Publications (54)14.47 Total impact
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Article: Studies of Cosmic Ray Composition and Air Shower Structure with the Pierre Auger Observatory
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ABSTRACT: Studies of the composition of the highest energy cosmic rays with the Pierre Auger Observatory, including examination of hadronic physics effects on the structure of extensive air showers. Submissions to the 31st ICRC, Lodz, Poland (July 2009). -
Article: Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
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ABSTRACT: Atmospheric parameters, such as pressure (P), temperature (T) and density, affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of pressure and density. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.Astroparticle Physics. -
Article: Operations of and Future Plans for the Pierre Auger Observatory
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ABSTRACT: Technical reports on operations and features of the Pierre Auger Observatory, including ongoing and planned enhancements and the status of the future northern hemisphere portion of the Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009. -
Article: The Cosmic Ray Energy Spectrum and Related Measurements with the Pierre Auger Observatory
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ABSTRACT: Studies of the cosmic ray energy spectrum at the highest energies with the Pierre Auger Observatory. -
Article: Calibration and Monitoring of the Pierre Auger Observatory
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ABSTRACT: Reports on the atmospheric monitoring, calibration, and other operating systems of the Pierre Auger Observatory. Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009. -
Article: Astrophysical Sources of Cosmic Rays and Related Measurements with the Pierre Auger Observatory
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ABSTRACT: Studies of the correlations of ultra-high energy cosmic ray directions with extra-Galactic objects, of general anisotropy, of photons and neutrinos, and of other astrophysical effects, with the Pierre Auger Observatory. Contributions to the 31st ICRC, Lodz, Poland, July 2009. -
Article: The Pierre Auger Observatory scaler mode for the study of solar activity modulation of galactic cosmic rays
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ABSTRACT: Since data-taking began in January 2004, the Pierre Auger Observatory has been recording the count rates of low energy secondary cosmic ray particles for the self-calibration of the ground detectors of its surface detector array. After correcting for atmospheric effects, modulations of galactic cosmic rays due to solar activity and transient events are observed. Temporal variations related with the activity of the heliosphere can be determined with high accuracy due to the high total count rates. In this study, the available data are presented together with an analysis focused on the observation of Forbush decreases, where a strong correlation with neutron monitor data is found.Journal of Instrumentation. -
Article: The exposure of the hybrid detector of the Pierre Auger Observatory
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ABSTRACT: The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a surface array to measure secondary particles at ground level and a fluorescence detector to measure the development of air showers in the atmosphere above the array. The “hybrid” detection mode combines the information from the two subsystems. We describe the determination of the hybrid exposure for events observed by the fluorescence telescopes in coincidence with at least one water-Cherenkov detector of the surface array. A detailed knowledge of the time dependence of the detection operations is crucial for an accurate evaluation of the exposure. We discuss the relevance of monitoring data collected during operations, such as the status of the fluorescence detector, background light and atmospheric conditions, that are used in both simulation and reconstruction.Astroparticle Physics. -
Article: Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
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ABSTRACT: From direct observations of the longitudinal development of ultra-high energy air showers performed with the Pierre Auger Observatory, upper limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtained on the fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV (1 EeV = 10^18 eV) respectively. These are the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results complement previous constraints on top-down models from array data and they reduce systematic uncertainties in the interpretation of shower data in terms of primary flux, nuclear composition and proton-air cross-section.Astroparticle Physics. -
Article: Erratum to “Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory” [Astroparticle Physics 32(2) (2009), 89–99]
Astroparticle Physics. -
Article: Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory
[show abstract] [hide abstract]
ABSTRACT: Atmospheric parameters, such as pressure (P), temperature (T) and density (ρ∝P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a not, vert, similar 10% seasonal modulation and not, vert, similar 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and ρ. The former affects the longitudinal development of air showers while the latter influences the Molière radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory. -
Article: Advanced functionality for radio analysis in the Offline software framework of the Pierre Auger Observatory
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ABSTRACT: The advent of the Auger Engineering Radio Array (AERA) necessitates the development of a powerful framework for the analysis of radio measurements of cosmic ray air showers. As AERA performs "radio-hybrid" measurements of air shower radio emission in coincidence with the surface particle detectors and fluorescence telescopes of the Pierre Auger Observatory, the radio analysis functionality had to be incorporated in the existing hybrid analysis solutions for fluoresence and surface detector data. This goal has been achieved in a natural way by extending the existing Auger Offline software framework with radio functionality. In this article, we lay out the design, highlights and features of the radio extension implemented in the Auger Offline framework. Its functionality has achieved a high degree of sophistication and offers advanced features such as vectorial reconstruction of the electric field, advanced signal processing algorithms, a transparent and efficient handling of FFTs, a very detailed simulation of detector effects, and the read-in of multiple data formats including data from various radio simulation codes. The source code of this radio functionality can be made available to interested parties on request.Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. -
Article: Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory
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ABSTRACT: We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5 × 10^17 eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.Astroparticle Physics. -
Article: Limit on the diffuse flux of ultra-high energy tau neutrinos with the surface detector of the Pierre Auger Observatory
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ABSTRACT: Data collected at the Pierre Auger Observatory are used to establish an upper limit on the diffuse flux of tau neutrinos in the cosmic radiation. Earth-skimming $\nu_{\tau}$ may interact in the Earth's crust and produce a $\tau$ lepton by means of charged-current interactions. The $\tau$ lepton may emerge from the Earth and decay in the atmosphere to produce a nearly horizontal shower with a typical signature, a persistent electromagnetic component even at very large atmospheric depths. The search procedure to select events induced by $\tau$ decays against the background of normal showers induced by cosmic rays is described. The method used to compute the exposure for a detector continuously growing with time is detailed. Systematic uncertainties in the exposure from the detector, the analysis and the involved physics are discussed. No $\tau$ neutrino candidates have been found. For neutrinos in the energy range $2\times10^{17}$ eV $< E_{\nu}$ $<$ $2\times10^{19}$ eV, assuming a diffuse spectrum of the form $E_{\nu}^{-2}$, data collected between 1 January 2004 and 30 April 2008 yield a 90% confidence-level upper limit of $E_\nu^{2} \mathrm{d}N_{\nu_\tau}/\mathrm{d}E_{\nu} < 9 \times 10^{-8}$ GeV cm$^{-2}$ s$^{-1}$ sr$^{-1}$.Physical Review D.
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Institutions
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2010
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Universidad Tecnológica Nacional
San Nicolás de los Arroyos, Provincia de Buenos Aires, Argentina
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