Analysis of simulation and reconstruction methods used by the Pierre Auger Observatory

Abstract

Though a great deal of knowledge has been gained on the physics of ultra-high energy cosmic radiation, many questions remain unanswered. The largest experiment to date, the Pierre Auger Observatory, has been built by an international collaboration to detect and measure the properties of cosmic rays at the highest energies with unprecedented statistics. The Pierre Auger Observatory is a hybrid detector, containing both a surface detector array, and a fluorescence detector. The surface detector array covers an area of 3000 km², consisting of ∼1600 water Čerenkov detectors, operating with a nearly 100% duty cycle. The Fluorescence detector overlooks the surface detector array with 27 telescopes, each containing 440 PMT’s, to measure the development of extensive air showers calorimetrically, operating on clear moonless nights. The two detectors each benefit each other, with the surface detector improving the geometric reconstruction of showers measured by the fluorescence detector, and the fluorescence detector providing an energy scale calibration for the surface detector. After over 15 years collecting data, the Pierre Auger Observatory is undergoing a number of upgrades, including upgrades to the surface detector to distinguish different particle types to better resolve the primary particles composition. This thesis contains a number of studies related to the detection of cosmic rays. First is an examination of the pointing directions of the fluorescence telescopes, where misalignments in both the pointing directions and in camera positions are found. Second, a new method of dethinning is developed, reducing biases introduced into detector simulations when thinning is employed in extensive air shower simulations. Third, with the ability to distinguish the muon component of extensive air showers being introduced in the upgrades, the shape of the muon shower front has been examined in simulated showers, to determine the feasibility of using the shape of the muon front for composition determination.