Surface Ionizing Dose for Space Applications Estimated With Low Energy Spectra Going Down to Hundreds of Electronvolt

Abstract

The contribution of low energy particles down to ~200 eV to the dose deposited on the very near surface of materials subject to the space environment is investigated by means of GEANT4 Monte Carlo simulations. The contribution to the dose, of the low energy parts of GREEN spectra ([200 eV-40 keV] for electrons, [200 eV-100 keV] for protons) are compared with calculations performed with AE8/AP8. Both GEO and LEO SPOT like orbits are studied. The dose depth profiles are estimated for silicon material. The impact on the dose calculation of different transport models is also investigated. Below 1 keV, the relevance of continuous processes is analysed for electrons by comparison with a discrete model (GEANT4/MICROELEC). This analysis is also performed for protons below 10 keV.

Surface ionizing dose deposited by low energy electrons (10 eV–10 keV) in eleven monoatomic materials: Monte Carlo calculations and analytical expressions

“…The comparison between MicroElec and GRAS for the other materials studied in this work can be found in Appendix III, and a more detailed comparison between MicroElec and other GEANT4 models can be found in ref. [1]. MicroElec has been chosen as the reference for the analytical dose model due to its ability to transport electrons below 250 eV down to a few eVs.…”

“…The transportation of low energy electrons in matter and its study is of great interest in many applications such as nuclear physics, medicine and space applications. In the field of space technologies, the estimation of the ionizing dose deposited near the surface of satellites (~10 nm) is a key concern for space missions [1], as the energy received by the materials (Al, Ag, Cu, Si, glasses, polymer coatings…) may cause some degradations and disturb the on-board systems.…”

“…In particular, the ionizing dose, which is the quantity of energy deposited per unit of mass of a target material, is a common metric very useful to several fields. For example, many degradations induced by radiations from the space environment are scaled according to the ionizing dose, such as electrical discharges, or the degradation of the optical properties of surface polymer coatings [1]. Some domains related to electron beams, such as electron spectroscopy also benefit from an accurate estimation of the dose.…”

Monte-Carlo simulation and analytical expressions for the extrapolated range and transmission rate of low energy electrons [10 eV–10 keV] in 11 monoatomic materials

“…We have already conducted a more extensive comparison between the different physics models of GEANT4, which can be found in ref. [35].…”

Implementation of the EPICS2017 database for photons in Geant4

“…Livermore physics models constitute an important component of the sub-package and are based on three evaluated data libraries of the Lawrence Livermore National Laboratory (LLNL) for elements with atomic number Z = 1-100: i) EPDL97 (Evaluated Photons Data Library) [7], ii) EEDL (Evaluated Electrons Data Library) [8], iii) EADL (Evaluated Atomic Data Library) [9]. These models have been utilized in space radiation [10], archeology [11] and medical physics applications, particularly in radiotherapy [12,13], micro-and nanodosimetry [14,15], imaging [16,17] and spectrometry [18,19]. Especially for medical physics, it is now possible to model the interaction of particles with living matter down to the molecular level (DNA), opening the way to a finer understanding of the mechanisms occurring during and following irradiation [20].…”