1,312 research outputs found
Radio detection of cosmic rays in the Pierre Auger Observatory
In small-scale experiments such as CODALEMA and LOPES, radio detection of
cosmic rays has demonstrated its potential as a technique for cosmic ray
measurements up to the highest energies. Radio detection promises measurements
with high duty-cycle, allows a direction reconstruction with very good angular
resolution, and provides complementary information on energy and nature of the
cosmic ray primaries with respect to particle detectors at ground and
fluorescence telescopes. Within the Pierre Auger Observatory, we tackle the
technological and scientific challenges for an application of the radio
detection technique on large scales. Here, we report on the results obtained so
far using the Southern Auger site and the plans for an engineering array of
radio detectors covering an area of ~20 km^2.Comment: 4 pages, Proceedings of the 11th Pisa Meeting on Advanced Detector
REAS3: Monte Carlo simulations of radio emission from cosmic ray air showers using an "end-point" formalism
In recent years, the freely available Monte Carlo code REAS for modelling
radio emission from cosmic ray air showers has evolved to include the full
complexity of air shower physics. However, it turned out that in REAS2 and all
other time-domain models which calculate the radio emission by superposing the
radiation of the single air shower electrons and positrons, the calculation of
the emission contributions was not fully consistent. In this article, we
present a revised implementation in REAS3, which incorporates the missing radio
emission due to the variation of the number of charged particles during the air
shower evolution using an "end-point formalism". With the inclusion of these
emission contributions, the structure of the simulated radio pulses changes
from unipolar to bipolar, and the azimuthal emission pattern becomes nearly
symmetric. Remaining asymmetries can be explained by radio emission due to the
variation of the net charge excess in air showers, which is automatically taken
into account in the new implementation. REAS3 constitutes the first
self-consistent time-domain implementation based on single particle emission
taking the full complexity of air shower physics into account, and is freely
available for all interested users.Comment: 18 pages, 13 figures accepted by Astroparticle Physics (2010
Theory and simulations of air shower radio emission
A precise understanding of the radio emission from extensive air showers is
of fundamental importance for the design of cosmic ray radio detectors as well
as the analysis and interpretation of their data. In recent years, tremendous
progress has been made in the understanding of the emission physics both in
macroscopic and microscopic frameworks. A consistent picture has emerged: the
emission stems mainly from time-varying transverse currents and a time-varying
charge excess; in addition, Cherenkov-like compression of the emission due to
the refractive index gradient in the atmosphere can lead to time-compression of
the emitted pulses and thus high-frequency contributions in the signal. In this
article, I discuss the evolution of the modelling in recent years, present the
emission physics as it is understood today, and conclude with a description and
comparison of the models currently being actively developed.Comment: Proceedings of the ARENA2012 conference (Erlangen, Germany), to be
published in AIP Conference Proceeding
Radio emission from cosmic ray air showers: simulation results and parametrization
We have developed a sophisticated model of the radio emission from extensive
air showers in the scheme of coherent geosynchrotron radiation, providing a
theoretical foundation for the interpretation of experimental data from current
and future experiments. Having verified the model through comparison of
analytic calculations, Monte Carlo simulations and historical experimental
data, we now present the results of extensive simulations performed with our
Monte Carlo code. Important results are the absence of significant asymmetries
in the total field strength emission pattern, the spectral dependence of the
radiation, the polarization characteristics of the emission (allowing an
unambiguous test of the geomagnetic emission mechanism), and the dependence of
the radio emission on important air shower and observer parameters such as the
shower zenith angle, the primary particle energy, the depth of the shower
maximum and the observer position. An analytic parametrization incorporating
the aforementioned dependences summarizes our results in a particularly useful
way.Comment: 33 pages, 24 figures, final version as accepted for publication by
Astropart. Physics, only minor updates since V
Dependence of geosynchrotron radio emission on the energy and depth of maximum of cosmic ray showers
Based on CORSIKA and REAS2 simulations, we investigate the dependence of
geosynchrotron radio emission from extensive air showers on the energy of the
primary cosmic ray and the depth of the shower maximum. It is found that at a
characteristic lateral distance, the amplitude of the bandpass-filtered radio
signal is directly proportional to the energy deposited in the atmosphere by
the electromagnetic cascade, with an RMS uncertainty due to shower-to-shower
fluctuations of less than 3%. In addition, the ratio of this radio amplitude
and that at a larger lateral distance is directly related to the atmospheric
depth of the shower maximum, with an RMS uncertainty of ~15-20 g cm-2. By
measuring these quantities, geosynchrotron radio emission from cosmic ray air
showers can be used to infer the energy of the primary particle and the depth
of the air shower maximum on a shower-to-shower basis.Comment: version accepted by Astroparticle Physics; slightly changed title and
wording; one additional figur
A Macroscopic Description of Coherent Geo-Magnetic Radiation from Cosmic Ray Air Showers
We have developed a macroscopic description of coherent electro-magnetic
radiation from air showers initiated by ultra-high energy cosmic rays due to
the presence of the geo-magnetic field. This description offers a simple and
direct insight in the relation between the properties of the air shower and the
time-structure of the radio pulse.Comment: 10 pages, 8 figures; submitted to Astroparticle Physic
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