Scattering efficiencies measurements of soft protons at grazing incidence from an Athena Silicon Pore Optics sample

TL;DR

This study measures how soft protons scatter off Silicon Pore Optics at grazing angles, providing data crucial for protecting the Athena X-ray mission's detectors from proton-induced background and damage.

Contribution

It presents the first detailed scattering efficiency measurements of soft protons on Silicon Pore Optics relevant for Athena, validating physical models and aiding diverter design.

Findings

Scattering efficiency peaks near the angle of specular reflection.

Results are consistent with previous measurements on eROSITA mirrors.

Data supports the development of magnetic diverters for Athena.

Abstract

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.