Neutron Production in Simulations of Extensive Air Showers

Although the electromagnetic and muonic components of extensive air showers have been studied in great detail, no comprehensive simulation study of the neutron component is available. This is related to the complexity of neutron transport processes that is typically not treated in standard simulation tools. In this work we use the Monte Carlo simulation package Fluka to study the production and the transport of neutrons in extensive air showers over the full range of neutron energies, extending down to thermal neutrons. The importance of different neutron production mechanisms and their impact on predicted neutron distributions in energy, lateral distance, atmospheric depth, and arrival time are discussed. In addition, the dependencies of the predictions on the properties of the primary particle are studied. The results are compared to the equivalent distributions of muons, which serve as reference.