Measurements of the soft proton reflectivity on x-ray optics

Orbital soft protons that reach the detector region of astronomical X-ray observatories can seriously degrade the instrumental performance. Firstly, they pose a non-reducible background component and, secondly, they might induce permanent sensor damage. A reliable performance estimation and risk assessment for new X-ray missions is only possible with experimental scattering data. Therefore, we conducted measurement campaigns at various accelerator facilities and at different energies below 1 MeV in the past decade. Targets ranged from classic gold-coated nickel shells to the silicon pore optics (SPO) design foreseen for Athena. The latest measurements were taken with a new setup at considerably lower energies from 20 keV to 50 keV, and with an MCP detector that features two dimensional position resolution. The results are highly relevant for background studies and have a finer angular coverage. Furthermore, the data yield hints that a significant fraction of scattered protons undergoes charge exchange and, thus, is not affected by a magnetic diverter. In this contribution, we present the new experimental setup and give an overview on the proton scattering results obtained so far.