European Photon Imaging Camera



XMM/EPIC interface
More Information


The European Photon Imaging Camera, EPIC, provides the prime focus CCD cameras for XMM. This gives XMM a CCD imaging and spectroscopy capability at the focus of each of its three mirror modules.  XMM carries two varieties of EPIC camera, the EPIC-MOS (2 modules) and the EPIC-pn.  An EPIC-MOS is at the prime focus of each of the two telescopes equipped with a reflection grating array, and thus receives about 50% of the X-ray light incident upon that telescope, whilst the EPIC-pn is at the focus of the third, gratingless telescope and therefore receives all the incident X-ray light focussed by the telescope (see the previous schematic).

The PI institute of the EPIC project is currently the University of Leicester, who also lead the EPIC-MOS project. The EPIC-pn is lead by the Max-Planck-Institut für extraterrestrische Physik (Garching), and the EPIC systems production is lead by CNR IFCTR, Milan.


The MOS camera system was produced by an international consortium lead by the University of Leicester (CCDs and camera head), and including the University of Birmingham (thermal control system) and CEN Service d'Astrophysique Saclay (control and event recognition electronics).

Each camera consists of an array of 7 Metal Oxide Semiconductor (MOS) front-illuminated CCD chips (manufactured by EEV of Chelmsford, UK) of 600x600 pixels each. These cameras use a revolutionary open electrode structure which increases the quantum efficiency of the CCDs to about 30% at low X-ray energies (around 270 eV). The chips are built and wired individually and then arranged into the pattern visible in the photo (below). This provides a large field of view at the prime focus of XMM. Note that the vertical offset of the chips with respect to each other is exaggerated in the photograph. The central chip does indeed sit farther back than the surrounding six, by about 5 millimetres, following the slight curvature of XMM's focal surface.

The whole EPIC-MOS array is shown on its mounting in the next picture.

The MOS, as with all other XMM instruments, has been subject to rigorous pre-flight testing and calibration procedures. The next photo shows the MOS camera engineering model being subjected to such a procedure.


The pn camera CCDs are new technology X-ray back-illuminated CCDs, with 6x2 chips on a single wafer. Thus, they are produced as one array and not assembled later, as in the case of the MOS camera. With 64x200 pixels per chip, the pn camera offers a square field of view with a size similar to that of the 7 MOS chips.

The chip array itself is embedded in a board carrying the camera electronics. This is shown here (the back of the pn chips are shown at the centre top position in the photo).

The EPIC pn camera was built by the Max-Planck-Institut für extraterrestrische Physik (Garching) and Astronomisches Institut Tübingen.

XMM/EPIC interface

The EPIC cameras are interfaced to XMM using digital electronics and software developed by CNR IFCTR, Milan, and collaborating institutes.

More information

Check out the University of Leicester Space Research Centre EPIC pages for more EPIC pictures and information.

Other institutes involved in the EPIC consortium also have dedicated web pages; for instance, the University of Birmingham; the Max-Planck-Institut für extraterrestrische Physik, Garching; IFCTR/CNR, Milan; and ITESRE/CNR Bologna.

A summary of the details of the performance of the instrument, along with proposal-specific information, is available in the EPIC section of the XMM User's Handbook (UHB).

The responsibilities of the EPIC consortium members are listed on the XMM Science Operations Centre EPIC page.

Find out more about the other XMM instruments: Back to the XMM schematic view.

These pages are adapted from various sources, mainly from the ESTEC page "Building XMM" and the University of Leicester Space Research Centre EPIC pages.

Various parties require acknowledgement for the photo material on this page. Particular thanks are due to the University of Leicester EPIC team, the Max-Planck-Institut für extraterrestrische Physik and the other members of the EPIC consortium.

Last updated: Thu Mar 4th 1999