111 research outputs found
Radioelectric Field Features of Extensive Air Showers Observed with CODALEMA
Based on a new approach to the detection of radio transients associated with
extensive air showers induced by ultra high energy cosmic rays, the
experimental apparatus CODALEMA is in operation, measuring about 1 event per
day corresponding to an energy threshold ~ 5. 10^16 eV. Its performance makes
possible for the first time the study of radio-signal features on an
event-by-event basis. The sampling of the magnitude of the electric field along
a 600 meters axis is analyzed. It shows that the electric field lateral spread
is around 250 m (FWHM). The possibility to determine with radio both arrival
directions and shower core positions is discussed.Comment: Accepted for publication in Astroparticle Physic
An active dipole for cosmic ray radiodetection with CODALEMA
A paraître dans NIM AInternational audienceThe CODALEMA experiment detects the electromagnetic pulses radiated during the development of Extensive Air Showers (EAS). Since 2005, in addition to spiral log-periodic antennas, ultra broad bandwidth active dipoles have been designed to detect the full electric pulse shape of these signals. A few performances of these new detectors are presented
Evidence for Radio Detection of Extensive Air Showers Induced by Ultra High Energy Cosmic Rays
Firm evidence for a radio emission counterpart of cosmic ray air showers is
presented. By the use of an antenna array set up in coincidence with ground
particle detectors, we find a collection of events for which both time and
arrival direction coincidences between particle and radio signals are observed.
The counting rate corresponds to shower energies eV.
These results open overwhelming perspectives to complete existing detection
methods for the observation of ultra high-energy cosmic rays.Comment: 4 pages, 4 figure
Features of radio-detected Extensive Air Shower with CODALEMA
Some performances of the present CODALEMA experiment, set up to analyse
radio-detected Extensive Air Shower (EAS) events, are presented.
Characteristics of the EAS electric field distribution sampled on a 600~m long
axis are discussed.Comment: 4 pages, 3 figures, proceeding des rencontres de l'astrophysique
francaise, Strasbourg, 200
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
Measurement of the Depth of Maximum of Extensive Air Showers above 10^18 eV
We describe the measurement of the depth of maximum, Xmax, of the
longitudinal development of air showers induced by cosmic rays. Almost four
thousand 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 found to
evolve with energy at a rate of (106 +35/-21) g/cm^2/decade below 10^(18.24 +/-
0.05) eV and (24 +/- 3) g/cm^2/decade above this energy. The measured
shower-to-shower fluctuations decrease from about 55 to 26 g/cm^2. The
interpretation of these results in terms of the cosmic ray mass composition is
briefly discussed.Comment: Accepted for publication by PR
The Pierre Auger Observatory III: Other Astrophysical Observations
Astrophysical observations of ultra-high-energy cosmic rays with the Pierre
Auger ObservatoryComment: Contributions to the 32nd International Cosmic Ray Conference,
Beijing, China, August 201
The exposure of the hybrid detector of the Pierre Auger Observatory
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.Comment: Paper accepted by Astroparticle Physic
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
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