FLUKA Calculation of the Neutron Albedo Encountered at Low Earth Orbits

Abstract : —This paper presents Monte-Carlo simulations based on the Fluka code aiming to calculate the contribution of the neutron albedo at a given date and altitude above the Earth chosen by the user. The main input parameters of our model are the solar modulation affecting the spectra of cosmic rays, and the date of the Earth's geomagnetic field. The results consist in a two-parameter distribution, the neutron energy and the angle to the tangent plane of the sphere containing the orbit of interest, and are provided by geographical position above the Earth at the chosen altitude. This model can be used to predict the temporal variation of the neutron flux encountered along the orbit, and thus constrain the determination of the instrumental background noise of space experiments in low earth orbit.