Shielding Electronic Devices from Monoenergetic 100-MeV Protons

Abstract

This paper investigates the interaction of monoenergetic, 100-MeV protons with aluminum, enriched B₄C, and C₂₉H₂₈O₈ polymer and their effectiveness for shielding silicon-based electronics. Although not representative of an actual space radiation energy spectrum, the 100-MeV protons are suitable to investigate important modes of interaction with potential shielding materials, including the production and attenuation of secondary particles. The calculated shielding effectiveness of these materials is compared with that of the lunar regolith. The components of the total energy deposition in a 1-cm-diam sphere of silicon, representing an electronic device, are calculated as functions of the type and thickness of the shield material. The major contributors to the displacement energy deposition in the silicon sphere are by far the incident protons and the secondary protons and neutrons generated in the spallation reactions of incident protons with the nuclei of the elements in the shield materials. The primary and secondary protons are also the major contributors to the ionizing energy deposition, which is several orders of magnitude higher than the displacement energy deposition; other secondary particles contribute minimally (<5%). While the regolith is an effective shielding material, the C₂₉H₂₈O₈ polymer is best for protecting electronics from incident high-energy protons.