| Paper | Title | Other Keywords | Page | ||
|---|---|---|---|---|---|
| TUPB05 | A Tagged Photon Source at the Frascati Beam-Test Facility (BTF) | electron, photon, target, luminosity | 63 | ||
|
The DAΦNE Beam Test Facility, operating at the Frascati National Laboratory of INFN, provides electron or positron beams with tunable energy from 25 MeV to 750 MeV, while the intensity can be varied from 1010/pulse@ 0-50Hz down to a single particle per pulse. Recently a tagged photon source has been designed, built and tested. The photons are produced by bremsstrahlung of electrons with a maximum momentum of 750 MeV/c on a pair of x-y silicon micro-strip chambers(1), placed before the last bending magnet of the BTF transfer line. The photons are tagged in energy using the same bending dipole, whose internal walls have been covered by 10 modules of silicon micro-strip detectors. Depending on the energy loss in the photon production, the electrons impinge on a different strip once the dipole current has been set to the nominal value. The correlation between the directions on the electron measured by silicon chambers and the impinging position on the tagging module inside the magnet allows the tagging on the photons. In this paper the configuration of the system is presented with some results obtained during the latest test-beams.
|
(1)Profile monitors for wide multiplicity range electron beams. Proceeding DIPAC 2005 Lyon, France,pp166-168. |
|
||
| TUPB07 | Electric -In-Air-X-Ray- Detectors for high Resolution Vertical Beam Position Measurement at the ESRF | feedback, diagnostics, vacuum, emittance | 69 | ||
|
The tiny fraction of the very hard X-rays that fully penetrate the dipole absorber structure and enter the free air space behind it can be detected in different ways to yield precise information on the vertical characteristics of the electron beam. In addition to a system of imaging detectors to measure the emittance, a 2nd detector type was developed that yields a direct electric signal. It consists of a high-Z blade in conjuction with a small In-Air ionization slot that generates a direct strong electric signal allowing for nanometer resolution measurements of vertical beam motion in a spectrum upto 1KHz. The high resolution performance of this detector type is explained by the fact that it touches the heart and center of the beam whereas other devices (X-BPMs or e-BPMs) have to work on the edges or tails of the beam or feel the beam indirectly by wall-current pick-ups. The results obtained with prototypes will be presented together with the prospects of an installation of 8 units in 2007. The intrinsic advantages of this In-Air detector like costs and simplicity, thanks to a total absence of cooling and UHV requirements, will be emphasized.
|
|
|
||
| TUPB13 | Design Considerations of a Spectrometer Dipole Magnet for the Photo Injector Test facility at DESY in Zeuthen (PITZ) | emittance, booster, quadrupole, diagnostics | 87 | ||
|
The goal of the Photoinjector Test Facility at DESY in Zeuthen (PITZ) is to test and optimise electron guns for FELs like FLASH and XFEL at DESY in Hamburg and study emittance conservation by using a matched booster cavity. The physical specifications of a second spectrometer for measurements after the booster cavity at the beam momentum range from 4 to 40 MeV/c will be described. It will be used for measurements of the momentum distribution and the longitudinal phase space using two methods. The first method combines the dipole magnet with a RF transverse deflecting cavity, the second combines it with a Cherenkov radiator whose light is measured by a streak camera. Especially the first method is aiming for a good resolution in order to determine slice momentum spread. The design has to meet the demands of all these techniques for a measurement with high resolution and a bunch train containing 7200 pulses of 1nC charge and a repetition rate of 10Hz. Since there is not enough space for a separate beam dump after the dispersive section the beam has to be transported to the dump of the main beamline.
|
|
|
||
| TUPB15 | Beam Position Monitors Using a Re-entrant Cavity | linac, single-bunch, linear-collider, collider | 93 | ||
|
Two designs of high resolution beam position monitor, based on a radiofrequency re-entrant cavity, are developed at CEA/Saclay. The main radio-frequency modes excited by the beam in the cavity are monopole and dipole modes. The first monitor is developed in the framework of the European CARE/SRF program. It is designed to work at cryogenic temperature, in a clean environment and to get a high resolution and the possibility to perform bunch to bunch measurements. Two prototypes with a large aperture (78 mm) are installed in the FLASH linac, at DESY. The other design with an aperture of 18 mm and a large frequency separation between monopole and dipole modes, as well as a low loop exposure to the electric fields is developed for the CTF3 probe beam CALIFES at CERN. It is operated in single bunch and multi-bunches. This paper presents the mechanical and signal processing designs of both systems. Simulation and experimental results will be discussed.
|
|
|
||
| TUPC03 | Synchrotron Radiation Monitor for Energy Spectrum Measurements in the Bunch Compressor at FLASH | electron, acceleration, synchrotron, synchrotron-radiation | 150 | ||
|
Longitudinal bunch compression in magnetic chicanes is used at the Free-electron LASer in Hamburg FLASH for the generation of ultra-short electron bunches. A Synchrotron Radiation (SR) monitor has been installed behind the third dipole of the first bunch compressor to measure the energy and energy profile of the dispersed bunches. An intensified CCD camera records the emitted SR in the visible and enables one to select single bunches out of a bunch train. The performance of the system has been tested for different accelerator settings. The setup serves as a test bed for the European XFEL.
|
|
|
||
| TUPC06 | Coherent Radiation Studies For The FERMI@Elettra Relative Bunch Length Diagnostics | radiation, diagnostics, electron, synchrotron | 156 | ||
|
Bunch compressors are key components of the seeded FEL FERMI@elettra. Assuring their stable operation requires multiple non-destructive diagnostics to provide error signals to the feedback systems. Both the energy and the peak current of the electron bunch have to be stabilized by the feedback systems. The peak current stabilization implies charge and bunch length stabilization. The latter will be achieved by a redundant diagnostics based on Coherent Synchrotron Radiation (CSR) and Coherent Diffraction Radiation (CDR). In this paper we describe a study of Coherent Radiation emission downstream bunch compressors as the source of a relative bunch length measurement diagnostics. The study evaluates the most critical parameters in the design of such a diagnostic using numerical integration to calculate the spectral angular properties of the radiation for both CSR and CDR.
|
|
|
||
| TUPC07 | Design and Construction of the Multipurpose Dispersive Section at PITZ | quadrupole, emittance, diagnostics, electron | 159 | ||
|
For the characterization of rf photo-electron guns a full set of beam parameters has to be measured. For this purpose a new high energy dispersive arm will be used at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) in addition to the existing beam diagnostics. The multipurpose dispersive arm (HEDA1) is designed [1] for an electron energy range up to 40 MeV and will be put into operation in autumn 2007. It combines the functionality of (i) an electron spectrometer, (ii) a device for the characterization of the longitudinal phase space, and (iii) a transverse slice emittance measuring system. HEDA1 consists of a 180 degree dipole magnet followed by a slit, a quadrupole magnet, and two screen stations. One of the screen stations will be equipped with an optical read-out for a streak camera. We report about the detailed design of individual components and the construction progress.
|
[1] S. Khodyachykh, et al., Proccedings of the 28th International FEL Conference, Berlin (2006). |
|
||
| TUPC09 | Design of the cavity BPM system for FERMI@elettra | linac, coupling, simulation, diagnostics | 165 | ||
|
The cavity Beam Position Monitor (BPM) is a fundamental instrument for a seeded FEL, as FERMI@elettra. It allows the measurement of the bunch trajectory non-destructively, on a shot-by shot basis and with sub-micron resolution. The high resolution the cavity BPM is providing relies on the excitation of the dipole mode, originated when the bunch passes off axis in the cavity. Here we present the electromagnetic (EM) design and the cold test of the prototype BPM developed for the FERMI@elettra. The design adopted a C-band cavity with its dipole mode at fDIP=6.5GHz. The prototype is actually fitted with two cavities: one for the position measurement and one for the generation of the reference signal for the demodulator. Furthermore, the design of the prototype electronics for the acquisition and processing of the BPM signals is presented. The adopted scheme consists of a down converter from C-band to the intermediate frequency, followed by an IQ demodulator to generate the base-band signal, proportional to the transverse beam position. The performed simulation session is presented as well which we run before building the hardware for bench tests.
|
|
|
||
| TUPC23 | Design of a Submicron Resolution Cavity BPM for the ILC Main Linac | coupling, linear-collider, vacuum, collider | 192 | ||
|
A high resolution Beam Position Monitor (BPM) is necessary for the beam-based alignment and feedback systems of the future international linear collider (ILC). We present the cavity BPM developed at Fermilab within ILC collaboration. This monitor will be operated at cryogenic temperature and rigidly attached to the quad magnet. The same cylindrical cavity is used to obtain the signals from both dipole and monopole modes excited by beam. Such a scheme makes the BPM more compact for placing it inside the magnet space and simplifying the signal processing. The dipole TM110 mode is utilized to measure pulse to pulse beam motion at a theoretical resolution of approximately 50 nm. In order to measure a single bunch trajectory within 300 ns timescale we use a resonant coupling to lower cavity Q-factor. The ceramic windows are brazed inside coupling slots for vacuum isolation and easy cavity cleaning. We will present a BPM detailed numerical study and analyze its tolerance requirements for submicron resolution.
|
|
|
||
| WEPB01 | Design of an Electron Beam Energy Control Loop Using Transverse Dispersion | controls, electron, optics, target | 229 | ||
|
Stability in mean electron beam energy is of highest interest for a number of experiments performed at the ELBE accelerator. Energy drifts affect parameters of the generated Bremsstrahlung spectra, X-rays or infrared light, as well as the beam trajectory at the production targets or through the FEL waveguide, respectively. In practise, we observe a slow drifting of the effective accelerating field during the first hours after a machine power-up or after switching to different nominal beam energies. Initially, this effect was compensated manually. A first order automation solution has been developed that corrects the resulting energy drift continuously, using a non-intrusive beam position monitor placed in a transversely dispersive part of the beam guide. This paper describes the beam line setup and the simplified dynamic model of the control loop derived from it. Calculation of controller parameters using standard a standard method is shown. The user interface of the control system and working conditions for the loop are explained. Operational performance and conclusions towards improvements close this contribution.
|
|
|
||
| WEPB02 | Design of an Intra-Bunch-Train Feedback System for the European X-Ray FEL | feedback, kicker, pick-up, electron | 232 | ||
|
After joining the preparatory phase of the European X-ray FEL project, the Paul Scherrer Institute agreed in taking over responsibility for electron beam stabilization by developing a fast intra-bunch-train feedback (IBFB) system, which will be tested in its prototype version at the FLASH linac of the collaboration partner DESY. The proposed IBFB topology consists of two beam position monitors ("upstream BPMs") followed by two kicker magnets for each transverse plane and two more BPMs ("downstream BPMs"). By measuring the position of each bunch at the upstream BPMs and applying suitable transverse kicks individually to the following bunches, the architecture of the FPGA-based digital IBFB electronics (with a latency preferably below the bunch spacing of 200 ns and 1000 ns for the XFEL and FLASH) allows to damp beam motions up to hundreds of kHz. In addition to the FPGA-based feedback, DSPs enable adaptive feed-forward correction of repetitive beam motions as well as feedback parameter optimisation using the downstream BPMs. This paper gives an overview of the architecture and status of the IBFB subsystems being developed, like stripline BPMs, digital electronics and kicker magnets.
|
|
|
||
| WEO3A01 | Low-Latency High-Resolution Single-Shot Beam Position Monitors | pick-up, feedback, linac, alignment | 376 | ||
|
In this paper design aspects of high-resolution, single-shot transverse beam position monitors (BPMs) are discussed. The focus is put on BPMs which can provide (sub-)micrometer precision at measurement speeds of less than a few hundred nanoseconds. Different pickups, analog signal conditioning electronics, and digital post processing schemes are reviewed. Their characteristics and limitations with respect to application in high-resolution, fast BPMs are pointed out. Exemplary implementations of successful BPM realizations found in the literature are reviewed. A specific implementation of a BPM based on a resonant stripline pickup, developed for a fast transverse feedback system for the European X-FEL, is also presented.
|
|
|