The role of atmospheric multiple scattering in the transmission of fluorescence light from extensive air showers

The contribution of multiply scattered photons to the air fluorescence signal from extensive air showers (EAS) is examined in this paper. A laser measurement, made with the Pierre Auger Observatory fluorescence detectors, is given as an example of the effect of atmospheric multiple scattering. Failure to account for multiple scattering can lead to errors in estimating the primary cosmic-ray energy and mass. Results from Monte Carlo simulations of multiple scattering are presented. Based on these simulations, the multiply scattered light fraction is parameterized in terms of the optical characteristics of the atmosphere and the geometry of the EAS. The application of this parameterization to beamed light sources, such as lasers and Cherenkov light, is also examined