Cosmic-ray Transport Simulation though the Atmosphere in the South Atlantic Magnetic Anomaly
M. T. Pazianotto 1*, C. A. Federico 2, O. L. Gonçalez 2, B. V. Carlson 1
1 Instituto Tecnológico de Aeronáutica in Brazil
2 Divisão de Física Aplicada, Instituto de Estudos Avançados in Brazil
Brazil and South America have a large region subject to the South Atlantic Magnetic Anomaly (SAMA) that may modify the behavior of cosmic radiation showers as a function of altitude  and great effort is required to understand it better. When the primary cosmic-rays interact with atmospheric atoms, many particles will be produced. Neutrons generated by the interaction of cosmic-rays with the atmosphere make an important contribution to the dose accumulated in electronic circuits and aircraft crew members at flight altitude and cosmic-ray induced neutron spectra (CRINS) have been essential for evaluating these . High-energy neutrons are produced in spallation reactions and intranuclear cascade processes by primary cosmic-ray particle interactions with atoms in the atmosphere. These neutrons can produce secondary neutrons and also undergo a moderation process due to atmosphere interactions, resulting in a wider energy spectrum, ranging from thermal energies (0.025 eV) to energies of several hundreds of MeV. Therefore it is important understand cosmic-ray propagation in the atmosphere to obtain the neutron spectra as a function of altitude, which would allow one to estimate aircrew dose and calibrate neutron detectors for this radiation field. The goal of this study is to assess the CRINS using the Monte Carlo (MC) computational code MCNPX (Monte Carlo N-Particle eXtended)  and compare the results with experimental data. To do this, it is necessary to understand the geometry that will reproduce the realistic situation  in which one has protons with a wide spectrum arriving at the top of the atmosphere. The simulations were performed using physics models of the intranuclear cascade at higher energies and nuclear data libraries in the lower energy region in which they are available.
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