46 research outputs found
Operations of and Future Plans for the Pierre Auger Observatory
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.Comment: Contributions to the 31st ICRC, Lodz, Poland, July 200
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
Data from the Pierre Auger Observatory are analyzed to search for
anisotropies near the direction of the Galactic Centre at EeV energies. The
exposure of the surface array in this part of the sky is already significantly
larger than that of the fore-runner experiments. Our results do not support
previous findings of localized excesses in the AGASA and SUGAR data. We set an
upper bound on a point-like flux of cosmic rays arriving from the Galactic
Centre which excludes several scenarios predicting sources of EeV neutrons from
Sagittarius . Also the events detected simultaneously by the surface and
fluorescence detectors (the `hybrid' data set), which have better pointing
accuracy but are less numerous than those of the surface array alone, do not
show any significant localized excess from this direction.Comment: Matches published versio
The Fluorescence Detector of the Pierre Auger Observatory
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.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics
Research Section
Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
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.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle
Physic
Studies of Cosmic Ray Composition and Air Shower Structure with the Pierre Auger Observatory
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).Comment: Submissions to the 31st International Cosmic Ray Conference, Lodz,
Poland (July 2009
Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
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.Comment: 20 pages, 7 figures, 2 tables. Minor changes. Accepted by
Astroparticle Physic
2-octyl cyanoacrylate versus reintervention for closure of urethrocutaneous fistulae after urethroplasty for hypospadias: a randomized controlled trial
Effect of the artisanal shrimp fishery on the ichthyofauna in the coastal lagoon of Santa María la Reforma, southeastern Gulf of California
The effect of the artisanal shrimp fishery on the fish fauna in the coastal lagoon of Santa María la Reforma, Mexico, was assessed. Twenty-nine stations were sampled monthly for shrimp and fin fish during six months, from December 2001 to May 2002, using small boats fitted with outboard engines and the three fishing gears employed by shrimp fishermen in the area: small shrimp trawl net, gillnet, and suripera net. Each sampling period lasted five days. In total, 11,368 individuals were caught, comprising 173 fish species. The species best represented in terms of number and biomass included the commercially important species Eucinostomus entomelas, Sphoeroides annulatus, Urotrygon chilensis, and Diapterus peruvianus. The highest abundance and biomass, as determined by boostrapping of the lognormal-based estimator, were caught with the shrimp trawl net. The mean total length of the fish captured was 17.4 cm for the gillnet, 15.8 cm for the shrimp trawl net, and 13.4 cm for the suripera net. The fishing gear that had a greater impact on the fish fauna were the shrimp trawl net and the gillnet, because they caught the greatest number of fish, biomass and diversity, and a large quantity of small individuals. These two fishing gears caught fish fauna from both the bottom and the water column, and showed the lowest fish/shrimp ratio in kilograms. The shrimp trawl net caught a 6:1 ratio, the gillnet a 15:1 ratio, and the suripera net a 1:1 ratio