X-ray baffle of the XMM telescope: development and results

The high throughput x-ray spectroscopy mission XMM is the second cornerstone project in the European Space Agency (ESA) long-term program for space science. This observatory has at its heart three large x-ray telescopes, which will provide a large collection area with a spatial resolution around 15 arcsec. Five flight models of the XMM x-ray telescope have been delivered to ESA in 1998. They show optical performance, which is far better than the specifications, especially in terms of optical and x-ray stray light reduction. The low level of x-ray stray light will be an important benefit for the observation of the extended faint sources such as super nova remnants or clusters of active galaxies. This reduction of x-ray stray light is due, in particular, to the implementation of a very complex and accurate x-ray baffle mounted at the entrance of the telescope. In this paper, we present first the need, the design, the manufacturing and the integration of the x-ray baffle. Then, we concentrate on the verification of the performance of the baffle at the Centre Spatial de Liege. Finally, we will present the excellent results obtained with these baffles.