Related papers: Hadron-gamma discrimination from an orbital UHECR …
The origin of the highest energy cosmic rays is still unknown. At present, the major uncertainties are located at energies above $\sim 10^{19.5}$ eV, the expected beginning of the GZK suppression. This is mainly due to the low statistics…
We investigate the detection of exotic massive strongly interacting hadrons (uhecrons) in ultra high energy cosmic ray telescopes. The conclusion is that experiments such as the Pierre Auger Observatory have the potential to detect these…
The search for photons at EeV energies and beyond has considerable astrophysical interest and will remain one of the key challenges for ultra-high energy cosmic ray (UHECR) observatories in the near future. Several upper limits to the…
Although the photon structure is most efficiently studied with the accelerator instruments, there is also a scientifically complementary potential in investigations on photons produced in the outer space. This potential is already being…
To search for ultra-high-energy photons in primary cosmic rays, air shower observables are needed that allow a good separation between primary photons and primary hadrons. We present a new observable, $F_\gamma$, which can be extracted from…
In this thesis, an introduction to the Ultra-High Energy Cosmic Ray (UHECR) field is given, including air shower physics, UHECR astrophysics, and experimental techniques. The current questions in UHECR physics are mentioned, along with the…
Ultra-high energy cosmic rays (UHECRs) are the highest energy messengers of the present universe, with energies up to $10^{20}$ eV. Studies of astrophysical particles (nuclei, electrons, neutrinos and photons) at their highest observed…
The content of extremely high energy (EHE) photons in the highest energy cosmic rays can be investigated by analyzing showers arriving from directions where the perpendicular component of the Earth's magnetic field is high or showers…
We investigate the proposal that primary cosmic rays of energy above the Greisen-Zatsepin-Kuzmin cutoff are exotic massive strongly interacting particles (uhecrons). We study the properties of air showers produced by uhecrons and find that…
A major challenge in ground-based ultra-high-energy gamma-ray observations remains in discriminating sporadic gamma-ray signals from a huge background of cosmic-ray events. To achieve good discrimination power of gamma rays against protons,…
Observations of cosmic rays have been improving at all energies, with higher statistics and reduced systematics. Fundamental questions remain regarding the origins of cosmic rays both within the Galaxy and in extragalactic sources, and new…
The field of UHECRs (Ultra-High energy cosmic Rays) and the understanding of particle acceleration in the cosmos, as a key ingredient to the behaviour of the most powerful sources in the universe, is of outmost importance for astroparticle…
We discuss in some detail the production of extremely high energy (EHE) neutrinos with energies above 10^18 eV. The most certain process for producing such neutrinos results from photopion production by EHE cosmic rays in the cosmic…
Wide field-of-view gamma-ray observatories must fight the overwhelming cosmic ray background to identify very-high-energy astrophysical gamma-ray events. This work introduces a novel gamma/hadron discriminating variable, $LCm$, which…
We report a calculation of the expected rate of inclined air showers induced by ultra high energy cosmic rays to be obtained by the Auger Southern Observatory assuming different mass compositions. We describe some features that can be used…
The shape of the longitudinal development of the showers generated in the atmosphere by very high energy cosmic ray particles encodes information about the mass composition of the flux, and about the properties of hadronic interactions that…
We argue that the increase of the ratio baryon/meson due to the presence of strong colour fields and percolation in ultra-high energy hadronic collisions, helps to explain some of the global features of ultra-high energy cosmic ray cascades…
Astrophysical flares are one of the possible prominent source classes of ultra-high-energy (UHE, $E > 10^{17}$ eV) cosmic rays, which can be detected by recording clusters of extensive air showers in arrays of detectors. The search for…
The nature and origin of ultra-high energy (UHE: reffering to > 10^19 eV) cosmic rays are great mysteries in modern astrophysics. The current theories for their explanation include the so-called "top-down" decay scenarios whose main…
Experimental conclusions from air shower observations on cosmic-ray photons above 10^19 eV are based on the comparison to detailed shower simulations. For the calculations, the photonuclear cross-section needs to be extrapolated over…