  Soft protons are a potential threat for X-ray missions using grazing
incidence optics, as once focused onto the detectors they can contribute to
increase the background and possibly induce radiation damage as well. The
assessment of these undesired effects is especially relevant for the future ESA
X-ray mission Athena, due to its large collecting area. To prevent degradation
of the instrumental performance, which ultimately could compromise some of the
scientific goals of the mission, the adoption of ad-hoc magnetic diverters is
envisaged. Dedicated laboratory measurements are fundamental to understand the
mechanisms of proton forward scattering, validate the application of the
existing physical models to the Athena case and support the design of the
diverters. In this paper we report on scattering efficiency measurements of
soft protons impinging at grazing incidence onto a Silicon Pore Optics sample,
conducted in the framework of the EXACRAD project. Measurements were taken at
two different energies, ~470 keV and ~170 keV, and at four different scattering
angles between 0.6 deg and 1.2 deg. The results are generally consistent with
previous measurements conducted on eROSITA mirror samples, and as expected the
peak of the scattering efficiency is found around the angle of specular
reflection.
