Lederer, S.

Paper	Title	Page
MOPPH055	Measurements of the Projected Normalized Transverse Emittance at PITZ	138
	G. Asova, K. Boyanov, I. Tsakov INRNE, Sofia J. W. Baehr, C. H. Boulware, H.-J. Grabosch, L. H. Hakobyan, M. Hänel, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, S. Lederer, A. Oppelt, B. Petrosyan, S. Riemann, S. Rimjaem, J. Roensch, A. Shapovalov, F. Stephan, L. Staykov DESY Zeuthen, Zeuthen K. Floettmann DESY, Hamburg R. Richter BESSY GmbH, Berlin
	The main objective of the Photo Injector Test facility at DESY in Zeuthen (PITZ) is the production of electron beams with minumum transverse emittance at 1 nC bunch charge. PITZ consists of a photo cathode RF gun, solenoids for the compensation of space charge induced emittance growth and a booster cavity. In order to study the emittance evolution along the beam line three Emittance Measurement SYstems (EMSY's) were installed downstream of the booster cavity. In a first operation periode in October 2006 the emittance was measured for moderate gun gradients of about 40 MV/m. A new gun cavity is presently installed at PITZ and conditioning up to a gradient of 60 MV/m is ongoing. In this work we present recent results from measurements of the normalized projected transverse emittance of the electron beam. The emittance is measured using the so called single slit technique. Data are presented for different gun and booster gradients, solenoid strengths and initial beam size at the cathode.
WEPPH048	XPS Studies of Cs2Te Photocathodes	457
	H. A. Duerr, R. Ovsyannikov, M. Sperling, A. Vollmer BESSY GmbH, Berlin J. H. Han, S. Schreiber, S. Lederer DESY, Hamburg P. Michelato, L. Monaco, C. Pagani, D. Sertore INFN/LASA, Segrate (MI) F. Stephan DESY Zeuthen, Zeuthen
	Cesium Telluride (Cs2Te) photocathodes are used as sources for electron beams because of their high quantum efficiency (QE) and their ability to release high peak current electron bunches in a high gradient RF-gun. Starting from a high QE level of about 10% the quantum efficiency of these cathodes decreases during operation in a photo-injector to below 0.5%. To understand this behaviour, XPS investigations on the chemical composition were performed at BESSY. In this contribution we compare two fresh cathodes from INFN with one used under normal operation at FLASH and one used at PITZ at a higher than usual RF-gradient of 60 MV/m.
WEPPH050	Proposal for an Automatized Beam Position Alignment System Using BPM's and Rotating Steerers
	G. Asova, J. W. Baehr, C. H. Boulware, H.-J. Grabosch, L. H. Hakobyan, M. Hänel, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, B. Petrosyan, S. Riemann, L. Staykov, F. Stephan, T. A. Scholz DESY Zeuthen, Zeuthen K. Boyanov INRNE, Sofia S. Lederer DESY, Hamburg R. Richter BESSY GmbH, Berlin J. Roensch Uni HH, Hamburg A. Shapovalov MEPhI, Moscow
	The Photo Injector Test facility in Zeuthen (PITZ) is dedicated to improve the performance of high brilliant electron beams. The electron beam is emitted from a CsTe-photocathode placed in a normal conducting 1.5 cell L-band RF gun. The electron beam is further accelerated to 15 up to 30 MeV by a booster cavity. For an optimized acceleration it is important that the beam passes the booster on the symmetry axis. This should be done with a controlling system consisting of two beam position monitors (BPM) and two rotatable steerer magnets to align the beam. A software analyzes the information given by the BPM's and controls the steerer settings to adjust the beam in a feedback loop up to a certain preset limit. Integration of this tool into the PITZ control system has been provided. This contribution will describe the method of calculation, the algorithm, the graphical user interface as well as first experimental results.
WEPPH009	Recent Measurements of the Longitudinal Phase Space at PITZ	342
	G. Asova, J. W. Baehr, C. H. Boulware, H.-J. Grabosch, L. H. Hakobyan, M. Hänel, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, S. Lederer, B. Petrosyan, S. Riemann, S. Rimjaem, T. A. Scholz, L. Staykov, F. Stephan DESY Zeuthen, Zeuthen R. Richter BESSY GmbH, Berlin K. Rosbach Humboldt University Berlin, Institut für Physik, Berlin J. Rossbach, J. Roensch Uni HH, Hamburg
	The Photo Injector Test facility at DESY in Zeuthen (PITZ) was built to test and optimize electron guns for short wavelength Free-Electron Lasers (FELs) like FLASH and XFEL at DESY in Hamburg. For a detailed analysis of the behaviour of the electron bunch, the longitudinal phase space and it projections can be measured behind the gun cavity. The electric field at the photo cathode was increased from 40 MV/m to 60 MV/m, to optimize the transverse emittance. The momentum distributions for different gradients and gun phases will be presented. The determination of the field balance from the momentum distribution will be discussed. In order to study emittance conservation, a booster cavity and additional diagnostics were installed. The evolution of the longitudinal phase space in the booster cavity will be investigated. Measurements of the momentum distribution and longitudinal distribution behind the booster cavity will be discussed.
WEBAU02	Recent Experimental Results from PITZ
	G. Asova, K. Boyanov INRNE, Sofia J. W. Baehr, C. H. Boulware, H.-J. Grabosch, M. Hänel, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, S. Lederer, A. Oppelt, B. Petrosyan, S. Riemann, S. Rimjaem, T. A. Scholz, L. Staykov, F. Stephan DESY Zeuthen, Zeuthen K. Floettmann DESY, Hamburg L. H. Hakobyan YerPhI, Yerevan R. Richter BESSY GmbH, Berlin J. Roensch Uni HH, Hamburg A. Shapovalov MEPhI, Moscow
	The Photo Injector Test facility at DESY in Zeuthen (PITZ) was built to develop and optimize electron sources for superconducting linac driven, high power, short wavelength FELs. A 1.5 cell L-band gun cavity characterized at PITZ has provided beam for FLASH since 2004. A spare RF gun has been characterized at PITZ and delivered to Hamburg as well. To meet the stringent requirements on beam quality for the European XFEL, a substantial upgrade program is ongoing at PITZ. In a first operation period during October 2006, projected normalized transverse emittances in both transverse planes between 1.2 and 1.5 mm mrad for a bunch charge of 1 nC were measured. These results are in good agreement with simulations. A major step towards even lower emittance is the increase of the electric field at the photo cathode from 40 MV/m to 60 MV/m. With the upgrades ongoing now, simulations predict a projected normalized transverse emittance of 1.2 mm mrad and better for 1 nC bunch charge in the running period scheduled for summer 2007. This contribution will give an overview of the experimental results obtained at PITZ in the operation periods of October 2006 and summer 2007 (e.g. transverse and longitudinal phase space measurements, dark current and cathode properties). The main steps of the further upgrade program at PITZ will be mentioned as well.
	Slides
WEPPH012	Investigations on the Thermal Emittance of Cs2Te Photocathodes at PITZ	350
	G. Asova, J. W. Baehr, C. H. Boulware, H.-J. Grabosch, M. Hänel, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, B. Petrosyan, S. Rimjaem, J. Roensch, T. A. Scholz, L. Staykov, F. Stephan, S. Lederer DESY Zeuthen, Zeuthen K. Boyanov INRNE, Sofia L. H. Hakobyan YerPhI, Yerevan R. Richter BESSY GmbH, Berlin A. Shapovalov MEPhI, Moscow
	The main objective of the Photo Injector Test facility at DESY in Zeuthen (PITZ) is the production of electron beams with minimal transverse emittance. The lower limit of this property of electron beams produced with a photocathode in an RF-gun is determined by the thermal emittance. To understand this crucial parameter for high performance FEL’s, measurements under RF operation conditions for Cesium Telluride (Cs2Te) photocathodes are done. Results for various accelerating gradients and the dependence on the laser spot size in the cathode plane are presented and discussed in this work.
WEPPH013	Status and Perspectives of the PITZ Facility Upgrade	354
	G. Asova, J. W. Baehr, C. H. Boulware, H.-J. Grabosch, L. H. Hakobyan, M. Hänel, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, S. Lederer, A. Oppelt, B. Petrosyan, S. Riemann, T. A. Scholz, L. Staykov, F. Stephan, S. Rimjaem DESY Zeuthen, Zeuthen K. Boyanov INRNE, Sofia K. Floettmann DESY, Hamburg R. Richter BESSY GmbH, Berlin J. Roensch Uni HH, Hamburg K. Rosbach Humboldt University Berlin, Institut für Physik, Berlin A. Shapovalov MEPhI, Moscow
	The Photo Injector Test facility at DESY in Zeuthen (PITZ) has been established to develop and optimize electron sources that cover requirements of FEL facilities such as FLASH and the European XFEL. A major upgrade of the facility is ongoing in steps, in parallel to the commissioning of the extended setup and first experiments. The new setup towards the final design mainly includes a photo cathode RF gun, a post acceleration booster cavity and several diagnostic systems. In order to fulfil the high brightness electron source characterization, the diagnostic systems will consist of three emittance measurement systems, two high-energy dispersive arms, an RF deflecting cavity and a longitudinal phase space tomography module as well as bunch length diagnostics. In this paper, results of the commissioning of the new RF gun, which has been installed and conditioned at PITZ in spring and summer of 2007, the current PITZ status and details of the future facility upgrade will be presented.