AN ESTIMATE OF THE SECONDARY-PROTON SPECTRUM AT SMALL ATMOSPHERIC DEPTHS

We have calculated the energy spectrum of secondary protons produced i n the atmosphere as a function of the atmospheric depth and zenith ang les at a location with zero geomagnetic cut-off. In this calculation, we have included all relevant energy losses and production processes. It is shown that the protons produced from the target nuclei through r ecoil and evaporation processes dominate the spectrum below 350 MeV; T hese calculations have been carried out over an energy region from 20 MeV to 40 GeV and up to a depth of 40 g/cm(2) of the atmosphere over a latitude with zero geomagnetic cut-off for both the periods of minimu m and maximum solar modulation.