Athena charged particle diverter simulations: effects of micro-roughness on proton scattering using Geant4

Breuer, Jean-Paul; Galgóczi, Gábor; Fioretti, V.; Zlámal, Jakub; Liška, Petr; Werner, Norbert; Santin, G.; Boudin, N.; Ferreira, Ivo; Guainazzi, M.; Kienlin, A. von; Lotti, Simone; Mineo, T.; Molendi, S.; Perinati, E.

doi:10.1117/12.2630076

Cited by 1 publication

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is important to mention that an undergoing investigation shows that surface roughness can increase the scattering efficiency for such low energy protons. Although preliminary studies show that this increase has a negligible impact on the residual background, a dedicated study is ongoing 15 to include the surface roughness in the Geant4 CPD simulation.…”

Section: Conclusion and Final Remarksmentioning

confidence: 99%

Geant4 simulation of the residual background in the ATHENA wide field imager from protons deflected by the charged particle diverter

Galgóczi¹,

Jean-Paul²,

Fioretti³

et al. 2022

Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray

Self Cite

View full text Add to dashboard Cite

X-ray telescopes opened up a new window into the high-energy universe. However, the last generation of these telescopes encountered an unexpected problem: their optics focused not only X-rays but low-energy (so called soft) protons as well. These protons are very hard to model and can not be distinguished from X-rays. For example, 40% of XMM-Newton observations is significantly contaminated by soft proton induced background flares. In order to minimize the background from such low-energy protons the Advanced Telescope for High ENergy Astrophysics (ATHENA) satellite introduced a novel concept, the so called Charged Particle Diverter (CPD). It is an array of magnets in a Hallbach design, which deflects protons below 76 keV before they would hit the Wide Field Imager (WFI) detector. In this work, we investigate the effect of scattering of the deflected protons with the CPD walls and the inner surfaces of the WFI detector assembly. Such scattered protons can loose energy, change direction and still hit the WFI. In order to adopt the most realistic instrument model, we imported the CAD model of both the CPD and the WFI focal plane assembly. Soft protons corresponding to ≈2.5 hours of exposure to the L1 solar wind are simulated in this work. The inhomogeneous magnetic field of the CPD is included in the simulation. We present a preliminary estimate of the WFI residual background induced by soft proton secondary scattering, in the case of the optical blocking filter present in the field of view. A first investigation of the volumes responsible for scattering the protons back into the field of view is reported.

show abstract

Section: Conclusion and Final Remarksmentioning

confidence: 99%