first analysis of the auger apf light source eli visbal (carnegie mellon university) advisor: stefan...
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First Analysis of the Auger APF Light Source
Eli Visbal (Carnegie Mellon University)
Advisor: Stefan Westerhoff
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
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
Pierre Auger Observatory
Hybrid detector Located in Malargue,
Argentina 4 Fluorescence
Detector and 1600 Surface Detector Stations
Auger Observatory
Fluorescence Detector
Cosmic Rays are studied by observing nitrogen fluorescence light caused by relativistic electrons created in a shower
Fluorescence Detector
Shower Profile
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
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
APF Light Sources
Coihueco FD
Alpha ~ 26 degrees
Beta ~ 38 degrees
Gamma ~ 20 degrees
APF Shot
APF Shot as seen by the Coihueco fluorescence detector
APF Measurement
Geometrical Corrections
Phase Function Fit
Mie:
Rayleigh:
Fit Function:
APF shot Angle Determination
A Rayleigh dominated night was found
According to theory scattering should be symmetric about 90 degrees
Scattering angle [radians]
Rayleigh Dominated Data
APF Fits
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?
Effects on Energy Reconstruction
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
Conclusions
Aerosol phase function measured successfully
Energy correction less than 1% Some additional work required