author = "Diniz, Gabriel Sousa and Rutjes, Casper and Ebert, Ute and 
                         Ferreira, I. S. and S{\~a}o Sabbas, Eliah Fernanda de Maria 
          affiliation = "{Universidade de Bras{\'{\i}}lia (UnB)} and {Centrum Wiskunde 
                         \& Informatica (CWI)} and {Centrum Wiskunde \& Informatica 
                         (CWI)} and {Universidade de Bras{\'{\i}}lia (UnB)} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)}",
                title = "Modeling neutron emissions in high energy atmospheric phenomena",
              journal = "Journal of Geophysical Research: Atmospheres",
                 year = "2018",
               volume = "123",
               number = "22",
                pages = "12726--12737",
                month = "Dec.",
             abstract = "Neutron emissions with different durations have been observed 
                         during thunderstorms. These neutrons can be produced by 
                         microsecond to millisecond fast Terrestrial Gamma-ray Flashes 
                         correlated with lightning, or by Gamma-ray Glows lasting several 
                         seconds to minutes. In both cases, the neutrons are produced 
                         through a photonuclear reaction of gamma rays in the energy range 
                         of 10 to 30 MeV with nuclei of air molecules. Here we present 
                         simulations of gamma-ray beams propagating downward from different 
                         source altitudes. In our analysis the primary photons with 
                         energies between 10 and 30 MeV are separated into four energy 
                         intervals, each of 5 MeV width. From these data, arbitrary spectra 
                         of primary photons and of their products can be composed. Our 
                         results indicate that the neutrons are created essentially along 
                         the trajectory of the primary photons and that they reach ground 
                         within a transversal area of radius below 500 m. This lateral 
                         spreading is dominated by neutron diffusion due to collisions with 
                         air molecules. A secondary longer lasting photon pulse at sea 
                         level is predicted as well by our simulations. We have introduced 
                         this Terrestrial Gamma-ray Flash afterglow already in (Rutjes et 
                         al. 2017, 
                         It is due to neutron capture by air molecules, and it has recently 
                         been observed by Bowers et al. (2017, 
                         and Enoto et al. (2017, 
                  doi = "10.1029/2018JD028962",
                  url = "http://dx.doi.org/10.1029/2018JD028962",
                 issn = "2169-8996 and 2169-897X",
             language = "en",
           targetfile = "diniz_modeling.pdf",
        urlaccessdate = "28 nov. 2020"