Cosmic-Ray Composition Measurements Using Radio Signals

Contains fulltext : 232970.pdf (Publisher’s version ) (Open Access)The discovery of cosmic rays with ultra-high energies has opened a window to observe the far and unknown universe. Only the most violent phenomena in the universe can accelerate particles to such extreme energies. However, nature does not give away her secrets easily: as the cosmic rays travel through the universe magnetic forces bend their flight paths making it hard to locate their sources. Additionally, ultra-high-energy cosmic rays reaching the Earth are very rare: a detector with a size of one square kilometer would, on average, observe only one particle every hundred years. For this reason cosmic-ray observatories must have a very large detection area. The biggest experiment built so far devoted to the study of ultra-high-energy cosmic rays is the Pierre Auger Observatory in the Argentinean Pampas. When such a high-energy particle enters the Earth’s atmosphere it collides with air molecules generating an air shower consisting of billions of secondary particles with a lower energy that propagate through the atmosphere. Electrons and positrons in the air shower, accelerated in the Earth’s magnetic field, emit radio waves that can be detected using a sparse array of radio antennas. The Auger Engineering Radio Array (AERA) is the radio extension of the Pierre Auger Observatory. It consists of more that 150 radio detector stations covering an area of 17 km2 and it has been designed to explore the feasibility of the radio-detection technique on large instrumented areas. In this thesis a new method to measure the mass composition of the most energetic cosmic rays combining energy and spectral information from radio signals is described.Radboud University, 10 mei 2021Promotores : Jong, S.J. de, Bentvelsen, S.C.M. Co-promotor : Timmermans, C.W.J.P.viii, 141 p