The European XFEL in Hamburg: current status

Linear accelerator based lasers, so called Free Electron Lasers (FEL) are now becoming a reality as 4th generation x-ray light sources. Currently based on the SASE (Self Amplified Spontaneous Emission) process, they deliver ultra-short coherent light in the x-ray photon energy range. After the first successful development of FEL in the soft x-ray region at FLASH (Free electron LASer in Germany), several hard x-ray facilities are under construction (European XFEL in Germany, SWISSFEL in Switzerland) or recently started (SACLA in Japan, LCLS in the USA).
An overview of the European XFEL up-dated parameters will be given. Starting from 2015, the x-ray beam will be delivered through 2 hard x-ray beamlines (SASE 1 and 2) and 1 soft x-ray beamline (SASE3). Variable gap undulators will allow tuning the photon energy of the fundamental radiation from 3 to 24 keV and 0.3 to 3 keV with 1012 to 1014 photons/pulses. Higher harmonic will also be available extending the useful photon energy range up to 50 to 200 keV with reduced photon flux. Using different bunch charge will also allow tuning the pulse duration in the range of 2 to 100 fs. Finally, the unique high repetition rate (up to 27 000 pulse/s), provided by super-conducting technology for the linear accelerator will enable more than two orders of magnitude increased average photon flux and three times higher peak brightness compared to other X-ray laser projects. An emphasis will be given on the development of the beamline systems. In fact some experiments foreseen rely on the high photon flux or coherence properties of the beam. In this photon energy range any degradation of the beamline components might disable to perform these experiments. We will describe the on-going program which aims at preserving the beam quality. The current status of the 6 experimental stations (2 per beamline) will also be described. Each of these stations is devoted to a specific field ranging from the study of high energy density matter to single bio-molecule imaging