92 research outputs found
Prospects for determining air shower characteristics through geosynchrotron emission arrival times
Using simulations of geosynchrotron radiation from extensive air showers, we
present a relation between the shape of the geosynchrotron radiation front and
the distance of the observer to the maximum of the air shower. By analyzing the
relative arrival times of radio pulses at several radio antennas in an air
shower array, this relation may be employed to estimate the depth of maximum of
an extensive air shower if its impact position is known, allowing an estimate
for the primary particle's species. Vice versa, the relation provides an
estimate for the impact position of the shower's core if an external estimate
of the depth of maximum is available. In realistic circumstances, the method
delivers reconstruction uncertainties down to 30 g/cm^2 when the distance to
the shower core does not exceed 7 km. The method requires that the arrival
direction is known with high precision.Comment: 7 pages, 9 figures. Accepted for publication in Astroparticle
Physics
Possibility of Using a Satellite-Based Detector for Recording Cherenkov Light from Ultrahigh-Energy Extensive Air Showers Penetrating into the Ocean Water
We have estimated the reflected component of Cherenkov radiation, which
arises in developing of an extensive air shower with primary energy of 10^20 eV
over the ocean surface. It has been shown that, under conditions of the TUS
experiment, a flash of the reflected Cherenkov photons at the end of the
fluorescence track can be identified in showers with zenith angles up to 20
degrees.Comment: 5 pages, 3 figures. This preprint corrects errors which appeared in
the English version of the article published in Bull. Rus. Acad. Sci. Phys.,
2011, Vol. 75, No. 3, p. 381. The original russian text was published in Izv.
RAN. Ser. Fiz., 2011, Vol. 75, No. 3, p. 41
Air Shower Measurements with LOFAR
Air showers from cosmic rays emit short, intense radio pulses. LOFAR is a new
radio telescope, that is being built in the Netherlands and Europe. Designed
primarily as a radio interferometer, the core of LOFAR will have a high density
of radio antennas, which will be extremely well calibrated. This makes LOFAR a
unique tool for the study of the radio properties of single air showers.
Triggering on the radio emission from air showers means detecting a short
radio pulse and discriminating real events from radio interference. At LOFAR we
plan to search for pulses in the digital data stream - either from single
antennas or from already beam-formed data - and calculate several parameters
characterizing the pulse shape to pick out real events in a second stage. In
addition, we will have a small scintillator array to test and confirm the
performance of the radio only trigger.Comment: Proceedings of the ARENA 2008 workshop, to be published in NIM
Universality of electron-positron distributions in extensive air showers
Using a large set of simulated extensive air showers, we investigate
universality features of electron and positron distributions in
very-high-energy cosmic-ray air showers. Most particle distributions depend
only on the depth of the shower maximum and the number of particles in the
cascade at this depth. We provide multi-dimensional parameterizations for the
electron-positron distributions in terms of particle energy, vertical and
horizontal momentum angle, lateral distance, and time distribution of the
shower front. These parameterizations can be used to obtain realistic
electron-positron distributions in extensive air showers for data analysis and
simulations of Cherenkov radiation, fluorescence signal, and radio emission.Comment: 13 pages, 22 figures, 1 tabl
Simulation of propagating EAS Cherenkov radiation over the ocean surface
We present computing results of the Cherenkov light propagation in air and
water from extensive air showers developing over the ocean. Limits on zenith
angles of the showers, at which the registration of flashes of reflected
Cherenkov photons by the satellite-based detector TUS is possible, are analyzed
with consideration for waves on the ocean surface.Comment: 10 pages, 2 figures, 1 table. This preprint corrects errors which
appeared in the English version of the article published in Mosc. Univ. Phys.
Bull., 2011, Vol. 66, No. 5, p. 478. The original russian text was published
in Vest. Mosk. Univ. Fiz., 2011, No. 5, p. 6
Radio detection of cosmic ray air showers with LOPES
In the last few years, radio detection of cosmic ray air showers has
experienced a true renaissance, becoming manifest in a number of new
experiments and simulation efforts. In particular, the LOPES project has
successfully implemented modern interferometric methods to measure the radio
emission from extensive air showers. LOPES has confirmed that the emission is
coherent and of geomagnetic origin, as expected by the geosynchrotron
mechanism, and has demonstrated that a large scale application of the radio
technique has great potential to complement current measurements of ultra-high
energy cosmic rays. We describe the current status, most recent results and
open questions regarding radio detection of cosmic rays and give an overview of
ongoing research and development for an application of the radio technique in
the framework of the Pierre Auger Observatory.Comment: 8 pages; Proceedings of the CRIS2006 conference, Catania, Italy; to
be published in Nuclear Physics B, Proceedings Supplement
Radio Emission in Atmospheric Air Showers: First Measurements with LOPES-30
When Ultra High Energy Cosmic Rays interact with particles in the Earth's
atmosphere, they produce a shower of secondary particles propagating toward the
ground. LOPES-30 is an absolutely calibrated array of 30 dipole antennas
investigating the radio emission from these showers in detail and clarifying if
the technique is useful for largescale applications. LOPES-30 is co-located and
measures in coincidence with the air shower experiment KASCADE-Grande. Status
of LOPES-30 and first measurements are presented.Comment: Proceedings of ARENA 06, June 2006, University of Northumbria, U
Radio emission of highly inclined cosmic ray air showers measured with LOPES
LOPES-10 (the first phase of LOPES, consisting of 10 antennas) detected a
significant number of cosmic ray air showers with a zenith angle larger than
50, and many of these have very high radio field strengths. The most
inclined event that has been detected with LOPES-10 has a zenith angle of
almost 80. This is proof that the new technique is also applicable
for cosmic ray air showers with high inclinations, which in the case that they
are initiated close to the ground, can be a signature of neutrino events.Our
results indicate that arrays of simple radio antennas can be used for the
detection of highly inclined air showers, which might be triggered by
neutrinos. In addition, we found that the radio pulse height (normalized with
the muon number) for highly inclined events increases with the geomagnetic
angle, which confirms the geomagnetic origin of radio emission in cosmic ray
air showers.Comment: A&A accepte
On noise treatment in radio measurements of cosmic ray air showers
Precise measurements of the radio emission by cosmic ray air showers require
an adequate treatment of noise. Unlike to usual experiments in particle
physics, where noise always adds to the signal, radio noise can in principle
decrease or increase the signal if it interferes by chance destructively or
constructively. Consequently, noise cannot simply be subtracted from the
signal, and its influence on amplitude and time measurement of radio pulses
must be studied with care. First, noise has to be determined consistently with
the definition of the radio signal which typically is the maximum field
strength of the radio pulse. Second, the average impact of noise on radio pulse
measurements at individual antennas is studied for LOPES. It is shown that a
correct treatment of noise is especially important at low signal-to-noise
ratios: noise can be the dominant source of uncertainty for pulse height and
time measurements, and it can systematically flatten the slope of lateral
distributions. The presented method can also be transfered to other experiments
in radio and acoustic detection of cosmic rays and neutrinos.Comment: 4 pages, 6 figures, submitted to NIM A, Proceedings of ARENA 2010,
Nantes, Franc
The LOPES experiment - recent results, status and perspectives
The LOPES experiment at the Karlsruhe Institute of Technology has been taking
radio data in the frequency range from 40 to 80 MHz in coincidence with the
KASCADE-Grande air shower detector since 2003. Various experimental
configurations have been employed to study aspects such as the energy scaling,
geomagnetic dependence, lateral distribution, and polarization of the radio
emission from cosmic rays. The high quality per-event air shower information
provided by KASCADE-Grande has been the key to many of these studies and has
even allowed us to perform detailed per-event comparisons with simulations of
the radio emission. In this article, we give an overview of results obtained by
LOPES, and present the status and perspectives of the ever-evolving experiment.Comment: Proceedings of the ARENA2010 conference, Nantes, Franc
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