The e. m. component of extensive air showers, as sample at a given atmospheric depth, may be cinsidered as the superposition of sub-showers initiated by photons and electrons (positrons) mainly coming from the decay of secondary mesons. A detailed simulation of showers in atmosphere as produced by gammas and electrons has been performed by means of standard high energy physics Monte Carlo codes. We developed a set of parametrizations of these sub-showers to be included in the full simulations of extensive air showers with the aim to reduce the required computer power. Comparison with previous results found in the literature are shown.
G. et al. (1995) studied this question.