Saldin, E.

Paper	Title	Page
TUPC114	Results from the Optical Replica Experiments in FLASH	1332
	V. G. Ziemann, G. Angelova UU/ISV, Uppsala J. Boedewadt, S. Khan, A. Winter Uni HH, Hamburg M. Hamberg, M. Larsson, P. M. Salen, P. van der Meulen FYSIKUM, AlbaNova, Stockholm University, Stockholm F. Loehl, E. Saldin, H. Schlarb, E. Schneidmiller, M. V. Yurkov DESY, Hamburg A. Meseck BESSY GmbH, Berlin
	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 a laser pulse lengthened to about 2 ps and replica pulses that are emitted from a second undulator are observed and diagnosed by frequency resolved optical gating methods.
WEOAM02	A Scheme for Stabilization of Output Power of an X-ray SASE FEL	1947
	E. Schneidmiller, G. Geloni, E. Saldin, 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
WEPC118	Study of Controllable Polarization SASE FEL by a Crossed-planar Undulator	2282
	B. Faatz, Y. Li, J. Pflueger, E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	A potential and economical access to generate arbitrary polarized XFEL is to utilize crossed-undulator scheme instead of helical undulators. In this paper, the polarization of x-ray radiation for the European XFEL is investigated. The degree of polarization and the Stokes parameters are calculated for different configurations. The shot-to-shot fluctuation of polarization and the degree of polarization distribution over the transverse plane are also studied.
THPC157	A Simple Method for Timing an XFEL Source to High-power Lasers	3357
	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.