The European Photon Imaging Camera on XMM-Newton: The MOS cameras
Bignami, G. F.; Tiengo, A.; Arnaud, M.; Boer, M.; Molendi, S.; Ghizzardi, S.; La Palombara, N.; Vigroux, L.; Reeves, J. N.; Gianotti, F.; Hochedez, J. F.; Ferrando, P.; Trümper, J.; Ward, M. J.; Bennie, P. J.; Kendziorra, E.; Stephen, J.; Jourdain, E.; Vercellone, S.; Trifoglio, M.; Pounds, K. A.; Turner, M. J. L.; Strüder, L.; Bernard, J. P.; Belsole, E.; Lumb, D.; Lortholary, M.; Holland, A. D.; Sembay, S.; Denby, M.; Cros, A.; Hainaut, O.; Rothenflug, R.; Sauvageot, J. L.; Marty, P.; Barbera, M.; Collura, A.; Cara, C.; Poindron, E.; Griffiths, R. G.; Balasini, M.; Reppin, C.; Villa, G.; Pigot, C.; Schmitt, D.; Short, A. D. T.; Abbey, A.; Briel, U.; Butler, I.; Chabaud, C.; Cole, R.; Conte, M.; Dhez, P.; Di Coco, G.; Dowson, J.; Goodall, C. V.; Gretton, L.; Lagostina, A.; Laine, R.; Salvetat, P.; Spragg, J.; Whitehead, S.; Zonca, E.
United Kingdom, France, Italy, Germany, Netherlands
Abstract
The EPIC focal plane imaging spectrometers on XMM-Newton use CCDs to record the images and spectra of celestial X-ray sources focused by the three X-ray mirrors. There is one camera at the focus of each mirror; two of the cameras contain seven MOS CCDs, while the third uses twelve PN CCDs, defining a circular field of view of 30' diameter in each case. The CCDs were specially developed for EPIC, and combine high quality imaging with spectral resolution close to the Fano limit. A filter wheel carrying three kinds of X-ray transparent light blocking filter, a fully closed, and a fully open position, is fitted to each EPIC instrument. The CCDs are cooled passively and are under full closed loop thermal control. A radio-active source is fitted for internal calibration. Data are processed on-board to save telemetry by removing cosmic ray tracks, and generating X-ray event files; a variety of different instrument modes are available to increase the dynamic range of the instrument and to enable fast timing. The instruments were calibrated using laboratory X-ray beams, and synchrotron generated monochromatic X-ray beams before launch; in-orbit calibration makes use of a variety of celestial X-ray targets. The current calibration is better than 10% over the entire energy range of 0.2 to 10 keV. All three instruments survived launch and are performing nominally in orbit. In particular full field-of-view coverage is available, all electronic modes work, and the energy resolution is close to pre-launch values. Radiation damage is well within pre-launch predictions and does not yet impact on the energy resolution. The scientific results from EPIC amply fulfil pre-launch expectations.