Saldin, E.

Paper	Title	Page
MOPPH011	A Simple Method for Timing an XFEL Source to High-Power Lasers	29
	G. Geloni, E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	We propose a technique for timing an XFEL to a high-power laser with femtosecond accuracy. The same electron bunch is used to produce an XFEL pulse and an ultrashort optical pulse that are, thus, naturally synchronized. Cross-correlation techniques will yield the relative jitter between the optical pulse (and, thus, the XFEL pulse) and a pulse from an external pump-laser with femtosecond resolution. Technical realization will be based on an optical replica synthesizer (ORS) setup to be installed after the final bunch-compressor. The electron bunch is modulated in the ORS by an external optical laser. Travelling through the main undulator, it produces the XFEL pulse. Then, a powerful optical pulse of coherent edge radiation is generated as the bunch passes through a long straight section and a separation magnet downstream of the main undulator. Relative synchronization of these pulses is preserved using the same mechanical support for X-ray and optical elements transporting radiation to the experimental area, where single-shot cross-correlation between optical pulse and pump-laser pulse is performed. We illustrate our technique with numerical examples referring to the European XFEL.
MOCAU05	A Scheme for Stabilization of Output Power of an X-ray SASE FEL	181
	G. Geloni, E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	Stability of XFEL radiation is naturally linked to stability of the linac RF system through bunch compression, leading to very tight requirements on RF amplitude and phase. We propose a new scheme that allows to relax these requirements by a large factor.
	Slides
TUPPH004	Study of Controllable Polarization SASE FEL using a Crossed-planar Undulator	239
	B. Faatz, W. Decking, Y. Li, J. Pflueger, E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	Several methods to produce variable polarization have been under discussion for the European XFEL facility. One such method is to utilize a crossed-undulator scheme. In this paper, the polarization of X-ray radiation for longer wavelengths (0.4 nm and longer) of the XFEL is investigated. The degree of polarization and the Stokes parameters are calculated for different configurations. A first attempt at optimization of the configuration for XFEL parameters is presented.
THBAU04	Results from the Optical Replica Experiments at FLASH	497
	S. Khan, J. Boedewadt Uni HH, Hamburg G. Angelova, V. G. Ziemann Uppsala University, Uppsala M. Larsson Stockholm University, Department of Physics, Stockholm F. Loehl, E. Saldin, H. Schlarb, E. Schneidmiller, A. Winter, M. V. Yurkov DESY, Hamburg A. Meseck BESSY GmbH, Berlin P. M. Salen, P. van der Meulen FYSIKUM, AlbaNova, Stockholm University, Stockholm
	We present experimental results from the optical replica synthesizer,a novel device to diagnose sub-ps electron bunches by creating a coherent optical pulse in the infrared that has the envelope of the electron bunch and analyzing the latter by frequency resolved optical gating methods. Such a device was recently installed in FLASH at DESY. During an experiment period the spatial and temporal overlap of a several ps long electron bunch and a 200 fs laser pulse were achieved within an undulator. Coherent transition radiation due to the induced micro-bunching was observed on a silver-coated silicon screen and varying the timing between electrons and laser pulse produced two-dimensional images of the slices as a function of the longitudinal position within the electron bunch. In a second experiment the strongly compressed electron bunch is modulated by the laser pulse and replica pulses that are emitted from a second undulator are observed and diagnosed by frequency resolved optical gating methods.
	Slides