One of the major and unfortunately unforeseen sources of background for the current generation of X-ray telescopes, in particular the ESA X-ray satellite XMM-Newton, is due to soft (few tens-hundreds of keV) protons concentrated by the X-ray mirrors. The observing time lost is 40% in the case of XMM, affecting all the major broad science goals of this observatory, ranging from cosmology to astrophysics of neutron stars and black holes.
The physical process at work and the connection with the magnetospheric population and acceleration sites originating the phenomenon are still poorly understood. The soft proton background can impact dramatically future large X-ray missions such as the ESA planned Athena mission. We propose a multi-disciplinary team of astrophysicists and magnetopsheric physicists to meet at ISSI with the goal to advance our understanding of the phenomenon.
We plan to investigate the rich datasets provided by XMM and the ESA magnetospheric mission CLUSTER over more than 15 years with the following objectives:
(i) to gauge the flux of soft protons at the XMM satellite location and orientation in the magnetosphere;  
(ii) to provide a necessary in flight assessment of the physical process complementary to what obtained by laboratory experiments;
(iii) to learn lessons to mitigate the impact for future X-ray missions.

Submitted proposal