High speed, large format X-ray CCDs for ESA's XEUS mission

摘要

The pn-CCD camera on EPIC-XMM is the most advanced imaging X-ray spectrometer, as it combines high quantum efficiency, high speed readout and high energy resolution. The camera operates for almost two years as calibrated prior to launch. Future missions, like ESA's XEUS (X-ray Evolving Universe Spectroscopy) mission require higher spatial resolution, higher response at energies above 20 keV and most important a full frame readout rate increased by at least a factor of 20 for the first operational phase. XEUS represents a potential follow-on mission to the cornerstone XMM-Newton, currently in orbit. The XEUS mission is considered as part of ESA's Horizon 2000~+ program within the context of the International Space Station (ISS). In order to match the above requirements for the wide field imager of XEUS, we propose a frame store pn-CCD camera system based on the technology development of the EPIC (European Photon Imaging Camera) camera on XMM-Newton. Our goal is readout rate of 250 complete frames per second for 1024 * 1024 pixels with a pixel size of 75*75μm~2, monolithically integrated on a 6 inch wafer. The concept and the new features of the frame store pn-CCD camera will be described. The focal plane layout, the readout concept and the expected scientific performance will be introduced. The implementation of thin aluminum filters, monolithically grown on the pn-CCD entrance window, will be discussed as well as the integration of a very fast spectroscopic detector being able to record 10~6 counts per second with a FWHM of about 250 eV.