Radiation Shielding of Energetic Electrons
Peter Beck, Michael Wind, Marcin Latocha
Seibersdorf Laboratories, Seibersdorf, Austria
Abstract
Seibersdorf Laboratories carried out experiments and numerical simulations studying the performance of a multilayer graded shielding in energetic electron-fields and compared with earlier ESA studies [1-2]. In this study box and plane shielding geometries composed of aluminium, lead and tantalum were used. Monte Carlo code simulations using FLUKA and GEANT4 are compared with experimental measurements for electron with an energy range of 6 MeV and 50 MeV.
The results obtained from both the experiments and the numerical studies indicate that for 6 MeV and 10 MeV electrons an increased shielding-performance (i.e. a decrease of dose) can be observed with an increase in high-Z material content. When lead or tantalum is used as a high-Z layer material the decrease in dose can be as high as ~60% (5 MeV electrons) or ~50% (10 MeV electrons). When titanium is used as a high-Z layer material the effect is much less distinct, i.e. ~25% decrease in dose in case of 5 MeV electrons and ~7% for 10 MeV electrons. It is found that for incident electron energies lower than 10 MeV the dose is more effectively reduced when the high-Z layer is on the inside of the shielding while for higher energies the dose is more effectively reduced when the high-Z material is on the outside of the shielding.
The results obtained from numerical simulations performed with an electron environment representative for the Ganymede mission phase are comparable with those obtained for isotropic mono-energetic electrons of 5 MeV when the high-Z layer is positioned on the outside. The presentation provides a summary of the ESA study e2RAD - Energetic Electrons Radiation Assessment Study [3].
References
[1] Giovanni Santin and Marie Ansart, “Investigation on the effects of combinations of shielding materials on the total ionising dose for the LAPLACE mission”, ESA Technical Note, TEC-EES/2010.613/GS/2.0, Issue 2, Rev 1, 30 May 2012.
[2] Marie Ansart, “Comparison of shielding and dose tools for GALILEO and Laplace/JUICE missions”, Master thesis, June 2012.
[3] Wind M., Bagalkote J., Beck P., Latocha M., Georg D., Stock M., Nieminen P., Truscott P.; e2-RAD: Results of the ESA Energetic Electrons Radiation Assessment Study, NSREC Contribution at the IEEE Nuclear and Space Radiation Effects Conference, Paris, 2014.
Acknowledgements
The authors gratefully acknowledge the support of research projects by the Austrian Research Promotion Agency (FFG), the European Space Agency and the European Commission.