Spatial and energy distribution of muons in gamma-induced air showers - art. no. 036002

The FLUKA Monte Carlo program is used to calculate the effects of hadroprod uction by primary gamma rays incident upon the Earth's atmosphere: for the results presented in this paper, only primary angles at 0 degrees from zeni th are considered. The FLUKA code is believed to be quite accurate in repro ducing experimental photon hadroproduction data in the 1 GeV to 10 TeV ener gy range studied. The charged pions which are so produced can decay to muon s with sufficient energy to reach ground level. The number of these muons a nd their radial and energy distribution are studied for incident gamma ray energies from 1 GeV to 10 TeV. The number of these muons is not negligible; they can, in certain circumstances, be used to study potential sources of gamma rays such as gamma ray bursts. It is found, for example, that a 10 Te V incident primary gamma ray produces, on average, 3.4 muons which reach gr ound level; the gamma ray energy which produces the maximum number of muons at ground level depends on the spectral index of the primary gamma spectru m, a constant which describes how the primary gamma flux rises with decreas ing primary energy. For example, for a differential spectral index of 2.7, there is a broad maximum number of muons coming from approximate to 30 GeV primary gamma ray energy.