Development of x-ray optics for advanced research light sources

Abstract

X-ray mirrors are needed for beam steering, beam alignment and monochromatisation at advanced research light sources like 3rd generation synchrotron sources (e.g. PETRA III in Hamburg) or Free-Electron Lasers (for instance FLASH or the European XFEL). At the Helmholtz-Zentrum Geesthacht (formerly GKSS), an in-house designed magnetron sputtering facility for the deposition of single layers and multilayers has been installed for the development of x-ray optics. Earlier results showed that the thin-film fabrication of 1.5 m long amorphous carbon coatings was very successful. These single layers are currently used as total reflection mirrors at FLASH to steer the photon beam to the various beamlines. A major advantage of the sputtering facility is that it is now possible to prepare one, two or more mirrors with similar properties over the whole deposition length. In this contribution we present results for the x-ray optical properties of C, B4C and W coatings and W/C multilayers. The goal of the development of x-ray mirrors is to optimize the deposition conditions in order to control the thickness of a single layer or the lateral period of a multilayer, and to achieve high reflectivity over the whole deposition length according to the application.