71 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
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 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
Radio emission of highly inclined cosmic ray air showers measured with LOPES
LOPES (LOFAR Prototype Station) is an array of dipole antennas used for
detection of radio emission from air showers. It is co-located and triggered by
the KASCADE (Karlsruhe Shower Core and Array Detector) experiment, which also
provides informations about air shower properties. Even though neither LOPES
nor KASCADE are completely optimized for the detection of highly inclined
events, a significant number of showers with zenith angle larger than 50
have been detected in the radio domain, and many with very high field
strengths. Investigation of inclined showers can give deeper insight into the
nature of primary particles that initiate showers and also into the possibility
that some of detected showers are triggered by neutrinos. In this paper, we
show the example of such an event and present some of the characteristics of
highly inclined showers detected by LOPES
Frequency spectra of cosmic ray air shower radio emission measured with LOPES
AIMS: We wish to study the spectral dependence of the radio emission from
cosmic-ray air showers around 100 PeV (1017 eV). METHODS: We observe short
radio pulses in a broad frequency band with the dipole-interferometer LOPES
(LOFAR Prototype Station), which is triggered by a particle detector array
named Karlsruhe Shower Core and Array Detector (KASCADE). LOFAR is the Low
Frequency Array. For this analysis, 23 strong air shower events are selected
using parameters from KASCADE. RESULTS: The resulting electric field spectra
fall off to higher frequencies. An average electric field spectrum is fitted
with an exponential, or alternatively, with a power law. The spectral slope
obtained is not consistent within uncertainties and it is slightly steeper than
the slope obtained from Monte Carlo simulations based on air showers simulated
with CORSIKA (Cosmic Ray Simulations for KASCADE). One of the strongest events
was measured during thunderstorm activity in the vicinity of LOPES and shows
the longest pulse length measured of 110 ns and a spectral slope of -3.6.
CONCLUSIONS: We show with two different methods that frequency spectra from air
shower radio emission can be reconstructed on event-by-event basis, with only
two dozen dipole antennae simultaneously over a broad range of frequencies.
According to the obtained spectral slopes, the maximum power is emitted below
40 MHz. Furthermore, the decrease in power to higher frequencies indicates a
loss in coherence determined by the shower disc thickness. We conclude that a
broader bandwidth, larger collecting area, and longer baselines, as will be
provided by LOFAR, are necessary to further investigate the relation of the
coherence, pulse length, and spectral slope of cosmic ray air showers.Comment: 13 pages, 21 figures. Nigl, A. et al. (LOPES Collaboration),
Frequency spectra of cosmic ray air shower radio emission measured with
LOPES, accepted by A&A on 17/06/200
Air Shower Measurements with the LOPES Radio Antenna Array
LOPES is set up at the location of the KASCADE-Grande extensive air shower
experiment in Karlsruhe, Germany and aims to measure and investigate radio
pulses from Extensive Air Showers. Since radio waves suffer very little
attenuation, radio measurements allow the detection of very distant or highly
inclined showers. These waves can be recorded day and night, and provide a
bolometric measure of the leptonic shower component. LOPES is designed as a
digital radio interferometer using high bandwidths and fast data processing and
profits from the reconstructed air shower observables of KASCADE-Grande. The
LOPES antennas are absolutely amplitude calibrated allowing to reconstruct the
electric field strength which can be compared with predictions from detailed
Monte Carlo simulations. We report about the analysis of correlations present
in the radio signals measured by the LOPES 30 antenna array. Additionally,
LOPES operates antennas of a different type (LOPES-STAR) which are optimized
for an application at the Pierre Auger Observatory. Status, recent results of
the data analysis and further perspectives of LOPES and the possible large
scale application of this new detection technique are discussed.Comment: 8 pages, 10 figures, Contribution to the Arena 2008 conference, Rome,
June 200
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