Chemical composition studies of the Ultra-High Energy Cosmic Rays with the surface detector of the Pierre Auger Observatory

• Grant number: 13/18489-6
• Support Opportunities: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): December 01, 2013
• Effective date (End): April 30, 2017
• Field of knowledge: Physical Sciences and Mathematics - Physics - Elementary Particle Physics and Fields
• Principal Investigator: Carola Dobrigkeit Chinellato
• Grantee: Mary Lucia Diaz Castro
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 10/07359-6 - Study of cosmic rays of highest energies with the Pierre Auger Observatory , AP.TEM
• Associated scholarship(s): 16/10747-4 - Study of mass composition of ultra-high energy cosmic rays using parameters measured by the surface detector of the Pierre Auger Observatory, BE.EP.PD

Abstract

The Pierre Auger Observatory is an ultra high energy cosmic ray detector (E e 10^18 eV) which has hybrid characteristics combining surface and fluorescence detectors. Determining the cosmic rays chemical composition is one of its most important challenges. There are evidences that cosmic ray primaries with energy above 10^18.5 eV change their composition, going from light to heavy primaries with the increasing of the energy. This conclusion is based on recent results on the evolution of extensive air showers (cascades of particles formed by the collision of primary cosmic rays in the top of the atmosphere with nitrogen and oxygen molecules). So, to find additional parameters supporting this characteristic is mandatory to reinforce it. In this project, parameters determined by the surface detector of the Auger Observatory will be analyzed, due to the high statistics in this operation mode, in order to obtain further evidences of the chemical composition of these cosmic rays. Special attention will be given to the intrinsic - shower to shower - fluctuations of some reconstruction parameters, that can characterize the shower and give clues of their composition. Moreover, it is planned to analyze the systematic errors in the reconstruction process of the events (determination of the characteristics of the primary cosmic ray). As an additional procedure, a complete simulation chain will be realized, going from the extensive air shower simulations to the response of the surface detector. All of which to complement and validate the experimental results obtained in the whole analysis. (AU)