Radiation Shielding during Deep-Space Missions: Dose Measurements, Monte Carlo Simulations, and Nuclear Cross-Sections

Deep-space radiation is among the biggest hindrances to human space exploration. Therefore, radiation protection in space is a very active field of research. Passive shielding is currently the most promising radiation protection strategy and it consists of adding shielding material to the walls of the spacecraft and the planetary bases. This thesis work presents results obtained in accelerator-based experimental campaigns with some of the most relevant ion beams for radiation protection in space and several structural, in situ, standard, and innovative shielding materials. Lithium-based hydrides stabilised with paraffin were proved to combine the promising dose attenuation properties of the pure hydrides and the mechanical and chemical stability of the paraffin, resulting in good candidate shielding materials for space missions. The experimental data were compared with the simulation results of the most commonly used Monte Carlo codes in this field of research, namely FLUKA, PHITS, and Geant4. The simulations showed significant and systematic differences among the codes mainly due to the different implemented nuclear cross-section models. Therefore, the last part of the work focuses on the presentation of the two nuclear cross-section databases (total reaction cross-sections and fragment production cross-sections) that were generated within this thesis work. The collected nuclear reaction cross-section data were compared to the parametrisations used in the Monte Carlo codes to understand which of them are more reliable. It was concluded that no parametrisation can well reproduce all the experimental data for every system and energy region. Therefore, an optimisation of the Tripathi parametrisation for reaction cross-sections was proposed. Additionally, an important gap in the experimental data was pointed out for high energies. The databases were uploaded online and made open access to provide the research communities interested in such data, with the possibility to access them and plot them alongside the parametrisations