A. Castellina

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Construction of the first stage of the Pierre Auger Observatory has begun. The aim of the Observatory is to collect unprecedented information about cosmic rays above 10 eV: The first phase of the project, the construction and operation of a prototype system, known as the engineering array, has now been completed. It has allowed all of the sub-systems that(More)
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these(More)
The surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth's crust. Tau leptons from nu(tau) charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and(More)
The energy spectrum of cosmic rays above 2.5 x 10;{18} eV, derived from 20,000 events recorded at the Pierre Auger Observatory, is described. The spectral index gamma of the particle flux, J proportional, variantE;{-gamma}, at energies between 4 x 10;{18} eV and 4 x 10;{19} eV is 2.69+/-0.02(stat)+/-0.06(syst), steepening to 4.2+/-0.4(stat)+/-0.06(syst) at(More)
We describe the measurement of the depth of maximum, X{max}, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 10;{18} eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was(More)
The primary cosmic ray (CR) proton, helium and CNO fluxes in the energy range 80–300 TeV are studied at the National Gran Sasso Laboratories by means of EAS-TOP (Campo Imperatore, 2005 m a.s.l.) and MACRO (deep underground, 3100 m w.e., the surface energy threshold for a muon reaching the detector being E l 1:3 TeV). The measurement is based on: (a) the(More)
We discuss the potential of different experimental configurations directly measuring charged cosmic ray nuclei at energies 100 GeV/n. Using a two-zone diffusion model for the propagation of stable cosmic rays, we generate different predictions of the primary and secondary fluxes of light nuclei. It is shown that the new detectors exploiting the long and(More)
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the(More)