Charged-particle induced background expected in X-ray detecting CCDs in highly eccentric earth orbits

Abstract

Charged particle fluxes on satellites in highly eccentric Earth orbits are studied, using data from ISEE1 and EXOSAT missions. The effects of minimum-ionizing particles, low-energy electrons and secondary radiation produced by these particles on CCDs used as X-ray detectors are identified. A technique to discriminate events caused by minimum-ionizing particles from X-ray events is proposed. The need for a deflecting system against low-energy electrons with focusing X-ray optics is demonstrated. An expected secondary radiation spectrum behind a typical detector shielding based on Monte-Carlo-simulations is presented. For the EPIC detectors on XMM, detection rates due to this radiation environment are estimated.