MOS CCDs for the Wide Field Imager on the XEUS Spacecraft
In recent years the XEUS mission concept has evolved and has been the subject of several industrial studies. The mission concept has now matured to the point that it could be proposed for a Phase A study and subsequent flight programme. The key feature of XEUS will be its X-ray optic with collecting area ∼30-100x that of XMM. The mission is envisaged at an orbit around the L2 point in space, and is formed from two spacecraft; one for the mirrors, and the other for the focal plane detectors. With a focal length of 50m, the plate scale of the optic is 6.5x that of XMM, which using existing focal plane technology will reduce the effective field of view to a few arc minutes. Cryogenic instrumentation, with detector sizes of a few mm can only be used for narrow field studies of target objects, and a wide field instrument is under consideration using a DEPFET pixel array to image out to a diameter of 5 arcminutes, requiring an array of dimension 70mm. It is envisaged to extend this field of view possibly out to 15 arcminutes through the use of an outer detection ring comprised of MOS CCDs.
