Related papers: Energy evolution of cosmic-ray mass and intensity …
The Pierre Auger Observatory is the largest facility in the world to study ultra-high-energy cosmic rays. It has a hybrid detection technique that combines the observation of the longitudinal development of extensive air showers and the…
The Auger Engineering Radio Array (AERA), part of the Pierre Auger Observatory, is currently the largest array of radio antenna stations deployed for the detection of cosmic rays, spanning an area of $17$ km$^2$ with 153 radio stations. It…
The accurate determination of the absolute energy scale in cosmic ray measurements is both a challenging and fundamentally important task. We present how measurements of radio pulses from extensive air showers with the Auger Engineering…
The energy spectrum of cosmic rays above 2.5 EeV has been measured across the declination range $-90^\circ \leq\delta\leq +44.8^\circ$ using data from $\sim 310{,}000$ events accrued at the Pierre Auger Observatory from an exposure of…
The first interactions of photon-induced showers are of electromagnetic nature, and the transfer of energy to the hadron/muon channel is reduced with respect to the bulk of hadron-induced showers. This results in a lower number of secondary…
The Pierre Auger Observatory has recently undergone a major upgrade, called AugerPrime, tailored to answer the current most pressing questions in the ultra-high-energy cosmic ray (UHECR) detection. The AugerPrime upgrade consists of the…
For the first time a proper comparison of the average depth of shower maximum ($X_{\rm max}$) published by the Pierre Auger and Telescope Array Observatories is presented. The $X_{\rm max}$ distributions measured by the Pierre Auger…
The standard method to estimate the mass of a cosmic ray is the measurement of the atmospheric depth of the shower maximum ($X_\text{max}$). This depth is strongly correlated with the mass of the primary because it depends on the…
We review in these notes the status of the construction of the Pierre Auger Observatory and present the first Physics results, based on the data collected during the first year and a half of operation. These results are preliminary, once…
The Pierre Auger (cosmic ray) Observatory provides a laboratory for studying fundamental physics at energies far beyond those available at colliders. The Observatory is sensitive not only to hadrons and photons, but can in principle detect…
We report a measurement of the energy spectrum of cosmic rays for energies above $2.5 {\times} 10^{18}~$eV based on 215,030 events recorded with zenith angles below $60^\circ$. A key feature of the work is that the estimates of the energies…
The Southern part of the Pierre Auger Observatory is nearing completion, and has been in stable operation since January 2004 while it has grown in size. The large sample of data collected so far has led to a significant improvement in the…
It is anticipated that the Pierre Auger Observatory can be used to detect cosmic neutrinos of >10^19 eV that arrive at very large zenith angles. However showers created by neutrino interactions close to the detector must be picked out…
Based on observations of the depth of shower maximum performed with the hybrid detector of the Auger Observatory, an upper limit on the cosmic-ray photon fraction of 26% (at 95% confidence level) is derived for primary energies above 10^19…
The development of an extensive air shower depends not only on the nature of the primary ultra-high-energy cosmic ray but also on the properties of the hadronic interactions. For energies above those achievable in human-made accelerators,…
Unveiling the sources of ultra-high-energy cosmic rays remains one of the main challenges of high-energy astrophysics. Measurements of anisotropies in their arrival directions are key to identifying their sources, yet magnetic deflections…
The sources of the observed ultra-high energy cosmic rays must also generate ultra-high energy neutrinos. Deep inelastic scattering of these neutrinos with nucleons on Earth probe center-of-mass energies $\sqrt{s} \sim 100$ TeV, well beyond…
With the Surface Detector array (SD) of the Pierre Auger Observatory we can detect neutrinos with energy between $10^{17}\,$eV and $10^{20}\,$eV from point-like sources across the sky, from close to the Southern Celestial Pole up to…
One of the most fascinating puzzles in particle astrophysics today is that of the origin and nature of the highest energy cosmic rays. The Pierre Auger Observatory (PAO), currently under construction in Province of Mendoza, Argentina, and…
Measuring proton-proton interaction cross-sections at center-of-mass energies above 40 TeV remains a significant challenge in particle physics. The Pierre Auger Observatory provides a unique opportunity to study the interactions at the…