Gamma-Rays from Grazing Incidence Cosmic Rays in the Earth's Atmosphere
  Interactions of grazing incidence, ultra high energy cosmic rays with the earth's atmosphere may provide a new method of studying energetic cosmic rays with gamma-ray satellites. It is found that these cosmic ray interactions may produce gamma-rays on millisecond time scales which may be detectable by satellites. An extremely low gamma-ray background for transient gamma-ray events and a large area of interaction, the earth's surface, make the scheme plausible. The effective cross section of detection of interactions for cosmic rays above 10^20 eV is found to be more than two orders of magnitude higher than earth based detection techniques. This method may eventually offer an efficient way of probing this region of the cosmic ray energy spectrum where events are scarce. In this paper, a conceptual model is presented for the production of short bursts of gamma-rays based on these grazing incidence encounters with the earth's atmosphere. 
Andrew Ulmer