RESUMO
Cosmic-ray-induced particles at flight altitude present an increasing concern because of the development of aircraft with high maximum cruising altitude (higher than 40 000 ft) and because of the miniaturisation of and increase in the amount of embedded electronic systems. There are different codes used to estimate the radiation field through the atmosphere, using different approaches and Monte Carlo methods. This work aims to evaluate the influence on the neutron spectra at ground and flight altitude of the parameterizations employed to describe spallation reactions and the density profile of the atmosphere. The results show that different versions of Geant4 and the data driven models used significantly change the neutron fluence rate and the ambient dose equivalent rate. The results show that the different atmospheric density profiles considered do not significantly change the neutron spectra. In this work, we also present comparisons with onboard and ground level measurements.
Assuntos
Radiação Cósmica , Monitoramento de Radiação , Altitude , Doses de Radiação , Monitoramento de Radiação/métodos , Nêutrons , AeronavesRESUMO
Flight missions were made in Brazilian territory in 2009 and 2011 with the aim of measuring the cosmic radiation dose rate incident on aircraft in the South Atlantic Magnetic Anomaly and to compare it with Monte Carlo simulations. During one of these flights, small fluctuations were observed in the vicinity of the aircraft with formation of Cumulonimbus clouds. Motivated by these observations, in this work, the authors investigated the relationship between the presence of clouds and the neutron flux and dose rate incident on aircraft using computational simulation. The Monte Carlo simulations were made using the MCNPX and Geant4 codes, considering the incident proton flux at the top of the atmosphere and its propagation and neutron production through several vertically arranged slabs, which were modelled according to the ISO specifications.