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First Analysis of Auger APF Light Source by Eli Visbal - Carnegie Mellon University

This study delves into the Auger APF light source to determine aerosol phase function through fluorescence detector event reconstruction, emphasizing the significance of cosmic rays and atmospheric calibration. The findings, challenges, and potential future work are discussed in detail.

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First Analysis of Auger APF Light Source by Eli Visbal - Carnegie Mellon University

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  1. First Analysis of the Auger APF Light Source Eli Visbal (Carnegie Mellon University) Advisor: Stefan Westerhoff

  2. Overview • Cosmic Rays and Auger • Atmospheric Calibration Overview • APF Light Sources • Determination of Aerosol Phase Function • Fluorescence Detector Event Reconstruction • Problems and Future Work • Summary and Conclusions

  3. Cosmic Rays • Cosmic Rays are very energetic particles • These particles can have energies over 1020 eV • When these particles enter the atmosphere they produce a shower of lower energy secondary particles • The origin of those with highest energies remains a mystery • This is in part due to magnetic deflection • GZK cutoff prevents particles above 6x1019 eV from traveling more than roughly 150 million light years

  4. Pierre Auger Observatory • Hybrid detector • Located in Malargue, Argentina • 4 Fluorescence Detector and 1600 Surface Detector Stations

  5. Auger Observatory

  6. Fluorescence Detector • Cosmic Rays are studied by observing nitrogen fluorescence light caused by relativistic electrons created in a shower

  7. Fluorescence Detector

  8. Shower Profile

  9. Atmospheric Calibration • Cherenkov beam builds up along shower axis • Atmospheric transmission • Multiple scattering • Aerosol (Mie) and Molecular (Rayleigh) scattering • Aerosol phase function (normalized differential scattering cross section) must be known to account for multiple-scattering and Cherenkov subtraction

  10. APF Light Sources • APF light sources shoot a near-horizontal pulse across the field of view of a FD • One FD at Coihueco and one at FD Los Morados • Wavelengths used: ~330nm, ~360nm and ~390nm

  11. APF Light Sources Coihueco FD Alpha ~ 26 degrees Beta ~ 38 degrees Gamma ~ 20 degrees

  12. APF Shot APF Shot as seen by the Coihueco fluorescence detector

  13. APF Measurement

  14. Geometrical Corrections

  15. Phase Function Fit Mie: Rayleigh: Fit Function:

  16. APF shot Angle Determination Rayleigh Dominated Data • A Rayleigh dominated night was found • According to theory scattering should be symmetric about 90 degrees Scattering angle [radians]

  17. APF Fits

  18. FD Reconstruction • Signal that reaches the telescope must be processed with reconstruction software to measure total energy • Simulated aerosol phase function used now • How big of correction when applying measured function?

  19. Effects on Energy Reconstruction

  20. Current Problems • Unstable fit • Geometry of APF needs to be measured • High angle and low angles not fit • Only one wavelength currently used • Quality of data • Too Many Parameters in Fit

  21. Conclusions • Aerosol phase function measured successfully • Energy correction less than 1% • Some additional work required

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