- Konzultant / Consultant: Mgr. Michal Brož, Ph.D.
Název anglicky / Title English: Study of the mass composition and hadronic interactions of the ultra-high-energy cosmic rays using hybrid data of the Pierre Auger Observatory
Abstrakt / Abstract
Cosmic rays are energetic particles (atomic nuclei) impinging upon the Earth from the vast reaches of the cosmos. They can have tremendous energies and thus must originate in remarkable but still mysterious astrophysical sources. If we understand the nature of these particles, we may be able to find the extragalactic sources of the highest energy cosmic rays. When an ultra-high-energy cosmic ray hits the atmosphere it produces billions of secondary particles that on their way cause an emission of the fluorescence light by the nitrogen molecules. Many of the secondary particles reach the ground and there their spatial and temporal distributions can be measured with particle detectors of different types. The Pierre Auger Observatory, the largest ever existed cosmic ray experiment, is a hybrid detector where fluorescence radiation is detected with the help of a system of dedicated telescopes, and the distribution of particles at ground is sampled using water-Cherenkov stations. The information from both types of detectors can be used to estimate the mass of the primary nucleus that initiated the particle cascade. Recently, the Auger Collaboration published results on the mass composition of cosmic rays obtained with a novel method where the correlation between information from both detectors is used to make a robust prediction on the spread of the masses in the primary cosmic ray beam. These results for the first time provided a reliable evidence on the presence of several different components in the primary radiation and helped to constrain astrophysical scenarios predicting a presence of a single component only. Nevertheless, the full potential of this method is yet to explore. First it should be extended to a wider range of energies helping this way to guide the astrophysical models that try to link the observed features of the cosmic rays to their characteristics at the possible production and acceleration sites. Second, study of fine details of the physics behind the observed correlation between different observables, might help in understanding of the drawbacks of the hadronic interaction models used for the modeling of particle cascades at energies beyond the reach of the largest man-made particle accelerators.
Literatura / reference:
 Lu Lu and Alan Watson, High energy cosmic rays, http://www.scholarpedia.org/article/High_energy_cosmic_rays
 A. Aab et al. (Pierre Auger Collaboration), Phys.Lett. B762 (2016) 288-295
 A. Aab et al. (Pierre Auger Collaboration), NIM A 798 (2015) 172-213