Papers by Juan Carlos Salinas Diaz
Physical Review Letters, 2010
We describe the measurement of the depth of maximum, X max , of the longitudinal development of a... 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
Science, 2007
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a... 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 ~ 6x10^{19} electron volts and the positions of active galactic nuclei (AGN) lying within ~ 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.
Astrophysical observations of ultra-high-energy cosmic rays with the Pierre Auger Observatory
Physics Letters B, 2010
The spectrum can be described by a broken power law E −γ with index γ = 3.3 below the ankle which... more The spectrum can be described by a broken power law E −γ with index γ = 3.3 below the ankle which is measured at log 10 (E ankle /eV) = 18.6. Above the ankle the spectrum is described by a power law with index 2.6 followed by a flux suppression, above about log 10 (E/eV) = 19.5, detected with high statistical significance.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2010
The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines ... more The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.
Ongoing and planned enhancements of the Pierre Auger Observatory
Journal of Instrumentation, 2011
Physical Review Letters, 2008
Studies of the composition of the highest energy cosmic rays with the Pierre Auger Observatory, i... more 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.
Studies of the cosmic ray energy spectrum at the highest energies with the Pierre Auger Observatory
Astroparticle Physics, 2011
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays. It consists of a su... more 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.
Technical reports on operations and monitoring of the Pierre Auger Observatory
Astroparticle Physics, 2009
From direct observations of the longitudinal development of ultra-high energy air showers perform... more 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.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2010
The surface detector array of the Pierre Auger Observatory consists of 1600 water-Cherenkov detec... more The surface detector array of the Pierre Auger Observatory consists of 1600 water-Cherenkov detectors, for the study of extensive air showers (EAS) generated by ultra-high-energy cosmic rays. We describe the trigger hierarchy, from the identification of candidate showers at the level of a single detector, amongst a large background (mainly random single cosmic ray muons), up to the selection of real events and the rejection of random coincidences. Such trigger makes the surface detector array fully efficient for the detection of EAS with energy above 3 × 10 18 eV, for all zenith angles between 0 • and 60 • , independently of the position of the impact point and of the mass of the primary particle. In these range of energies and angles, the exposure of the surface array can be determined purely on the basis of the geometrical 6 acceptance.
Astroparticle Physics, 2008
Astrophysical observations of ultra-high-energy cosmic rays with the Pierre Auger Observatory
Physics Letters B, 2010
The spectrum can be described by a broken power law E −γ with index γ = 3.3 below the ankle which... more The spectrum can be described by a broken power law E −γ with index γ = 3.3 below the ankle which is measured at log 10 (E ankle /eV) = 18.6. Above the ankle the spectrum is described by a power law with index 2.6 followed by a flux suppression, above about log 10 (E/eV) = 19.5, detected with high statistical significance.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2010
The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines ... more The Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions.
Ongoing and planned enhancements of the Pierre Auger Observatory
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Papers by Juan Carlos Salinas Diaz