Measurement of the Aerosol Differential Scattering Cross Section Using HiRes Fluorescence Detectors

The next generation of air fluorescence experiments studying cosmic rays with energies near 10 eV require significantly better atmospheric monitoring than the original Fly’ s Eye experiment in order to reconstruct accurately the energy of the cosmic rays. In this paper we review one proposed method to measure the combined molecular (Rayleigh) and aerosol (Mie) normalized differential scattering cross section using the HiRes fluorescence detectors. While the primary goal is to measure/monitor the unknown aerosol differential scattering cross section, the results may also be used in conjunction with the known Rayleigh scattering cross section to determine the absolute fluorescence detector efficienc y (photons to ADC readout).