Gamma ray and hadron generated Cverenkov photon spectra at various observation altitudes

Abstract

We have studied the propagation of Cverenkov photons generated by Very High Energy gamma-rays and hadrons in the atmosphere. Photon production height distributions derived from semi-empirical methods agree with those obtained by Monte Carlo simulations. The Cverenkov photon spectra at various observation altitudes are obtained after applying wavelength dependent corrections for the attenuation of photons in the atmosphere. The calculations were done both for gamma - ray and hadron primaries of various energies. The spectra are found to be dependent on altitude as well as primary energy. The peak of the photon spectrum seems to shift towards the shorter wavelength with increasing primary energy at a given altitude. The fraction of the UV component in the Cverenkov spectrum is also estimated. The hadron generated Cverenkov spectra are richer in UV light at higher altutudes.