| Paper | Title | Page |
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| TUPB05 | A Tagged Photon Source at the Frascati Beam-Test Facility (BTF) | 63 |
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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. |
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| TUPB13 | Design Considerations of a Spectrometer Dipole Magnet for the Photo Injector Test facility at DESY in Zeuthen (PITZ) | 87 |
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| 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. | ||
| TUPB23 | Design Considerations for Phase Space Tomography Diagnostics at the PITZ Facility | 117 |
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| A major goal of the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is to build and to optimise high brightness electron sources for SASE FELs where the detailed knowledge of the phase-space density distribution of the electron beam is very important. The current upgrade of the machine includes a diagnostic section suitable for transverse phase space tomography and multiscreen emittance measurement. The designed module should be capable of operation over a range of beam momenta between 15 and 40MeV/c. It mainly consists of four observation screens with three FODO cells in between them. An upstream section of a number quadrupoles is used to match the electron beam Twiss parameters to the tomography section. The design considerations of the tomography section and results from numerical simulations will be presented in this contribution. | ||
| TUPB29 | Experimental Optimization of the Cathode Laser Temporal Profile | 135 |
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| Producing a flat-top temporal intensity profile of the cathode laser pulse is a key issue for the XFEL photo injector. The photo injector test facility at DESY in Zeuthen (PITZ) serves as a test bench for FEL photo injectors. The PITZ cathode laser contains a pulse shaper to produce flat-top temporal pulse profiles. Based on birefringent filters the pulse shaper includes four degrees of freedom to achieve a pulse profile with parameters closer to the required XFEL photo injector specifications (20 ps FWHM, 2 ps rise/fall time). A procedure for experimental temporal laser profile optimization is presented in this paper. The laser profile is measured using a streak camera. The four parameters - pulse length (FWHM), rise and fall time as well as modulation of the flat-top which are obtained from a flat-top fit of the measured profile - are used in the profile evaluation. Utilizing results of beam dynamics simulations for various cathode laser profiles a single value of the goal function – the expected emittance growth due to measured imperfections of the profile - can be obtained. The procedure of the goal function minimization has been implemented and tested at PITZ. | ||
| TUPB32 | An RF Deflector for the Longitudinal and Transverse Beam Phase Space Analysis at PITZ | 144 |
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| A detailed characterization of the longitudinal and transverse phase space of the electron beam provided by the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is required to optimize photo injectors for Free-Electron Laser (FEL) applications. By means of a RF deflector the transverse slice emittance and the longitudinal phase space can be analysed. In this paper we present the status of the RF deflector design. The analysis of the prospect diagnostics shows the possibility to achieve a time resolution of about 0.5 ps, and a longitudinal momentum resolution of 10-4. The influence of the deflector on the beam longitudinal and transverse phase space is analysed. | ||
| TUPC02 | Photo Injector Cathode Laser Beam Intensity and Pointing Position Diagnostics at PITZ | 147 |
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| A photo cathode laser with unique parameters is used at the Photo Injector Test facility at DESY in Zeuthen, PITZ. It is cabable of producing laser pulse trains consisting of up to 800 pulses with a repetition rate of 1 MHz where each laser pulse has a flat-top temporal profile. The knowledge of the laser stability is very important for the emittance measurements procedure. Therefore, a system for monitoring the laser beam intensity and pointing position stability was created at PITZ. It is capable of measuring the laser spot position and pulse intensity for each of the laser pulses in the train using a quadrant diode and a photomultiplier tube, respectively. Taking into account the laser beam spot transverse intensity distribution measured by a CCD camera allows to study the position of the laser spot on the photo cathode with a resolution of 8.3 um. Laser intensity measurements can be done for a wide dynamical range of intensities due to the tunable photo multiplier tube gain. The first experiments with the new system show very small laser spot position jitter on the cathode surface of about 20 um and laser intensity fluctuations of about 14 %. | ||
| TUPC07 | Design and Construction of the Multipurpose Dispersive Section at PITZ | 159 |
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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). |
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| TUPC10 | A transverse RF deflecting cavity for the FERMI@elettra project | 168 |
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| The layout of FERMI@elettra includes a high energy transfer line (TL) which brings the accelerated electron bunch to the FEL undulator chains. The TL optics has been designed according to several space constraints and with the purpose of including diagnostics for the complete characterization of the electron bunch just before the FEL process starts. Basing on such optics, this paper reports the study of the electron bunch deflection at nominal energy of 1.2 GeV for the measurement of the bunch length, of the transverse slice emittance and of the slice energy spread, coupled to a downstream dipole. The effect of the cavity on the electron beam was simulated by tracking code and the specification on the deflecting voltage was thus confirmed. Furthermore the RF design and electromagnetic simulations are also presented here. | ||
| TUPC11 | The Beam Diagnostics System for the FERMI@elettra Photoinjector | 171 |
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| The quality of the photoinjector high brightness electron beam plays a crucial role for the performance of the seeded FERMI@elettra FEL. Optimization of the gun is possible with an extensive characterization of the 5 MeV electron beam longitudinal and transverse phase space. The photoinjector diagnostics system includes interceptive instrumentation as YAG:Ce screens for transverse position and profile measurements and Faraday cups for the absolute beam charge measurements; a Cherenkov radiator coupled to a streak camera provides an accurate reconstruction of the longitudinal profile and a pepper pot is foreseen for the transverse emittance measurement. Information on beam transverse position and charge is obtained non-disruptively with respectively stripline BPMs and a current transformer. A dispersive beamline is also foreseen for the beam energy, energy spread and longitudinal phase space measurements. The diagnostics system performances and design principles are presented. | ||
| TUPC18 | New Type Photocathode for X-Ray Streak Camera of the 10-Fs Resolution | 183 |
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High current streak camera with new principle of operation* allowing to get resolution of the order of 10 fs in the frequency range both of visible light and x-ray is described. One of the key units of the camera is photocathode of spherical configuration with its surface radius of 10…100 micrometers. For creating the photocathode new technologies, developed and realized, are described. The results of the photocathode fabrication and investigations of its main features are presented and discussed.
* A. M. Tron, I. G. Merinov, T. Gorlov. New generation streak camera design and investigation. Proc. of EPAC 2006, p. 1175. |