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[en] The operation of a Free Elector Laser, FEL, requires high energy, high peak current electron beams with small transverse emittance. In the contemporary FELs, the electron beam is passed through a periodic magnetic structure - an undulator - which modifies the straight beam trajectory into a sinusoidal one, where FEL light is generated at each bend. According to the energy, the transverse emittance and the peak current of the beam and the parameters of the undulator, FEL radiation with wavelength in the range of nano- to micrometers can be generated. Studies and development of FELs are done all over the world. The Free electron LASer in Hamburg, FLASH, and the international European X-ray FEL, XFEL, in Hamburg, Germany, are two leading projects of the Deutsches Elektronen SYnchrotron, DESY. Part of the research program on FELs in DESY is realized in Zeuthen within the project Photo-Injector Test Facility at DESY in Zeuthen, PITZ. PITZ is an international collaboration including Germany, Russia, Italy, France, Bulgaria, Thailand, United Kingdom. The Institute of Nuclear Research and Nuclear Energy, INRNE, at the Bulgarian Academy of Sciences participates from bulgarian side. PITZ studies and optimizes the photo-injectors for FLASH and the XFEL. The research program emphasizes on detailed measurements of the transverse phase-space density distribution. Until 2010 the single slit scan technique has been used to measure the beam transverse distributions. At the end of 2010 a module for tomographic diagnostics has been installed which extends the possibilities of PITZ to measure simultaneously the two transverse planes of a single micropulse with improved signal-to-noise ratio. The difficult conditions of low emittance for high bunch charge and low energy make the operation of the module challenging. This thesis presents the design considerations for the tomography module, a number of reconstruction algorithms and their applicability to limited data sets, the influence of the above mentioned challenges and approaches to solve them. The first measurements obtained with the device are shown. Using numerical particle tracking it is shown that the tomographic reconstruction is consistent with the simulated data. Cross-check of some of the measured data with results obtained at different locations along the beamline, using single slit scans, prove that the measured phase-space distributions and the corresponding emittance values are consistent. Shot-to-shot fluctuations are revealed which would not be possible with the standard slit scans. Despite certain difficulties related to asymmetry of the electron beam transverse profiles and the strong influence of space-charge forces, it is shown the module fulfills its purpose and improves the resolution of the measurements of the transverse phase spaces.
[en] The major objective of the photo injector test facility at DESY in Zeuthen (PITZ) is the development and optimisation of high brightness electron sources suitable for SASE FEL operation. This requires full characterization of the sources. Knowledge of the transverse phase-space density distribution can be obtained using tomographic reconstruction techniques. Therefore the PITZ beam line will be equipped with a tomography section in 2008. The module consists of a lattice of four observation screens with three FODO cells in between them. A number of upstream quadrupoles is used to match the electron beam to the optics of the lattice. It should be capable of operation in a range of beam momenta between 15 and 40 MeV/c. The low energies together with the high current imply difficulties in its manipulation. This work presents some major aspects concerning the design of the setup. The expected performance is studied and verified with data from numerical simulations
[en] The Photo-Injector Test Facility at DESY, Zeuthen site (PITZ), is dedicated to development and test of high brightness electron sources for linac-based FELs. The PITZ beamline is equipped with three dedicated stations for transverse emittance measurements and in the current shutdown period a section for transverse phase-space tomography diagnostics is being installed. The reconstruction algorithms for analysing the data obtained with the tomography setup are currently pre-evaluated with multiple projections of quadrupole scan data taken at PITZ. This work presents first experience with tomographic reconstruction from quadrupole scan data. Measurements of the transverse phase space of electron beams produced with gaussian and flat-top temporal laser pulses are presented and superimposed to simulated data. The results are also compared to those obtained with single slit technique.
[en] The Photo Injector Test Facility at DESY, Zeuthen site (PITZ), has been built in order to develop and optimize electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. The electron beam is generated by photoemission initiated with a laser pulse having a flat-top temporal profile. Compared to the Gaussian one, such a flat-top profile yields smaller transverse projected emittance. In order to estimate the difference between the two cases, systematic simulations for 500 pC bunch charge are presented. Dependences of electron beam properties, like beam momentum, transverse beam size, phase space, emittance, on various machine parameters, e.g. gun phase, solenoid current, are shown as well.
[en] The Photo Injector Test facility at DESY, Zeuthen site (PITZ) focuses on testing, characterizing and optimizing high brightness electron sources for free electron lasers. Among various diagnostic tools installed at PITZ, the tomography module is used to reconstruct the transverse phase space distribution of the electron beam by capturing its projections while rotating in the phase space. This diagnostic technique can resolve the two transverse planes simultaneously with an improved resolution for pulses of low charge or in the future even for individual bunches within a bunch train. The low emittance, high charge density and moderate energy of the electron beam at PITZ contribute to significant space-charge forces. The conducted study aims to investigate how the phase space rotations and thus the reconstruction result are affected when considering the linear space-charge effect along the tomography lattice. The beam dynamics simulations were done using the V-Code tool.
[en] The Department of Nuclear Medicine, St. Marina University Hospital in Varna, is equipped with a self-shielded BG-75 cyclotron and synthesis unit for production of single doses of 18F-FDG. The cyclotron is capable to deliver 7.5 MeV proton beam with maximal current of 5 μA. During irradiation, a small target volume of 18O-enriched water is bombarded with protons and the resulting neutron and gamma fields induce nuclear reactions within the target bulk, machine components and shielding, the walls of the cyclotron vault. The aim of the present work is to define the radiological characteristics of the activation products generated during the operation of the cyclotron that need to be considered for daily maintenance and for decommissioning of the facility in future. For that purpose Monte-Carlo calculations with detailed models of the vault and the machinery are used. Key words: cyclotron, target, vault, activation, radioactive waste, Monte-Carlo simulations
[en] The photo injector test facility in Zeuthen (PITZ), DESY, is an experimental setup for high brightness electron source characterization. The main studies are conducted with an electron RF photo injector designed for FLASH and European XFEL. This article shortly describes a measurement approach that delivers transverse emittance as a function of longitudinal position within a bunch. The first measurement results are presented and discussed. The emittance measurements are performed using the traditional quad scan and the single slit scan technique
[en] The photo injector test facility at DESY, Zeuthen site, PITZ develops and characterizes photoelectron sources for linac driven free electron lasers (FELs) such as FLASH and the European XFEL. The main goal of the PITZ is to obtain electron beams with low transverse normalize emittance which is necessary for the successful operation of SASE FEL. Major parts of the facility - gun and booster cavities, photocathode laser system were upgraded in 2010 in order to improve the photo injector performance. A slit technique is used at PITZ to reconstruct the transverse phase space of the electron beam. Many machine parameters were tuned to optimize the beam emittance for a wide range of the bunch charge - from 20 pC to 2 nC. Measured emittance depending on various machine parameters like a gun launching phase, booster gradient, laser spot size on the cathode and main solenoid current is presented.
[en] The Photo Injector Test facility in Zeuthen site (PITZ), DESY, is testing and optimizing high brightness electron sources for free electron lasers. A key issue for such studies is the accurate determination of the beam emittance using a dedicated setup. The tomography module at PITZ aims in reconstructing the phase space distribution of the electron beam from captured projections of the beam when rotated in the phase space. This diagnostic technique can resolve the two transverse planes simultaneously with an improved resolution for short pulse trains. After the successful installation and commissioning of the tomography module, the collected data allowed phase space measurements which are presented together with simulation results. The comparison between the two highlights the difficulties rising from the strong impact of space-charge force, due to the specific features of the electron beam: very low emittance, high charge density and moderate energy. Future improvements of the setup are discussed finally.
[en] The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) has an aim to develop and optimize high brightness electron sources for Free Electron Lasers like FLASH and the European XFEL. The new laser system allows to produce trains of laser pulses with flat-top temporal profiles of about 20 ps FWHM and rise/fall time of about 2 ps had been commissioned at PITZ in late autumn 2008. Photo electrons emitted from the Cs2Te cathode are accelerated by a 1.6-cell L band RF gun cavity operated at 60 MV/m maximum accelerating gradient at the cathode. For measuring of transverse projected emittance the so called single slit scan technique is used at PITZ. This procedure is discussed. Recent results on measured emittance of electron beam are presented.