391 research outputs found
Tunka-Rex: the Cost-Effective Radio Extension of the Tunka Air-Shower Observatory
Tunka-Rex is the radio extension of the Tunka cosmic-ray observatory in
Siberia close to Lake Baikal. Since October 2012 Tunka-Rex measures the radio
signal of air-showers in coincidence with the non-imaging air-Cherenkov array
Tunka-133. Furthermore, this year additional antennas will go into operation
triggered by the new scintillator array Tunka-Grande measuring the secondary
electrons and muons of air showers. Tunka-Rex is a demonstrator for how
economic an antenna array can be without losing significant performance: we
have decided for simple and robust SALLA antennas, and we share the existing
DAQ running in slave mode with the PMT detectors and the scintillators,
respectively. This means that Tunka-Rex is triggered externally, and does not
need its own infrastructure and DAQ for hybrid measurements. By this, the
performance and the added value of the supplementary radio measurements can be
studied, in particular, the precision for the reconstructed energy and the
shower maximum in the energy range of approximately eV. Here
we show first results on the energy reconstruction indicating that radio
measurements can compete with air-Cherenkov measurements in precision.
Moreover, we discuss future plans for Tunka-Rex.Comment: Proceeding of UHECR 2014, Springdale, Utah, USA, accepted by JPS
Conference Proceeding
Radio measurements of the energy and the depth of the shower maximum of cosmic-ray air showers by Tunka-Rex
We reconstructed the energy and the position of the shower maximum of air
showers with energies PeV applying a method using radio
measurements performed with Tunka-Rex. An event-to-event comparison to
air-Cherenkov measurements of the same air showers with the Tunka-133
photomultiplier array confirms that the radio reconstruction works reliably.
The Tunka-Rex reconstruction methods and absolute scales have been tuned on
CoREAS simulations and yield energy and values consistent
with the Tunka-133 measurements. The results of two independent measurement
seasons agree within statistical uncertainties, which gives additional
confidence in the radio reconstruction. The energy precision of Tunka-Rex is
comparable to the Tunka-133 precision of , and exhibits a
uncertainty on the absolute scale dominated by the amplitude calibration of the
antennas. For , this is the first direct experimental
correlation of radio measurements with a different, established method. At the
moment, the resolution of Tunka-Rex is approximately g/cm. This resolution can probably be improved by deploying additional
antennas and by further development of the reconstruction methods, since the
present analysis does not yet reveal any principle limitations.Comment: accepted for publication by JCA
Improved measurements of the energy and shower maximum of cosmic rays with Tunka-Rex
The Tunka Radio Extension (Tunka-Rex) is an array of 63 antennas located in
the Tunka Valley, Siberia. It detects radio pulses in the 30-80 MHz band
produced during the air-shower development. As shown by Tunka-Rex, a sparse
radio array with about 200 m spacing is able to reconstruct the energy and the
depth of the shower maximum with satisfactory precision using simple methods
based on parameters of the lateral distribution of amplitudes. The LOFAR
experiment has shown that a sophisticated treatment of all individually
measured amplitudes of a dense antenna array can make the precision comparable
with the resolution of existing optical techniques. We develop these ideas
further and present a method based on the treatment of time series of measured
signals, i.e. each antenna station provides several points (trace) instead of a
single one (amplitude or power). We use the measured shower axis and energy as
input for CoREAS simulations: for each measured event we simulate a set of
air-showers with proton, helium, nitrogen and iron as primary particle (each
primary is simulated about ten times to cover fluctuations in the shower
maximum due to the first interaction). Simulated radio pulses are processed
with the Tunka-Rex detector response and convoluted with the measured signals.
A likelihood fit determines how well the simulated event fits to the measured
one. The positions of the shower maxima are defined from the distribution of
chi-square values of these fits. When using this improved method instead of the
standard one, firstly, the shower maximum of more events can be reconstructed,
secondly, the resolution is increased. The performance of the method is
demonstrated on the data acquired by the Tunka-Rex detector in 2012-2014.Comment: Proceedings of the 35th ICRC 2017, Busan, Kore
Tunka-Rex: energy reconstruction with a single antenna station (ARENA 2016)
The Tunka-Radio extension (Tunka-Rex) is a radio detector for air showers in
Siberia. From 2012 to 2014, Tunka-Rex operated exclusively together with its
host experiment, the air-Cherenkov array Tunka-133, which provided trigger,
data acquisition, and an independent air-shower reconstruction. It was shown
that the air-shower energy can be reconstructed by Tunka-Rex with a precision
of 15\% for events with signal in at least 3 antennas, using the radio
amplitude at a distance of 120\,m from the shower axis as an energy estimator.
Using the reconstruction from the host experiment Tunka-133 for the air-shower
geometry (shower core and direction), the energy estimator can in principle
already be obtained with measurements from a single antenna, close to the
reference distance. We present a method for event selection and energy
reconstruction, requiring only one antenna, and achieving a precision of about
20\%. This method increases the effective detector area and lowers thresholds
for zenith angle and energy, resulting in three times more events than in the
standard reconstruction
Towards a cosmic-ray mass-composition study at Tunka Radio Extension (ARENA 2016)
The Tunka Radio Extension (Tunka-Rex) is a radio detector at the TAIGA
facility located in Siberia nearby the southern tip of Lake Baikal. Tunka-Rex
measures air-showers induced by high-energy cosmic rays, in particular, the
lateral distribution of the radio pulses. The depth of the air-shower maximum,
which statistically depends on the mass of the primary particle, is determined
from the slope of the lateral distribution function (LDF). Using a
model-independent approach, we have studied possible features of the
one-dimensional slope method and tried to find improvements for the
reconstruction of primary mass. To study the systematic uncertainties given by
different primary particles, we have performed simulations using the CONEX and
CoREAS software packages of the recently released CORSIKA v7.5 including the
modern high-energy hadronic models QGSJet-II.04 and EPOS-LHC. The simulations
have shown that the largest systematic uncertainty in the energy deposit is due
to the unknown primary particle. Finally, we studied the relation between the
polarization and the asymmetry of the LDF.Comment: ARENA proceedings, 4 pages, updated reference
Contribución al conocimiento de las epífitas vasculares del Área Natural Protegida “Reserva Ecológica Sierra de Otontepec”, Veracruz
Se presenta una contribución de la diversidad de epifítas vasculares del ANP Sierra de Otontepec, en tres tipos de vegetación: bosque mesófilo de montaña, bosque tropical perennifolio y acahual, en los municipios de Chontla y Citlaltepetl. Se encontró que este grupo de plantas está representado principalmente por las familias Bromeliaceae (26.4%) y Polypodiaceae (23.5 %), seguido de la familia Orchidaceae y Piperacea (14.7%). El BMM presento mayor riqueza de especies (46%), mientras que el BTP presento menor riqueza (23%) en comparación con el AC (31%). Se registraron dos especies en la NOM-059-SEMARNAT-2010, en la categoría de Amenazadas (Tillandsia imperialis y Prostecheae mariae). Este grupo de plantas se ven afectadas por la fragmentación y recolección ilegal, por lo que, se considera necesario generar conocimiento sobre las especies que se encuentran en la reserva
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
A comparison of the cosmic-ray energy scales of Tunka-133 and KASCADE-Grande via their radio extensions Tunka-Rex and LOPES
The radio technique is a promising method for detection of cosmic-ray air
showers of energies around PeV and higher with an array of radio
antennas. Since the amplitude of the radio signal can be measured absolutely
and increases with the shower energy, radio measurements can be used to
determine the air-shower energy on an absolute scale. We show that calibrated
measurements of radio detectors operated in coincidence with host experiments
measuring air showers based on other techniques can be used for comparing the
energy scales of these host experiments. Using two approaches, first via direct
amplitude measurements, and second via comparison of measurements with air
shower simulations, we compare the energy scales of the air-shower experiments
Tunka-133 and KASCADE-Grande, using their radio extensions, Tunka-Rex and
LOPES, respectively. Due to the consistent amplitude calibration for Tunka-Rex
and LOPES achieved by using the same reference source, this comparison reaches
an accuracy of approximately - limited by some shortcomings of LOPES,
which was a prototype experiment for the digital radio technique for air
showers. In particular we show that the energy scales of cosmic-ray
measurements by the independently calibrated experiments KASCADE-Grande and
Tunka-133 are consistent with each other on this level
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