| Paper | Title | Page |
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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. | ||
| 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. | ||
| 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 %. | ||
| TUPC05 | Screen studies at PITZ | 153 |
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| The Photo Injector Test facility at DESY in Zeuthen (PITZ) has been built to test and to optimize electron sources that fulfill the requirements of SASE FEL's such as FLASH and XFEL. Basic properties of the electron beam such as mean momentum, momentum spread, transverse emittance etc. are determined using measurement of the beam size on YAG or OTR screens. Detailed knowledge of the uncertainties and systematic errors associated with these measurements are important to understand the underlying beam physics. The screen stations consist of a screen set-up, an optical transmission line to a CCD camera, and the video data acquisition system. In this paper we make a detailed description of the screen based beam size measurement systems that we use at PITZ and discuss the systematic errors of uncertainties associated with each single element of a system. | ||
| 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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| WEPB20 | Optical System for Measuring Electron Bunch Length and Longitudinal Phase Space at Pitz: Extension and Methodical Investigations | 274 |
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An extended optical system* for the measurement of the electron bunch length and the longitudinal phase space** using a streak camera is installed at PITZ. This system will be extended by two new branches in 2007, one in the straight section behind the booster cavity and another one in the first magnet spectrometer behind the booster cavity. The physics design of the chambers containing the radiators and of the optical system are presented. The results of optical calculations of the whole system will be given. Results of methodical investigations will be shown as well, especially concerning transversal optical resolution and time dispersion.
* J. Baehr et al., DIPAC ‘03, Mainz, Germany 2003** J. Roensch et al. FEL ’05, SLAC, Stanford, USA, 2005 |