Simulating the Interplanetary Radiation Environment For Ground Based Space Radiation Studies Using Targeted Energy Loss and Spallation From 56Fe Nuclei In Hydrogen-Rich Crystalline Materials

Abstract

Currently ground-based radiobiology experiments are conducted with beams of single ions with single energies, a method that does not fully describe the radiation risks from the complex mixed ion field found in space. The health risks to humans during spaceflight would be better quantified if ground-based mixed field irradiations are utilized in radiobiology experiments and space vehicle shielding studies. Here we demonstrate that it is possible to reproduce the Linear Energy Transfer distribution in simulated tissue of the galactic cosmic ray spectrum expected during spaceflight. This is done by determining which intrinsic properties of polymer and hydrogen-rich crystalline materials influence desired nuclear spallation and fragmentation when placed in an accelerated heavy-ion beam. Using these results, we have matched a target moderator block made of multiple layers that generate the desired particle fragmentation and spallation products. The correct fluence of particles required for each layer (and thickness) will be determined using Monte Carlo methods. This final moderator block is then placed in front of a 1000 MeV per nucleon Iron (56Fe) particle beam, resulting in a complex mix of nuclei and energies similar to the galactic cosmic ray spectrum measured inside the Space Shuttle, International Space Station, and the Orion Exploration Vehicle. Our approach can be generalized to other radiation spectra and is therefore of wide applicability for general radiation studies, not just of biological material, but also for the deployment of shielding, electronics, and other materials in a space environment.