Evaluation of the neutron spectrum at flight altitude with Geant4 using different parameterizations.

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.

INVESTIGATION OF THE INFLUENCE OF THE POSITION INSIDE A SMALL AIRCRAFT ON THE COSMIC-RADIATION-INDUCED DOSE.

This article report the measurements on-board a small aircraft at the same altitude and around the same geographic coordinates. The measurements of Ambient Dose Equivalent Rate (H*(10)) were performed in several positions inside the aircraft, close and far from the pilot location and the discrimination between neutron and non-neutron components. The results show that the neutrons are attenuated close to fuel depots and the non-neutron component appears to have the opposite behavior inside the aircraft.

Influence of clouds on the cosmic radiation dose rate on aircraft.

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.