Simulation of cosmic rays inside an aircraft: spectral perturbation and dose reduction due to aircraft structures and contents.

This article focuses on evaluating the self-shielding effects of a Boeing 777-300ER aircraft on the energy spectra and effective doses of secondary cosmic rays at typical civil aviation altitudes (~10 km). Using a detailed combinatorial geometry model and Monte Carlo transport simulations, the study quantified how aircraft structures and contents reduce the effective radiation doses to occupants by approximately 12–16% on average, with reductions up to ~32% in the middle passenger cabin. The research considered various cosmic-ray components (neutrons, protons, photons, electrons, positrons, muons, and charged pions) under different geomagnetic cutoff rigidities and solar modulation potentials, and incorporated these findings into the NTHU Flight Dose Calculator (FDC) to improve dose assessment accuracy. The study also proposed dose correction factors accounting for the anisotropic angular distribution of cosmic rays, aiming to enhance the precision of aircrew and passenger radiation exposure estimates and support the interpretation of onboard measurement data.