Measurement of the Aerosol Phase Function at the Pierre Auger Observatory

Abstract

Air fluorescence detectors measure the energy of ultra-high energy cosmic rays by collecting fluorescence light emitted from nitrogen molecules along the extensive air shower cascade. To ensure a reliable energy determination, the light signal needs to be corrected for atmospheric effects, which not only attenuate the signal, but also produce a non-negligible background component due to scattered Cherenkov light and multiple-scattered light. The correction requires regular measurements of the aerosol attenuation length and the aerosol phase function, defined as the probability of light scattered in a given direction. At the Pierre Auger Observatory in Malargue, Argentina, the phase function is measured on an hourly basis using two Aerosol Phase Function (APF) light sources. These sources direct a UV light beam across the field of view of the fluorescence detectors; the phase function can be extracted from the image of the shots in the fluorescence detector cameras. This paper describes the design, current status, standard operation procedure, and performance of the APF system at the Pierre Auger Observatory.

arXiv comment19 pages, 10 figures (4 in color), replaced with version accepted for publication in Astroparticle Physics

References in corpus (3)

• An upper limit to the photon fraction in cosmic rays above 10^19 eV from the Pierre Auger Observatory
• Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
• The Lidar System of the Pierre Auger Observatory

Cited by in corpus (12)

• The Pierre Auger Cosmic Ray Observatory
• A Study of the Effect of Molecular and Aerosol Conditions in the Atmosphere on Air Fluorescence Measurements at the Pierre Auger Observatory
• Techniques for Measuring Aerosol Attenuation using the Central Laser Facility at the Pierre Auger Observatory
• The First Full-Scale Prototypes of the Fluorescence detector Array of Single-pixel Telescopes
• Atmospheric aerosols at the Pierre Auger Observatory and environmental implications
• Origin of atmospheric aerosols at the Pierre Auger Observatory using studies of air mass trajectories in South America
• Ramsauer approach for light scattering on non-absorbing spherical particles and application to the Henyey-Greenstein phase function
• Measurement of Aerosols at the Pierre Auger Observatory
• Atmospheric multiple scattering of fluorescence light from extensive air showers and effect of the aerosol size on the reconstruction of energy and depth of maximum
• Atmospheric effects in astroparticle physics experiments and the challenge of ever greater precision in measurements
• Atmospheric Calorimetry above 10${}^{19}$ eV: Shooting Lasers at the Pierre Auger Cosmic-Ray Observatory
• Atmospheric aerosol attenuation effect on FD data analysis at the Pierre Auger Observatory