Abstract
Abstract
Knowledge of the characteristics of secondary neutrons produced by the interaction of
Galactic Cosmic Radiation with spacecraft shielding materials is becoming increasingly important
for predicting and mitigating biological risks of space explorers during deep-space travel. Hadron
accelerators for medical applications are well suited to reproduce part of the conditions found in
deep-space in terms of ion species and energies. The objectives of this work are to measure the
secondary neutron spectra produced by proton and helium ion beams hitting an aluminum target with
energies that correspond to the Galactic Cosmic Radiation peak during solar minimal activity and
to validate and compare physical models of Monte Carlo simulations. Neutron spectra were measured
with the extended-range Bonner sphere system NEMUS at two positions, 0° and 90° relative to the
direction of the primary ion beam. The experimental setup consisted of 480 MeV proton and 430 MeV/u 4He beams colliding with a 30×30×63.5 cm3 aluminum
target. The experimental neutron spectra were analyzed using the MAXED unfolding code and compared
to several Monte Carlo simulation codes. The results show deviations in terms of the shape of the
neutron energy distributions ranging between 1% and 14% and of the integral quantities of
fluence and ambient dose equivalent ranging between 1% and 5.2%.