DESY, Hamburg, Germany
  
  Micro-bunching instabilities in high-brightness beams of linac-driven FELs can lead to coherence effects in the emission of optical transition radiation (OTR) used for standard transverse profile diagnostics, thus rendering it impossible to observe a direct image of the particle beam. By using a scintillation screen in combination with a fast gated CCD camera, coherence effects can be suppressed as OTR is created in an instantaneous process while scintillation light has a certain decay time. In addition, the emission of the scintillation light is a statistical process from many atoms which is completely insensitive to the longitudinal bunch structure and does not produce coherence effects. Gating the camera during the passage of the electron bunch should eliminate any influence of the coherent OTR (COTR). First experiments using this method have been performed successfully at FLASH as a proof-of-principle. In this paper, we study the applicability of scintillation screens for high-energy electron beams under operation conditions for which COTR is emitted. Experimental results together with simulations are presented and discussed in view of COTR suppression and spatial resolution.  
 
TUPD60 Optical Diagnostics for Frankfurt Neutron Source emittance, diagnostics, factory, neutron 443
 
  • H. Reichau, O. Meusel, U. Ratzinger, C. Wagner
    IAP, Frankfurt am Main, Germany
  
  A non-interceptive optical diagnostic system on the basis of beam tomography, was developed for the planned Frankfurt Neutron Source (FRANZ). The proton driver linac of FRANZ will provide energies up to 2.0 MeV. The measurement device will non-interceptively derive required beam parameters at the end of the LEBT at beam energies of 120 keV and a current of 200 mA. On a narrow space of 351.2 mm length a rotatable tomography tank will perform a multi-turn tomography with a high and stable vacuum pressure. The tank allows to plug different measurement equipment additionally to the CCD Camera installed, to perform optical beam tomography. A collection of developed algorithms provides information about the density distribution, shape, size, location and emittance on the basis of CCD images. Simulated, as well as measured data have been applied to the evaluation algorithms to test the reliability of the beam. The actual contribution gives an overview on the current diagnostic possibilities of this diagnostic system.  
poster icon Poster TUPD60 [1.886 MB]  
 
TUPD64 Test Measurements of a 20 m/s Carbon Wire Beam Scanner vacuum, controls, feedback, acceleration 452
 
  • M. Koujili, J. De Freitas, B. Dehning, J. Emery, J.F. Herranz Alvarez, D. Ramos, M. Sapinski
    CERN, Geneva, Switzerland
  • Y. Ait Amira
    UFC, Besançon, France
  • A. Djerdir
    UTBM, Belfort, France
  
  This paper presents the design of the actuator for the fast and high accuracy Wire Scanner system. The actuator consists of a rotary brush-less synchronous motor with the permanent magnet rotor installed inside the vacuum chamber and the stator installed outside. The fork, permanent magnet rotor and two angular position sensors are mounted on the same axis and located inside the beam vacuum chamber. The system has to resist a bake-out temperature of 200°C and ionizing radiation up to tenths of kGy/year. Maximum wire travelling speed of 20 m/s and a position measurement accuracy of 4 μm is required. Therefore, the system must avoid generating vibration and electromagnetic interference. A digital feedback controller will allow maximum flexibility for the loop parameters and feeds the 3-phase linear power driver. The performance of the presented design is investigated through simulations and experimental tests.  
 
TUPD82 First Results of the LHC Collision Rate Monitors luminosity, interaction-region, bunching, proton 497
 
  • E. Bravin, S. Bart Pedersen, A. Boccardi, S. Burger, C. Dutriat
    CERN, Geneva, Switzerland
  • L.R. Doolittle, H.S. Matis, M. Placidi, A. Ratti, H. Yaver, T. stezelberger
    LBNL, Berkeley, California, USA
  • R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  
  Funding: This work is partially supported by the US DoE through US-LARP
The aim of CERN’s large hadron collider (LHC) is to collide protons and heavy ions with centre of mass energies up to 14 zTeV. In order to monitor and optimize the collision rates special detectors have been developed and installed around the four luminous interaction regions. Due to the different conditions at the high luminosity experiments, ATLAS and CMS, and the low luminosity experiments, ALICE and LHC-b, two very different types of monitors are used, a fast ionisation chamber (BRAN-A) and a Cd-Te solid state detector (BRAN-B) respectively. Moreover in order to cope with the low collision rates foreseen for the initial run a third type of monitor, based on a simple scintillating pad, was installed in parallel with the BRAN-A. This contribution illustrates the results obtained during the 2010 run with an outlook for 2011 and beyond. 		 
 
TUPD83 Photodiode Calibration using an Electrical Substitution Radiometer in the Hard X-ray Region photon, alignment, radiation, cryogenics 500
 
  • N.I. Bolibruch, R. Igarashi, J.M. Vogt
    CLS, Saskatoon, Saskatchewan, Canada
  
  Funding: Work supported by NSERC, NRC, CIHR, WEDC.
An electrical substitution radiometer under development at the Canadian Light Source (CLS) has been used to calibrate a photodiode (AXUV100) from International Radiation Detectors Inc. within an energy range of 8 keV to 30 keV. These measurements were made using monochromatic X-rays on the Biomedical Imaging and Therapy bend magnet beam line and the Hard X-Ray Microanalysis beam line at the CLS. The results were then compared with silicon absorption calculations using data from the NIST mass absorption coefficient tables. Good agreement has been found between the diode calibration obtained from the radiometer and the theoretical calculation of the diode response. 		 
 
TUPD92 SPIRAL2 Beam Energy Measurement pick-up, linac, rfq, instrumentation 524
 
  • W. Le Coz, T.A. André, C. Doutresssoulles, C. Jamet, S. Loret
    GANIL, Caen, France
  
  In order to produce high intensity exotic beams in the existing experimental rooms of the GANIL facility, the SPIRAL2 project is under development and under construction at GANIL. The first phase of the SPIRAL2 project consists to build a new accelerator composed of two sources, an ion source and a proton/neutron source, a RFQ and a superconducting Linac. The linac is designed to accelerate 5 mA deuterons up to 40 MeV and 1 mA heavy ions up to 14.5 MeV/u. A new electronic device has been developed at GANIL to measure phase and amplitude of pick-up signals and calculate the beam energy. The principle consists of directly digitizing the pick-up pulses by under-sampling. The Phase and amplitude of different harmonics are then calculated with a FPGA by an I/Q method before the beam energy calculation. This paper gives results of the peak-up tests in laboratory and the comparisons with simulations. The tests in laboratory and on the GANIL accelerator of an electronic prototype are shown and presented.  
 
WEOC02 News About the Cryogenic Current Comparator for Beam Diagnostics ion, cryogenics, antiproton, pick-up 569
 
  • W. Vodel
    HIJ, Jena, Germany
  • R. Geithner, R. Neubert, P. Seidel
    FSU Jena, Jena, Germany
  • K.K. Knaack, K. Wittenburg
    DESY, Hamburg, Germany
  • A. Peters
    HIT, Heidelberg, Germany
  • H. Reeg, M. Schwickert
    GSI, Darmstadt, Germany
  
  An absolute and exact measurement of the intensity of charged particle beams - extracted from an accelerator or circulating in a Storage Ring - is one of the major problems of beam diagnostics. Also the measurement of so-called dark currents, generated by superconductive RF accelerator cavities at high voltage gradients to characterize the quality of these components becomes more and more important for the commissioning of new accelerators (XFEL). The Cryogenic Current Comparator (CCC) based on high precision LTS SQUIDs is an excellent tool to solve these problems. This contribution gives an overview on the development of SQUID-based CCC for nuclear physics from the first successful demonstration of the performance at GSI Darmstadt through the recently tested CCC for the XFEL at DESY to the latest improved version for FAIR.  
slides icon Slides WEOC02 [2.596 MB]  
 
WEOC03 Dark Current Monitor for the European XFEL solenoid, controls, impedance, FEL 572
 
  • D. Lipka, W. Kleen, J. Lund-Nielsen, D. Nölle, S. Vilcins, V. Vogel
    DESY, Hamburg, Germany
  
  Dark current is produced due from field emission in the accelerator. This generates a radiation background in the tunnel which damages the electronics and activates components. To decrease the dark current different methods like kickers and collimators are used. To control the dark current level and measure and optimize the efficiency of dark current reduction dark current monitors are required. To measure the dark current a cavity was designed and built with the operation frequency of the accelerator. Here the small charge of the dark current present in every RF bucket induces and superimposes a field up to a measurable level. The cavity is proven at the PITZ facility. In addition to dark current levels down to 50 nA, the monitor allows for charge measurements resolution below pC, better than the Faraday cup. In addition the ratio of amplitudes from higher order monopole modes is a function of the bunch length. Measurements show the same trend of bunch length compared with a destructive streak camera method with comparable resolution. Therefore this monitor is able to measure bunch charge, dark current and bunch length in a non-destructive manner.  
slides icon Slides WEOC03 [0.935 MB]