Determining the Mass Composition of Ultra High Energy Cosmic Rays Using the Principle of Shower Universality and Data from the Pierre Auger Observatory

Open Access
Author:
Biscoveanu, Andrea Sylvia
Area of Honors:
Physics
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Miguel Mostafa, Thesis Supervisor
  • Richard Robinett, Honors Advisor
Keywords:
  • ultra high energy cosmic rays
  • particle astrophysics
  • pierre auger observatory
  • shower universality
  • extensive air showers
Abstract:
The mass composition of cosmic rays is an important parameter for determining their origin. Using both fluorescence and surface detectors, The Pierre Auger Observatory measures the depth of shower maximum, Xmax, from which the mass of the primary particle can be inferred. The surface detector measurement, which is based on the principle of shower universality, increases the number of available statistics for Xmax by at least a factor of 10 since it is no longer limited by the low duty cycle of the fluorescence detector. We compare the energy and arrival directions determined using this new reconstruction to both the official surface and fluorescence detector reconstructions and present an event by event comparison of the \Xmax values calculated using both types of detectors for events with energies above 10^{18.8} eV. We use this new reconstruction method based on universality to conduct preliminary anisotropy studies discriminating by the mass of the primary particle.