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ADS astronomy entries on 2022-09-14
author:"Kuijpers, Jan M.E."
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Title: LOPES 3D -- studies on the benefits of EAS-radio measurements
with vertically aligned antennas
Authors: Huber, D.; Apel, W. D.; Arteaga-Velazquez, J. C.; Bähren,
L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog,
H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de
Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs,
B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Huege, T.; Isar, P. G.; Kampert,
K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.;
Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger,
J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth,
M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schoo, S.;
Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.;
Wochele, J.; Zabierowski, J.; Zensus, J. A.
2022arXiv220814664H Altcode:
The LOPES experiment was a radio interferometer built at the existing
air shower array KASCADE-Grande in Karlsruhe, Germany. The last
configuration of LOPES was called LOPES 3D and consisted of ten tripole
antennas. Each of these antennas consisted of three crossed dipoles
east-west, north-south, and vertically aligned. With this, LOPES 3D
had the unique possibility to study the benefits of measurements
with vertically aligned antennas in the environment of the well
understood and calibrated particle detector array KASCADE-Grande. The
measurements with three spatially coincident antennas allows a redundant
reconstruction of the electric field vector. Several methods to exploit
the redundancy were developed and tested. Furthermore, for the first
time in LOPES, the background noise could be studied polarization-
and direction dependent. With LOPES 3D it could be demonstrated that
radio detection reaches a higher efficiency for inclined showers when
including measurements with vertically aligned antennas and that the
vertical component gets more important for the measurement of inclined
showers. In this contribution we discuss a weighting scheme for the
best combination of three redundant reconstructed electric field
vectors. Furthermore, we discuss the influence of these weighting
schemes on the ability to reconstruct air showers using the radio
method. We show an estimate of the radio efficiency for inclined
showers with focus on the benefits of measurements with vertically
aligned antennas and we present the direction dependent noise in the
different polarizations.
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Title: Final results of the LOPES radio interferometer for cosmic-ray
air showers
Authors: Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.; Bekk, K.;
Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Cantoni, E.;
Chiavassa, A.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.;
Engel, R.; Falcke, H.; Fuchs, B.; Gemmeke, H.; Grupen, C.; Haungs,
A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege,
T.; Isar, P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers,
J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.;
Morello, C.; Nehls, S.; Oehlschläger, J.; Palmieri, N.; Pierog,
T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.;
Schieler, H.; Schmidt, A.; Schoo, S.; Schröder, F. G.; Sima, O.;
Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Lopes Collaboration
2021EPJC...81..176A Altcode: 2021arXiv210203928A
LOPES, the LOFAR prototype station, was an antenna array for cosmic-ray
air showers operating from 2003 to 2013 within the KASCADE-Grande
experiment. Meanwhile, the analysis is finished and the data of
air-shower events measured by LOPES are available with open access in
the KASCADE Cosmic Ray Data Center (KCDC). This article intends to
provide a summary of the achievements, results, and lessons learned
from LOPES. By digital, interferometric beamforming the detection of air
showers became possible in the radio-loud environment of the Karlsruhe
Institute of Technology (KIT). As a prototype experiment, LOPES tested
several antenna types, array configurations and calibration techniques,
and pioneered analysis methods for the reconstruction of the most
important shower parameters, i.e., the arrival direction, the energy,
and mass-dependent observables such as the position of the shower
maximum. In addition to a review and update of previously published
results, we also present new results based on end-to-end simulations
including all known instrumental properties. For this, we applied the
detector response to radio signals simulated with the CoREAS extension
of CORSIKA, and analyzed them in the same way as measured data. Thus,
we were able to study the detector performance more accurately than
before, including some previously inaccessible features such as the
impact of noise on the interferometric cross-correlation beam. These
results led to several improvements, which are documented in this
paper and can provide useful input for the design of future cosmic-ray
experiments based on the digital radio-detection technique.
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Title: Interferometric Radio Measurements of Air Showers with LOPES:
Final Results
Authors: Schröder, F. G.; Link, K.; Apel, W. D.; Arteaga-Velázquez,
J. C.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.;
Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa,
A.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.;
Falcke, H.; Fuchs, B.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.;
Kampert, K. H.; Kang, D.; Krömer, O.; Kuijpers, J.; Łuczak, P.;
Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger,
J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.;
Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schoo, S.; Sima,
O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Lopes Collaboration
2017ICRC...35..458S Altcode: 2017PoS...301..458S; 2017arXiv170800626S
LOPES was the radio extension of the KASCADE-Grande particle-detector
array consisting of up to 30 antennas measuring the radio emission of
cosmic-ray air showers between 40 and 80 MHz with an energy threshold
of around 100 PeV. Even with the external trigger by the particle
detectors, the separation of the air-shower signal from the radio
background was difficult in the noisy environment of the Karlsruhe
Institute of Technology. For the typical event this was only possible
because of the digital, interferometric beamforming technique pioneered
by LOPES for cosmic-ray detection. Using this technique LOPES made
important discoveries with respect to the radio emission of air showers
and their relation to the shower properties, such as its energy and
its longitudinal development. By now, practically all results have
been confirmed by subsequent antenna arrays, but regarding digital
interferometry the LOPES results are still unique. Lately we completed
an end-to-end pipeline for CoREAS simulations of the radio emission
including measured background and all known detector responses as well
as the interferometric analysis technique. As result we present an
update on the reconstruction of the most important shower parameters:
arrival direction, energy, and $X_\mathrm{max}$.
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Title: A comparison of the cosmic-ray energy scales of Tunka-133
and KASCADE-Grande via their radio extensions Tunka-Rex and LOPES
Authors: Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.;
Bezyazeekov, P. A.; Bekk, K.; Bertaina, M.; Biermann, P. L.;
Blümer, J.; Bozdog, H.; Brancus, I. M.; Budnev, N. M.; Cantoni, E.;
Chiavassa, A.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.;
Engel, R.; Falcke, H.; Fedorov, O.; Fuchs, B.; Gemmeke, H.; Gress,
O. A.; Grupen, C.; Haungs, A.; Heck, D.; Hiller, R.; Hörandel,
J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert,
K. -H.; Kang, D.; Kazarina, Y.; Kleifges, M.; Korosteleva, E. E.;
Kostunin, D.; Krömer, O.; Kuijpers, J.; Kuzmichev, L. A.; Link, K.;
Lubsandorzhiev, N.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas,
M.; Mirgazov, R. R.; Monkhoev, R.; Morello, C.; Oehlschläger, J.;
Osipova, E. A.; Pakhorukov, A.; Palmieri, N.; Pankov, L.; Pierog,
T.; Prosin, V. V.; Rautenberg, J.; Rebel, H.; Roth, M.; Rubtsov,
G. I.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schoo,
S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl,
A.; Wischnewski, R.; Wochele, J.; Zabierowski, J.; Zagorodnikov, A.;
Zensus, J. A.; Tunka-Rex Collaboration; Lopes Collaboration
2016PhLB..763..179A Altcode: 2016arXiv161008343A
The radio technique is a promising method for detection of cosmic-ray
air showers of energies around 100PeV 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 10% - 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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Title: Improved absolute calibration of LOPES measurements and its
impact on the comparison with REAS 3.11 and CoREAS simulations
Authors: Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.; Bekk, K.;
Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.;
Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro,
F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Gemmeke, H.; Grupen,
C.; Haungs, A.; Heck, D.; Hiller, R.; Hörandel, J. R.; Horneffer, A.;
Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.; Kang, D.; Krömer,
O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.;
Melissas, M.; Morello, C.; Nehls, S.; Oehlschläger, J.; Palmieri, N.;
Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu,
A.; Schieler, H.; Schmidt, A.; Schoo, S.; Schröder, F. G.; Sima,
O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.
2016APh....75...72A Altcode: 2015arXiv150707389L; 2015arXiv150707389A
LOPES was a digital antenna array detecting the radio emission of
cosmic-ray air showers. The calibration of the absolute amplitude scale
of the measurements was done using an external, commercial reference
source, which emits a frequency comb with defined amplitudes. Recently,
we obtained improved reference values by the manufacturer of the
reference source, which significantly changed the absolute calibration
of LOPES. We reanalyzed previously published LOPES measurements,
studying the impact of the changed calibration. The main effect is an
overall decrease of the LOPES amplitude scale by a factor of 2.6 ±
0.2, affecting all previously published values for measurements of
the electric-field strength. This results in a major change in the
conclusion of the paper 'Comparing LOPES measurements of air-shower
radio emission with REAS 3.11 and CoREAS simulations' published by Apel
et al. (2013) : With the revised calibration, LOPES measurements now
are compatible with CoREAS simulations, but in tension with REAS 3.11
simulations. Since CoREAS is the latest version of the simulation code
incorporating the current state of knowledge on the radio emission
of air showers, this new result indicates that the absolute amplitude
prediction of current simulations now is in agreement with experimental
data.
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Title: Electric Current Circuits in Astrophysics
Authors: Kuijpers, Jan; Frey, Harald U.; Fletcher, Lyndsay
2016mssf.book....3K Altcode:
No abstract at ADS
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Title: Investigation of the radio wavefront of air showers with
LOPES measurements and CoREAS simulations (ARENA 2014)
Authors: Schröder, F. G.; Apel, W. D.; Arteaga-Velazquez, J. C.;
Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller,
K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.;
Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck,
D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar,
P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link,
K.; Luczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.;
Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel,
H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.;
Schoo, S.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele,
J.; Zabierowski, J.; Zensus, J. A.
2015arXiv150707753S Altcode:
We investigated the radio wavefront of cosmic-ray air showers with
LOPES measurements and CoREAS simulations: the wavefront is of
approximately hyperbolic shape and its steepness is sensitive to
the shower maximum. For this study we used 316 events with an energy
above 0.1 EeV and zenith angles below $45^\circ$ measured by the LOPES
experiment. LOPES was a digital radio interferometer consisting of up to
30 antennas on an area of approximately 200 m x 200 m at an altitude of
110 m above sea level. Triggered by KASCADE-Grande, LOPES measured the
radio emission between 43 and 74 MHz, and our analysis might strictly
hold only for such conditions. Moreover, we used CoREAS simulations made
for each event, which show much clearer results than the measurements
suffering from high background. A detailed description of our result
is available in our recent paper published in JCAP09(2014)025. The
present proceeding contains a summary and focuses on some additional
aspects, e.g., the asymmetry of the wavefront: According to the CoREAS
simulations the wavefront is slightly asymmetric, but on a much weaker
level than the lateral distribution of the radio amplitude.
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Title: Electric Current Circuits in Astrophysics
Authors: Kuijpers, Jan; Frey, Harald U.; Fletcher, Lyndsay
2015SSRv..188....3K Altcode: 2014arXiv1403.0795K; 2014SSRv..tmp...19K
Cosmic magnetic structures have in common that they are anchored in a
dynamo, that an external driver converts kinetic energy into internal
magnetic energy, that this magnetic energy is transported as Poynting
flux across the magnetically dominated structure, and that the magnetic
energy is released in the form of particle acceleration, heating, bulk
motion, MHD waves, and radiation. The investigation of the electric
current system is particularly illuminating as to the course of events
and the physics involved. We demonstrate this for the radio pulsar wind,
the solar flare, and terrestrial magnetic storms.
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Title: Reconstruction of the energy and depth of maximum of cosmic-ray
air showers from LOPES radio measurements
Authors: Apel, W. D.; Arteaga-Velazquez, J. C.; Bähren, L.; Bekk,
K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus,
I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann,
D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.;
Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig,
M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.;
Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle,
C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima,
O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Lopes Collaboration
2014PhRvD..90f2001A Altcode: 2014arXiv1408.2346A
LOPES is a digital radio interferometer located at Karlsruhe
Institute of Technology (KIT), Germany, that measures radio emission
from extensive air showers at MHz frequencies in coincidence with
KASCADE-Grande. In this article, we explore a method (slope method)
that leverages the slope of the measured radio lateral distribution to
reconstruct crucial attributes of primary cosmic rays. First, we present
an investigation of the method on the basis of pure simulations. Second,
we directly apply the slope method to LOPES measurements. Applying
the slope method to simulations, we obtain uncertainties on the
reconstruction of energy and depth of shower maximum (X<SUB>max</SUB>)
of 13% and 50 g /<SUP>cm2</SUP>, respectively. Applying it to LOPES
measurements, we are able to reconstruct energy and Xmax of individual
events with upper limits on the precision of 20%-25% for the primary
energy and 95 g /cm2 for Xmax, despite strong human-made noise at the
LOPES site.
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Title: The wavefront of the radio signal emitted by cosmic ray
air showers
Authors: Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.; Bekk,
K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus,
I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Gemmeke, H.;
Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.;
Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.; Kang, D.; Krömer,
O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.;
Melissas, M.; Morello, C.; Oehlschläger, J.; Palmieri, N.; Pierog,
T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.;
Schieler, H.; Schmidt, A.; Schoo, S.; Schröder, F. G.; Sima, O.;
Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.
2014JCAP...09..025A Altcode: 2014arXiv1404.3283A
Analyzing measurements of the LOPES antenna array together with
corresponding CoREAS simulations for more than 300 measured events
with energy above 10<SUP>17</SUP> eV and zenith angles smaller than
45<SUP>̂</SUP>, we find that the radio wavefront of cosmic-ray air
showers is of approximately hyperbolic shape. The simulations predict
a slightly steeper wavefront towards East than towards West, but
this asymmetry is negligible against the measurement uncertainties of
LOPES. At axis distances ≳ 50 m, the wavefront can be approximated by
a simple cone. According to the simulations, the cone angle is clearly
correlated with the shower maximum. Thus, we confirm earlier predictions
that arrival time measurements can be used to study the longitudinal
shower development, but now using a realistic wavefront. Moreover, we
show that the hyperbolic wavefront is compatible with our measurement,
and we present several experimental indications that the cone angle is
indeed sensitive to the shower development. Consequently, the wavefront
can be used to statistically study the primary composition of ultra-high
energy cosmic rays. At LOPES, the experimentally achieved precision
for the shower maximum is limited by measurement uncertainties to
approximately 140 g/c <SUP>2</SUP>. But the simulations indicate that
under better conditions this method might yield an accuracy for the
atmospheric depth of the shower maximum, X<SUB>max</SUB>, better than
30 g/c <SUP>2</SUP>. This would be competitive with the established
air-fluorescence and air-Cherenkov techniques, where the radio technique
offers the advantage of a significantly higher duty-cycle. Finally,
the hyperbolic wavefront can be used to reconstruct the shower geometry
more accurately, which potentially allows a better reconstruction of
all other shower parameters, too.
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Title: Comparing LOPES measurements of air-shower radio emission
with REAS 3.11 and CoREAS simulations
Authors: Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.; Bekk,
K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus,
I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann,
D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.;
Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig,
M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.;
Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle,
C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima,
O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.
2013APh....50...76A Altcode: 2013arXiv1309.5920A
Cosmic ray air showers emit radio pulses at MHz frequencies, which can
be measured with radio antenna arrays - like LOPES at the Karlsruhe
Institute of Technology in Germany. To improve the understanding of the
radio emission, we test theoretical descriptions with measured data. The
observables used for these tests are the absolute amplitude of the radio
signal, and the shape of the radio lateral distribution. We compare
lateral distributions of more than 500 LOPES events with two recent and
public Monte Carlo simulation codes, REAS 3.11 and CoREAS (v 1.0). The
absolute radio amplitudes predicted by REAS 3.11 are in good agreement
with the LOPES measurements. The amplitudes predicted by CoREAS are
lower by a factor of two, and marginally compatible with the LOPES
measurements within the systematic scale uncertainties. In contrast to
any previous versions of REAS, REAS 3.11 and CoREAS now reproduce the
shape of the measured lateral distributions correctly. This reflects a
remarkable progress compared to the situation a few years ago, and it
seems that the main processes for the radio emission of air showers are
now understood: The emission is mainly due to the geomagnetic deflection
of the electrons and positrons in the shower. Less important but not
negligible is the Askaryan effect (net charge variation). Moreover, we
confirm that the refractive index of the air plays an important role,
since it changes the coherence conditions for the emission: Only the
new simulations including the refractive index can reproduce rising
lateral distributions which we observe in a few LOPES events. Finally,
we show that the lateral distribution is sensitive to the energy and
the mass of the primary cosmic ray particles.
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Title: Mass sensitivity in the radio lateral distribution function
Authors: Apel, W. D.; Arteaga, J. C.; Bähren, L.; Bekk, K.; Bertaina,
M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz,
P.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro,
F.; Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuchs, B.; Fuhrmann,
D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. H.;
Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig,
M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.;
Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle,
C.; Saftoiu, A.; Schieler, H.; Schmid, A.; Schröder, F. G.; Sima,
O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Wommer, M.;
Zabierowski, J.; Zensus, J. A.
2013arXiv1308.0046A Altcode:
Measuring the mass composition of ultra-high energy cosmic rays is
one of the main tasks in the cosmic rays field. Here we are exploring
the composition signature in the coherent electromagnetic emission
from extensive air showers, detected in the MHz frequency range. One
of the experiments that successfully detects radio events in the
frequency band of 40-80 MHz is the LOPES experiment at KIT. It is a
digital interferometric antenna array and has the important advantage
of taking data in coincidence with the particle detector array
KASCADE-Grande. A possible method to look at the composition signature
in the radio data, predicted by simulations, concerns the radio lateral
distribution function, since its slope is strongly correlated with
Xmax. Recent comparison between REAS3 simulations and LOPES data showed
a significantly improved agreement in the lateral distribution function
and for this reason an analysis on a possible LOPES mass signature
through the slope method is promising. Trying to reproduce a realistic
case, proton and iron showers are simulated with REAS3 using the LOPES
selection information as input parameters. The obtained radio lateral
distribution slope is analyzed in detail. The lateral slope method to
look at the composition signature in the radio data is shown here and
a possible signature of mass composition in the LOPES data is discussed.
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Title: Reconstructing energy and X<SUB>max</SUB> of cosmic ray air
showers using the radio lateral distribution measured with LOPES
Authors: Palmieri, N.; Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren,
L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro,
F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann, D.; Gemmeke,
H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.;
Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.; Kang, D.; Krömer,
O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.;
Melissas, M.; Morello, C.; Oehlschläger, J.; Pierog, T.; Rautenberg,
J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.;
Schmidt, A.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.;
Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.
2013AIPC.1535...89P Altcode: 2013arXiv1308.0053A
The LOPES experiment, a digital radio interferometer located at KIT
(Karlsruhe Institute of Technology), obtained remarkable results for
the detection of radio emission from extensive air showers at MHz
frequencies. Features of the radio lateral distribution function (LDF)
measured by LOPES are explored in this work for a precise reconstruction
of two fundamental air shower parameters: the primary energy and the
shower X<SUB>max</SUB>. The method presented here has been developed on
(REAS3-)simulations, and is applied to LOPES measurements. Despite the
high human-made noise at the LOPES site, it is possible to reconstruct
both the energy and X<SUB>max</SUB> for individual events. On the
one hand, the energy resolution is promising and comparable to the
one of the co-located KASCADE-Grande experiment. On the other hand,
X<SUB>max</SUB> values are reconstructed with the LOPES measurements
with a resolution of 90 g/cm<SUP>2</SUP>. A precision on X<SUB>max</SUB>
better than 30 g/cm<SUP>2</SUP> is predicted and achievable in a region
with a lower human-made noise level.
---------------------------------------------------------
Title: Cosmic ray measurements with LOPES: Status and recent results
Authors: Schröder, F. G.; Apel, W. D.; Arteaga-Velázquez, J. C.;
Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Chiavassa, A.; Daumiller, K.; de Souza, V.;
Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann,
D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.;
Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.;
Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.; Palmieri,
N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.;
Saftoiu, A.; Schieler, H.; Schmidt, A.; Sima, O.; Toma, G.; Trinchero,
G. C.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.
2013AIPC.1535...78S Altcode: 2013arXiv1301.2557S
LOPES is a digital antenna array at the Karlsruhe Institute of
Technology, Germany, for cosmic-ray air-shower measurements. Triggered
by the co-located KASCADE-Grande air-shower array, LOPES detects the
radio emission of air showers via digital radio interferometry. We
summarize the status of LOPES and recent results. In particular,
we present an update on the reconstruction of the primary-particle
properties based on almost 500 events above 100PeV. With LOPES, the
arrival direction can be reconstructed with a precision of at least
0.65°, and the energy with a precision of at least 20%, which, however,
does not include systematic uncertainties on the absolute energy
scale. For many particle and astrophysics questions the reconstruction
of the atmospheric depth of the shower maximum, X<SUB>max</SUB>,
is important, since it yields information on the type of the primary
particle and its interaction with the atmosphere. Recently, we found
experimental evidence that the slope of the radio lateral distribution
is indeed sensitive to the longitudinal development of the air shower,
but unfortunately, the X<SUB>max</SUB> precision at LOPES is limited
by the high level of anthropogenic radio background. Nevertheless,
the developed methods can be transferred to next generation experiments
with lower background, which should provide an X<SUB>max</SUB> precision
competitive to other detection technologies.
---------------------------------------------------------
Title: LOPES 3D reconfiguration and first measurements
Authors: Huber, D.; Apel, W. D.; Arteaga, J. C.; Bähren, L.; Bekk,
K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus,
I. M.; Buchholz, P.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de
Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Finger,
M.; Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.;
Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege, T.; Isar, P. G.;
Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.;
Luczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.;
Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel,
H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.;
Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.;
Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.
2013arXiv1303.7070H Altcode:
The Radio detection technique of high-energy cosmic rays is based on the
radio signal emitted by the charged particles in an air shower due to
their deflection in the Earth's magnetic field. The LOPES experiment at
Karlsruhe Institute of Technology, Germany with its simple dipoles made
major contributions to the revival of this technique. LOPES is working
in the frequency range from 40 to 80 MHz and was reconfigured several
times to improve and further develop the radio detection technique. In
the current setup LOPES consists of 10 tripole antennas which measure
the complete electric field vector of the radio emission from cosmic
rays. LOPES is the first experiment measuring all three vectorial
components at once and thereby gaining the full information about the
electric field vector and not only a two-dimensional projection. Such
a setup including also measurements of the vertical electric field
component is expected to increase the sensitivity to inclined showers
and help to advance the understanding of the emission mechanism. We
present the reconfiguration and calibration procedure of LOPES 3D and
discuss first measurements.
---------------------------------------------------------
Title: LOPES 3D - vectorial measurements of radio emission from
cosmic ray induced air showers
Authors: Apel, W. D.; Arteaga, J. C.; Bähren, L.; Bekk, K.;
Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus,
I. M.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro, F.;
Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann, D.; Gemmeke,
H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.; Kang, D.;
Krömer, O.; Kuijpers, J.; Link, K.; Luczak, P.; Ludwig, M.; Mathes,
H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.; Palmieri, N.;
Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu,
A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima, O.; Toma, G.;
Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus,
J. A.
2013arXiv1303.7080A Altcode:
LOPES 3D is able to measure all three components of the electric
field vector of the radio emission from air showers. This allows
a better comparison with emission models. The measurement of the
vertical component increases the sensitivity to inclined showers. By
measuring all three components of the electric field vector LOPES 3D
demonstrates by how much the reconstruction accuracy of primary cosmic
ray parameters increases. Thus LOPES 3D evaluates the usefulness of
vectorial measurements for large scale applications.
---------------------------------------------------------
Title: Radio Measurements of Air Showers with LOPES
Authors: Schröder, F. G.; Apel, W. D.; Arteaga-Velazquez, J. C.;
Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller,
K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.;
Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck,
D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar,
P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link,
K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello,
C.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.;
Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt,
A.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.;
Zabierowski, J.; Zensus, J. A.
2013JPhCS.409a2075S Altcode:
LOPES is a digital antenna array for the radio measurement of cosmic-ray
air showers at energies around 10<SUP>17</SUP> eV. It is triggered
by the KASCADE-Grande air-shower array at the Karlsruhe Institute of
Technology (KIT), Germany. Because of an absolute amplitude calibration
and a sophisticated data analysis, LOPES can test models for the
radio emission to an up-to-now unachieved level, thus improving our
understanding of the radio emission mechanisms. Recent REAS simulations
of the air-shower radio emission come closer to the measurements
than any previously tested simulations. We have determined the
radio-reconstruction precision of interesting air-shower parameters
by comparing LOPES reconstructions to both REAS simulations and
KASCADE-Grande measurements, and present our latest results for the
angular resolution, the energy and the X<SUB>max</SUB> reconstruction
based on the radio measurement of about 500 air showers. Although the
precision of LOPES is limited by the high level of anthropogenic noise
at KIT, it opens a promising perspective for next-generation radio
arrays in regions with a lower ambient noise level.
---------------------------------------------------------
Title: Experimental Proof for the Sensitivity of Air Shower Radio
Emission to the Longitudinal Shower Development
Authors: Schroder, F. G.; Apel, W. D.; Arteaga-Velazquez, J. C.;
Bahren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blumer, J.;
Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller,
K.; De Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.;
Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck,
D.; Horandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar,
P. G.; Kampert, K. -H.; Kang, D.; Kromer, O.; Kuijpers, J.; Link,
K.; Luczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.;
Oehlschlager, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.;
Roth, M.; Ruhle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schoo,
S.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.;
Zabierowski, J.; Zensus, J. A.
2013ICRC...33.1685S Altcode:
We observe a correlation between the slope of the radio lateral
distribution measured with LOPES and the mean pseudorapidity of
high-energy muons. The latter is reconstructed by combining the
measurements of the muon tracking detector and the particle detector
array of KASCADE-Grande. Since the mean muon pseudorapidity depends
on the longitudinal shower development, the measured correlation is
experimental evidence that also the radio signal is sensitive to the
shower development — as has been predicted by simulations for a
long time. For air showers interacting earlier in the atmosphere,
i.e. old showers, the high-energy muons on average have a large
pseudorapidity, and the lateral distribution of the radio signal is
relatively flat. Contrary, young showers exhibit a smaller mean muon
pseudorapidity and a steeper radio lateral distribution. The radio
measurements seem to primarily depend on the geometrical distance
between the shower maximum and the radio detector, and only as a
consequence to the atmospheric depth of the shower maximum, Xmax. The
observed correlation is statistically significant and has been published
in Physical Review D 85, 071101(R).
---------------------------------------------------------
Title: Vectorial Radio Interferometry with LOPES 3D
Authors: Huber, D.; Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren,
L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog,
H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de
Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs,
B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Huege, T.; Isar, P. G.; Kampert,
K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.;
Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger,
J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth,
M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder,
F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele,
J.; Zabierowski, J.; Zensus, J. A.
2013ICRC...33.1643H Altcode: 2013arXiv1308.2512H
One successful detection technique for high-energy cosmic rays is
based on the radio signal emitted by the charged particles in an
air shower [1]. The LOPES experiment [2] at Karlsruhe Institute of
Technology, Germany, has made major contributions to the evolution of
this technique. LOPES was reconfigured several times to improve and
further develop the radio detection technique. In the latest setup
LOPES consisted of 10 tripole antennas. With this, LOPES 3D [3] was
the first cosmic ray experiment measuring all three vectorial field
components at once and thereby gaining the full information about the
electric field vector. We present an analysis based on the data taken
with special focus on the benefits of a direct measurement of the
vertical polarization component. We demonstrate that by measuring all
polarization components the detection and reconstruction efficiency
is increased and noisy single channel data can be reconstructed by
utilising the information from the other two channels of one antenna
station.
---------------------------------------------------------
Title: A Comparison of LOPES Lateral Distributions of the Air-shower
Radio Signal with REAS 3.11 and CoREAS Simulations
Authors: Schröder, F. G.; Apel, W. D.; Arteaga-Velázquez, J. C.;
Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller,
K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.;
Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck,
D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar,
P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link,
K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello,
C.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.;
Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt,
A.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.;
Zabierowski, J.; Zensus, J. A.
2013ICRC...33.1589S Altcode:
We compare radio lateral distributions measured with LOPES to REAS
3.11 and CoREAS simulations of the radio emission. These simulation
codes describe the measured radio signal significantly better than
previous versions of REAS, which did not yet include the refractive
index of air. The refractive index changes the coherence conditions
of the radio emission. This causes flatter lateral distributions at
LOPES distances (up to a few 100 m). In a few events the amplitude
even falls towards the shower axis: a behavior which we observe both
in simulations and measurements. Generally, REAS 3.11 and CoREAS can
reproduce the measured slope of the lateral distributions within
the uncertainties. With respect to the absolute amplitude of the
radio signal, however, there is a difference between REAS 3.11 and
CoREAS. The amplitude predicted by REAS 3.11 is approximately twice as
large as the one predicted by CoREAS in frequency range (43 - 74 MHz)
of LOPES, and REAS 3.11 is closer to the LOPES measurements. Overall,
the comparison shows that the understanding of the radio emission has
clearly advanced in the last years. It confirms that in addition to the
dominant geomagnetic and the sub-dominant Askaryan effect (charge excess
variation) the refractive index of the air plays an important role.
---------------------------------------------------------
Title: Comparison of LOPES data and CoREAS Simulations using a Full
Detector Simulation
Authors: Link, K.; Apel, W. D.; Arteaga-Velazquez, J. C.; Bahren,
L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blumer, J.; Bozdog,
H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; De
Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.;
Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Horandel,
J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert,
K. -H.; Kang, D.; Kromer, O.; Kuijpers, J.; Luczak, P.; Ludwig, M.;
Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschlager, J.; Palmieri,
N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.;
Saftoiu, A.; Schieler, H.; Schmidt, A.; Schroder, F. G.; Sima, O.;
Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.
2013ICRC...33.1705L Altcode: 2013arXiv1308.2523L
The LOPES experiment at the Karisruhe Tnstitute of Technology,
Germany, has been measuring radio emission of air showers for almost 10
years. For a better understanding of the emission process a detailed
comparison of data with simulations is necessary. This is possible
using a newly developed detector simulation including all LOPES
detector components. After propagating a simulated event through
this full detector simulation a standard LOPES like event file is
written. LOPES data and CoREAS simulations can then be treated equally
and the same analysis software can be applied to both. This gives the
opportunity to compare data and simulations directly. Furthermore, the
standard analysis software can be used with simulations which provide
the possibility to check the accuracy regarding reconstruction of
air shower parameters. We point out the advantages and present first
results using such a full LOPES detector simulation. A comparison of
LOPES data and the Monte Carlo code CoREAS based on an analysis using
this detector simulation is shown.
---------------------------------------------------------
Title: Investigation on the Energy and Mass Composition of Cosmic
Rays Using LOPES Radio Data
Authors: Palmieri, N.; Apel, W. D.; Arteaga-Velázquez, J. C.;
Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller,
K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.;
Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck,
D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar,
P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link,
K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello,
C.; Oehlschläger, J.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth,
M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder,
F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele,
J.; Zabierowski, J.; Zensus, J. A.; Lopes Collaboration
2013ICRC...33..360P Altcode: 2013arXiv1309.2410P
The sensitivity to the mass composition as well as the reconstruction of
the energy of the primary particle are explored here by leveraging the
features of the radio lateral distribution function. For the purpose
of this analysis, a set of events measured with the LOPES experiment
is reproduced with the latest CoREAS radio simulation code. Based on
simulation predictions, a method which exploits the slope of the radio
lateral distribution function is developed (Slope Method) and directly
applied on measurements. As a result, the possibility to reconstruct
both the energy and the Xmax, i.e. depth of the shower maximum, of
the cosmic ray air shower using radio data and achieving relatively
small uncertainties is presented.
---------------------------------------------------------
Title: Gravitational and Magnetohydrodynamic Waves
Authors: Kuijpers, J.
2013ASPC..470..197K Altcode:
Gravity is known to have important effects on electromagnetic fields
in the environs of compact objects. After a brief introduction to
electromagnetism in general relativity, we focus on the interaction
between gravitational waves (GWs) and magnetohydrodynamic (MHD)
waves. We use the ideal MHD approximation, and the familiar 1+3 split of
the reference frame, which allows a direct interpretation of the results
by the physical observer. We show how fast magneto-sonic waves and
Alfvén waves can grow in a magneto-plasma by action of gravitational
waves on the ambient magnetic field in the far-field approximation
for various configurations of ambient field and wave directions.
---------------------------------------------------------
Title: LOPES-3D: An antenna array for full signal detection of
air-shower radio emission
Authors: Apel, W. D.; Arteaga, J. C.; Bähren, L.; Bekk, K.; Bertaina,
M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz,
P.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro,
F.; Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuchs, B.; Fuhrmann,
D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.;
Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig,
M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.;
Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle,
C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima,
O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Wommer, M.;
Zabierowski, J.; Zensus, J. A.
2012NIMPA.696..100A Altcode: 2013arXiv1303.6808A
To better understand the radio signal emitted by extensive
air-showers and to further develop the radio detection technique
of high-energy cosmic rays, the LOPES experiment was reconfigured to
LOPES-3D. LOPES-3D is able to measure all three vectorial components of
the electric field of radio emission from cosmic ray air showers. The
additional measurement of the vertical component ought to increase the
reconstruction accuracy of primary cosmic ray parameters like direction
and energy, provides an improved sensitivity to inclined showers,
and will help to validate simulation of the emission mechanisms in
the atmosphere. LOPES-3D will evaluate the feasibility of vectorial
measurements for large scale applications. In order to measure all
three electric field components directly, a tailor-made antenna type
(tripoles) was deployed. The change of the antenna type necessitated
new pre-amplifiers and an overall recalibration. The reconfiguration
and the recalibration procedure are presented and the operationality
of LOPES-3D is demonstrated.
---------------------------------------------------------
Title: Experimental evidence for the sensitivity of the air-shower
radio signal to the longitudinal shower development
Authors: Apel, W. D.; Arteaga, J. C.; Bähren, L.; Bekk, K.; Bertaina,
M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buchholz,
P.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro,
F.; Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuchs, B.; Fuhrmann,
D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K. -H.;
Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig,
M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.;
Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle,
C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima,
O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Wommer, M.;
Zabierowski, J.; Zensus, J. A.
2012PhRvD..85g1101A Altcode: 2012arXiv1203.3971A
We observe a correlation between the slope of radio lateral
distributions and the mean muon pseudorapidity of 59 individual
cosmic-ray-air-shower events. The radio lateral distributions are
measured with LOPES, a digital radio interferometer colocated with
the multidetector-air-shower array KASCADE-Grande, which includes a
muon-tracking detector. The result proves experimentally that radio
measurements are sensitive to the longitudinal development of cosmic-ray
air showers. This is one of the main prerequisites for using radio
arrays for ultra-high-energy particle physics and astrophysics.
---------------------------------------------------------
Title: The evolution of ultracompact X-ray binaries
Authors: van Haaften, L. M.; Nelemans, G.; Voss, R.; Wood, M. A.;
Kuijpers, J.
2012A&A...537A.104V Altcode: 2011arXiv1111.5978V
Context. Ultracompact X-ray binaries (UCXBs) typically consist of
a white dwarf donor and a neutron star or black hole accretor. The
evolution of UCXBs and very low mass ratio binaries in general is poorly
understood. In particular, the dynamical behavior of an accretion disk
extending to a large radius (relative to the orbit) is unclear. <BR />
Aims: We investigate the evolution of UCXBs in order to learn for which
mass ratios and accretor types these systems can exist, and if they do,
what are their orbital and neutron star spin periods, mass transfer
rates and evolutionary timescales. <BR /> Methods: We compute tracks
of a binary containing a Roche-lobe overflowing helium white dwarf
in which mass transfer is driven by gravitational wave emission. For
different assumptions concerning accretion disk behavior we calculate
for which system parameters dynamical instability, thermal-viscous
disk instability or the propeller effect emerge. The significance of
these processes during the evolution of an UCXB is considered. <BR
/> Results: At the onset of mass transfer, the survival of the UCXB
is determined by how efficiently the accretor can eject matter in
the case of a super-Eddington mass transfer rate. At later times,
the evolution of systems strongly depends on the binary's capacity to
return angular momentum from the disk to the orbit. We find that this
feedback mechanism most likely remains effective even at very low mass
ratio. In the case of steady mass transfer, the propeller effect can
stop accretion onto recycled neutron stars completely at a sufficiently
low mass transfer rate, based on energy considerations. However, mass
transfer will likely be non-steady because disk instability allows for
accretion of some of the transferred matter. Together, the propeller
effect and disk instability cause the low mass ratio UCXBs to be
visible a small fraction of the time at most, thereby explaining the
lack of observations of such systems. <BR /> Conclusions: Most likely
UCXBs avoid late-time dynamically unstable mass loss from the donor
and continue to evolve as the age of the Universe allows. This implies
the existence of a large population of low mass ratio binaries with
orbital periods ~70-80 min, unless some other mechanism has destroyed
these binaries. Even though none have been discovered yet, black hole
UCXBs could also exist, at orbital periods of typically 100-110 min.
---------------------------------------------------------
Title: On noise treatment in radio measurements of cosmic ray
air showers
Authors: Schröder, F. G.; Apel, W. D.; Arteaga, J. C.; Asch, T.;
Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Buchholz, P.; Buitink, S.; Cantoni,
E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Doll, P.; Engel, R.;
Falcke, H.; Finger, M.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs,
A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege,
T.; Isar, P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers,
J.; Lafebre, S.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.;
Melissas, M.; Morello, C.; Nehls, S.; Oehlschläger, J.; Palmieri, N.;
Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu,
A.; Schieler, H.; Schmidt, A.; Sima, O.; Toma, G.; Trinchero, G. C.;
Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.
2012NIMPA.662S.238S Altcode: 2010arXiv1009.3444S
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 transferred
to other experiments in radio and acoustic detection of cosmic rays
and neutrinos.
---------------------------------------------------------
Title: The LOPES experiment—Recent results, status and perspectives
Authors: Huege, T.; Apel, W. D.; Arteaga, J. C.; Asch, T.; Bähren,
L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Buchholz, P.; Buitink, S.; Cantoni, E.; Chiavassa,
A.; Daumiller, K.; de Souza, V.; Doll, P.; Engel, R.; Falcke, H.;
Finger, M.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck,
D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Isar, P. G.; Kampert,
K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Link, K.;
Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.;
Nehls, S.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.;
Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt,
A.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl,
A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.
2012NIMPA.662S..72H Altcode: 2010arXiv1009.0345H
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.
---------------------------------------------------------
Title: Thunderstorm observations by air-shower radio antenna arrays
Authors: Apel, W. D.; Arteaga, J. C.; Bähren, L.; Bekk, K.; Bertaina,
M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.;
Buchholz, P.; Buitink, S.; Cantoni, E.; Chiavassa, A.; Daumiller, K.;
de Souza, V.; di Pierro, F.; Doll, P.; Ender, M.; Engel, R.; Falcke,
H.; Finger, M.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.;
Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar,
P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link,
K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.;
Nehls, S.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.;
Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt,
A.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl,
A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.
2011AdSpR..48.1295A Altcode: 2013arXiv1303.7068A
Relativistic, charged particles present in extensive air showers (EAS)
lead to a coherent emission of radio pulses which are measured to
identify the shower initiating high-energy cosmic rays. Especially
during thunderstorms, there are additional strong electric fields
in the atmosphere, which can lead to further multiplication and
acceleration of the charged particles and thus have influence on
the form and strength of the radio emission. For a reliable energy
reconstruction of the primary cosmic ray by means of the measured
radio signal it is very important to understand how electric fields
affect the radio emission. In addition, lightning strikes are a
prominent source of broadband radio emissions that are visible over
very long distances. This, on the one hand, causes difficulties in the
detection of the much lower signal of the air shower. On the other hand
the recorded signals can be used to study features of the lightning
development. The detection of cosmic rays via the radio emission and
the influence of strong electric fields on this detection technique
is investigated with the LOPES experiment in Karlsruhe, Germany. The
important question if a lightning is initiated by the high electron
density given at the maximum of a high-energy cosmic-ray air shower
is also investigated, but could not be answered by LOPES. But, these
investigations exhibit the capabilities of EAS radio antenna arrays
for lightning studies. We report about the studies of LOPES measured
radio signals of air showers taken during thunderstorms and give a
short outlook to new measurements dedicated to search for correlations
of lightning and cosmic rays.
---------------------------------------------------------
Title: New measurements of cosmic ray air showers with the digital
radio interferometer LOPES
Authors: Schröder, F. G.; Apel, W. D.; Arteaga, J. C.; Asch, T.;
Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Buchholz, P.; Buitink, S.; Cantoni,
E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Doll, P.; Engel, R.;
Falcke, H.; Finger, M.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs,
A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege,
T.; Isar, P. G.; Kampert, K. -H.; Kang, D.; Krömer, O.; Kuijpers,
J.; Lafebre, S.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.;
Melissas, M.; Morello, C.; Nehls, S.; Oehlschläger, J.; Palmieri, N.;
Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu,
A.; Schieler, H.; Schmidt, A.; Sima, O.; Toma, G.; Trinchero, G. C.;
Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.
2011ASTRA...7..303S Altcode:
LOPES is a digital radio interferometer which measures the
radio emission of extensive cosmic ray air showers. It mainly
consists of 30 dipole antennas installed in co-location with
KASCADE-Grande at the Karlsruhe Institute of Technology (KIT) in
Germany. KASCADE-Grande measures the secondary air shower particles
at ground. Whenever KASCADE-Grande detects a high-energy cosmic ray
event (≳10<SUP>16</SUP> eV), it triggers LOPES which then digitally
records the radio signal in the frequency band from 40 to 80 MHz. Using
interferometric methods, LOPES is able to successfully detect air shower
induced radio pulses, even in the noisy environment at the KIT. In the
present studies, a considerable progress in understanding the radio
emission mechanism is shown: The latest version of the "radio emission
in air shower" simulation program, REAS3, seems to be the first Monte
Carlo tool which is able to reproduce the magnitude and slope of most
of the measured lateral distributions.
---------------------------------------------------------
Title: Measurement of radio emission from extensive air showers
with LOPES
Authors: Hörandel, J. R.; Apel, W. D.; Arteaga, J. C.; Asch,
T.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann,
P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.;
Buchholz, P.; Buitink, S.; Cantoni, E.; Chiavassa, A.; Cossavella,
F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Ender, M.;
Engel, R.; Falcke, H.; Finger, M.; Fuhrmann, D.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Horneffer,
A.; Huege, T.; Isar, P. G.; Kampert, K. -H.; Kang, D.; Kickelbick,
D.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Link, K.; Łuczak, P.;
Ludwig, M.; Mathes, H. J.; Mayer, H. J.; Melissas, M.; Mitrica, B.;
Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.; Oehlschläger, J.;
Over, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rautenberg, J.; Rebel,
H.; Roth, M.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F.;
Sima, O.; Singh, K.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl,
A.; Wochele, J.; Wommer, M.; Zabierowski, J.; Zensus, J. A.
2011NIMPA.630..171H Altcode: 2009arXiv0911.2371H
A new method is explored to detect extensive air showers: the
measurement of radio waves emitted during the propagation of
the electromagnetic shower component in the magnetic field of
the Earth. Recent results of the pioneering experiment LOPES are
discussed. It registers radio signals in the frequency range between 40
and 80 MHz. The intensity of the measured radio emission is investigated
as a function of different shower parameters, such as shower energy,
angle of incidence, and distance to shower axis. In addition, new
antenna types are developed in the framework of LOPES<SUP>star</SUP>
and new methods are explored to realize a radio self-trigger algorithm
in real time.
---------------------------------------------------------
Title: Prospects for determining air shower characteristics through
geosynchrotron emission arrival times
Authors: Lafebre, S.; Falcke, H.; Hörandel, J.; Huege, T.; Kuijpers,
J.
2010APh....34...12L Altcode: 2010arXiv1004.0647L
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 <SUP>2</SUP>
when the distance to the shower core does not exceed 7 km. The method
requires that the arrival direction is known with high precision.
---------------------------------------------------------
Title: Simulation of radio emission from air showers in atmospheric
electric fields
Authors: Buitink, S.; Huege, T.; Falcke, H.; Kuijpers, J.
2010APh....33..296B Altcode: 2010arXiv1002.4849B
We study the effect of atmospheric electric fields on the radio pulse
emitted by cosmic ray air showers. Under fair weather conditions
the dominant part of the radio emission is driven by the geomagnetic
field. When the shower charges are accelerated and deflected in an
electric field additional radiation is emitted. We simulate this effect
with the Monte Carlo code REAS2, using CORSIKA-simulated showers as
input. In both codes a routine has been implemented that treats the
effect of the electric field on the shower particles. We find that the
radio pulse is significantly altered in background fields of the order
of ∼100 V/cm and higher. Practically, this means that air showers
passing through thunderstorms emit radio pulses that are not a reliable
measure for the shower energy. Under other weather circumstances
significant electric field effects are expected to occur rarely,
but nimbostratus clouds can harbor fields that are large enough. In
general, the contribution of the electric field to the radio pulse
has polarization properties that are different from the geomagnetic
pulse. In order to filter out radio pulses that have been affected
by electric field effects, radio air shower experiments should keep
weather information and perform full polarization measurements of the
radio signal.
---------------------------------------------------------
Title: Monte Carlo simulations of air showers in atmospheric
electric fields
Authors: Buitink, S.; Huege, T.; Falcke, H.; Heck, D.; Kuijpers, J.
2010APh....33....1B Altcode: 2009arXiv0910.5268B
The development of cosmic ray air showers can be influenced by
atmospheric electric fields. Under fair weather conditions these
fields are small, but the strong fields inside thunderstorms can
have a significant effect on the electromagnetic component of a
shower. Understanding this effect is particularly important for radio
detection of air showers, since the radio emission is produced by the
shower electrons and positrons. We perform Monte Carlo simulations
to calculate the effects of different electric field configurations
on the shower development. We find that the electric field becomes
important for values of the order of 1 kV/cm. Not only can the energy
distribution of electrons and positrons change significantly for such
field strengths, it is also possible that runaway electron breakdown
occurs at high altitudes, which is an important effect in lightning
initiation.
---------------------------------------------------------
Title: Observation of a VHE cosmic-ray flare-signal with the L3+C
muon spectrometer
Authors: Adriani, O.; van den Akker, M.; Aziz, T.; Bähr, J.; Banerjee,
S.; Becattini, F.; Bellucci, L.; Betev, B. L.; Blaising, J. J.;
Bobbink, G. J.; Bottai, S.; Bourilkov, D.; Cartacci, A.; Chemarin,
M.; Chen, G.; Chen, G. M.; Chen, H. S.; Chiarusi, T.; Coignet,
G.; Ding, L. K.; Duran, I.; Eline, A.; El Mamouni, H.; Faber, G.;
Fay, J.; Filthaut, F.; Ganguli, S. N.; Gong, Z. F.; Grabosch, H. J.;
Groenstege, H.; Guo, Y. N.; Gupta, S.; Gurtu, A.; Haller, Ch.; Hayashi,
Y.; He, Z. X.; Hebbeker, T.; Hervé, A.; Hofer, H.; Hofer, H.; Huo,
A. X.; Ito, N.; Jing, C. L.; Jones, L. W.; Kantserov, V.; Kawakami,
S.; Kittel, W.; König, A. C.; Kok, E.; Kuang, H. H.; Kuijpers, J.;
Ladron de Guevara, P.; Le Coultre, P.; Lei, Y.; Leich, H.; Leiste, R.;
Li, L.; Li, Z. C.; Liu, Z. A.; Lohmann, W.; Lu, Y. S.; Ma, W. G.; Ma,
X. H.; Ma, Y. Q.; Mele, S.; Meng, X. W.; Meschini, M.; Metzger, W. J.;
van Mil, A.; Milcent, H.; Mohanty, G. B.; Monteleoni, B.; Nahnhauer,
R.; Naumov, V. A.; Nowak, H.; Parriaud, J. -F.; Pauss, F.; Petersen,
B.; Pieri, M.; Pohl, M.; Pojidaev, V.; Qing, C. R.; Ramelli, R.;
Ranieri, R.; Ravindran, K. C.; Rewiersma, P.; Riemann, S.; Rojkov,
A.; Romero, L.; Schmitt, V.; Schoeneich, B.; Schotanus, D. J.; Shen,
C. Q.; Spillantini, P.; Sulanke, H.; Tang, X. W.; Timmermans, C.;
Tonwar, S. C.; Trowitzsch, G.; Unger, M.; Verkooijen, H.; van de
Walle, R. T.; Vogt, H.; Wang, R. G.; Wang, Q.; Wang, X. L.; Wang,
X. W.; Wang, Z. M.; van Wijk, R.; Wijnen, T. A. M.; Wilkens, H.; Xu,
Y. P.; Xu, J. S.; Xu, Z. Z.; Yang, C. G.; Yang, X. F.; Yao, Z. G.; Yu,
Z. Q.; Zhang, C.; Zhang, F.; Zhang, J.; Zhang, S.; Zhou, S. J.; Zhu,
G. Y.; Zhu, Q. Q.; Zhuang, H. L.; Zwart, A. N. M.; L3+C Collaboration
2010APh....33...24A Altcode: 2010APh....33...24T
The data collected by the L3+C muon spectrometer at the CERN Large
Electron-Positron collider, LEP, have been used to search for short
duration signals emitted by cosmic point sources. A sky survey performed
from July to November 1999 and from April to November 2000 has revealed
one single flux enhancement (chance probability=2.6×10<SUP>-3</SUP>)
between the 17th and 20th of August 2000 from a direction with a
galactic longitude of (265.02 ± 0.42)° and latitude of (55.58 ±
0.24)°. The energy of the detected muons was above 15 GeV.
---------------------------------------------------------
Title: Lateral distribution of the radio signal in extensive air
showers measured with LOPES
Authors: Apel, W. D.; Arteaga, J. C.; Asch, T.; Badea, A. F.; Bähren,
L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Cantoni,
E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuhrmann,
D.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.; Haungs,
A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege, T.; Isar, P. G.;
Kampert, K. -H.; Kang, D.; Kickelbick, D.; Krömer, O.; Kuijpers, J.;
Lafebre, S.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Mayer, H. J.;
Melissas, M.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl,
A.; Oehlschläger, J.; Over, S.; Palmieri, N.; Petcu, M.; Pierog,
T.; Rautenberg, J.; Rebel, H.; Roth, M.; Saftoiu, A.; Schieler, H.;
Schmidt, A.; Schröder, F.; Sima, O.; Singh, K.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski,
J.; Zensus, J. A.; LOPES Collaboration
2010APh....32..294A Altcode: 2009arXiv0910.4866L
The 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. The
coincident measurements allow us to reconstruct the electric
field strength at observation level in dependence of general EAS
parameters. In the present work, the lateral distribution of the radio
signal in air showers is studied in detail. It is found that the lateral
distributions of the electric field strengths in individual EAS can
be described by an exponential function. For about 20% of the events
a flattening towards the shower axis is observed, preferentially for
showers with large inclination angle. The estimated scale parameters
R<SUB>0</SUB>, describing the slope of the lateral profiles range
between 100 and 200 m. No evidence for a direct correlation of
R<SUB>0</SUB> with shower parameters like azimuth angle, geomagnetic
angle, or primary energy can be found. This indicates that the lateral
profile is an intrinsic property of the radio emission during the
shower development which makes the radio detection technique suitable
for large scale applications.
---------------------------------------------------------
Title: LOFAR - A new experiment to record radio emission from cosmic
particles
Authors: Hörandel, J. R.; Bähren, L.; Buitink, S.; Falcke, H.;
Horneffer, A.; Kuijpers, J.; Lafèbre, S.; Nigl, A.; Scholten, O.;
Singh, K.
2009NuPhS.196..289H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Air shower measurements with LOFAR
Authors: Horneffer, A.; Bähren, L.; Buitink, S.; Falcke, H.;
Hörandel, J. R.; Kuijpers, J.; Lafebre, S.; Nigl, A.; Scholten, O.;
Singh, K.
2009NIMPA.604S..20H Altcode: 2009arXiv0903.2398H
Air showers from cosmic rays emit short, intense radio pulses. The
Low Frequency Array (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.
---------------------------------------------------------
Title: Air shower measurements with the LOPES radio antenna array
Authors: Lopes Collaboration; Haungs, A.; Apel, W. D.; Arteaga,
J. C.; Asch, T.; Auffenberg, J.; Badea, F.; Bähren, L.; Bekk, K.;
Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.;
Brüggemann, M.; Buchholz, P.; Buitink, S.; Cantoni, E.; Chiavassa,
A.; Cossavella, F.; Daumiller, K.; de Souza, V.; di Pierro, F.;
Doll, P.; Engel, R.; Falcke, H.; Finger, M.; Fuhrmann, D.; Gemmeke,
H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.; Heck, D.; Hörandel,
J. R.; Horneffer, A.; Huege, T.; Isar, P. G.; Kampert, K. -H.; Kang,
D.; Kickelbick, D.; Kolotaev, Y.; Krömer, O.; Kuijpers, J.; Lafebre,
S.; Łuczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica,
B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.; Oehlschläger,
J.; Over, S.; Petcu, M.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth,
M.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F.; Sima, O.;
Singh, K.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.;
Walkowiak, W.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.;
Zensus, J. A.; LOPES Collaboration
2009NIMPA.604S...1L Altcode: 2008arXiv0811.1919H
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 (LOPESSTAR<SUP></SUP>) 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.
---------------------------------------------------------
Title: Universality of electron-positron distributions in extensive
air showers
Authors: Lafebre, S.; Engel, R.; Falcke, H.; Hörandel, J.; Huege,
T.; Kuijpers, J.; Ulrich, R.
2009APh....31..243L Altcode: 2009arXiv0902.0548L
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.
---------------------------------------------------------
Title: Physics of Drifting Sub-pulses in Radio Pulsars
Authors: Kuijpers, Jan M. E.
2009ASSL..357..543K Altcode:
Sophisticated analysis of single pulses from radio pulsars with
the most sensitive radio telescopes available have taught us that
most pulsars exhibit the phenomenon of drifting sub-pulses [43],
see Figs. 20.1 and 20.2. Already as early as 1970 [41], it has been
proposed that these ‘marching’ sub-pulses circulate around the
pulsar magnetic axis, and are caused by short-period waves which form
part of a long-period wave which circulates about the star at the same
angular velocity. Let P1 be the rotation period of the pulsar, P2 the
period between sub-pulses within the primary-pulse envelope, P3 the time
interval between drifting bands of sub-pulses, and P4 the circulation
period around the magnetic axis, all expressed in units of time, then
[41], see Fig. 20.2, 1 P_4 ≈ {{P_1 P_3 } over {P_2 (1 + NP_3 /P_1 )}}
= {{P_1 P_3 } over {P_2 }} if, in the last equality, the integer N is
put to zero. After all these years, in a few cases, such a carousel of
emission columns drifting around the magnetic axis has been constructed
from the observations [4, 11,12], see Fig. 20.7. Understanding the
phenomenon of drifting sub-pulses may, therefore, well be crucial to
our understanding of radio pulsar electrodynamics which despite the
largely classical nature of the relevant physics is still shrouded in
mysteries, to date 40 years after the discovery of pulsars.
---------------------------------------------------------
Title: Study of the solar anisotropy of cosmic ray primaries of
about 200 GeV energy with the L3+C muon detector
Authors: L3 Collaboration; Achard, P.; Adriani, O.; Aguilar-Benitez,
M.; van den Akker, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio,
A.; Alviggi, M. G.; Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev,
A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay,
L.; Bähr, J.; Baldew, S. V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.;
Barillère, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston,
R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.;
Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.;
Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.;
Bobbink, G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.;
Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu,
F.; Burger, J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Cara Romeo,
G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo,
N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y. H.; Chemarin,
M.; Chen, A.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.;
Chiarusi, T.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.;
Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.;
Cucciarelli, S.; de Asmundis, R.; Déglon, P.; Debreczeni, J.; Degré,
A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.;
DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Ding,
L. K.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau,
D.; Duda, M.; Duran, I.; Echenard, B.; Eline, A.; El Mamouni, H.;
Engler, A.; Eppling, F. J.; Extermann, P.; Faber, G.; Falagan, M. A.;
Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson,
T.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher, W.; Forconi,
G.; Freudenreich, K.; Furetta, C.; Galaktionov, Yu.; Ganguli, S. N.;
Garcia-Abia, P.; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z. F.;
Grabosch, H. J.; Grenier, G.; Grimm, O.; Groenstege, H.; Gruenewald,
M. W.; Guo, Y. N.; Gupta, S.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.;
Haas, D.; Haller, Ch.; Hatzifotiadou, D.; Hayashi, Y.; He, Z. X.;
Hebbeker, T.; Hervé, A.; Hirschfelder, J.; Hofer, H.; Hoferjun, H.;
Hohlmann, M.; Holzner, G.; Hou, S. R.; Huo, A. X.; Ito, N.; Jin, B. N.;
Jindal, P.; Jing, C. L.; Jones, L. W.; de Jong, P.; Josa-Mutuberría,
I.; Kantserov, V.; Kaur, M.; Kawakami, S.; Kienzle-Focacci, M. N.;
Kim, J. K.; Kirkby, J.; Kittel, W.; Klimentov, A.; König, A. C.;
Kok, E.; Korn, A.; Kopal, M.; Koutsenko, V.; Kräber, M.; Kuang,
H. H.; Kraemer, R. W.; Krüger, A.; Kuijpers, J.; Kunin, A.; Ladron
de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.;
Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J. M.;
Lei, Y.; Leich, H.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li,
C.; Li, L.; Li, Z. C.; Likhoded, S.; Lin, C. H.; Lin, W. T.; Linde,
F. L.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo, E.; Lu, Y. S.; Luci,
C.; Luminari, L.; Lustermann, W.; Ma, W. G.; Ma, X. H.; Ma, Y. Q.;
Malgeri, L.; Malinin, A.; Maña, C.; Mans, J.; Martin, J. P.; Marzano,
F.; Mazumdar, K.; McNeil, R. R.; Mele, S.; Meng, X. W.; Merola, L.;
Meschini, M.; Metzger, W. J.; Mihul, A.; van Mil, A.; Milcent, H.;
Mirabelli, G.; Mohanty, G. B.; Monteleoni, B.; Muanza, G. S.; Muijs,
A. J. M.; Musy, M.; Nagy, S.; Nahnhauer, R.; Naumov, V. A.; Natale,
S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak,
T.; Nowak, H.; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares,
C.; Paolucci, P.; Paramatti, R.; Parriaud, J. -F.; Passaleva, G.;
Patricelli, S.; Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace,
M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.;
Pierella, F.; Pieri, M.; Pioppi, M.; Piroué, P. A.; Pistolesi, E.;
Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.;
Qing, C. R.; Rahal-Callot, G.; Rahaman, M. A.; Raics, P.; Raja, N.;
Ramelli, R.; Rancoita, P. G.; Ranieri, R.; Raspereza, A.; Ravindran,
K. C.; Razis, P.; Rembeczki, S.; Ren, D.; Rescigno, M.; Reucroft,
S.; Rewiersma, P.; Riemann, S.; Riles, K.; Roe, B. P.; Rojkov, A.;
Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, S.; Rubio, J. A.;
Ruggiero, G.; Rykaczewski, H.; Saidi, R.; Sakharov, A.; Saremi, S.;
Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer, C.; Schegelsky, V.;
Schmitt, V.; Schoeneich, B.; Schopper, H.; Schotanus, D. J.; Sciacca,
C.; Servoli, L.; Shen, C. Q.; Shevchenko, S.; Shivarov, N.; Shoutko,
V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.;
Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar,
K.; Sulanke, H.; Sultanov, G.; Sun, L. Z.; Suter, H.; Swain, J. D.;
Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.; Taylor, L.;
Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, Samuel C. C.; Ting,
S. M.; Tonwar, S. C.; Tóth, J.; Trowitzsch, G.; Tully, C.; Tung,
K. L.; Ulbricht, J.; Unger, M.; Valente, E.; Verkooijen, H.; Van de
Walle, R. T.; Vasquez, R.; Vesztergombi, G.; Vetlitsky, I.; Viertel,
G.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt,
H.; Vorobiev, I.; Vorobyov, A. A.; Wadhwa, M.; Wang, R. G.; Wang, Q.;
Wang, X. L.; Wang, X. W.; Wang, Z. M.; Weber, M.; van Wijk, R.; Wijnen,
T. A. M.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Y. P.; Xu, J. S.; Xu,
Z. Z.; Yamamoto, J.; Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.;
Yang, X. F.; Yao, Z. G.; Yeh, S. C.; Yu, Z. Q.; Zalite, An.; Zalite,
Yu.; Zhang, C.; Zhang, F.; Zhang, J.; Zhang, S.; Zhang, Z. P.; Zhao,
J.; Zhou, S. J.; Zhu, G. Y.; Zhu, R. Y.; Zhu, Q. Q.; Zhuang, H. L.;
Zichichi, A.; Zimmermann, B.; Zöller, M.; Zwart, A. N. M.
2008A&A...488.1093L Altcode:
Context: Primary cosmic rays experience multiple deflections in
the non-uniform galactic and heliospheric magnetic fields which may
generate anisotropies. <BR />Aims: A study of anisotropies in the
energy range between 100 and 500 GeV is performed. This energy range
is not yet well explored. <BR />Methods: The L3 detector at the CERN
electron-positron collider, LEP, is used for a study of the angular
distribution of atmospheric muons with energies above 20 GeV. This
distribution is used to investigate the isotropy of the time-dependent
intensity of the primary cosmic-ray flux with a Fourier analysis. <BR
/>Results: A small deviation from isotropy at energies around 200
GeV is observed for the second harmonics at the solar frequency. No
sidereal anisotropy is found at a level above 10<SUP>-4</SUP>. The
measurements were performed in the years 1999 and 2000.
---------------------------------------------------------
Title: Frequency spectra of cosmic ray air shower radio emission
measured with LOPES
Authors: Nigl, A.; Apel, W. D.; Arteaga, J. C.; Asch, T.; Auffenberg,
J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.;
Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz,
P.; Buitink, S.; Butcher, H.; Cantoni, E.; Chiavassa, A.; Cossavella,
F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel,
R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen,
C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege,
T.; Isar, P. G.; Kampert, K. -H.; Kickelbick, D.; Kolotaev, Y.;
Krömer, O.; Kuijpers, J.; Lafebre, S.; Łuczak, P.; Manewald, M.;
Mathes, H. J.; Mayer, H. J.; Meurer, C.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.;
Petcu, M.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Saftoiu,
A.; Schieler, H.; Schmidt, A.; Schröder, F.; Sima, O.; Singh, K.;
Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; van Buren, J.;
Walkowiak, W.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.
2008A&A...488..807N Altcode: 2008arXiv0809.2751N
Aims: We wish to study the spectral dependence of the radio emission
from cosmic-ray air showers around 100 PeV (10<SUP>17</SUP> eV). <BR
/>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. The radio data are digitally beam-formed before the spectra are
determined by sub-band filtering and fast Fourier transformation. <BR
/>Results: The resulting electric field spectra fall off to higher
frequencies. An average electric field spectrum is fitted with an
exponential E<SUB>ν</SUB>=K\cdotexp (ν/MHz/β) and β=-0.017±0.004,
or alternatively, with a power law ɛ<SUB>ν</SUB>=K\cdotν<SUP>α</SUP>
and a spectral index of α=-1±0.2. 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). For
the analyzed sample of LOPES events, we do not find any significant
dependence of the spectral slope on the electric field amplitude,
the azimuth angle, the zenith angle, the curvature radius, nor on the
average distance of the antennae from the shower core position. But
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 α=-3.6. <BR />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. <P />Table 2 and
Fig. 14 are only available in electronic form at http://www.aanda.org
---------------------------------------------------------
Title: Direction identification in radio images of cosmic-ray air
showers detected with LOPES and KASCADE
Authors: Nigl, A.; Apel, W. D.; Arteaga, J. C.; Asch, T.; Auffenberg,
J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.;
Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz,
P.; Buitink, S.; Butcher, H.; Cantoni, E.; Chiavassa, A.; Cossavella,
F.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel,
R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen,
C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege,
T.; Isar, P. G.; Kampert, K. -H.; Kickelbick, D.; Kolotaev, Y.;
Krömer, O.; Kuijpers, J.; Lafebre, S.; Łuczak, P.; Manewald, M.;
Mathes, H. J.; Mayer, H. J.; Meurer, C.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.;
Petcu, M.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Saftoiu,
A.; Schieler, H.; Schmidt, A.; Schröder, F.; Sima, O.; Singh, K.;
Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; van Buren, J.;
Walkowiak, W.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.
2008A&A...487..781N Altcode: 2008arXiv0809.2742N
Aims: We want to understand the emission mechanism of radio emission
from air showers to determine the origin of high-energy cosmic
rays. Therefore, we study the geometry of the air shower radio emission
measured with LOPES and search for systematic effects between the
direction determined on the radio signal and the direction provided by
the particle detector array KASCADE. <BR />Methods: We produce 4D radio
images on time-scales of nanoseconds using digital beam-forming. Each
pixel of the image is calculated for three spatial dimensions and
as a function of time. The third spatial dimension is obtained by
calculating the beam focus for a range of curvature radii fitted to
the signal wave front. We search this multi-dimensional parameter space
for the direction of maximum coherence of the air shower radio signal
and compare it to the direction provided by KASCADE. <BR />Results:
The maximum radio emission of air showers is obtained for curvature
radii being larger than 3 km. We find that the direction of the emission
maximum can change when optimizing the curvature radius. This dependence
dominates the statistical uncertainty for the direction determination
with LOPES. Furthermore, we find a tentative increase of the curvature
radius to lower elevations, where the air showers pass through a
larger atmospheric depth. The distribution of the offsets between
the directions of both experiments is found to decrease linearly with
increasing signal-to-noise ratio. Significantly increased offsets and
enhanced signal strengths are found in events which were modified by
strong electric fields in thunderstorm clouds. <BR />Conclusions:
We conclude that the angular resolution of LOPES is sufficient to
determine the direction which maximizes the observed electric field
amplitude. However, the statistical uncertainty of the directions is
not determined by the resolution of LOPES, but by the uncertainty of
the curvature radius. We do not find any systematic deviation between
the directions determined from the radio signal and from the detected
particles. This result places a strong supportive argument for the use
of the radio technique to study the origin of high-energy cosmic rays.
---------------------------------------------------------
Title: Prospects for direct cosmic ray mass measurements through
the Gerasimova-Zatsepin effect
Authors: Lafèbre, S.; Falcke, H.; Hörandel, J.; Kuijpers, J.
2008A&A...485....1L Altcode: 2008arXiv0804.2633L
Context: The solar radiation field may break ultra-high-energy cosmic
nuclei apart, after which both remnants will be deflected in the
interplanetary magnetic field in different ways. This process is
known as the Gerasimova-Zatsepin effect after its discoverers. <BR
/>Aims: We investigate the possibility of using the detection of
the separated air showers produced by a pair of remnant particles
as a way to identify the species of the original cosmic ray primary
directly. Event rates for current and proposed detectors are estimated,
and requirements are defined for ideal detectors of this phenomenon. <BR
/>Methods: Detailed computational models of the disintegration and
deflection processes for a wide range of cosmic ray primaries in the
energy range of 10<SUP>16</SUP> to 10<SUP>20</SUP> eV were combined
with sophisticated detector models to calculate realistic detection
rates. <BR />Results: The fraction of Gerasimova-Zatsepin events is
found to be approximately 10<SUP>-5</SUP> of the cosmic ray flux,
implying an intrinsic event rate of around 0.07 km<SUP>-2</SUP>
sr<SUP>-1</SUP> yr<SUP>-1</SUP> in the defined energy range. Event
rates in any real experiment, whether existing or under construction,
will probably not exceed 10<SUP>-2</SUP> yr<SUP>-1</SUP>.
---------------------------------------------------------
Title: Primary Particle Energy Calibration of the EAS Radio Pulse
Height
Authors: Horneffer, A.; Apel, W. D.; Arteaga, J. C.; Asch, T.;
Auffenberg, J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.;
Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann,
M.; Buchholz, P.; Buitink, S.; Butcher, H.; Chiavassa, A.; Cossavella,
F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel,
R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen,
C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.;
Kampert, K. -H.; Kickelbick, D.; Kolotaev, Y.; Krömer, O.; Kuijpers,
J.; Lafebre, S.; Luczak, P.; Mathes, H. J.; Mayer, H. J.; Meurer,
C.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.;
Nigl, A.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.;
Petrovic, J.; Pierog, T.; Plewina, S.; Rautenberg, J.; Rebel, H.;
Roth, M.; Schieler, H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.;
Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl,
A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.
2008ICRC....4...83H Altcode: 2008ICRC...30d..83H
LOPES is one the pioneering experiments for the measurement of radio
emission from air showers with digital radio receivers. It is set up
at the site of the KASCADE-Grande air shower array and takes data in
conjunction with it. This gives us the unique possibility to combine
LOPES and KASCADE-Grande data. In its second phase LOPES has been
extended to 30 antennas, which increases the detection rate of well
reconstructed events. Also a new, absolute calibration of the radio
antennas is now available. By correlating the measured radio pulse
height with air shower parameters measured by KASCADE-Grande, we have
derived a formula that describes the radio pulse height as a function
of air shower geometry and primary particle energy. Thus allowing us
to estimate the cosmic ray energy from radio data.
---------------------------------------------------------
Title: The LOFAR air shower front evolution library
Authors: Lafebre, S.; Huege, T.; Falcke, H.; Kuijpers, J.
2008ICRC....4..577L Altcode: 2008ICRC...30d.577L
The LOFAR radio telescope, under construction in the Netherlands,
will be a powerful instrument to measure extensive air showers through
their radio signal. In order to fully understand the properties of
these signals, we are building a library of CORSIKA simulations of
showers at 10<SUP>16</SUP>--10<SUP>20.5</SUP> eV on the LOFAR BlueGene
supercomputer. This library contains histogrammed data on the particle
energy and spatial and angular distributions throughout the course of
the air showers. The REAS2 code is used to calculate geosynchrotron
radio emission from these simulations. We present parametrisations of
various characteristics of the particle distributions and radio signal
from showers in this library.
---------------------------------------------------------
Title: Update on radio detection of inclined air showers with LOPES-10
Authors: Săftoiu, A.; Apel, W. D.; Arteaga, J. C.; Asch, T.;
Auffenberg, J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.;
Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann,
M.; Buchholz, P.; Buitink, S.; Butcher, H.; Chiavassa, A.; Cossavella,
F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel,
R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen,
C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege, T.;
Isar, P. G.; Kampert, K. -H.; Kickelbick, D.; Kolotaev, Y.; Krömer,
O.; Kuijpers, J.; Lafebre, S.; Luczak, P.; Mathes, H. J.; Mayer,
H. J.; Meurer, C.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.;
Nehls, S.; Nigl, A.; Oehlschläger, J.; Ostapchenko, S.; Over, S.;
Petcu, M.; Petrovic, J.; Pierog, T.; Plewnia, S.; Rautenberg, J.;
Rebel, H.; Roth, M.; Schieler, H.; Sima, O.; Singh, K.; Stümpert,
M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak,
W.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.
2008ICRC....4..231S Altcode: 2008ICRC...30d.231S
Inclined air showers are a particularly interesting target for
observation with the radio technique. They are expected to be well
detectable and allow analyses of angular correlations over a much
broader range in geomagnetic angle than near-vertical events. We
present an updated analysis of highly inclined (>50° zenith
angle), high energy (>10<SUP>5</SUP> N_mu) air showers measured
with KASCADE-Grande in coincidence with LOPES-10. Data from the
Grande rather than the KASCADE array are used for the reconstruction
of the air shower events, giving us access to a broader range of core
distances for an independent cross-check with the earlier analysis.
---------------------------------------------------------
Title: Investigations of the lateral extension of radio emission in
air showers by LOPES30 measurements
Authors: Nehls, S.; Apel, W. D.; Arteaga, J. C.; Asch, T.; Auffenberg,
J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.;
Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.;
Butcher, H.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza,
V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel,
J. R.; Horneffer, A.; Huege, T.; Isar, P. G.; Kampert, K. -H.;
Kickelbick, D.; Kolotaev, Y.; Krömer, O.; Kuijpers, J.; Lafebre,
S.; Luczak, P.; Mathes, H. J.; Mayer, H. J.; Meurer, C.; Milke,
J.; Mitrica, B.; Morello, C.; Navarra, G.; Nigl, A.; Oehlschläger,
J.; Ostapchenko, S.; Over, S.; Petcu, M.; Petrovic, J.; Pierog, T.;
Plewnia, S.; Rautenberg, J.; Rebel, H.; Roth, M.; Schieler, H.; Sima,
O.; Singh, K.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich,
H.; van Buren, J.; Walkowiak, W.; Weindl, Wochele, J.; Zabierowski,
J.; Zensus, J. A.
2008ICRC....4..131N Altcode: 2008ICRC...30d.131N
LOPES30 is a digital radio antenna array working in the frequency
range 40 -- 80 MHz with 30 dipole antennas triggered by the air
shower experiment KASCADE-Grande. From an absolute calibration the
measured field strength of the LOPES30 antenna system is known and
the invesitigation of a large data set taken in east-west polarisation
is performed. The reconstructed pulse height of the radio emission in
extensive air showers is the measured quantity to be compared with the
KASCADE-Grande reconstruction parameters, like primary energy or shower
geometrie on a single air hower basis. The resulting correlations
will also be compared with expectations from detailed Monte Carlo
simulations.
---------------------------------------------------------
Title: Shower evolution and radio emission of air showers in
thunderstorm electric fields
Authors: Buitink, S.; Apel, W. D.; Arteaga, J. C.; Asch, T.;
Auffenberg, J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.;
Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann,
M.; Buchholz, P.; Butcher, H.; Chiavassa, A.; Cossavella, F.;
Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.;
Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.;
Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege, T.; Isar,
P. G.; Kampert, K. -H.; Kickelbick, D.; Kolotaev, Y.; Krömer, O.;
Kuijpers, J.; Lafebre, S.; Luczak, P.; Mathes, H. J.; Mayer, H. J.;
Meurer, C.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls,
S.; Nigl, A.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu,
M.; Petrovic, J.; Pierog, T.; Plewnia, S.; Rautenberg, J.; Rebel, H.;
Roth, M.; Schieler, H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.;
Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl,
Wochele, J.; Zabierowski, J.; Zensus, J. A.
2008ICRC....4..161B Altcode: 2008ICRC...30d.161B
The radio emission from cosmic ray air showers consists in large part
of geosynchrotron radiation. Since the radiation mechanism is based
on particle acceleration, atmospheric electric fields may play an
important role. LOPES results show that electric fields under fair
weather conditions do not alter the radio emission considerably,
but during thunderstorms strongly amplified pulses are measured. The
electric field influence on the shower development and radio emission
is simulated with a modified version of CORSIKA and with REAS2,
respectively We present results from both data analysis and simulation.
---------------------------------------------------------
Title: Operation of LOPES-30 for Polarization Measurements of the
Radio Emission of Cosmic Ray Air Showers
Authors: Isar, P. G.; Apel, W. D.; Arteaga, J. C.; Asch, T.;
Auffenberg, J.; Badea, F.; Bähren, L.; Bekk, K.; Bertaina, M.;
Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann,
M.; Buchholz, P.; Buitink, S.; Butcher, H.; Chiavassa, A.; Cossavella,
F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel,
R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen,
C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege,
T.; Kampert, K. -H.; Kickelbick, D.; Kolotaev, Y.; Krömer, O.;
Kuijpers, J.; Lafebre, S.; Luczak, P.; Mathes, H. J.; Mayer, H. J.;
Meurer, C.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls,
S.; Nigl, A.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu,
M.; Petrovic, J.; Pierog, T.; Plewnia, S.; Rautenberg, J.; Rebel, H.;
Roth, M.; Schieler, H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.;
Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl A.;
Wochele, J.; Zabierowski, J.; Zensus, J. A.
2008ICRC....5.1093I Altcode: 2008ICRC...30e1093I
The LOPES-30 experiment, located with the air shower experiment
KASCADE-Grande at Forschungszentrum Karlsruhe, Germany, is an array
of 30 dipole antennas set-up to investigate the pulsed radio emission
from cosmic ray air showers in the Earth's atmosphere. After one year of
measurements of the East-West polarization by all 30 antennas, recently,
the LOPES-30 set-up was reconfigured to perform dual-polarization
measurements. Half of the antennas have been configured for measurements
of the North-South polarization direction. Only by measuring at the
same time both, the E-W and N-S polarization components of the radio
emission, the geosynchrotron effect as the dominant emission mechanism
in air showers can be verified. The status of the measurements,
including the absolute calibration of the antennas, the monitoring
of the environmental conditions and a preliminary analysis of the
dual-polarized events are reported.
---------------------------------------------------------
Title: VLBI observations of Jupiter with the initial test station
of LOFAR and the Nançay decametric array
Authors: Nigl, A.; Zarka, P.; Kuijpers, J.; Falcke, H.; Bähren, L.;
Denis, L.
2007A&A...471.1099N Altcode: 2008arXiv0809.2740N
Aims:To demonstrate and test the capability of the next generation of
low-frequency radio telescopes to perform high resolution observations
across intra-continental baselines. Jupiter's strong burst emission
is used to perform broadband full signal cross-correlations on time
intervals of up to hundreds of milliseconds. <BR />Methods: Broadband
VLBI observations at about 20 MHz on a baseline of ~50 000 wavelengths
were performed to achieve arcsecond angular resolution. lofar's Initial
Test Station (lofar/its, The Netherlands) and the Nançay Decametric
Array (nda, France) digitize the measured electric field with 12 bit and
14 bit in a 40 MHz baseband. The fine structure in Jupiter's signal was
used for data synchronization prior to correlation on the time-series
data. <BR />Results: Strong emission from Jupiter was detected during
snapshots of a few seconds and detailed features down to microsecond
time-scales were identified in dynamic spectra. Correlations of
Jupiter's burst emission returned strong fringes on 1 ms time-scales
over channels as narrow as a hundred kilohertz bandwidth. <BR
/>Conclusions: Long baseline interferometry is confirmed at low
frequencies, in spite of phase shifts introduced by variations in
ionospheric propagation characteristics. Phase coherence was preserved
over tens to hundreds of milliseconds with a baseline of ~700 km. No
significant variation with time was found in the correlations and an
estimate for the fringe visibility of 1, suggested that the source was
not resolved. The upper limit on the source region size of Jupiter Io-B
S-bursts corresponds to an angular resolution of ~3 arcsec. Adding
remote stations to the lofar network at baselines up to thousand
kilometers will provide 10 times higher resolution down to an arcsecond.
---------------------------------------------------------
Title: Radio Emission in Atmospheric Air Showers: Results of LOPES-10
Authors: Haungs, A.; Apel, W. D.; Asch, T.; Badea, F.; Bähren, L.;
Bekk, K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink,
S.; Butcher, H.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; Di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.;
Glasstetter, R.; Grupen, C.; Hakenjos, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huege, T.; Isar, P. G.; Kampert, K. H.; Kolotaev,
Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Mathes, H. J.; Mayer,
H. J.; Meurer, C.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.;
Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.;
Over, S.; Petcu, M.; Petrovic, J.; Pierog, T.; Plewnia, S.; Rebel, H.;
Risse, A.; Roth, M.; Schieler, H.; Sima, O.; Singh, K.; Stümpert, M.;
Toma, G.; Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.;
Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2007JPhCS..81a2005H Altcode: 2006astro.ph.10553H
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. Data taken during
half a year of operation of 10 LOPES antennas (LOPES-10), triggered
by showers observed with KASCADE-Grande have been analyzed. We report
about results of correlations found of the measured radio signals by
LOPES-10 with shower parameters.
---------------------------------------------------------
Title: Cosmic rays studied with a hybrid high school detector array
Authors: Nigl, A.; Timmermans, C.; Schellart, P.; Kuijpers, J.;
Falcke, H.; Horneffer, A.; de Vos, C. M.; Koopman, Y.; Pepping, H. J.;
Schoonderbeek, G.
2007ENews..38e..25N Altcode: 2007ENews..38...25N; 2008arXiv0809.2717N
The LORUN/NAHSA system is a pathfinder for hybrid cosmic ray research
combined with education and outreach in the field of astro-particle
physics. Particle detectors and radio antennae were mainly setup by
students and placed on public buildings. After fully digital data
acquisition, coincidence detections were selected. Three candidate
events confirmed a working prototype, which can be multiplied to extend
further particle detector arrays on high schools.
---------------------------------------------------------
Title: Radio Emission in Atmospheric Air Showers: First Measurements
with LOPES-30
Authors: Isar, P. G.; Nehls, S.; Apel, W. D.; Asch, T.; Badea, F.;
Bähren, L.; Bekk, K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.;
Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz,
P.; Buitink, S.; Butcher, H.; Chiavassa, A.; Cossavella, F.; Daumiller,
K.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Hakenjos, A.; Haungs, A.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Huege, T.; Kampert, K. H.; Kolotaev,
Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Mathes, H. J.; Mayer,
H. J.; Meurer, C.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.;
Nigl, A.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Over, S.;
Petcu, M.; Petrovic, J.; Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.;
Roth, M.; Schieler, H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.;
Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl,
A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2007JPhCS..81a2006I Altcode: 2006astro.ph.10554I
When Ultra High Energy Cosmic Rays (UHECR) 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 large-scale 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.
---------------------------------------------------------
Title: Amplified radio emission from cosmic ray air showers in
thunderstorms
Authors: Buitink, S.; Apel, W. D.; Asch, T.; Badea, F.; Böhren, L.;
Bekk, K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Butcher,
H.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; di Pierro, F.; Doll,
P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter,
R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kolotaev, Y.; Krömer, O.; Kuijpers,
J.; Lafebre, S.; Mathes, H. J.; Mayer, H. J.; Meurer, C.; Milke, J.;
Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.; Obenland,
R.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Petrovic,
J.; Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.; Trinchero, G. C.;
Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl, A.; Wochele, J.;
Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2007A&A...467..385B Altcode: 2007astro.ph..2432B
Context: The detection of radio pulses from cosmic ray air showers is
a potentially powerful new detection mechanism for studying spectrum
and composition of ultra high energy cosmic rays that needs to be
understood in greater detail. The radiation consists in large part
of geosynchrotron radiation. The intensity of this radiation depends,
among other factors, on the energy of the primary particle and the angle
of the shower axis with respect to the geomagnetic field. <BR />Aims:
Since the radiation mechanism is based on particle acceleration, the
atmospheric electric field can play an important role. Especially
inside thunderclouds large electric fields can be present. In
this paper we examine the contribution of an electric field to the
emission mechanism theoretically and experimentally. <BR />Methods:
Two mechanisms of amplification of radio emission are considered:
the acceleration radiation of the shower particles and the radiation
from the current that is produced by ionization electrons moving
in the electric field. For both mechanisms analytical estimates are
made of their effects on the radio pulse height. We selected lopes
data recorded during thunderstorms, periods of heavy cloudiness and
periods of cloudless weather. We tested whether the correlations
with geomagnetic angle and primary energy vary with atmospheric
conditions. <BR />Results: We find that during thunderstorms the radio
emission can be strongly enhanced. The present data suggests that
the observed amplification is caused by acceleration of the shower
electrons and positrons. In the near future, extensions of lopes and
the construction of lofar will help to identify the mechanism in more
detail. No amplified pulses were found during periods of cloudless sky
or heavy cloudiness, suggesting that the electric field effect for radio
air shower measurements can be safely ignored during non-thunderstorm
conditions.
---------------------------------------------------------
Title: Anisotropy studies around the galactic centre at EeV energies
with the Auger Observatory
Authors: Abraham, J.; Aglietta, M.; Aguirre, C.; Allard, D.; Allekotte,
I.; Allison, P.; Alvarez, C.; Alvarez-Muñiz, J.; Ambrosio, M.;
Anchordoqui, L.; Anjos, J. C.; Aramo, C.; Arisaka, K.; Armengaud,
E.; Arneodo, F.; Arqueros, F.; Asch, T.; Asorey, H.; Atulugama,
B. S.; Aublin, J.; Ave, M.; Avila, G.; Bacelar, J.; Bäcker, T.;
Badagnani, D.; Barbosa, A. F.; Barbosa, H. M. J.; Barkhausen, M.;
Barnhill, D.; Barroso, S. L. C.; Bauleo, P.; Beatty, J.; Beau, T.;
Becker, B. R.; Becker, K. H.; Bellido, J. A.; Benzvi, S.; Berat,
C.; Bergmann, T.; Bernardini, P.; Bertou, X.; Biermann, P. L.;
Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blasi, P.; Bleve, C.;
Blümer, H.; Boghrat, P.; Boháčová, M.; Bonifazi, C.; Bonino,
R.; Boratav, M.; Brack, J.; Brunet, J. M.; Buchholz, P.; Busca,
N. G.; Caballero-Mora, K. S.; Cai, B.; Camin, D. V.; Capdevielle,
J. N.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazón, L.; Cester,
R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chye,
J.; Claes, D.; Clark, P. D. J.; Clay, R. W.; Clay, S. B.; Connolly,
B.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Cronin, J.;
Dagoret-Campagne, S.; Quang, T. Dang; Darriulat, P.; Daumiller, K.;
Dawson, B. R.; de Almeida, R. M.; de Carvalho, L. A.; de Donato, C.;
de Jong, S. J.; de Mello, W. J. M.; de Mello Neto, J. R. T.; de Mitri,
I.; de Oliveira, M. A. L.; de Souza, V.; Del Peral, L.; Deligny, O.;
Della Selva, A.; Delle Fratte, C.; Dembinski, H.; di Giulio, C.; Diaz,
J. C.; Dobrigkeit, C.; D'Olivo, J. C.; Dornic, D.; Dorofeev, A.; Dova,
M. T.; D'Urso, D.; Duvernois, M. A.; Engel, R.; Epele, L.; Erdmann, M.;
Escobar, C. O.; Etchegoyen, A.; Ewers, A.; Facal San Luis, P.; Falcke,
H.; Fauth, A. C.; Fazio, D.; Fazzini, N.; Fernández, A.; Ferrer, F.;
Ferry, S.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck, I.; Fokitis,
E.; Fonte, R.; Fuhrmann, D.; Fulgione, W.; García, B.; Garcia-Pinto,
D.; Garrard, L.; Garrido, X.; Geenen, H.; Gelmini, G.; Gemmeke, H.;
Geranios, A.; Ghia, P. L.; Giller, M.; Gitto, J.; Glass, H.; Gobbi, F.;
Gold, M. S.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Herrero,
R.; Gonçalves Do Amaral, M.; Gongora, J. P.; Gonzalez, D.; Gonzalez,
J. G.; González, M.; Góra, D.; Gorgi, A.; Gouffon, P.; Grassi, V.;
Grillo, A.; Grunfeld, C.; Grupen, C.; Guarino, F.; Guedes, G. P.;
Gutiérrez, J.; Hague, J. D.; Hamilton, J. C.; Harakeh, M. N.; Harari,
D.; Harmsma, S.; Hartmann, S.; Harton, J. L.; Haungs, A.; Healy,
M. D.; Hebbeker, T.; Heck, D.; Hojvat, C.; Homola, P.; Hörandel, J.;
Horneffer, A.; Horvat, M.; Hrabovský, M.; Huege, T.; Iarlori, M.;
Insolia, A.; Kaducak, M.; Kalashev, O.; Kampert, K. H.; Keilhauer,
B.; Kemp, E.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik,
R.; Knapp, J.; Koang, D. -H.; Kolotaev, Y.; Kopmann, A.; Krömer,
O.; Kuhlman, S.; Kuijpers, J.; Kunka, N.; Kusenko, A.; Lachaud, C.;
Lago, B. L.; Lebrun, D.; Lebrun, P.; Lee, J.; Letessier-Selvon, A.;
Leuthold, M.; Lhenry-Yvon, I.; Longo, G.; López, R.; Lopez Agüera,
A.; Lucero, A.; Maldera, S.; Malek, M.; Maltezos, S.; Mancarella,
G.; Manceñido, M. E.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.;
Maris, I. C.; Martello, D.; Martinez, N.; Martínez, J.; Martínez,
O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.;
Maurin, G.; Maurizio, D.; Mazur, P. O.; McCauley, T.; McEwen, M.;
McNeil, R. R.; Medina, G.; Medina, M. C.; Medina Tanco, G.; Meli, A.;
Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, Chr.; Meyhandan, R.;
Micheletti, M. I.; Miele, G.; Miller, W.; Mollerach, S.; Monasor, M.;
Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno,
E.; Morris, C.; Mostafá, M.; Muller, M. A.; Mussa, R.; Navarra, G.;
Nellen, L.; Newman-Holmes, C.; Newton, D.; Thi, T. Nguyen; Nichol,
R.; Nierstenhöfer, N.; Nitz, D.; Nogima, H.; Nosek, D.; Nožka,
L.; Oehlschläger, J.; Ohnuki, T.; Olinto, A.; Oliveira, L. F. A.;
Olmos-Gilbaja, V. M.; Ortiz, M.; Ostapchenko, S.; Otero, L.; Palatka,
M.; Pallotta, J.; Parente, G.; Parizot, E.; Parlati, S.; Patel, M.;
Paul, T.; Payet, K.; Pech, M.; PeĶala, J.; Pelayo, R.; Pepe, I. M.;
Perrone, L.; Petrera, S.; Petrinca, P.; Petrov, Y.; Pham Ngoc, D.;
Pham Thi, T. N.; Piegaia, R.; Pierog, T.; Pisanti, O.; Porter, T. A.;
Pouryamout, J.; Prado, L.; Privitera, P.; Prouza, M.; Quel, E. J.;
Rautenberg, J.; Reis, H. C.; Reucroft, S.; Revenu, B.; Řídký, J.;
Risi, A.; Risse, M.; Rivière, C.; Rizi, V.; Robbins, S.; Roberts, M.;
Robledo, C.; Rodriguez, G.; Rodríguez Frías, D.; Rodriguez Martino,
J.; Rodriguez Rojo, J.; Ros, G.; Rosado, J.; Roth, M.; Roucelle,
C.; Rouillé-D'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida,
F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santos,
E. M.; Sarkar, S.; Sato, R.; Scherini, V.; Schieler, H.; Schmidt,
T.; Scholten, O.; Schovánek, P.; Schüssler, F.; Sciutto, S. J.;
Scuderi, M.; Semikoz, D.; Sequeiros, G.; Shellard, R. C.; Siffert,
B. B.; Sigl, G.; Skelton, P.; Slater, W.; de Grande, N. Smetniansky;
Smiałkowski, A.; Šmída, R.; Smith, B. E.; Snow, G. R.; Sokolsky,
P.; Sommers, P.; Sorokin, J.; Spinka, H.; Strazzeri, E.; Stutz, A.;
Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Swain, J.; Szadkowski,
Z.; Tamashiro, A.; Tamburro, A.; Tascau, O.; Ticona, R.; Timmermans,
C.; Tkaczyk, W.; Todero Peixoto, C. J.; Tonachini, A.; Torresi,
D.; Travnicek, P.; Tripathi, A.; Tristram, G.; Tscherniakhovski,
D.; Tueros, M.; Tunnicliffe, V.; Ulrich, R.; Unger, M.; Urban, M.;
Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.;
van Elewyck, V.; Vazquez, R. A.; Veberič, D.; Veiga, A.; Velarde,
A.; Venters, T.; Verzi, V.; Videla, M.; Villaseñor, L.; Vo van, T.;
Vorobiov, S.; Voyvodic, L.; Wahlberg, H.; Wainberg, O.; Waldenmaier,
T.; Walker, P.; Warner, D.; Watson, A. A.; Westerhoff, S.; Wiebusch,
C.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.;
Wileman, C.; Winnick, M. G.; Xu, J.; Yamamoto, T.; Younk, P.; Zas,
E.; Zavrtanik, D.; Zavrtanik, M.; Zech, A.; Zepeda, A.; Zha, M.;
Ziolkowski, M.; Pierre Auger Collaboration
2007APh....27..244A Altcode: 2006astro.ph..7382T
Data from the Pierre Auger Observatory are analyzed to search
for anisotropies near the direction of the Galactic Centre at EeV
energies. The exposure of the surface array in this part of the
sky is already significantly larger than that of the fore-runner
experiments. Our results do not support previous findings of localized
excesses in the AGASA and SUGAR data. We set an upper bound on a
point-like flux of cosmic rays arriving from the Galactic Centre
which excludes several scenarios predicting sources of EeV neutrons
from Sagittarius A. Also the events detected simultaneously by the
surface and fluorescence detectors (the ‘hybrid’ data set), which
have better pointing accuracy but are less numerous than those of the
surface array alone, do not show any significant localized excess from
this direction.
---------------------------------------------------------
Title: The geometry of <ASTROBJ>PSR B0031-07</ASTROBJ>
Authors: Smits, J. M.; Mitra, D.; Stappers, B. W.; Kuijpers, J.;
Weltevrede, P.; Jessner, A.; Gupta, Y.
2007A&A...465..575S Altcode: 2007astro.ph..1893S
Context: <ASTROBJ>PSR B0031-07</ASTROBJ> is well known to exhibit
three different modes of drifting sub-pulses (mode A, B and C). It
has recently been shown that in a multifrequency observation,
consisting of 2700 pulses, all driftmodes were visible at low
frequencies, while at 4.85 GHz only mode-A drift or non-drifting
emission was detected. This suggests that modes A and B are emitted
in sub-beams, rotating at a fixed distance from the magnetic axis,
with the mode-B sub-beams being closer to the magnetic axis than the
mode-A sub-beams. Diffuse emission between the sub-beams can account
for the non-drifting emission. <BR />Aims: Using the results of an
analysis of simultaneous multifrequency observations of <ASTROBJ>PSR
B0031-07</ASTROBJ>, we set out to construct a geometrical model that
includes emission from both sub-beams and diffuse emission and describes
the regions of the radio emission of <ASTROBJ>PSR B0031-07</ASTROBJ>
at each emission frequency for driftmodes A and B. <BR />Methods:
Based on the vertical spacing between driftbands, we have determined
the driftmode of each sequence of drift. To restrict the model, we
calculated average polarisation and intensity characteristics for each
driftmode and at each frequency. <BR />Results: The model reproduces the
observed polarisation and intensity characteristics, suggesting that
diffuse emission plays an important role in the emission properties
of <ASTROBJ>PSR B0031-07</ASTROBJ>. The model further suggests that
the emission heights of this pulsar range from a few kilometers to a
little over 10 kilometers above the pulsar surface. We also find that
the relationships between height and frequency of emission that follow
from curvature radiation and from plasma-frequency emission could not
be used to reproduce the observed frequency dependence of the width
of the average intensity profiles.
---------------------------------------------------------
Title: An upper limit to the photon fraction in cosmic rays above
10<SUP>19</SUP> eV from the Pierre Auger Observatory
Authors: Abraham, J.; Aglietta, M.; Aguirre, C.; Allard, D.; Allekotte,
I.; Allison, P.; Alvarez, C.; Alvarez-Muñiz, J.; Ambrosio, M.;
Anchordoqui, L.; Anjos, J. C.; Aramo, C.; Arisaka, K.; Armengaud,
E.; Arneodo, F.; Arqueros, F.; Asch, T.; Asorey, H.; Atulugama,
B. S.; Aublin, J.; Ave, M.; Avila, G.; Bacelar, J.; Bäcker, T.;
Badagnani, D.; Barbosa, A. F.; Barbosa, H. M. J.; Barkhausen, M.;
Barnhill, D.; Barroso, S. L. C.; Bauleo, P.; Beatty, J.; Beau, T.;
Becker, B. R.; Becker, K. H.; Bellido, J. A.; Benzvi, S.; Berat,
C.; Bergmann, T.; Bernardini, P.; Bertou, X.; Biermann, P. L.;
Billoir, P.; Blanch-Bigas, O.; Blanco, F.; Blasi, P.; Bleve, C.;
Blümer, H.; Boghrat, P.; Boháčová, M.; Bonifazi, C.; Bonino,
R.; Boratav, M.; Brack, J.; Brunet, J. M.; Buchholz, P.; Busca,
N. G.; Caballero-Mora, K. S.; Cai, B.; Camin, D. V.; Capdevielle,
J. N.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazón, L.; Cester,
R.; Chauvin, J.; Chiavassa, A.; Chinellato, J. A.; Chou, A.; Chye,
J.; Claes, D.; Clark, P. D. J.; Clay, R. W.; Clay, S. B.; Connolly,
B.; Cordier, A.; Cotti, U.; Coutu, S.; Covault, C. E.; Cronin, J.;
Dagoret-Campagne, S.; Dang Quang, T.; Darriulat, P.; Daumiller, K.;
Dawson, B. R.; de Almeida, R. M.; de Carvalho, L. A.; de Donato, C.;
de Jong, S. J.; de Mello, W. J. M.; de Mello Neto, J. R. T.; de Mitri,
I.; de Oliveira, M. A. L.; de Souza, V.; Del Peral, L.; Deligny, O.;
Della Selva, A.; Delle Fratte, C.; Dembinski, H.; di Giulio, C.; Diaz,
J. C.; Dobrigkeit, C.; D'Olivo, J. C.; Dornic, D.; Dorofeev, A.; Dova,
M. T.; D'Urso, D.; Duvernois, M. A.; Engel, R.; Epele, L.; Erdmann,
M.; Escobar, C. O.; Etchegoyen, A.; Ewers, A.; Facal San Luis, P.;
Falcke, H.; Fauth, A. C.; Fazio, D.; Fazzini, N.; Fernández, A.;
Ferrer, F.; Ferry, S.; Fick, B.; Filevich, A.; Filipčič, A.; Fleck,
I.; Fokitis, E.; Fonte, R.; Fuhrmann, D.; Fulgione, W.; García, B.;
Garcia-Pinto, D.; Garrard, L.; Garrido, X.; Geenen, H.; Gelmini, G.;
Gemmeke, H.; Geranios, A.; Ghia, P. L.; Giller, M.; Gitto, J.; Glass,
H.; Gobbi, F.; Gold, M. S.; Gomez Albarracin, F.; Gómez Berisso,
M.; Gómez Herrero, R.; Gonçalves Do Amaral, M.; Gongora, J. P.;
Gonzalez, D.; Gonzalez, J. G.; González, M.; Góra, D.; Gorgi,
A.; Gouffon, P.; Grassi, V.; Grillo, A.; Grunfeld, C.; Grupen, C.;
Guarino, F.; Guedes, G. P.; Gutiérrez, J.; Hague, J. D.; Hamilton,
J. C.; Harakeh, M. N.; Harari, D.; Harmsma, S.; Hartmann, S.; Harton,
J. L.; Healy, M. D.; Hebbeker, T.; Heck, D.; Hojvat, C.; Homola, P.;
Hörandel, J.; Horneffer, A.; Horvat, M.; Hrabovský, M.; Iarlori, M.;
Insolia, A.; Kaducak, M.; Kalashev, O.; Kampert, K. H.; Keilhauer,
B.; Kemp, E.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapik,
R.; Knapp, J.; Koang, D. -H.; Kolotaev, Y.; Kopmann, A.; Krömer,
O.; Kuhlman, S.; Kuijpers, J.; Kunka, N.; Kusenko, A.; Lachaud, C.;
Lago, B. L.; Lebrun, D.; Lebrun, P.; Lee, J.; Letessier-Selvon, A.;
Leuthold, M.; Lhenry-Yvon, I.; Longo, G.; López, R.; Lopez Agüera,
A.; Lucero, A.; Maldera, S.; Malek, M.; Maltezos, S.; Mancarella,
G.; Manceñido, M. E.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.;
Maris, I. C.; Martello, D.; Martinez, N.; Martínez, J.; Martínez,
O.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.;
Maurin, G.; Maurizio, D.; Mazur, P. O.; McCauley, T.; McEwen, M.;
McNeil, R. R.; Medina, G.; Medina, M. C.; Medina Tanco, G.; Meli, A.;
Melo, D.; Menichetti, E.; Menshikov, A.; Meurer, Chr.; Meyhandan, R.;
Micheletti, M. I.; Miele, G.; Miller, W.; Mollerach, S.; Monasor, M.;
Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno,
E.; Morris, C.; Mostafá, M.; Muller, M. A.; Mussa, R.; Navarra, G.;
Nellen, L.; Newman-Holmes, C.; Newton, D.; Nguyen Thi, T.; Nichol,
R.; Nierstenhöfer, N.; Nitz, D.; Nogima, H.; Nosek, D.; Nožka,
L.; Oehlschläger, J.; Ohnuki, T.; Olinto, A.; Oliveira, L. F. A.;
Olmos-Gilbaja, V. M.; Ortiz, M.; Ostapchenko, S.; Otero, L.; Palatka,
M.; Pallotta, J.; Parente, G.; Parizot, E.; Parlati, S.; Patel, M.;
Paul, T.; Payet, K.; Pech, M.; PeĶala, J.; Pelayo, R.; Pepe, I. M.;
Perrone, L.; Petrera, S.; Petrinca, P.; Petrov, Y.; Pham Ngoc, D.;
Pham Thi, T. N.; Piegaia, R.; Pierog, T.; Pisanti, O.; Porter, T. A.;
Pouryamout, J.; Prado, L.; Privitera, P.; Prouza, M.; Quel, E. J.;
Rautenberg, J.; Reis, H. C.; Reucroft, S.; Revenu, B.; Řídký, J.;
Risi, A.; Risse, M.; Rivière, C.; Rizi, V.; Robbins, S.; Roberts, M.;
Robledo, C.; Rodriguez, G.; Rodríguez Frías, D.; Rodriguez Martino,
J.; Rodriguez Rojo, J.; Ros, G.; Rosado, J.; Roth, M.; Roucelle,
C.; Rouillé-D'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Salamida,
F.; Salazar, H.; Salina, G.; Sánchez, F.; Santander, M.; Santos,
E. M.; Sarkar, S.; Sato, R.; Scherini, V.; Schmidt, T.; Scholten, O.;
Schovánek, P.; Schüssler, F.; Sciutto, S. J.; Scuderi, M.; Semikoz,
D.; Sequeiros, G.; Shellard, R. C.; Siffert, B. B.; Sigl, G.; Skelton,
P.; Slater, W.; Smetniansky de Grande, N.; Smiałkowski, A.; Šmída,
R.; Smith, B. E.; Snow, G. R.; Sokolsky, P.; Sommers, P.; Sorokin,
J.; Spinka, H.; Strazzeri, E.; Stutz, A.; Suarez, F.; Suomijärvi,
T.; Supanitsky, A. D.; Swain, J.; Szadkowski, Z.; Tamashiro, A.;
Tamburro, A.; Tascau, O.; Ticona, R.; Timmermans, C.; Tkaczyk,
W.; Todero Peixoto, C. J.; Tonachini, A.; Torresi, D.; Travnicek,
P.; Tripathi, A.; Tristram, G.; Tscherniakhovski, D.; Tueros, M.;
Tunnicliffe, V.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia,
J. F.; Valiño, I.; Valore, L.; van den Berg, A. M.; van Elewyck,
V.; Vazquez, R. A.; Veberič, D.; Veiga, A.; Velarde, A.; Venters,
T.; Verzi, V.; Videla, M.; Villaseñor, L.; Vo van, T.; Vorobiov, S.;
Voyvodic, L.; Wahlberg, H.; Wainberg, O.; Waldenmaier, T.; Walker, P.;
Warner, D.; Watson, A. A.; Westerhoff, S.; Wiebusch, C.; Wieczorek,
G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Wileman, C.;
Winnick, M. G.; Xu, J.; Yamamoto, T.; Younk, P.; Zas, E.; Zavrtanik,
D.; Zavrtanik, M.; Zech, A.; Zepeda, A.; Zha, M.; Ziolkowski, M.
2007APh....27..155A Altcode: 2006astro.ph..6619P
An upper limit of 16% (at 95% c.l.) is derived for the photon fraction
in cosmic rays with energies greater than 10<SUP>19</SUP> eV, based on
observations of the depth of shower maximum performed with the hybrid
detector of the Pierre Auger Observatory. This is the first such limit
on photons obtained by observing the fluorescence light profile of air
showers. This upper limit confirms and improves on previous results from
the Haverah Park and AGASA surface arrays. Additional data recorded with
the Auger surface detectors for a subset of the event sample support the
conclusion that a photon origin of the observed events is not favored.
---------------------------------------------------------
Title: Radio detection of cosmic ray air showers with LOPES
Authors: Huege, T.; Lopes Collaboration; Apel, W. D.; Asch, T.;
Badea, A. F.; Bähren, L.; Bekk, K.; Bercuci, A.; Bertaina, M.;
Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Buitink,
S.; Brüggemann, M.; Buchholz, P.; Butcher, H.; Chiavassa, A.;
Cossavella, F.; Daumiller, K.; di Pierro, F.; Doll, P.; Engel, R.;
Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.;
Hakenjos, A.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.;
Isar, P. G.; Kampert, K. H.; Kolotaev, Y.; Krömer, O.; Kuijpers,
J.; Lafebre, S.; Mathes, H. J.; Mayer, H. J.; Meurer, C.; Milke, J.;
Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.; Obenland,
R.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Petrovic,
J.; Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.; Trinchero, G. C.;
Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl, A.; Wochele, J.;
Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2007NuPhS.165..341H Altcode: 2006astro.ph..9427H; 2007NuPhS.165..341T
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.
---------------------------------------------------------
Title: The geometry of PSR B0031-07
Authors: Smits, R.; Mitra, D.; Stappers, B.; Kuijpers, J.; Weltevrede,
P.; Jessner, A.; Gupta, Y.
2007whsn.conf..161S Altcode: 2006astro.ph.12684S
Here we present the results from an analysis of a multifrequency
simultaneous observation of PSR B0031$-$07. We have constructed a
geometrical model, based on an empirical relationship between height
and frequency of emission, that reproduces many of the observed
characteristics. The model suggests very low emission altitudes for
this pulsar of only a few kilometers above the star's surface.
---------------------------------------------------------
Title: Radio emission of highly inclined cosmic ray air showers
measured with LOPES
Authors: Petrovic, J.; Apel, W. D.; Asch, T.; Badea, F.; Bähren, L.;
Bekk, K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink,
S.; Butcher, H.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.;
Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.;
Horneffer, A.; Huege, T.; Kampert, K. -H.; Kolotaev, Y.; Krömer, O.;
Kuijpers, J.; Lafebre, S.; Mathes, H. J.; Mayer, H. J.; Meurer, C.;
Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.;
Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.; Trinchero, G. C.;
Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl, A.; Wochele, J.;
Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2007A&A...462..389P Altcode: 2006astro.ph..4273P
Aims:The capability of radio antenna arrays to measure cosmic ray
air showers with very large zenith angles is explored. This is
important, since a possible neutrino detection has to fulfill two
requirements. First: antennas should be able to detect very inclined
cosmic ray air showers, and second: it should be possible to estimate
the distance to the shower maximum, since neutrinos are most likely
to travel far through the Earth's atmosphere without interaction
and induce air showers close to the ground. <BR />Methods: LOPES
(LOFAR PrototypE Station; LOFAR - LOw Frequency ARray), an array
of dipole antennas, is used for the detection of inclined cosmic
ray air showers. LOPES is co-located and triggered by the KASCADE
(KArlsruhe Shower Core and Array DEtector) experiment, which also
provides information on air shower properties such as electron and
muon numbers on the ground, as well as the arrival direction. Radio
emission of nearly vertical cosmic ray air showers has been detected
by LOPES. <BR />Results: 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. <BR />Conclusions:
.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.
---------------------------------------------------------
Title: Frequency Dependence of the Drifting Sub-Pulses of PSR
B 0031-07
Authors: Smits, J. M.; Mitra, D.; Kuijpers, J.
2006ChJAS...6b..24S Altcode:
The well known drifter PSR B0031-07 is known to exhibit drifting
sub-pulses where the spacing between the drift bands (P_3) shows
three distinct modes A, B and C corresponding to 13, 7 and 4 times
the pulsar period, respectively. We have investigated periodicities
and polarisation properties of PSR B0031-07 for a sequence of 2700
single pulses taken simultaneously at 328 MHz and 4.85 GHz. We found
that mode A occurs simultaneously at these frequencies, while modes B
and C only occur at 328 MHz. However, when the pulsar is emitting in
mode B at the lower frequency there is still emission at the higher
frequency, hinting towards the presence of mode B emission at a weaker
level. Further, we have established that modes A and B are associated
with two orthogonal modes of polarisation, respectively. Based on
these observations, we suggest a geometrical model where modes A and
B at a given frequency are emitted in two concentric rings around the
magnetic axis with mode B being nested inside mode A.
---------------------------------------------------------
Title: Progress in air shower radio measurements: Detection of
distant events
Authors: LOPES Collaboration; Apel, W. D.; Asch, T.; Badea, A. F.;
Bähren, L.; Bekk, K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.;
Blümer, J.; Bozdog, H.; Brancus, I. M.; Buitink, S.; Brüggemann, M.;
Buchholz, P.; Butcher, H.; Chiavassa, A.; Cossavella, F.; Daumiller,
K.; di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel,
J. R.; Horneffer, A.; Huege, T.; Kampert, K. H.; Kolotaev, Y.; Krömer,
O.; Kuijpers, J.; Lafebre, S.; Mathes, H. J.; Mayer, H. J.; Meurer,
C.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.;
Nigl, A.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Over, S.;
Petcu, M.; Petrovic, J.; Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.;
Roth, M.; Schieler, H.; Sima, O.; Singh, K.; Stümpert, M.; Toma, G.;
Trinchero, G. C.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl,
A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2006APh....26..332L Altcode: 2006astro.ph..7495A; 2006APh....26..332A
Data taken during half a year of operation of 10 LOPES antennas
(LOPES-10), triggered by EAS observed with KASCADE-Grande have been
analysed. We report about the analysis of correlations of radio signals
measured by LOPES-10 with extensive air shower events reconstructed
by KASCADE-Grande, including shower cores at large distances. The
efficiency of detecting radio signals induced by air showers up to
distances of 700 m from the shower axis has been investigated. The
results are discussed with special emphasis on the effects of the
reconstruction accuracy for shower core and arrival direction on the
coherence of the measured radio signal. In addition, the correlations
of the radio pulse amplitude with the primary cosmic ray energy and
with the lateral distance from the shower core are studied.
---------------------------------------------------------
Title: LOFAR - Opening up a new window on the Universe
Authors: Rottgering, H. J. A.; Braun, R.; Barthel, P. D.; van Haarlem,
M. P.; Miley, G. K.; Morganti, R.; Snellen, I.; Falcke, H.; de Bruyn,
A. G.; Stappers, R. B.; Boland, W. H. W. M.; Butcher, H. R.; de Geus,
E. J.; Koopmans, L.; Fender, R.; Kuijpers, J.; Schilizzi, R. T.;
Vogt, C.; Wijers, R. A. M. J.; Wise, M.; Brouw, W. N.; Hamaker,
J. P.; Noordam, J. E.; Oosterloo, T.; Bahren, L.; Brentjens, M. A.;
Wijnholds, S. J.; Bregman, J. D.; van Cappellen, W. A.; Gunst, A. W.;
Kant, G. W.; Reitsma, J.; van der Schaaf, K.; de Vos, C. M.
2006astro.ph.10596R Altcode:
LOFAR, the Low Frequency Array, is a next-generation radio telescope
that is being built in Northern Europe and expected to be fully
operational at the end of this decade. It will operate at frequencies
from 15 to 240 MHz (corresponding to wavelengths of 20 to 1.2 m). Its
superb sensitivity, high angular resolution, large field of view
and flexible spectroscopic capabilities will represent a dramatic
improvement over previous facilities at these wavelengths. As such,
LOFAR will carry out a broad range of fundamental astrophysical
studies. The design of LOFAR has been driven by four fundamental
astrophysical applications: (i) The Epoch of Reionisation, (ii)
Extragalactic Surveys and their exploitation to study the formation and
evolution of clusters, galaxies and black holes, (iii) Transient Sources
and their association with high energy objects such as gamma ray bursts,
and (iv) Cosmic Ray showers and their exploitation to study the origin
of ultra-high energy cosmic rays. In this conference the foreseen LOFAR
work on the epoch of reionisation has been covered by de Bruyn and on
cosmic ray showers by Falcke. During this contribution we will first
present the LOFAR project with an emphasis on the challenges faced when
carrying out sensitive imaging at low radio frequencies. Subsequently,
we will discuss LOFAR's capabilities to survey the low-frequency
radio sky. Main aims for the planned surveys are studies of z>6
radio galaxies, diffuse emission associated with distant clusters and
starbursting galaxies at z>2.
---------------------------------------------------------
Title: The solar flare of the 14th of July 2000 (L3+C detector
results)
Authors: Achard, P.; Adrian, O.; Aguilar-Benitez, M.; van den Akker,
M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M. G.;
Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev, A.; Azemoon, T.;
Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Bähr, J.;
Baldew, S. V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillère,
R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.;
Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.;
Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.;
Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.; Bobbink,
G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov,
D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu, F.; Burger,
J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Cara Romeo, G.; Carlino,
G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.;
Cerrada, M.; Chamizo, M.; Chiarusi, T.; Chang, Y. H.; Chemarin, M.;
Chen, A.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chiefari,
G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.;
Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; de
Asmundis, R.; Déglon, P.; Debreczeni, J.; Degré, A.; Dehmelt, K.;
Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani,
F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Ding, L. K.; Dionisi,
C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau, D.; Duda, M.;
Duran, I.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.;
Engler, A.; Eppling, F. J.; Extermann, P.; Faber, G.; Falagan, M. A.;
Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson,
T.; Fesefeldt, H; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher,
W.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Yu.;
Ganguli, S. N.; Garcia-Abia, P.; Gataullin, M.; Gentile, S.; Giagu,
S.; Gong, Z. F.; Grabosch, H. J.; Grenier, G.; Grimm, O.; Groenstege,
H.; Gruenewald, M. W.; Guida, M.; Guo, Y. N.; Gupta, S. K.; Gupta,
V. K.; Gurtu, A.; Gutay, L. J.; Haas, D.; Haller, Ch.; Hatzifotiadou,
D.; Hayashi, Y.; He, Z. X.; Hebbeker, T.; Hervé, A.; Hirschfelder,
J.; Hofer, H.; Hofer, H.; Hohlmann, M.; Holzner, A.; Hou, S. R.; Huo,
A. X.; Ito, N.; Jin, B. N.; Jindal, P.; Jing, C. L.; Jones, L. W.;
de Jong, P.; Josa-Mutuberría, I.; Kantserov, V.; Kaur, M.; Kawakami,
S.; Kienzle-Focacci, M. N.; Kim, J. K.; Kirkby, J.; Kittel, W.;
Klimentov, A.; König, A. C.; Kok, E.; Korn, A.; Kopal, M.; Koutsenko,
V.; Kräber, M.; Kuang, H. H.; Kraemer, R. W.; Krüger, A.; Kuijpers,
J.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau,
M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre,
P.; Le Goff, J. M.; Lei, Y.; Leich, H.; Leiste, R.; Levtchenko, M.;
Levtchenko, P.; Li, C.; Li, L.; Li, Z. C.; Likhoded, S.; Lin, C. H.;
Lin, W. T.; Linde, F. L.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo,
E.; Lu, Y. S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W. G.;
Ma, X. H.; Ma, Y. Q.; Malgeri, L.; Malinin, A.; Maña, C.; Mans, J.;
Martin, J. P.; Marzano, F.; Mazumdar, K.; McNeil, R. R.; Meng, X. W.;
Merola, L.; Meschini, M.; Metzger, W. J.; Mihul, A.; van Mil, A.;
Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G. B.; Monteleoni,
B.; Muanza, G. S.; Muijs, A. J. M.; Musy, M.; Nagy, S.; Nahnhauer,
R.; Naumov, V. A.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.;
Newman, H.; Nisati, A.; Novak, T.; Nowak, H.; Ofierzynski, R.;
Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.;
Parriaud, J. -F.; Passaleva, G.; Patricelli, S.; Paul, T.; Pauluzzi,
M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix,
D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pieri, M.; Pioppi, M.;
Piroué, P. A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.;
Pothier, J.; Prokofiev, D.; Qing, C. R.; Rahal-Callot, G.; Rahaman,
M. A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P. G.; Ranieri,
R.; Raspereza, A.; Ravindran, K. C.; Razis, P.; Rembeczki, S.; Ren,
D.; Rescigno, M.; Reucroft, S.; Rewiersma, P.; Riemann, S.; Rojkov,
A.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees,
S.; Roth, S.; Rubio, J. A.; Ruggiero, G.; Rykaczewski, H.; Sakharov,
A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer,
C.; Schegelsky, V.; Schoeneich, B.; Schotanus, D. J.; Sciacca, C.;
Servoli, L.; Shen, C. Q.; Shevchenko, S.; Shivarov, N.; Shoutko,
V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.;
Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar,
K.; Sultanov, G.; Sun, L. Z.; Sushkov, S.; Suter, H.; Swain, J. D.;
Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.; Taylor, L.;
Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, Samuel C. C.; Ting,
S. M.; Tonwar, S. C.; Tóth, J.; Trowitzsch, G.; Tully, C.; Tung,
K. L.; Ulbricht, J.; Unger, M.; Valente, E.; Verkooijen, H.; Van de
Walle, R. T.; Vasquez, R.; Vesztergombi, G.; Vetlitsky, I.; Viertel,
G.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt,
H.; Vorobiev, I.; Vorobyov, A. A.; Wadhwa, M.; Wang, R. G.; Wang,
Q.; Wang, X. L.; Wang, X. W.; Wang, Z. M.; Weber, M.; van Wijk, R.;
Wijnen, T. A. M.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Y. P.; Xu,
Z. Z.; Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.; Yang, X. F.;
Yao, Z. G.; Yeh, S. C.; Yu, Z. Q.; Zalite, An.; Zalite, Yu.; Zhang,
C.; Zhang, F.; Zhang, J.; Zhang, S.; Zhang, Z. P.; Zhao, J.; Zhou,
S. J.; Zhu, G. Y.; Zhu, R. Y; Zhu, Q. Q.; Zhuang, H. L.; Zichichi,
A.; Zimmermann, B.; Zöller, M.; Zwart, A. N. M.; L3 Collaboration
2006A&A...456..351A Altcode: 2006A&A...456..351L
Aims.Several experiments have reported observations on possible
correlations between the flux of high energy muons and intense solar
flares. If confirmed, these observations would have significant
implications for acceleration processes in the heliosphere able
to accelerate protons and other ions to energies of at least
tens of GeV. Methods: The solar flare of the 14 of July 2000
offered a unique opportunity for the L3+C experiment to search for
a correlated enhancement in the flux of muons using the L3 precision
muon spectrometer. Its capabilities for observing a directional excess
in the flux of muons above 15 GeV (corresponding to primary proton
energies above 40 GeV) are presented along with observations made on
the 14th of July 2000. Results: We report an excess which appeared at
a time coincident with the peak increase of solar protons observed
at lower energies. The probability that the excess is a background
fluctuation is estimated to be 1%. No similar excess of the muon flux
was observed up to 1.5 h after the solar flare time.
---------------------------------------------------------
Title: A search for flaring very-high-energy cosmic γ-ray sources
with the L3+C muon spectrometer
Authors: L3 Collaboration; Adriani, O.; Aguilar-Benitez, M.; van
den Akker, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.;
Alviggi, M. G.; Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev,
A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay,
L.; Bähr, J.; Baldew, S. V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.;
Barillère, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.;
Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco,
R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.;
Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.; Bobbink,
G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov,
D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu, F.; Burger,
J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Cara Romeo, G.; Carlino,
G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.;
Cerrada, M.; Chamizo, M.; Chang, Y. H.; Chemarin, M.; Chen, A.; Chen,
G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chiarusi, T.; Chiefari, G.;
Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino,
N.; Costantini, S.; de La Cruz, B.; Cucciarelli, S.; de Asmundis,
R.; Déglon, P.; Debreczeni, J.; Degré, A.; Dehmelt, K.; Deiters,
K.; Della Volpe, D.; Delmeire, E.; Denes, P.; Denotaristefani, F.;
de Salvo, A.; Diemoz, M.; Dierckxsens, M.; Ding, L. K.; Dionisi,
C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau, D.; Duda, M.;
Duran, I.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.;
Engler, A.; Eppling, F. J.; Extermann, P.; Faber, G.; Falagan, M. A.;
Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson,
T.; Fesefeldt, H.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher,
P. H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta,
C.; Galaktionov, Yu.; Ganguli, S. N.; Garcia-Abia, P.; Gataullin, M.;
Gentile, S.; Giagu, S.; Gong, Z. F.; Grabosch, H. J.; Grenier, G.;
Grimm, O.; Groenstege, H.; Gruenewald, M. W.; Guida, M.; Guo, Y. N.;
Gupta, S. K.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Haas, D.; Haller,
Ch.; Hatzifotiadou, D.; Hayashi, Y.; He, Z. X.; Hebbeker, T.; Hervé,
A.; Hirschfelder, J.; Hofer, H.; Hofer, H.; Hohlmann, M.; Holzner, G.;
Hou, S. R.; Huo, A. X.; Ito, N.; Jin, B. N.; Jindal, P.; Jing, C. L.;
Jones, L. W.; de Jong, P.; Josa-Mutuberría, I.; Kantserov, V.; Kaur,
M.; Kawakami, S.; Kienzle-Focacci, M. N.; Kim, J. K.; Kirkby, J.;
Kittel, W.; Klimentov, A.; König, A. C.; Kok, E.; Korn, A.; Kopal,
M.; Koutsenko, V.; Kräber, M.; Kuang, H. H.; Kraemer, R. W.; Krüger,
A.; Kuijpers, J.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.;
Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq,
P.; Le Coultre, P.; Le Goff, J. M.; Lei, Y.; Leich, H.; Leiste, R.;
Levtchenko, M.; Levtchenko, P.; Li, C.; Li, L.; Li, Z. C.; Likhoded,
S.; Lin, C. H.; Lin, W. T.; Linde, F. L.; Lista, L.; Liu, Z. A.;
Lohmann, W.; Longo, E.; Lu, Y. S.; Luci, C.; Luminari, L.; Lustermann,
W.; Ma, W. G.; Ma, X. H.; Ma, Y. Q.; Malgeri, L.; Malinin, A.; Maña,
C.; Mans, J.; Martin, J. P.; Marzano, F.; Mazumdar, K.; McNeil, R. R.;
Mele, S.; Meng, X. W.; Merola, L.; Meschini, M.; Metzger, W. J.; Mihul,
A.; van Mil, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G. B.;
Monteleoni, B.; Muanza, G. S.; Muijs, A. J. M.; Musicar, B.; Musy,
M.; Nagy, S.; Nahnhauer, R.; Naumov, V. A.; Natale, S.; Napolitano,
M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Nowak, H.;
Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci,
P.; Paramatti, R.; Parriaud, J. -F.; Passaleva, G.; Patricelli, S.;
Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti,
S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.;
Pieri, M.; Pioppi, M.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.;
Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Quartieri, J.;
Qing, C. R.; Rahal-Callot, G.; Rahaman, M. A.; Raics, P.; Raja, N.;
Ramelli, R.; Rancoita, P. G.; Ranieri, R.; Raspereza, A.; Ravindran,
K. C.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Rewiersma, P.;
Riemann, S.; Riles, K.; Roe, B. P.; Rojkov, A.; Romero, L.; Rosca, A.;
Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, S.; Rubio, J. A.;
Ruggiero, G.; Rykaczewski, H.; Saidi, R.; Sakharov, A.; Saremi, S.;
Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer, C.; Schegelsky, V.;
Schmitt, V.; Schoeneich, B.; Schopper, H.; Schotanus, D. J.; Sciacca,
C.; Servoli, L.; Shen, C. Q.; Shevchenko, S.; Shivarov, N.; Shoutko,
V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.;
Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar,
K.; Sulanke, H.; Sultanov, G.; Sun, L. Z.; Sushkov, S.; Suter, H.;
Swain, J. D.; Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.;
Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, Samuel
C. C.; Ting, S. M.; Tonwar, S. C.; Tóth, J.; Trowitzsch, G.; Tully,
C.; Tung, K. L.; Ulbricht, J.; Unger, M.; Valente, E.; Verkooijen,
H.; van de Walle, R. T.; Vasquez, R.; Veszpremi, V.; Vesztergombi,
G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent,
M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobiev, I.;
Vorobyov, A. A.; Wadhwa, M.; Wang, R. G.; Wang, Q.; Wang, X. L.;
Wang, X. W.; Wang, Z. M.; Weber, M.; van Wijk, R.; Wijnen, T. A. M.;
Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Y. P.; Xu, J. S.; Xu, Z. Z.;
Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.; Yang, X. F.; Yao,
Z. G.; Yeh, S. C.; Yu, Z. Q.; Zalite, An.; Zalite, Yu.; Zhang, C.;
Zhang, F.; Zhang, J.; Zhang, S.; Zhang, Z. P.; Zhao, J.; Zhou, S. J.;
Zhu, G. Y.; Zhu, R. Y.; Zhu, Q. Q.; Zhuang, H. L.; Zichichi, A.;
Zimmermann, B.; Zöller, M.; Zwart, A. N. M.
2006APh....25..298A Altcode: 2006APh....25..298L; 2006APh....25..298T
The L3+C muon detector at the CERN electron positron collider, LEP,
is used for the detection of very-high-energy cosmic γ-ray sources
through the observation of muons of energies above 20, 30, 50 and
100 GeV. Daily or monthly excesses in the rate of single-muon events
pointing to some particular direction in the sky are searched for. The
periods from mid July to November 1999, and April to November 2000 are
considered. Special attention is also given to a selection of known
γ-ray sources. No statistically significant excess is observed for
any direction or any particular source.
---------------------------------------------------------
Title: Scattering of magnetosonic waves in a relativistic and
anisotropic magnetized plasma
Authors: Moortgat, Joachim; Kuijpers, Jan
2006MNRAS.368.1110M Altcode: 2006astro.ph..2314M
Gravitational waves (GW) propagating through a magnetized plasma
excite low-frequency magnetohydrodynamic (MHD) waves. In this paper, we
investigate whether these waves can produce observable radio emission
at higher frequencies by scattering on an anisotropic intrinsically
relativistic distribution of electrons and positrons in the force-free
wind surrounding a double neutron star binary merger. The relativistic
particle distribution is assumed to be strictly along the magnetic field
lines, while the magneto-plasma streams out at a relativistic speed from
the neutron stars. In the case of Compton scattering of an incident MHD
wave transverse to the magnetic field, we find that the probability
of scattering to both a transverse x-mode and a quasi-longitudinal
Langmuir-ordinary mode is suppressed when the frequency of the incident
wave is below the local relativistic gyro-frequency, that is, when
the magnetic field is very strong.
---------------------------------------------------------
Title: Radio emission of highly inclined cosmic ray air showers
measured with LOPES - possibility for neutrino detection
Authors: Petrovic, J.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Buitink, S.; Brüggemann, M.; Buchholz, P.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.;
Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel,
J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein,
U.; Kolotaev, Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre,
S.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica,
B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.;
Oehlschläger, J.; Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu,
M.; Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Mstümpert; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2006JPhCS..39..471P Altcode: 2006astro.ph.11225J
LOPES - LOFAR PrototypE Station (LOFAR - LOw Frequency ARray) is an
array of dipole antennas used for the detection of radio emission
from cosmic ray air showers. It is co-located and triggered by
the KASCADE (KArlsruhe Shower Core and Array Detector) experiment,
which also provides information about air shower properties like
electron number N<SUB>e</SUB>, muon number N<SUB>µ</SUB>, azimuth
and zenith angle. 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 those have very high field
strengths. The most inclined event that has been detected with LOPES-10
has a zenith angle of almost 80°. This is important, because cosmic
ray air showers with large inclinations, triggered close to the ground,
would be a signature of neutrino events. Due to the small baseline of
the LOPES-10 detector, it is not yet possible to determine accuratelly
the radius of curvature of the showers front, which is related to the
distance to the maximum of shower development. However, this should be
possible in the future with a large baseline radio telescope like LOFAR.
---------------------------------------------------------
Title: Results from the KASCADE, KASCADE-Grande, and LOPES experiments
Authors: Hörandel, J. R.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk,
K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog,
H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.;
Butcher, H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos,
C. M.; Di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Falcke, H.;
Gemmeke, H.; Ghia, P. L.; Gils, H. -J.; Glasstetter, R.; Grupen, C.;
Heck, D.; Haungs, A.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant,
G. W.; Klages, H. O.; Klein, U.; Kolotaev, Y.; Koopman, Y.; Krömer,
O.; Kuijpers, J.; Lafebre, S.; Maier, G.; Mathes, H. J.; Mayer, H. J.;
Milke, J.; Mitrica, B.; Morello, C.; Müller, M.; Navarra, G.; Nehls,
S.; Nigl, A.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Over,
S.; Pepping, H. J.; Petcu, M.; Petrovic, J.; Pierog, T.; Plewnia, S.;
Rebel, H.; Risse, A.; Roth, M.; Schieler, H.; Schoonderbeek, G.; Sima,
O.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; van Buren,
J.; van Capellen, W.; Wwalkowiak; Aweindl; Wijnholds, S.; Jwochele;
Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2006JPhCS..39..463H Altcode: 2005astro.ph.11649H
The origin of high-energy cosmic rays in the energy range from
10<SUP>14</SUP> to 10<SUP>18</SUP> eV is explored with the KASCADE
and KASCADE-Grande experiments. Radio signals from air showers are
measured with the LOPES experiment. An overview on results is given.
---------------------------------------------------------
Title: High-Energy Cosmic Rays Investigated by Air-Shower Measurements
with KASCADE, Kascade-Grande and Lopes
Authors: Haungs, A.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.;
di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Falcke, H.; Gemmeke,
H.; Ghia, P. L.; Gils, H. -J.; Glasstetter, R.; Grupen, C.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant,
G. W.; Klages, H. O.; Klein, U.; Kolotaev, Y.; Koopman, Y.; Krömer,
O.; Kuijpers, J.; Lafebre, S.; Maier, G.; Mathes, H. J.; Mayer, H. J.;
Milke, J.; Mitrica, B.; Morello, C.; Müller, M.; Navarra, G.; Nehls,
S.; Nigl, A.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Over,
S.; Pepping, H. J.; Petcu, M.; Petrovic, J.; Pierog, T.; Plewnia,
S.; Rebel, H.; Risse, A.; Roth, M.; Schieler, H.; Schoonderbeek, G.;
Sima, O.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.; van
Buren, J.; van Capellen, W.; Walkowiak, W.; Weindl, A.; Wijnholds,
S.; Wochele, J.; Zabierowski, J.; Zensus, J. A.; Zimmermann, D.
2006apsp.conf..229H Altcode:
Recent results from the multi-detector set-up KASCADE on measurements
of cosmic rays in the energy range of the so called knee (at ≈ 3
PeV) are presented. The multidimensional analysis of the air shower
data indicates a distinct knee in the energy spectra of light primary
cosmic rays and an increasing dominance of heavy ones towards higher
energies. This provides, together with the results of large scale
anisotropy studies, implications for discriminating astrophysical models
of the origin of the knee. To improve the reconstruction quality and
statistics at higher energies, where the knee of the heavy primaries
is expected at around 100 PeV, KASCADE has recently been extended by
a factor 10 in area to the new experiment KASCADE-Grande. LOPES is
set up at the location of the KASCADE-Grande experiment and measures
radio pulses from extensive air showers. LOPES is designed as digital
radio interferometer using high bandwidths and fast data processing and
profits from the reconstructed air shower observables of KASCADE-Grande.
---------------------------------------------------------
Title: Frequency dependence of orthogonal polarisation modes in
pulsars
Authors: Smits, J. M.; Stappers, B. W.; Edwards, R. T.; Kuijpers,
J.; Ramachandran, R.
2006A&A...448.1139S Altcode: 2005astro.ph.12107S
We have carried out a study of the orthogonal polarisation mode
behaviour as afunction of frequency of 18pulsars, using average pulsar
data from the European Pulsar Network(EPN). Assuming that the radiation
consists of two100% polarised completely orthogonal superposed modes we
separated these modes, resulting in average pulse profiles of each mode
at multiple frequencies for each pulsar. Furthermore, we studied the
frequency dependence of the relative intensity of these modes. We found
in many pulsars that the average pulse profiles of the twomodes differ
in their dependence on frequency. In particular, we found that pulse
components that are dominated by onemode tend to increase in intensity
with increasing frequency with respect to the rest of the profile.
---------------------------------------------------------
Title: Radio pulsar drifting sub-pulses and diocotron instability
Authors: Fung, P. K.; Khechinashvili, D.; Kuijpers, J.
2006A&A...445..779F Altcode:
The potential role of a diocotron instability in causing drifting
sub-pulses in radio pulsar emission is investigated for aligned magnetic
rotators. It is assumed that the out-flowing plasma above a pulsar
polar cap consists of an initially axially symmetric, hollow beam of
relativistic electron positron pair plasma which carries an electric
charge as well as a current. The occurrence of instability depends on
shear in the angular velocity distribution of the beam as a function
of axial distance. Instability occurs under typical pulsar conditions
at mode numbers ≤ 40. It destroys the symmetry of the equilibrium
configuration and leads to a carousel of density columns which rotates
at fixed angular pattern speed. The process is applied to two pulsars
with observed carousels of drifting sub-pulses, and the diocotron
instability at corresponding mode number and axial distance is used
as a diagnostic for the charge and current density of the polar flow.
---------------------------------------------------------
Title: Advanced Detection Methods of Radio Signals from Cosmic Rays
for KASCADE Grande and Auger
Authors: Gemmeke, H.; Apel, W. D.; Badea, F. A.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; De Bruyn, A. G.; De Vos, C. M.; Di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Ghia, P. L.; Glasstetter,
R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev,
Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Maier, G.;
Mathes, H. J.; Mayers, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Van Buren, J.; Van Capellen, W.; Walkowiak, W.;
Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski, J.; Zensus,
J. A.; Zimmermann, D.
2006aren.conf..242G Altcode:
The LOPES experiment (LOfar Prototype Station) has been built at the
KASCADE-Grande experiment in order to test the LOFAR (LOw Frequency
ARray) technology and demonstrate its capability for radio measurements
in Extensive Air Showers (EAS). After the first positive results in
the framework of the KASCADE-Grande experiment we developed the next
generation of antennas, electronics, and trigger. The main new features
are easy calibration of antennas with precise detection of polarization,
and good capability of self-triggering. The results from this new design
are under test in Karlsruhe. Furthermore the background situation was
measured and analyzed.
---------------------------------------------------------
Title: Absolute Calibration of the LOPES Antenna System
Authors: Nehls, S.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; De Bruyn, A. G.; De Vos, C. M.;
Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Hakenjos, A.; Haungs, A.; Heck,
D.; Hörandel, J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant,
G. W.; Klein, U.; Kolotaev, Y.; Koopman, Y.; Krömer, O.; Kuijpers,
J.; Lafebre, S.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke,
J.; Mitrica, B.; Morello, C.; Navarra, G.; Nigl, A.; Obenland, R.;
Oehlschläger, J.; Ostapchenko, S.; OVer, S.; Pepping, H. J.; Petcu,
M.; Petrovic, J.; Pierogs, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth,
M.; Schieler, H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma,
G.; Trinchero, G. C.; Ulrich, H.; Van Buren, J.; Van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; ZImmermann, D.
2006aren.conf..187N Altcode:
Radio emission in extensive air showers arises from an interaction
with the geomagnetic field and is subject of theoretical studies. This
radio emission has advantages for the detection of high energy cosmic
rays compared to secondary particle or fluorescence measurement
methods. Radio antennas like the LOPES30 antenna system are suited to
investigate this emission process by detecting the radio pulses. The
characteristic observable parameters like electric field strength and
pulse length require a calibration which was done with a reference radio
source resulting in an amplification factor representing the system
behavior in the environment of the KASCADE-Grande experiment. Knowing
the amplification factor and the gain of the LOPES antennas LOPES30
is calibrated absolutely for systematic analyses of the radio emission.
---------------------------------------------------------
Title: Combined Lopes and Kascade-Grande Data Analysis
Authors: Haungs, A.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.; di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.;
Glasstetter, R.; Grupen, C.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev,
Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Maier, G.;
Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; van Buren, J.; van Capellen, W.; Walkowiak, W.;
Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski, J.; Zensus,
J. A.; Zimmermann, D.
2006IJMPA..21S.182H Altcode: 2005astro.ph.10352H
First analyses of coincident data of the LOPES (LOfar PrototypE Station)
radio antennas with the particle air shower experiment KASCADE-Grande
show basic correlations in the observed shower parameters, like the
strength of the radio signal and the particle number, or comparing
the estimated shower directions. In addition, an improvement of the
experimental resolution of the shower parameters reconstructed by
KASCADE-Grande can be obtained by including the data of the radio
antennas. This important feature will be shown in this article
explicitely by an example event.
---------------------------------------------------------
Title: Jupiter Burst Observation with LOFAR/ITS
Authors: Nigl, A.; Kuijpers, J.; Falcke, H.; Zarka, P.; Bähren, L.
2006pre6.conf..517N Altcode: 2006pre4.conf..517N
Io-induced Jupiter emission lies mainly in the frequency range from
about 2 to 40 MHz [Zarka et al., 2001], which happens to coincide
with the frequency band of the Low-Frequency Radio Array Initial Test
Station (LOFAR/ITS). ITS is capable of measuring the radio signal with
high time and frequency resolution, which makes it well-suited for
the study of Jovian decametric emission (DAM). We present the first
simultaneous Io-DAM observations of Jupiter at about 700 km distance
between two instruments, LOFAR/ITS and the Nancay Decametric Array
(NDA). We have detected emission from Jupiter during snapshots of a
few seconds and identified detailed features in dynamic spectra taken
with both instruments. This will be the basis for VLBI-like correlation
of both waveforms. This article presents first and preliminary Jupiter
observations with ITS. We analyze Faraday rotation, which is measured
with linearly polarized antennas. We observe frequency modulation over
a broad spectral range and demonstrate that the effect comes mainly
from the Earth's ionosphere. This article presents first observations
and discusses frequency modulated Faraday rotation.
---------------------------------------------------------
Title: Absolute Calibration of the Lopes Antenna System
Authors: Nehls, S.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.;
di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Hakenjos, A.; Haungs, A.; Heck,
D.; Hörandel, J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant,
G. W.; Klein, U.; Kolotaev, Y.; Koopman, Y.; Krömer, O.; Kuijpers,
J.; Lafebre, S.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke,
J.; Mitrica, B.; Morello, C.; Navarra, G.; Nigl, A.; Obenland, R.;
Oehlschläger, J.; Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu,
M.; Petrovic, J.; Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth,
M.; Schieler, H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma,
G.; Trinchero, G. C.; Ulrich, H.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2006IJMPA..21S.187N Altcode: 2005astro.ph.10353N
Radio emission in extensive air showers arises from an interaction
with the geomagnetic field and is subject of theoretical studies. This
radio emission has advantages for the detection of high energy cosmic
rays compared to secondary particle or fluorescence measurement
methods. Radio antennas like the LOPES30 antenna system are suited to
investigate this emission process by detecting the radio pulses. The
characteristic observable parameters like electric field strength and
pulse length require a calibration which was done with a reference radio
source resulting in an amplification factor representing the system
behavior in the environment of the KASCADE-Grande experiment. Knowing
the amplification factor and the gain of the LOPES antennas LOPES30
is calibrated absolutely for systematic analyses of the radio emission.
---------------------------------------------------------
Title: Combined LOPES and KASCADE-GRANDE Data Analysis
Authors: Haungs, A.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; De Bruyn, A. G.; De Vos, C. M.; Di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.;
Glasstetter, R.; Grupen, C.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev,
Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Maier, G.;
Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Van Buren, J.; Van Capellen, W.; Walkowiak, W.;
Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski, J.; Zensus,
J. A.; Zimmermann, D.; Lopes Collaboration
2006aren.conf..182H Altcode:
First analyses of coincident data of the LOPES (LOfar PrototypE Station)
radio antennas with the particle air shower experiment KASCADE-Grande
show basic correlations in the observed shower parameters, like the
strength of the radio signal and the particle number, or comparing
the estimated shower directions. In addition, an improvement of the
experimental resolution of the shower parameters reconstructed by
KASCADE-Grande can be obtained by including the data of the radio
antennas. This important feature will be shown in this article
explicitely by an example event.
---------------------------------------------------------
Title: Radio Detection of Cosmic Rays with LOPES
Authors: Horneffer, A.; Apel, W. D.; Badea, F.; Bähren, Bekk, K.;
Bercuci, A.; Beraina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Buitink, S.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; De Bruyn, A. G.; De Vos, C. M.;
Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel,
J. R.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev,
Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Maier, G.;
Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Van Buren, J.; Van Capellen, W.; Walkowiak, W.;
Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski, J.; Zensus,
J. A.; Zimmermann, D.
2006aren.conf..168H Altcode:
Measuring radio pulses from cosmic ray air showers offers various
new opportunities. New digital radio receivers allow measurements
of these radio pulses even in environments that have lots of radio
interference. With high bandwidth ADCs and fast data processing it is
possible to store the whole waveform information in digital form and
analyse transient events like air showers even after they have been
recorded. Digital filtering and beam forming can be used to suppress the
radio interference so that it is possible to measure the radio pulses
even in radio loud environments. LOPES is a prototype station for the
new digital radio interferometer LOFAR and is tailored to measure air
showers. For this it is located at the site of the KASCADE-Grande air
shower experiment. Already with the first phase of LOPES we have been
able to measure radio pulses from air showers and show correlations
between the radio pulse height and air shower parameters. <P />The first
part gives an introduction and presents the science results of LOPES,
while the second part presents the hard- and software that enables
LOPES to detect air short pulses.
---------------------------------------------------------
Title: Indirect Visibility of Gravitational Waves in
Magnetohydrodynamic Plasmas
Authors: Moortgat, J.; Kuijpers, J.
2005tsra.conf..326M Altcode: 2005gr.qc.....3074M
We propose a mechanism to make gravitational waves (GWs) visible
in the electromagnetic domain. Gravitational waves that propagate
through a strongly magnetized plasma interact with the plasma through
its anisotropic stress-energy tensor and excite magnetohydrodynamic
(MHD) wave modes. In catastrophic events such as the merger of a double
neutron star binary, a large fraction of the total binding energy of
the system is released in the form of GWs observable by LIGO, and the
amount of energy transferred to the MHD waves is substantial. These
modes, however, are excited at the same frequency as the GW and are not
directly observable. In this paper we investigate radiation processes
that operate in the presence of the gravitationally excited MHD waves
and radiate in the radio regime accessible to LOFAR. We present order
of magnitude estimates for the spectral flux of a merger detectable
by a LOFAR.
---------------------------------------------------------
Title: Frequency dependence of the drifting subpulses of PSR B0031-07
Authors: Smits, J. M.; Mitra, D.; Kuijpers, J.
2005A&A...440..683S Altcode: 2005astro.ph..6264S
The well known drifter PSR B0031-07 is known to exhibit drifting
subpulses where the spacing between the drift bands (P<SUB>3</SUB>)
shows three distinct modes A, B and C corresponding to 12, 6 and 4
s respectively. We have investigated periodicities and polarisation
properties of PSR B0031-07 for a sequence of 2700 single pulses taken
simultaneously at 328 MHz and 4.85 GHz. We found that mode A occurs
simultaneously at these frequencies, while modes B and C only occur at
328 MHz. However, when the pulsar is emitting in mode B at the lower
frequency there is still emission at the higher frequency, hinting
towards the presence of mode B emission at a weaker level. Further, we
have established that modes A and B are associated with two orthogonal
modes of polarisation, respectively. Based on these observations, we
suggest a geometrical model where modes A and B at a given frequency
are emitted in two concentric rings around the magnetic axis with mode
B being nested inside mode A. Further, it is evident that this nested
configuration is preserved across frequency with the higher frequency
arising closer to the stellar surface compared to the lower one,
consistent with the well known radius-to-frequency mapping operating
in pulsars.
---------------------------------------------------------
Title: An outreach project for LOFAR and cosmic ray detection.
Authors: Nigl, A.; Timmermans, C.; Schellart, P.; Kuijpers, J.;
Falcke, H.; Horneffer, A.; de Vos, C. M.; Koopman, Y.; Pepping, H. J.;
Schoonderbeek, G.
2005AN....326..619N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection and imaging of atmospheric radio flashes from cosmic
ray air showers
Authors: Falcke, H.; Apel, W. D.; Badea, A. F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Buitink, S.; Brüggemann, M.; Buchholz, P.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.; di
Pierro, F.; Doll, P.; Engel, R.; Gemmeke, H.; Ghia, P. L.; Glasstetter,
R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev, Y.;
Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Maier, G.; Mathes,
H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.;
Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.; Ostapchenko,
S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.; Plewnia, S.;
Rebel, H.; Risse, A.; Roth, M.; Schieler, H.; Schoonderbeek, G.;
Sima, O.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich, H.;
Valchierotti, S.; van Buren, J.; van Cappellen, W.; Walkowiak, W.;
Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski, J.; Zensus,
J. A.; Zimmermann, D.
2005Natur.435..313F Altcode: 2005astro.ph..5383F
The nature of ultrahigh-energy cosmic rays (UHECRs) at energies
>10<SUP>20</SUP>eV remains a mystery. They are likely to be of
extragalactic origin, but should be absorbed within ~50Mpc through
interactions with the cosmic microwave background. As there are no
sufficiently powerful accelerators within this distance from the Galaxy,
explanations for UHECRs range from unusual astrophysical sources
to exotic string physics. Also unclear is whether UHECRs consist of
protons, heavy nuclei, neutrinos or γ-rays. To resolve these questions,
larger detectors with higher duty cycles and which combine multiple
detection techniques are needed. Radio emission from UHECRs, on the
other hand, is unaffected by attenuation, has a high duty cycle, gives
calorimetric measurements and provides high directional accuracy. Here
we report the detection of radio flashes from cosmic-ray air showers
using low-cost digital radio receivers. We show that the radiation can
be understood in terms of the geosynchrotron effect. Our results show
that it should be possible to determine the nature and composition of
UHECRs with combined radio and particle detectors, and to detect the
ultrahigh-energy neutrinos expected from flavour mixing.
---------------------------------------------------------
Title: Measurement of the shadowing of high-energy cosmic rays by
the Moon: A search for TeV-energy antiprotons
Authors: L3 Collaboration; Achard, P.; Adriani, O.; Aguilar-Benitez,
M.; van den Akker, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio,
A.; Alviggi, M. G.; Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev,
A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay,
L.; Bähr, J.; Baldew, S. V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.;
Barillère, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.;
Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco,
R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.;
Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.; Bobbink,
G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov,
D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu, F.; Burger,
J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Romeo, G. Cara; Carlino,
G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.;
Cerrada, M.; Chamizo, M.; Chiarusi, T.; Chang, Y. H.; Chemarin, M.;
Chen, A.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chiefari,
G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.;
Colino, N.; Costantini, S.; de La Cruz, B.; Cucciarelli, S.; de
Asmundis, R.; Déglon, P.; Debreczeni, J.; Degré, A.; Dehmelt, K.;
Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; Denotaristefani,
F.; de Salvo, A.; Diemoz, M.; Dierckxsens, M.; Ding, L. K.; Dionisi,
C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau, D.; Duda, M.;
Duran, I.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.;
Engler, A.; Eppling, F. J.; Extermann, P.; Faber, G.; Falagan, M. A.;
Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson,
T.; Fesefeldt, H.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher,
P. H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta,
C.; Galaktionov, Yu.; Ganguli, S. N.; Garcia-Abia, P.; Gataullin,
M.; Gentile, S.; Giagu, S.; Gong, Z. F.; Grabosch, H. J.; Grenier,
G.; Grimm, O.; Groenstege, H.; Gruenewald, M. W.; Guida, M.; Guo,
Y. N.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Haas, D.; Haller, Ch.;
Hatzifotiadou, D.; Hayashi, Y.; He, Z. X.; Hebbeker, T.; Hervé, A.;
Hirschfelder, J.; Hofer, H.; Hofer, H.; Hohlmann, M.; Holzner, G.;
Hou, S. R.; Huo, A. X.; Ito, N.; Jin, B. N.; Jindal, P.; Jing, C. L.;
Jones, L. W.; de Jong, P.; Josa-Mutuberría, I.; Kantserov, V.; Kaur,
M.; Kawakami, S.; Kienzle-Focacci, M. N.; Kim, J. K.; Kirkby, J.;
Kittel, W.; Klimentov, A.; König, A. C.; Kok, E.; Korn, A.; Kopal,
M.; Koutsenko, V.; Kräber, M.; Kuang, H. H.; Kraemer, R. W.; Krüger,
A.; Kuijpers, J.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.;
Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq,
P.; Le Coultre, P.; Le Goff, J. M.; Lei, Y.; Leich, H.; Leiste, R.;
Levtchenko, M.; Levtchenko, P.; Li, C.; Li, L.; Li, Z. C.; Likhoded,
S.; Lin, C. H.; Lin, W. T.; Linde, F. L.; Lista, L.; Liu, Z. A.;
Lohmann, W.; Longo, E.; Lu, Y. S.; Luci, C.; Luminari, L.; Lustermann,
W.; Ma, W. G.; Ma, X. H.; Ma, Y. Q.; Malgeri, L.; Malinin, A.; Maña,
C.; Mans, J.; Martin, J. P.; Marzano, F.; Mazumdar, K.; McNeil, R. R.;
Mele, S.; Meng, X. W.; Merola, L.; Meschini, M.; Metzger, W. J.; Mihul,
A.; van Mil, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G. B.;
Monteleoni, B.; Muanza, G. S.; Muijs, A. J. M.; Musicar, B.; Musy,
M.; Nagy, S.; Nahnhauer, R.; Naumov, V. A.; Natale, S.; Napolitano,
M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Nowak, H.;
Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci,
P.; Paramatti, R.; Parriaud, J. -F.; Passaleva, G.; Patricelli, S.;
Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti,
S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.;
Pieri, M.; Pioppi, M.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.;
Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Quartieri, J.;
Qing, C. R.; Rahal-Callot, G.; Rahaman, M. A.; Raics, P.; Raja, N.;
Ramelli, R.; Rancoita, P. G.; Ranieri, R.; Raspereza, A.; Ravindran,
K. C.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Rewiersma, P.;
Riemann, S.; Riles, K.; Roe, B. P.; Rojkov, A.; Romero, L.; Rosca, A.;
Rosemann, C.; Rosier-Lees, S.; Rosenbleck, C.; Roth, S.; Rubio, J. A.;
Ruggiero, G.; Rykaczewski, H.; Saidi, R.; Sakharov, A.; Saremi, S.;
Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer, C.; Schegelsky, V.;
Schmitt, V.; Schoeneich, B.; Schopper, H.; Schotanus, D. J.; Sciacca,
C.; Servoli, L.; Shen, C. Q.; Shevchenko, S.; Shivarov, N.; Shoutko,
V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.;
Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar,
K.; Sulanke, H.; Sultanov, G.; Sun, L. Z.; Sushkov, S.; Suter, H.;
Swain, J. D.; Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.;
Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, Samuel
C. C.; Ting, S. M.; Tonwar, S. C.; Tóth, J.; Trowitzsch, G.; Tully,
C.; Tung, K. L.; Ulbricht, J.; Unger, M.; Valente, E.; Verkooijen,
H.; van de Walle, R. T.; Vasquez, R.; Veszpremi, V.; Vesztergombi,
G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent,
M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobiev, I.;
Vorobyov, A. A.; Wadhwa, M.; Wang, R. G.; Wang, Q.; Wang, X. L.; Wang,
X. W.; Wang, Z. M.; Weber, M.; van Wijk, R.; Wijnen, T. A. M.; Wilkens,
H.; Wynhoff, S.; Xia, L.; Xu, Y. P.; Xu, J. S.; Xu, Z. Z.; Yamamoto,
J.; Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.; Yang, X. F.;
Yao, Z. G.; Yeh, S. C.; Yu, Z. Q.; Zalite, An.; Zalite, Yu.; Zhang,
C.; Zhang, F.; Zhang, J.; Zhang, S.; Zhang, Z. P.; Zhao, J.; Zhou,
S. J.; Zhu, G. Y.; Zhu, R. Y.; Zhu, Q. Q.; Zhuang, H. L.; Zichichi,
A.; Zimmermann, B.; Zöller, M.; Zwart, A. N. M.
2005APh....23..411L Altcode: 2005astro.ph..3472L
The shadowing of high-energy cosmic rays by the Moon has been observed
with a significance of 9.4 standard deviations with the L3 + C muon
spectrometer at CERN. A significant effect of the Earth magnetic field
is observed. Since no event deficit on the east side of the Moon has
been observed, an upper limit at 90% confidence level on the antiproton
to proton ratio of 0.11 is obtained for primary energies around 1 TeV.
---------------------------------------------------------
Title: Radio emission of highly inclined cosmic ray air showers
measured with LOPES
Authors: Petrovic, J.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Buitink, S.; Brüggemann, M.; Buchholz, P.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.;
Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel,
J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein,
U.; Kolotaev, Y.; Koopman, Y.; Krömer, B.; Kuijpers, J.; Lafebre,
S.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica,
B.; Morello, C.; Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.;
Oehlschläger, J.; Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu,
M.; Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Winjnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2005ICRC....6..337P Altcode: 2005ICRC...29f.337P
No abstract at ADS
---------------------------------------------------------
Title: Radio Detection of High-Energy Cosmic Rays: LOPES
Authors: Haungs, A.; Apel, W. D.; Badea, F.; Bekk, K.; Blümer, J.;
Bozdog, H.; Daumiller, K.; Doll, P.; Engel, R.; Heck, D.; Mathes,
H. J.; Mayer, H. J.; Milke, J.; Nehls, S.; Obenland, R.; Oehlschläger,
J.; Ostapchenko, S.; Plewnia, S.; Rebel, H.; Schieler, H.; Ulrich,
H.; van Buren, J.; Weindl, A.; Wochele, J.; Bähren, L.; Butcher,
H.; de Bruyn, G.; de Vos, C. M.; Falcke, H.; Kant, G. W.; Koopman,
Y.; Pepping, H. J.; Schoonderbeek, G.; van Capellen, W.; Wijnholds,
S.; Bercuci, A.; Brancus, I. M.; Mitrica, B.; Petcu, M.; Sima,
O.; Toma, G.; Bertaina, M.; Chiavassa, A.; di Pierro, F.; Navarra,
G.; Valchierotti, S.; Biermann, P. L.; Horneffer, A.; Huege, T.;
Zensus, J. A.; Brüggemann, M.; Buchholz, P.; Kolotaev, Y.; Over, S.;
Walkowiak, W.; Zimmermann, D.; Buitink, S.; Kuijpers, J.; Lafebre, S.;
Nigl, A.; Petrovic, J.; Gemmeke, H.; Krömer, O.; Ghia, P. L.; Morello,
C.; Trinchero, G. C.; Glasstetter, R.; Kampert, K. -H.; Hörandel,
J. R.; Roth, M.; Stümpert, M.; Klein, U.; Risse, A.; Zabierowski, J.
2005tsra.conf..687H Altcode:
The detection of radio pulses emitted in the atmosphere during the
air shower development of high-energy primary cosmic rays is the task
of the LOPES (LOFAR Prototype Station) project. LOFAR (Low Frequency
Array) is a new digital radio interferometer under development using
high bandwidth ADCs and fast data processing to filter out most of the
interference. By storing the whole waveform information in digital form
transient events like air showers can be analyzed even after they have
been recorded. To test this technology and to demonstrate its ability
to measure air showers a LOPES is set up to operate in conjunction
with an existing air shower experiment (KASCADE-Grande). The LOPES
antennas are operating in the frequency range of 40-80 MHz. For several
air-shower events a coincident and coherent signal has been found and
a preliminary analysis has already been performed. The main goal of
further investigations is to calibrate the radio signal with help of
the observables of the individual air-showers given by KASCADE-Grande.
---------------------------------------------------------
Title: An Outreach Project for LOFAR and Cosmic Ray Detection
Authors: Nigl, A.; Timmermans, C.; Schllarts, P.; Kuijpers, J.;
Falcke, H.; Horneffer, A.; de Vos, C. M.; Koopman, Y.; Pepping, H. J.;
Schoonderbeek, G.
2005ICRC....6..341N Altcode: 2005ICRC...29f.341N
No abstract at ADS
---------------------------------------------------------
Title: LOPES30: A digital antenna array for measuring high-energy
cosmic ray air showers
Authors: Nehls, S.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Buitink, S.; Brüggemann, M.; Buchholz, P.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.;
Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia,
P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel,
J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein,
U.; Kolotaev, Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre,
S.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.;
Morello, C.; Navarra, G.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2005ICRC....8...45N Altcode: 2005ICRC...29h..45N
No abstract at ADS
---------------------------------------------------------
Title: Gravitational Wave Interactions with Magnetized Plasmas
Authors: Moortgat, Joachim; Kuijpers, Jan
2005ASIB..210..103M Altcode: 2004gr.qc....11128M; 2005esns.conf..103M
Gravitational waves (GWs) propagating through a uniformly magnetized
plasma interact directly with the magnetic field and excite
magnetohydrodynamic (MHD) waves with both electromagnetic and matter
components. We study this process for arbitrary geometry in the
MHD approximation and find that all three fundamental MHD modes --
slow and fast magnetosonic, and Alfven -- are excited depending on
both the polarization of the GW and the orientation of the ambient
magnetic field. The latter two modes can interact coherently with the
GW resulting in damping of the GW and linear growth of the plasma waves.
---------------------------------------------------------
Title: A Cosmic Ray Trigger for LOFAR
Authors: Lafebre, S.; Nigl, A.; Apel, W. D.; Badea, F.; Bähren, L.;
Bekk, K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Buitink, S.; Brüggemann, M.; Buchholz,
P.; Butcher, H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de
Vos, C. M.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke,
H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant,
G. W.; Klein, U.; Kolotaev, Y.; Koopman, Y.; Krömer, O.; Kuijpers,
J.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.;
Morello, C.; Navarra, G.; Nehls, S.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2005ICRC....8..245N Altcode: 2005ICRC...29h.245N
No abstract at ADS
---------------------------------------------------------
Title: Cosmic Ray Trigger for LOFAR: First results
Authors: Lafebre, S.; Nigl, A.; Apel, W. D.; Badea, F.; Bähren, L.;
Bekk, K.; Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.;
Bozdog, H.; Brancus, I. M.; Buitink, S.; Brüggemann, M.; Buchholz,
P.; Butcher, H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de
Vos, C. M.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke,
H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Huege, T.; Kampert, K. -H.; Kant,
G. W.; Klein, U.; Kolotaev, Y.; Koopman, Y.; Krömer, O.; Kuijpers,
J.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.;
Morello, C.; Navarra, G.; Nehls, S.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2005ICRC....8..249L Altcode: 2005ICRC...29h.249L
No abstract at ADS
---------------------------------------------------------
Title: Electric field influence on the radio emission of air showers
Authors: Buitink, S.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Butcher, H.; Chiavassa,
A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.; Di Pierro, F.; Doll,
P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter,
R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev,
Y.; Koopman, Y.; Krömer, B.; Kuijpers, J.; Lafebre, S.; Maier, G.;
Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Winjnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D
2005ICRC....6..333B Altcode: 2005ICRC...29f.333B
No abstract at ADS
---------------------------------------------------------
Title: Fluctuations in the EAS radio signal derived with improved
Monte Carlo simulations based on CORSIKA
Authors: Huege, T.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog,
H.; Brancus, I. M.; Buitnink, S.; Brüggemann, M.; Buchholz, P.;
Butcher, H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos,
C. M.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Gemmeke,
H.; Ghia, P. L.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.;
Hörandel, J. R.; Horneffer, A.; Kuijpers, J.; Lafebre, S.; Maier,
G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; sToma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2005ICRC....7..107H Altcode: 2005ICRC...29g.107H; 2005astro.ph..7026H
Cosmic ray air showers are known to emit pulsed radio emission which
can be understood as coherent geosynchrotron radiation arising from
the deflection of electron-positron pairs in the earth's magnetic
field. Here, we present simulations carried out with an improved
version of our Monte Carlo code for the calculation of geosynchrotron
radiation. Replacing the formerly analytically parametrised longitudinal
air shower development with CORSIKA-generated longitudinal profiles,
we study the radio flux variations arising from inherent fluctuations
between individual air showers. Additionally, we quantify the dependence
of the radio emission on the nature of the primary particle by comparing
the emission generated by proton- and iron-induced showers. This is
only the first step in the incorporation of a more realistic air shower
model into our Monte Carlo code. The inclusion of highly realistic
CORSIKA-based particle energy, momentum and spatial distributions
together with an analytical treatment of ionisation losses will soon
allow simulations of the radio emission with unprecedented detail. This
is especially important to assess the emission strengths at large
radial distances, needed for event-to-event comparisons of the radio
signals measured by LOPES in conjunction with KASCADE-Grande and for
considerations regarding large arrays of radio antennas intended
to measure the radio emission from ultra-high energy cosmic rays,
as with LOFAR or in the Pierre Auger Observatory.
---------------------------------------------------------
Title: Remote event analyses of LOPES-10
Authors: Badea, A. F.; Apel, W. D.; Bähren, L.; Bekk, K.; Bercuci, A.;
Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.;
Buitink, S.; Brüggemann, M.; Buchholz, P.; Butcher, H.; Chiavassa, A.;
Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.; Di Pierro, F.; Doll,
P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter,
R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev,
Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Maier, G.;
Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plenia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stüpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wiknholds, S.; Wochele, J.; Zabierowski,
J.; Zensuz, J. A.; Zimmermann, D.
2005ICRC....6..277B Altcode: 2005ICRC...29f.277B
No abstract at ADS
---------------------------------------------------------
Title: First determination of the reconstruction resolution of an
EAS radio detector
Authors: Badea, A. F.; Apel, W. D.; Bähren, L.; Bekk, K.; Bercuci, A.;
Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.;
Buitink, S.; Brüggemann, M.; Buchholz, P.; Butcher, H.; Chiavassa, A.;
Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.; Di Pierro, F.; Doll,
P.; Engel, R.; Falcke, H.; Gemmeke, H.; Ghia, P. L.; Glasstetter,
R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer,
A.; Huege, T.; Kampert, K. -H.; Kant, G. W.; Klein, U.; Kolotaev,
Y.; Koopman, Y.; Krömer, O.; Kuijpers, J.; Lafebre, S.; Maier, G.;
Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Morello, C.;
Navarra, G.; Nehls, S.; Nigl, A.; Obenland, R.; Oehlschläger, J.;
Ostapchenko, S.; Over, S.; Pepping, H. J.; Petcu, M.; Petrovic, J.;
Pierog, T.; Plewnia, S.; Rebel, H.; Risse, A.; Roth, M.; Schieler,
H.; Schoonderbeek, G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero,
G. C.; Ulrich, H.; Valchierotti, S.; van Buren, J.; van Capellen, W.;
Walkowiak, W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski,
J.; Zensus, J. A.; Zimmermann, D.
2005ICRC....6..273B Altcode: 2005ICRC...29f.273B
No abstract at ADS
---------------------------------------------------------
Title: Detection of radio pulses from extensive air showers
Authors: Horneffer, A.; Apel, W. D.; Badea, F.; Bähren, L.; Bekk, K.;
Bercuci, A.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.;
Brancus, I. M.; Buitink, S.; Brüggemann, M.; Buchholz, P.; Butcher,
H.; Chiavassa, A.; Daumiller, K.; de Bruyn, A. G.; de Vos, C. M.; Di
Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Koopman, Y.; Krömer,
O.; Kuijpers, J.; Lafebre, S.; Maier, G.; Mathes, H. J.; Mayer,
H. J.; Milke, J.; Mitrica, B.; Morello, C.; Navarra, G.; Nehls, S.;
Nigl, A.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Over,
S.; Pepping, H. J.; Petcu, M.; Petrovic, J.; Pierog, T.; Plewnia,
S.; Rebel, H.; Risse, A.; Roth, M.; Schieler, H.; Schoonderbeek,
G.; Sima, O.; Stümpert, M.; Toma, G.; Trinchero, G. C.; Ulrich,
H.; Valchierotti, S.; van Buren, J.; van Capellen, W.; Walkowiak,
W.; Weindl, A.; Wijnholds, S.; Wochele, J.; Zabierowski, J.; Zensus,
J. A.; Zimmermann, D.
2005ICRC....6..285H Altcode: 2005ICRC...29f.285H
No abstract at ADS
---------------------------------------------------------
Title: A free-electron laser in the pulsar magnetosphere
Authors: Fung, P. K.; Kuijpers, J.
2004A&A...422..817F Altcode: 2004astro.ph..5345F
We have studied systematically the free-electron laser in the context
of high brightness pulsar radio emission. In this paper, we have
numerically examined the case where a transverse electromagnetic
wave is distorting the motion of a relativistic electron beam while
travelling over one stellar radius (≈10 km). For different sets
of parameters, coherent emission is generated by bunches of beam
electrons in the radio domain, with bandwidths of 3 GHz. Pulse power
often reached 10<SUP>13</SUP> W, which corresponds with brightness
temperature of 10<SUP>30</SUP> K. The duration of these pulses is of
the order of nanoseconds. In the context of pulsar radio emission,
our results indicate that the laser can produce elementary bursts of
radiation which build up the observed microstructures of a few tens
of microseconds duration. The process is sensitive mostly to the beam
particles energy, number density and the background magnetic field,
but much less so to the transverse wave parameters. We demonstrate
that the operation of a free-electron laser with a transverse
electromagnetic wiggler in the pulsar magnetosphere occurs preferably
at moderate Lorentz factors γ ≥ 100, high beam density n ≳
0.1;n<SUB>GJ</SUB>(r<SUB>*</SUB>) where n<SUB>GJ</SUB>(r<SUB>*</SUB>)
is the Goldreich-Julian density at a stellar radius r<SUB>*</SUB>,
and finally, at large altitude where the background magnetic field
is low B<SUB>0</SUB> ≤ 10<SUP>-2</SUP>;T. <P />Appendix A is only
available in electronic form at <P />http://www.edpsciences.org
---------------------------------------------------------
Title: Gravitational waves in magnetized relativistic plasmas
Authors: Moortgat, J.; Kuijpers, J.
2004PhRvD..70b3001M Altcode: 2004gr.qc.....5086M
We study the propagation of gravitational waves (GW’s) in a uniformly
magnetized plasma at arbitrary angles to the magnetic field. No a
priori assumptions are made about the temperature, and we consider
both a plasma at rest and a plasma flowing out at ultrarelativistic
velocities. In the 3+1 orthonormal tetrad description, we find that
all three fundamental low-frequency plasma wave modes are excited by
the GW’s. Alfvén waves are excited by a × polarized GW, whereas the
slow and fast magnetoacoustic modes couple to the + polarization. The
slow mode, however, does not interact coherently with the GW. The
most relevant wave mode is the fast magnetoacoustic mode which in
a strongly magnetized plasma has a vanishingly small phase lag with
respect to the GW allowing for coherent interaction over large length
scales. When the background magnetic field is almost, but not entirely,
parallel to the GW’s direction of propagation even the Alfvén waves
grow to first order in the GW amplitude. Finally, we calculate the
growth of the magnetoacoustic waves and the damping of the GW.
---------------------------------------------------------
Title: Lofar: a New Radio Telescope for Low Frequency Radio
Observations:. Science and Project Status
Authors: Röttgering, H.; de Bruyn, A. G.; Fender, R. P.; Kuijpers,
J.; van Haarlem, M. P.; Johnston-Hollitt, M.; Miley, G. K.
2003tsra.symp...69R Altcode: 2003astro.ph..7240R
LOFAR, the Low Frequency Array, is a large radio telescope consisting
about 100 soccer field sized antenna stations spread over a region of
400 km in diameter. It will operate in the frequency range from ~ 10 to
240 MHz, with a resolution at 240 MHz of better than an arcsecond. Its
superb sensitivity will allow for a broad range of astrophysical
studies. In this contribution we first discuss four major areas of
astrophysical research in which LOFAR will undoubtedly make important
contributions: reionisation, distant galaxies and AGNs, transient radio
sources and cosmic rays. Subsequently, we will discuss the technical
concept of the instrument and the status of the LOFAR project.
---------------------------------------------------------
Title: On the search for coherent radiation from radio pulsars
Authors: Smits, J. M.; Stappers, B. W.; Macquart, J. -P.; Ramachandran,
R.; Kuijpers, J.
2003A&A...405..795S Altcode: 2003astro.ph..6306S
We have examined data from pulsars B0950+08 and B0329+54 for evidence
of temporally coherent radiation using the modified coherence function
(MCF) technique of \citet{Jenet}. We consider the influence of both
instrumental bandpass and interstellar propagation effects. Even after
removal of the effects due to the instrumental bandpass, we detect a
signature in the MCF of our PSR B0329+54 data which is consistent with
the definition of a coherent signal. However, we model the effects
due to interstellar scintillation for this pulsar and show that it
reproduces the observed signature. In particular, the temporal coherence
time is close to the reciprocal of the decorrelation bandwidth due to
diffractive scintillation. Furthermore, comparison of the coherence
times of three pulsars reported by \citet{Jenet} with their expected
diffractive decorrelation bandwidths suggests that the detection of
coherence in these pulsars is also likely a result of interstellar
scintillation, and is not intrinsic to the pulsars.
---------------------------------------------------------
Title: Gravitational and magnetosonic waves in gamma-ray bursts
Authors: Moortgat, J.; Kuijpers, J.
2003A&A...402..905M Altcode: 2003gr.qc.....2055M
One of the possible sources of gamma-ray bursts (GRBs) are merging,
compact neutronstar binaries. More than 90% of the binding energy of
such a binary is released in the form of gravitational waves (GWs) in
the last few seconds of the spiral-in phase before the formation of a
black hole. In this article we investigate whether a fraction of this GW
energy is transferred to magnetohydrodynamic waves in the magnetized
plasma wind around the binary. Using the 3+1 orthonormal tedrad
formalism, we study the propagation of a monochromatic, plane fronted,
linearly polarized GW perpendicular to the ambient magnetic field in an
ultra-relativistic wind, first in the comoving and then in the observer
frame. A closed set of general relativistic magnetohydrodynamic (GRM)
equations is derived in the form of conservation laws for electric
charge, matter energy, momentum and magnetic energy densities. We
linearize the GRM equations under the action of a monochromatic GW,
which acts as a driver and find that fast magneto-acoustic waves grow,
with amplitudes proportional to the GW amplitude and frequency and
the strength of the background magnetic field.
---------------------------------------------------------
Title: Gravitational Wave Interaction with Gamma-Ray Burst Plasma.
Authors: Moortgat, Joachim B.; Kuijpers, Jan
2003IAUJD...1E...3M Altcode:
In a merging binary scenario for gamma-ray bursts most of the
binding energy is released in the form of gravitational waves
in the last seconds before the collapse to a black hole. In an
attempt to investigate the nature of the central engine we consider
neutronstar-neutronstar mergers and apply the general relativistic
3+1 formalism to the interaction of the gravitational waves with the
ultra-relativistic wind of magnetized plasma around the binary. We
show that these waves distort the magnetic field frozen into the plasma
and excite growing magnetosonic waves in the wind. Already before the
merger the binary is embedded in a relativistically expanding magnetized
wind of (mainly) leptons from the orbiting neutronstars so even a
small transfer of gravitational wave energy to the wind may result in
interesting observational signatures of a gamma-ray bursts fireball.
---------------------------------------------------------
Title: Preface (Solar variability: from core to outer frontiers)
Authors: Kuijpers, Jan
2002ESASP.506D..21K Altcode: 2002svco.confD..21K; 2002ESPM...10...21K; 2002ESASP.506.....K
No abstract at ADS
---------------------------------------------------------
Title: The L3+C detector, a unique tool-set to study cosmic rays
Authors: Adriani, O.; van den Akker, M.; Banerjee, S.; Bähr, J.;
Betev, B.; Bourilkov, D.; Bottai, S.; Bobbink, G.; Cartacci, A.;
Chemarin, M.; Chen, G.; Chen, H. S.; Chiarusi, T.; Dai, C. J.; Ding,
L. K.; Duran, I.; Faber, G.; Fay, J.; Grabosch, H. J.; Groenstege,
H.; Guo, Y. N.; Gupta, S.; Haller, Ch.; Hayashi, Y.; He, Z. X.;
Hebbeker, T.; Hofer, H.; Hoferjun, H.; Huo, A. X.; Ito, N.; Jing,
C. L.; Jones, L.; Kantserov, V.; Kawakami, S.; Kittel, W.; König,
A. C.; Kok, E.; Korn, A.; Kuang, H. H.; Kuijpers, J.; Ladron de
Guevara, P.; Le Coultre, P.; Lei, Y.; Leich, H.; Leiste, R.; Li, D.;
Li, L.; Li, Z. C.; Liu, Z. A.; Liu, H. T.; Lohmann, W.; Lu, Y. S.;
Ma, X. H.; Ma, Y. Q.; van Mil, A.; Monteleoni, B.; Nahnhauer, R.;
Pauss, F.; Parriaud, J. -F.; Petersen, B.; Pohl, M.; Qing, C. R.;
Ramelli, R.; Ravindran, K. C.; Rewiersma, P.; Rojkov, A.; Saidi, R.;
Schmitt, V.; Schöneich, B.; Schotanus, D. J.; Shen, C. Q.; Sulanke,
H.; Tang, X. W.; Timmermans, C.; Tonwar, S.; Trowitzsch, G.; Unger,
M.; Verkooijen, H.; Wang, X. L.; Wang, X. W.; Wang, Z. M.; van Wijk,
R.; Wijnen, Th. A. M.; Wilkens, H.; Xu, Y. P.; Xu, Z. Z.; Yang, C. G.;
Yang, X. F.; Yao, Z. G.; Yu, Z. Q.; Zhang, S.; Zhu, G. Y.; Zhu, Q. Q.;
Zhuang, H. L.; Zwart, A. N. M.
2002NIMPA.488..209A Altcode:
The L3 detector at the CERN electron-positron collider, LEP, has been
employed for the study of cosmic ray muons. The muon spectrometer
of L3 consists of a set of high-precision drift chambers installed
inside a magnet with a volume of about 1000m<SUP>3</SUP> and a field of
0.5T. Muon momenta are measured with a resolution of a few percent at
50GeV. The detector is located under 30m of overburden. A scintillator
air shower array of 54m by 30m is installed on the roof of the surface
hall above L3 in order to estimate the energy and the core position of
the shower associated with a sample of detected muons. Thanks to the
unique properties of the /L3+C detector, muon research topics relevant
to various current problems in cosmic ray and particle astrophysics
can be studied.
---------------------------------------------------------
Title: Fast magnetosonic waves driven by gravitational waves
Authors: Papadopoulos, D.; Stergioulas, N.; Vlahos, L.; Kuijpers, J.
2001A&A...377..701P Altcode: 2001astro.ph..7043P
The propagation of a gravitational wave (GW) through a magnetized
plasma is considered. In particular, we study the excitation of
fast magnetosonic waves (MSW) by a gravitational wave, using the
linearized general-relativistic hydromagnetic equations. We derive the
dispersion relation for the plasma, treating the gravitational wave
as a perturbation in a Minkowski background space-time. We show that
the presence of gravitational waves will drive magnetosonic waves in
the plasma and discuss the potential astrophysical implications.
---------------------------------------------------------
Title: A cellular automaton model for the magnetic activity in
accretion discs
Authors: Pavlidou, V.; Kuijpers, J.; Vlahos, L.; Isliker, H.
2001A&A...372..326P Altcode:
In this paper we attempt, for the first time, to simulate the magnetic
activity of an accretion disc using a probabilistic cellular automaton
model. Our model is based on three free parameters, the probabilities of
spontaneous and stimulated generation of magnetic flux above the surface
of the disc (S<SUB>0</SUB>, and, respectively, P), and the probability
of diffusive disappearance of flux below the surface (D). The model
describes a changing collection of flux tubes which stick out of the
disc and are anchored inside the disc at their foot-points. Magnetic
flux tubes transfer angular momentum outwards at a rate which is
analytically estimated for each single loop. Our model monitors the
dynamic evolution of both the distribution of magnetic loops and the
mass transfer which results from angular momentum transport due to
this distribution. The energy release due to magnetic flaring is also
recorded as a function of time and exhibits temporal fluctuations with
power spectra that depend on the assumed emission-profile of single
flaring loops: (i) for instantaneous emission, the power-spectra
are flat at low frequencies and turn over at high frequencies to a
power-law with index -0.3; (ii) for emission-profiles in the form
of one-sided exponentials, the power-spectra exhibit clear power-law
behaviour with index -1.7. Fluctuations with a power law index between
-1 and -1.7 are observed in many systems undergoing accretion. We found
that our approach allows steady accretion in a disc by the action
of coronal magnetic flux tubes alone. If we express the effective
viscosity caused by coronal loops in the usual Shakura-Sunyaev alpha
parameter of viscosity, we find values which are in good agreement
with observed values.
---------------------------------------------------------
Title: Equatorial Pulsar Winds
Authors: Kuijpers, Jan
2001PASA...18..407K Altcode:
Atraditional problem in pulsar wind physics has been the nature of
the pulsar wind. Ontheoretical grounds, the wind is expected to be
dominated by Poynting flux associated with the outgoing magnetic
field lines anchored on the polar caps of the rotating neutron star,
while observations of the Crab Nebula demonstrate that the wind must
be dominated by kinetic energy before the termination shock. Here we
suggest a new approach to this old problem by studying the distributed
currents rather than the singular sheet currents which have been
the object of study in most work. We find that, at a distance well
in between the light cylinder and the termination shock, current
starvation sets in, and electric fields develop along the magnetic
field lines which cause the current to dissipate and convert at least
half of the Poynting flux into kinetic energy flux in a relatively
thin shell. In the shell, at least half of the current closes across
the magnetic field lines, the pitch of the spiralling magnetic field
lines jumps downward strongly, and the outer pattern of magnetic field
lines slips over the inner pattern.
---------------------------------------------------------
Title: Flare Physics in Accretion Discs
Authors: Pavlidou, V.; Kuijpers, J.; Vlahos, L.; Isliker, H.
1999ESASP.448..859P Altcode: 1999mfsp.conf..859P; 1999ESPM....9..859P
No abstract at ADS
---------------------------------------------------------
Title: Magnetodipole Oven
Authors: Istomin, Ya. N.; Kuijpers, J.
1998tx19.confE.247I Altcode:
We found that electromagnetic fields of magnetodipole radiation can
penetrate to the conducting matter of the neutron star's crust and
create there the electric currents and tangential magnetic field
of high magnitude. The obtained solution has the form of surface of
magnetic field discontinuous slowly propagating through the crust to
the core. This model explains the phenomena of Anomalous X-ray pulsars
and Magnetars.
---------------------------------------------------------
Title: Het gelijk van Einstein. De zwaartekracht als weegschaal
en telescoop.
Authors: Kuijpers, J.
1998Zenit..25..196K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Coriolis Effect and the Origin of Prominences
Authors: Kuijpers, J.; Mestel, L.
1998ESASP.417..247K Altcode: 1998cesh.conf..247K
No abstract at ADS
---------------------------------------------------------
Title: A Solar Prominence Model
Authors: Kuijpers, Jan
1997ApJ...489L.201K Altcode: 1997astro.ph..9178K
We propose a model for solar prominences based on converging flow
observed in the chromosphere and photosphere. In contrast with
existing models, we do not apply a shearing motion along the neutral
line. Instead, we assume that bipolar loops approaching on different
sides of the neutral line have a nonvanishing magnetic helicity of
the same sign. In the converging flow the individual loops kink and
develop a skew. For loops of the same helicity the skew is in the same
sense. As a result the "chiral" symmetry of an aligned distribution of
loops is broken, and the reconnecting loop system forms a filament with
the observed magnetic orientation and anchoring of the barbs in regions
of parasitic polarity. The filament consists of a number of individual
strands of coaxial coronal electric currents, each of which is current
neutralized. The filament material is suspended in dips in the magnetic
field, and the transverse field direction coincides with that in the
Kuperus-Raadu model. Above the filament a cavity forms with an overlying
arcade consisting of the outer portions of the reconnected loops.
---------------------------------------------------------
Title: Magnetic pumping in the cataclysmic variable AE Aquarii.
Authors: Kuijpers, J.; Fletcher, L.; Abada-Simon, M.; Horne, K. D.;
Raadu, M. A.; Ramsay, G.; Steeghs, D.
1997A&A...322..242K Altcode:
We propose that the radio outbursts of the cataclysmic variable
AE Aqr are caused by eruptions of bubbles of fast particles from
a magnetosphere surrounding the white dwarf. We investigate the
acceleration process of magnetic pumping in the magnetosphere which
is periodically driven both by the relative motion with the companion
and with the infalling spray of gas at the spin frequency of the white
dwarf. As the accretion rate is relatively low, the conversion of spin
energy into acceleration (rather than heating) of electrons and protons
can be efficient. The accelerated particles are trapped in the white
dwarf magnetosphere until their total energy content becomes comparable
to that of the trapping magnetic field structure and a MHD instability
sets in. Synchrotron radiation is emitted in the expelled expanding
plasmoid at radio and down to millimetric wavelengths. We find that
there is sufficient energy transferred from the rotation energy of the
rapidly-spinning white dwarf to fast particles by magnetic pumping to
explain quiescent and flaring radio emissions.
---------------------------------------------------------
Title: Are Coronal Mass Ejections Caused by Magnetic Pumping?
Authors: Kuijpers, Jan; Fletcher, Lyndsay
1996SoPh..169..415K Altcode:
Magnetic pumping in the solar corona is revisited. We derive conditions
under which magnetic pumping can be the cause of heating of loops
rather than of particle acceleration. Candidate sources for such a
process are coronal mass ejections (CMEs). Large loops are susceptible
to heating primarily of protons by magnetic compressions with periods
between 50 and 5000 s, the observed spectrum of the photospheric
driver. Efficient heating by pumping occurs since in these large loops
the density is low enough that the proton-proton collision time is
comparable to the periods of the external compressions. We suggest
that CMEs may be pressure-driven explosions of large-beta loops
caused by magnetic pumping, in contrast to current-driven `flares'
in low-beta environments.
---------------------------------------------------------
Title: Radiation-driven envelopes around magnetic white
dwarfs. Radiation-driven diskons.
Authors: Zheleznyakov, V. V.; Serber, A. V.; Kuijpers, J.
1996A&A...308..465Z Altcode:
We investigate the formation of a plasma envelope in the magnetosphere
of a hot white dwarf by cyclotron radiation pressure. The radiation
pressure distribution (both in the continuum and in the cyclotron line)
is derived for an optically thin, dipolar magnetosphere of an isolated,
non-rotating star emitting blackbody radiation. For an isothermal,
fully ionized, pure hydrogen plasma the hydrostatic solution consists
of a closed plasma shell accumulated in a potential well near the
equilibrium surface, where radiation pressure cancels gravity, and an
equatorial disk inside this surface. The presence of a finite optical
depth leads to a temporal variation of the plasma envelope and of the
observed radiation. We apply these results to the strongly magnetized
white dwarf GD229, which is a candidate for such a radiation-driven
envelope or "diskon". The deep unidentified 2000-3000. in its UV
spectrum is explained as the result of cyclotron scattering in optically
thick gyroresonant layers around the star. We predict a temporal and
spectral variability of this feature with a characteristic time of
>=1hr due to non-stationary plasma motions in the envelope.
---------------------------------------------------------
Title: Triggering the radio emission from AE Aqr:
Authors: Steeghs, D.; Kuijpers, J.; Fletcher, L.; et al.
1996ASSL..208..167S Altcode: 1996IAUCo.158..167S; 1996cvro.coll..167S
No abstract at ADS
---------------------------------------------------------
Title: Radio emission from polar caps in pulsars
Authors: Kuijpers, J.; Volwerk, M.
1996ASPC..105..181K Altcode: 1996IAUCo.160..181K; 1996ppp..conf..181K
No abstract at ADS
---------------------------------------------------------
Title: Radio Emission from AE Aquarii
Authors: Abada-Simon, M.; Bastian, T. S.; Fletcher, L.; Horne, K.;
Kuijpers, J.; Steeghs, D.; Bookbinder, J. A.
1996ASPC...93..182A Altcode: 1996ress.conf..182A
No abstract at ADS
---------------------------------------------------------
Title: Particle Acceleration
Authors: Kuijpers, J.
1996LNP...468..101K Altcode: 1996plas.conf..101K
It is the purpose of this series of lectures to give an overview of our
understanding of (electromagnetic) particle acceleration processes in
astrophysics. For each process I emphasize the basic physics and point
out differences and correspondences with other mechanisms. Remaining
problems are summarized with references to the recent literature. For
instructive reasons I first discuss a number of fundamental aspects
which are common to several acceleration processes. Thereafter I have
grouped the various processes for particle accelaration into three
chapters according to their underlying physical mechanism: plasma
turbulence, shock waves, and direct electric fields.
---------------------------------------------------------
Title: Cosmic magnetic fields
Authors: Kuijpers, Jan
1995PhyB..211..306K Altcode:
After a summary of the observations of cosmic magnetic fields, I
briefly discuss the status of dynamos, the use of electric circuits,
the physics of magnetic explosions, the role of magnetic tension and
our strongest magnet known, the radio pulsar. Finally I mention a few
problem areas which may show a breakthrough in the near future.
---------------------------------------------------------
Title: Flares in Accretion Disks
Authors: Kuijpers, J.
1995LNP...444..135K Altcode: 1995cmer.conf..135K
Present understanding of solar flares suggests that violent flare
phenomena are common place in coronae of accretion disks. In particular
near magnetized compact objects accretion can be modified by repeated
magnetic energy storage and release. Further also in the absence of a
central magnetosphere, such as around galactic and extragalactic black
holes, magnetic flaring activity is possible in a corona on both sides
of the disk.
---------------------------------------------------------
Title: A magnetic explanation for the rapid burster.
Authors: Kuijpers, J.; Kuperus, M.
1994A&A...286..491K Altcode:
The main observations of Type II bursts in the low-mass X-ray binary
MXB 1730-335 (the Rapid Burster) can be understood if the neutron star's
magnetic field is strong (7 x 10^11^ - 2 x 10^12^ gauss at the surface)
and rotationally symmetric around the axis of a steadily accreting
disk. We show that a Keplerian disk of matter develops inside the
pressure balance radius where it is compressed into a very thin disk
by the external magnetic field. At the inner edge of the disk a ring
of matter is suspended in the stellar magnetic field and corotates
with the star. During quiescence the disk penetrates more and more
into the magnetosphere, the ring accumulates gas and shifts to lower
altitudes. The stellar field sets a maximum to the amount of supported
gas. As soon as the threshold is passed an ideal mhd instability occurs,
the matter ring falls onto the surface and triggers a violent burst of
accretion. As the stellar field relaxes outward accretion onto the star
continues to be enhanced until a new magnetic equilibrium is attained,
the burst ends and a smaller ring is left at higher altitudes. As the
(steady) external accretion continues the ring load increases again
and moves inward until the threshold is reached and the sequence
repeats. Such a bursting behaviour only occurs if the star is an
aligned rotator.
---------------------------------------------------------
Title: A magnetic explanation for the rapid burster
Authors: Kuijpers, J.; Kuperus, M.
1994SSRv...68..333K Altcode:
The observations of X-ray Type II bursts from the low-mass X-ray
binary MXB 1730-335 can be explained by a particular form of magnetic
gating in the presence of steady external accretion. The requirements
are a strong magnetic field of the neutron star (7×10<SUP>11</SUP>
2×10<SUP>12</SUP> gauss at the surface), rotational symmetry and
alignment of the field axis with the axis of a steadily accreting disk
to within 6°.
---------------------------------------------------------
Title: Pair creation in double layers
Authors: Volwerk, Martin; Kuijpers, J.
1994SSRv...68..363V Altcode:
Pair creation in relativistic double layers in shown to have
consequences for the charge density in the double layer and the current
flowing through it.
---------------------------------------------------------
Title: Foreword
Authors: van den Oord, Bert; Kuijpers, Jan; Kuperus, Max; Benz, A. O.;
Brown, J. C.; Einaudi, G.; Kuperus, M.; Raadu, M. A.; Trottet, G.;
van den Oord, G. H. J.; Vlahos, L.; Zheleznyakov, V. V.; Wijburg,
Marion; Fletcher, Lyndsay; Volwerk, Martin
1994SSRv...68D..17V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Strong Double Layers, Existence Criteria, and Annihilation:
an Application to Solar Flares
Authors: Volwerk, Martin; Kuijpers, Jan
1994ApJS...90..589V Altcode: 1994IAUCo.142..589V
We present some conditions for the stability of a strong double
layer in a warm, current-carrying plasma, which can be extended into
the relativistic regime. We apply a model for plama heating by the
electron beam emitted from the double layer and show that this leads
to a finite life time to the double layer. We also show that the radio
emission accompanying this process can well describe the observed
phenomena in Type I radio bursts using a direct emission mechanism,
not involving Langmuir waves.
---------------------------------------------------------
Title: Magnetic flares near accreting black holes
Authors: Volwerk, M.; van Oss, R. F.; Kuijpers, J.
1993A&A...270..265V Altcode:
The present treatment of magnetic flaring interactions between a
black hole and an ionized accretion disk assumes that magnetic fields
created in the disk, and extending into a force-free corona, will be
transported onto the black hole time-horizon by the accreting plasma;
magnetic links between disk and horizon would then occur. An equilibrium
condition on the field structure of the connection is found not to be
generally satisfied. It is concluded that these magnetic connections
will release their free energy during flares, and that the form this
can take, as a sequence of magnetic explosions, can be a measurable
fraction of disk luminosity for stellar-mass black hole candidates.
---------------------------------------------------------
Title: Elastiekjes, magneten en vuurwerk.
Authors: Kuijpers, J.
1993Zenit..20..125K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book reviews
Authors: Pallottino, G. V.; Heintze, J. R. W.; van Delden, A. J.;
Marov, Mikhail Ya.; Kuijpers, J. M. E.; Spoelstra, T. A. Th.; Voigt,
H. H.; van Gent, R. H.; Thé, P. S.; Henrichs, Huib; Icke, V.
1993SSRv...63..191P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book Review: Transition radiation and transition scattering /
Adam Hilger, 1990
Authors: Kuijpers, J.
1993SSRv...63..195K Altcode: 1993SSRv...63..195G
No abstract at ADS
---------------------------------------------------------
Title: Pulsar core emission and double layers
Authors: Volwerk, M.; Kuijpers, J.
1993dlon.conf..459V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Physical Processes in Hot Cosmic Plasma
Authors: Brinkmann, W.; Fabian, A. C.; Giovannelli, F.; Kuijpers,
J. M. E.
1993SSRv...63..193B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A magnetic flare model for X-ray variability in AGN.
Authors: de Vries, M.; Kuijpers, J.
1992A&A...266...77D Altcode:
The power spectra of X-ray light curves of active galactic nuclei
(AGN) observed with EXOSAT, show approximately the same 1/v power
law dependence. To explain the X-ray variability we propose a flare
model based on recurrent explosive release of stored magnetic energy
in coronae of accretion disks in AGN. Based on the virial theorem
we develop an analytical model for the power released in magnetic
flares in a radiation pressure dominated accretion disk corona. A major
difference exists with the solar case: beams of relativistic electrons
produced by the flare in the corona, loose all their energy by inverse
Compton scattering on UV disk photons before being able to reach the
disk. These Compton losses determine the X-ray variability. It is shown
how the dependence of the flare characteristics on the distance to the
central object provides the required range in time-scales and power to
reproduce the observed power spectra. Finally we present a worked out
model based on the van Tend- Kuperus solar flare model. Our results
on the predicted power spectra are however independent of the assumed
applicability of the lather model.
---------------------------------------------------------
Title: Magnetic flares near black holes.
Authors: Volwerk, M.; Kuijpers, J.; van Oss, R.
1992ASIC..377..537V Altcode: 1992xrb..work..537V
No abstract at ADS
---------------------------------------------------------
Title: Physics of Flares in Stars and Accretion Disks
Authors: Kuijpers, J.
1992ASIC..373..535K Altcode: 1992sla..conf..535K
No abstract at ADS
---------------------------------------------------------
Title: Book reviews
Authors: Hayakawa, S.; Kuijpers, J.; Kleczek, J.; Valnicek, Boris;
Kresak, L.; de Ruiter, H. R.
1991SSRv...57..189H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Flaring interactions between accretion disk and neutron star
magnetosphere.
Authors: Aly, J. J.; Kuijpers, J.
1990A&A...227..473A Altcode:
The effect of magnetic reconnections between the magnetosphere of a
neutron star and the accretion disk is considered using a model of
a neutron-star/disk system, which assumes the existence of magnetic
'loops' anchored in the disk and extending into a corona on both
sides of the disk. It is shown that these magnetic links are efficient
transmitters of angular momentum. At the disk plane, the linked field
is forced to rotate with near-Keplerian velocity, while it corotates
with the star at the other end. The magnetic energy is stored in the
sheared and expanding field link, which is released upon a transition
to a lower energy state again caused by reconnection. This process
leads to a release of flaring energy in the magnetosphere and to
the transport of angular momentum between the disk and the star. It
is proposed that these magnetic flares might be an explanation for
quasi-periodic oscillations.
---------------------------------------------------------
Title: A Nonsteady Reconnection Model for Solar Prominences.
Authors: Kuijpers, J.
1990ppsa.conf..227K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Coherent Radiation from Electrostatic Double Layers.
Authors: Kuijpers, J.
1990ppsa.conf...17K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Flares in Close Binaries
Authors: Kuijpers, J.
1990ASIC..319..761K Altcode: 1990acb..proc..761K
No abstract at ADS
---------------------------------------------------------
Title: Coherent Radiation from Electrostatic Double Layers
Authors: Kuijpers, Jan
1990IAUS..142..365K Altcode:
The efficiency of two coherent radiation processes - antenna radiation
and a maser process - is studied. Both processes are found capable
of operating in electrostatic double layers (DLs) to produce intense
and narrow-band emission. Antenna radiation occurs if the dimensions
of the double layer are smaller than the wavelength of the emitted
radiation. The maser requires an amplification length inside the
double layer much larger than the emitted wavelength, and can lead
to observable emission in astrophysical circumstances. The growth is
exponential and the rate depends only on the electric field energy
density of the DL. Since the latter is externally controlled by the
electric circuit, it is a constant for the emission process so as
to constitute a true maser. The maximum brightness temperature is of
the order of 10 exp 25 K. Masing radiation from electrostatic DLs is
therefore a candidate for some of the observed intense narrow-band
cosmic radio emission.
---------------------------------------------------------
Title: A magnetic flare model for X-ray variability in AGN.
Authors: de Vries, Mark; Kuijpers, Jan
1989ESASP.296.1069D Altcode: 1989ttxa.symp.1069D
The authors develop a model to explain the observed, approximately 1/f,
power spectrum of the X-ray variability in low-luminosity Seyferts. The
proposed model involves a current carrying mass filament in the corona
of an accretion disk. Using arguments similar to the ones put forward
for solar flares, the authors estimate the amount of magnetic energy
which can be stored inside the tube. They determine the kinetic energy
of particle beams which result from this flare process. Inverse Compton
loss times and emitted power from the beams are calculated and they
seem to fit the observations very well. Possible means of verification
of the model are indicated.
---------------------------------------------------------
Title: Radio Emission from Stellar Flares
Authors: Kuijpers, Jan
1989SoPh..121..163K Altcode: 1989IAUCo.104..163K
An overview is given of the observations of stellar radio `flares',
defined as radio emission which is both variable in time and created
by explosive releases of magnetic energy. The main sources of such
flares are late-type Main-Sequence stars, classic close binaries,
X-ray binaries, and pre-Main-Sequence stars.
---------------------------------------------------------
Title: A combined radio and X-ray observation of Algol.
Authors: van den Oord, G. H. J.; Kuijpers, J.; White, N. E.; van der
Hulst, J. M.; Culhane, J. L.
1989A&A...209..296V Altcode:
The detection of Algol (Beta Per) at 1.4 GHz is reported. The eclipsing
phase of Algol has been observed in radio and at X-ray energies. The
radio emission is explained as synchrotron radiation from electrons
with energies of about 1 MeV. The magnetic field strength is of the
order of tens of Gauss. The radio and X-ray emission are cospatial but
the energy in the radio component is 1,000,000 times smaller than that
of the X-ray component. The simultaneous observation indicates that
an energetic particle component can be present in a quiescent X-ray
emitting corona.
---------------------------------------------------------
Title: MHD waves from inhomogeneous accretion in T Tauri stellar
magnetospheres
Authors: Scheurwater, R.; Kuijpers, J.
1988A&A...190..178S Altcode:
The authors consider the radiation of MHD-waves when a
protostellar plasma cloud falls along an ambient magnetic
field onto the surface of a T Tauri star. It is shown that the
excitation mechanism is efficient in the frequency interval
0 < ω ⪉ 4 v<SUB>c</SUB>/r<SUB>c</SUB> where the infall
velocity v<SUB>c</SUB> of the cloud is taken to be subalfvénic
and r<SUB>c</SUB> is the radius of the cloud. The efficiency
of wave-excitation is calculated and turns out to be of order 0.1
(ρ<SUB>c</SUB>/ρ<SUB>0</SUB>)(v<SUB>c</SUB>/c<SUB>A</SUB>)<SUP>3</SUP>
for the Alfvén mode and of order 1.8
(ρ<SUB>c</SUB>/ρ<SUB>0</SUB>)(v<SUB>c</SUB>/c<SUB>A</SUB>)<SUP>7</SUP>
for the fast mode (c<SUB>A</SUB> is the Alfvén speed, ρ<SUB>c</SUB>
is the mass density inside the cloud and ρ<SUB>0</SUB> that of the
ambient atmosphere).
---------------------------------------------------------
Title: On the Controversy Concerning Turbulent Bremsstrahlung
Authors: Melrose, D. B.; Kuijpers, J.
1987ApJ...323..338M Altcode:
It is shown that the derivation of a nonzero growth rate for
turbulent bremsstrahlung involves an incomplete summation of the
nonlinear responses. When the classically correct expression is used,
the growth rate is identically zero. Next the authors show that the
radiative correction to the resonant emission of ion sound waves in the
presence of nonresonant Langmuir waves is derived explicitly. Finally,
they reply to criticisms by Nambu (1986) of an earlier paper and show
that the inclusion of a background magnetic field gives a zero growth
rate for this proposed kind of turbulent bremsstrahlung.
---------------------------------------------------------
Title: Book Review: Instabilities in space and laboratory plasmas. /
CUP, 1986.
Authors: Kuijpers, J.
1987SSRv...45..408K Altcode: 1987SSRv...45..408M
No abstract at ADS
---------------------------------------------------------
Title: A High-Energy Solar Flare Burst Complex and the Physical
Properties of its Source Region
Authors: de Jager, Cornelis; Kuijpers, Jan; Correia, Emilia; Kaufmann,
Pierre
1987SoPh..110..317D Altcode:
We discuss a solar flare microwave burst complex, which included a
major structure consisting of some 13 spikes of 60 ms FWHM each,
observed 21 May, 1984 at 90 GHz (3 mm). It was associated with a
simultaneous very hard X-ray burst complex. We suggest that the
individual spikes of both bursts were caused by the same electron
population: the X-bursts by their bremsstrahlung, and the microwave
bursts by their gyrosynchrotron emission. This latter conclusion
is based on the evidence that the radio turnover frequency was ≤
150 GHz. It follows that the emission sources were characterized
by an electron density of about 10<SUP>11</SUP> cm<SUP>−3</SUP>,
a temperature of 5 × 10<SUP>8</SUP> K and a magnetic field of about
1400-2000 G. They had a size of about 350 km; if the energy release is
caused by reconnection the sources of primary instability could have
been smaller and in the form of thin sheets with reconnection speed at
a fraction of the Alfvén velocity and burst-like energy injections
of ≈ 10<SUP>27</SUP> erg during about 50 ms each. The energized
plasma knots lost their injection energy by saturated convective flux
(collisionless conduction) in about 30 ms.
---------------------------------------------------------
Title: A high energy solar flare burst complex and the physical
properties of its source region
Authors: De Jager, C.; Kuijpers, J.; Correia, E.; Kaufmann, P.
1986cospar........D Altcode:
A solar flare microwave burst complex, which exhibited a major structure
consisting of some 13 spikes of 60 ms FWHM each, observed 21 May 1984
at 90 GHz (3 mn) is discussed. It was associated with a simultaneous
very hard X-ray burst complex. A possible explanation in which the
individual spikes of both bursts were caused by the same electron
population is developed: the X-ray bursts by their bremsstrahlung, and
the microwave bursts by their gyro-synchrotron emission. This latter
explanation is based on the assumption that the radio turnover frequency
is less than 150 GHz. The emission sources were characterized by an
electron density of about 10 to the 11th power/cu cm, a temperature
of 5 x 10 to the 8th power K and magnetic field of about 1400 to 2000
G. They had a size of about 350 km; if the energy release is caused
by reconnection the sources of primary instability could have been
smaller and in the form of thin sheets with reconnection speed at
a fraction of the Alfven velocity and burst-like energy injections
of 10 to the 27th power erg during about 50 ms each. The energized
plasma knots lost their injection energy by saturated convective flux
(collisionless conduction) in about 30 ms.
---------------------------------------------------------
Title: Bombardment solutions to the "soft X-ray puzzle" in radial
white dwarf accretion.
Authors: Thompson, A. M.; Brown, J. C.; Kuijpers, J.
1986A&A...159..202T Altcode:
The problem of the observed low ratio of hard to soft X-rays in
accreting white dwarfs, with low accretion rate (e.g. AM Her), is
discussed in terms of models where the accreting matter is treated as
a nonthermal stream bombarding a static atmosphere cooled by optically
thin radiation (Kuijpers and Pringle, 1982). It is shown that the
proton collisional mean free path used by Kuijpers and Pringle (1982)
was inappropriate for the inferred temperature regime and that when
the correct expression is used the global mean temperature of a steady
state bombardment solution is much lower (about 10 to the 5 K) and much
closer to observations. It is seen that no steady state solution is
possible without invoking some other kind of energy transport mechanism;
such bombardment models cannot explain the 'soft X-ray puzzle'. The
shock solution of Frank and King (1984) - and its failure to solve
the puzzle - are discussed.
---------------------------------------------------------
Title: An EXOSAT Observation of Quiescent and Flare Coronal X-Ray
Emission from Algol
Authors: White, N. E.; Culhane, J. L.; Parmar, A. N.; Kellett, B. J.;
Kahn, S.; van den Oord, G. H. J.; Kuijpers, J.
1986ApJ...301..262W Altcode:
X-ray emission from the Algol system is believed to originate in a
corona associated with the K star. The authors have used the EXOSAT
Observatory to make a 35 hr continuous observation centered on the
occultation of the K star by the B star primary. The spectrum of
the quiescent emission in the 1 - 10 keV band gives a temperature of
2.5×10<SUP>7</SUP>K. This spectrum, extrapolated to lower energies,
can account for more than 80% of the observed count rate. No obvious
X-ray eclipse was seen. An X-ray flare was detected with a rise time
of ≡1700 s and an exponential decay of ≡7000 s. The 0.1 - 10 keV
peak luminosity was 1.4×10<SUP>31</SUP>ergs s<SUP>-1</SUP>. The peak
temperature was 6×10<SUP>7</SUP>K, with an iron K line confirming
the thermal character of the emission.
---------------------------------------------------------
Title: Solar VLBI.
Authors: Tapping, K. F.; Kuijpers, J.
1986NASCP2449..211T Altcode: 1986rfsf.nasa..211T
In April, 1981, radio telescopes at Dwingeloo (The Netherlands)
and Onsala (Sweden) were used as a long-baseline interferometer at a
wavelength of 18 cm. The baseline of 619 km gave a spatial resolution on
the Sun of about 45 km. The major problems of Solar Very Long Baseline
Interferometry are discussed.
---------------------------------------------------------
Title: Book-Review - Cold Plasma Waves
Authors: Booker, H. G.; Kuijpers, J.
1985SSRv...41..402B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Interpretation of unpolarized radio emission from RS CVn stars.
Authors: Kuijpers, J.; van der Hulst, J. M.
1985A&A...149..343K Altcode:
The authors investigate the emission process and the energy budget
of radio flares in RS CVn stars by applying various mechanisms to
the close binary σ<SUP>2</SUP>CrB (HD 146361) of RS CVn type. Radio
emission from this system observed with the WSRT at 21 cm is explained
as synchrotron emission from electrons with Lorentz factors 3.5-3.1 in
magnetic fields of strength 27 - 35 G. The energy source of the radio
emitting electrons and of the previously observed X-ray gas is studied;
the authors show that a solar-like filament flare forms an attractive
mechanism to explain the observed energy release.
---------------------------------------------------------
Title: Nonexistence of two forms of turbulent bremsstrahlung
Authors: Kuijpers, J.; Melrose, D. B.
1985ApJ...294...28K Altcode:
It is shown that the forms of turbulent bremsstrahlung proposed by
Tsytovich, Stenflo, and Wilhelmsson (1975) and by Nambu (1981) do
not exist. The proposed mechanisms involve upconversion of ion sound
turbulence into Langmuir turbulence, with the ion sound waves being
emitted and absorbed resonantly and the Langmuir waves being emitted
and absorbed nonresonantly. It is pointed out that a symmetry implicit
in a standard QED treatment implies that there is another contribution
to turbulent bremsstrahlung in addition to that calculated by Tsytovich,
Stenflo, and Wilhelmsson and that the two contributions cancel exactly,
leading to the null result. Nambu made an approximation inconsistently,
and when this approximation is not made, two terms in his analytic
treatment cancel exactly. It is argued that turbulent bremsstrahlung
is related to a radiative correction in which the resonant emission
of ion sound turbulence is modified by the nonresonant emission and
absorption of Langmuir waves. Physically the nonexistence of turbulent
bremsstrahlung is interpreted as being due to each emission of a
Langmuir quantum being associated with an absorption of an identical
Langmuir quantum so that the Langmuir turbulence is unchanged. Proposed
astrophysical applications of turbulent bremsstrahlung need to be
reconsidered.
---------------------------------------------------------
Title: Bombardment Models of White Dwarf Accretion Columns
Authors: Thompson, A. M.; Brown, J. C.; Kuijpers, J.
1985ASSL..116...43T Altcode: 1985rst..conf...43T
The problem of the observed low ratio of hard to soft X-rays in
accreting white dwarfs, with low accretion rates, (e.g. AM Her) is
discussed in terms of models where the accreting matter is treated as
a non-thermal stream bombarding a static atmosphere cooled by optically
thin radiation (Kuijpers & Pringle, 1982).
---------------------------------------------------------
Title: An EXOSAT Observation of the Morphology of the Coronal X-Ray
Emission from Algol
Authors: White, N. E.; Culhane, J. L.; Parmar, A. N.; Kellett, B.;
Kahn, S.; van den Oord, G. H. J.; Kuijpers, J.
1985SSRv...40...25W Altcode:
The X-ray emission from Algol is thought to originate in a corona
associated with the K star in this system. We report the results of a 35
hr continuous EXOSAT observation through secondary optical eclipse that
was designed to measure the structure of the corona. No obvious X-ray
eclipse was seen. The spectrum measured by the ME gives a temperature of
2.5 × 10<SUP>7</SUP> K, consistent with the hard component previously
seen by the Einstein SSS. The soft component previously reported by
the SSS would only contribute at most 25% to the count rate seen in
the LE (used with Al/P). The lack of a hard X-ray eclipse indicates the
dimensions of the higher temperature emission region to be comparable
to or greater than the size of the K star. An X-ray flare was detected
with a peak luminosity of 1.4 × 10<SUP>31</SUP> erg s<SUP>-1</SUP>
and a total duration of 8 hours. The peak temperature was 5.0 keV with
an emission measure of 9.4 × 10<SUP>53</SUP> cm<SUP>-3</SUP>. The
thermal nature of the flare is confirmed by the detection of an iron
line with an EW of ∼2 keV. By equating the observed decay time of
the flare to a known cooling law gives a dimension for the flaring
loop of ∼0.3 stellar radii. This is much smaller than the dimensions
of the hard component inferred from the lack of an eclipse. It seems
probable that the flare occurred in one of the loops responsible for
the lower temperature component seen by the SSS.
---------------------------------------------------------
Title: The physics of active stellar systems.
Authors: Kuijpers, J.
1985NTNA...51...21K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Radio Observable Processes in Stars (Invited Paper)
Authors: Kuijpers, J.
1985ASSL..116....3K Altcode: 1985rst..conf....3K
The most important physical processes in the atmospheres of (noncompact)
stars that can be studied fruitfully with observations in the radio
continuum are reviewed. The emission mechanisms are free-free and
gyrosynchrotron radiation, (inverse) Compton scattered, and various
kinds of plasma radiation. The free-free emission in stellar winds
where observations of time variations are important for the study of
instabilities and relaxation oscillations is considered. The main part
of the paper concerns magnetic activity, and in particular stellar
flares. Mostly from a theoretical point of view, the problems of the
density of the flare plasma, the flare energy, dMe flare stars, detached
(RS CVn stars) and semidetached (Algols) close binaries, are considered,
together with the role of duplicity, magnetic interactions and mass
transfer, T Tauri stars, and particle acceleration in shocks and in
the unipolar inductor. Finally, the various kinds of plasma radiation
are reviewed, and the importance of establishing the brightness
temperature of flares with VLBI, and of observing the nature and degree
of polarization to find out the flare plasma physics, is pointed out.
---------------------------------------------------------
Title: Resonant parts of nonlinear response tensors
Authors: Melrose, D. B.; Kuijpers, J.
1984JPlPh..32..239M Altcode:
It is pointed out that ambiguities arise in taking the resonant parts
of nonlinear response tensors. A prescription is proposed and used
to evaluate the resonant parts explicitly in terms of a covariant
and gauge invariant formalism. Symmetry properties of the resonant
parts are identified. The prescription used can be justified by
analogy with a calculation based on QED where no ambiguity arises;
it is also justified directly by classical arguments. In some standard
treatments of nonlinear damping processes a necessary symmetry is not
imposed. When this symmetry is imposed, the relations derived here
imply that turbulent bremsstrahlung, as defined by Tsytovich et al.,
does not exist.
---------------------------------------------------------
Title: Book reviews
Authors: Kuijpers, Jan; Kleczek, Josip; Lamers, H. J. G. L. M.; Kruit,
P. C. V. D.; Kuperus, M.; Knott, K.
1984SSRv...38..385K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book reviews
Authors: Ooms, O.; van der Woerd, Hans; Lamers, Henny J. G. L. M.;
Kleczek, Josip; Kovalevsky, J.; Gathier, R.; Jarzebowski, T.; Swings,
J. P.; van der Hucht, K. A.; Namba, O.; Mewe, R.; Lynden-Bell,
D.; Kuijpers, Jan; van der Klis, M.; de Hoop, D.; Wittenberg, H.;
Iwanowska, W.; Thé, P. S.; Schrijver, J.; Pottasch, S. R.
1984SSRv...37..399O Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Diffusion of high energy electrons in the solar corona
Authors: Achterberg, A.; Kuijpers, J.
1984A&A...130..111A Altcode:
A theoretical mechanism explaining the soft X-ray halo observed around
the site of solar flares is proposed on the basis of an analytical
investigation of anomalous diffusion of high-energy electrons by
turbulent waves and magnetic irregularities. General expressions are
derived and applied to the conditions prevalent in the solar corona,
and the SMM (HXIS) and Culgoora radio observations of the flare of
May 21-22, 1980, reported by Zvestka et al. (1982) are summarized and
analyzed in the light of the analytical results. The X-ray halo can
be explained by electron escape from the flaring loop via anomalous
diffusion if electron energy is greater than about 100 keV, density
is 10 to the 10th/cu cm or less, and the magnetic disturbance has
(delta B)/B = a few percent.
---------------------------------------------------------
Title: Book-Review - Astrophysical Jets
Authors: Ferrari, A.; Pacholczyk, A. G.; Kuijpers, J.
1984SSRv...38..385F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Highlights of Astronomy V.6
Authors: West, R. M.; Kuijpers, J.
1984SSRv...37..404W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Radial white dwarf accretion.
Authors: Kuijpers, J.; Pringle, J. E.
1984PhST....7..120K Altcode: 1984PhyS....7..120K
The authors discuss radial accretion flow onto white dwarfs for which
cyclotron emission is insignificant. It is shown that a stationary
bombardment solution exists for not too large accretion rates in which
the accretion energy is transferred to the target atmosphere within one
collisional mean free path and then radiated at much lower temperatures
than in the shock model.
---------------------------------------------------------
Title: Book reviews
Authors: Namba, O.; Kuijpers, Jan; De Loore, C.; Roody, R. M.;
Marlborough, J. M.; Rasool, S. I.; Kovalesky, J.; van der Kruit, P. C.;
Kleczek, J.; de Jager, C.; Lewis, A.; Hovenier, J. W.; Grewing, M.
1983SSRv...35..293N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: VLBI of solar flares
Authors: Tapping, K. F.; Kuijpers, J.; Kaastra, J. S.; van Nieuwkoop,
J.; Graham, D.; Slottje, C.
1983A&A...122..177T Altcode:
From April 28 to May 3, 1981, a VLBI experiment was carried out
to observe small spatial scales in the initial energy release
in solar flares. The 25 m radio telescope at Onsala (Sweden) and
Dwingeloo (Netherlands) were used; the observing wavelength was 18
cm. Simultaneous observations were made using the Westerbork Synthesis
Radio Telescope at a wavelength of 6 cm. The VLBI baseline was 619
km. During the observing period, three weak outbursts were observed,
none yielding any strong correlated signals. However, the statistical
behaviour of the correlator output over the range of delay channels
shows significant indications of a correlated signal having a signal
to noise ratio of order unity, during the impulsive spikes preceding
the main phase of the event.
---------------------------------------------------------
Title: Book-Review - Gravity Particles and Astrophysics
Authors: Wesson, P. S.; Kuijpers, J.
1983SSRv...35..293W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Very long baseline interferometry of solar flares
Authors: Kuijpers, J.; Tapping, K. F.; Graham, D.
1983ASSL..102..339K Altcode: 1983ards.proc..339K; 1983IAUCo..71..339K
An experimental VLBI search for the occurrence of subarcsecond
microwave emission centers as tracers of the initial energy release in
solar flares is discussed. The observations extended over the period
April 28 to May 3, 1981, during which period three weak outbursts
occurred. No large correlations were observed, but a strong indication
of an unresolved source with a signal to noise ratio of order unity
was found during the impulsive bursts preceding the main phase of
one event. During the impulsive bursts the spread in number of the
channel which showed the maximum correlation amplitude was reduced
significantly below the value for random behavior. A clear reduction
in the amount of scatter from the expectation value during impulsive
bursts is shown. The derived brightness temperature is of the order 10
to the 12th K; the probable error box for the source position is shown.
---------------------------------------------------------
Title: Comments on radial white dwarf accretion
Authors: Kuijpers, J.; Pringle, J. E.
1982A&A...114L...4K Altcode:
The present study of radial accretion flow onto white dwarfs for which
cyclotron emission is insignificant has ascertained that conduction
cannot be the dominant energy loss mechanism if a stationary, standoff
shock exists above the stellar surface. It is inferred that, in such
cases, an abundance of hard X-rays is emitted. By analogy with solar
coronal loop models, however, conduction may lead to stellar material
evaporation and subsequent enhanced bremsstrahlung losses. Conduction
may therefore influence the stability and global behavior of the
post-shock region. It is demonstrated that there exists a stationary
bombardment solution for moderate accretion rates in which the accretion
energy is transferred to the target atmosphere within one collisional
mean free path, and then radiated at much lower temperatures than
in the shock model. A nonstationary model without standoff shock is
also proposed.
---------------------------------------------------------
Title: Runaway acceleration in a radio flare
Authors: Kuijpers, J.; van der Post, P.; Slottje, C.
1981A&A...103..331K Altcode:
Radio observations of a solar flare are explained by induced electric
fields in several small regions within a flaring flux tube. In each
acceleration region runaway electrons are produced which lead to
a pulsed production of high-frequency plasma waves. The model is
used for an accurate determination of the physical conditions in the
flare. During the runaway process an essential fraction of the runaway
energy is put into plasma waves. The required electric field strength
is of order E/E<SUB>c</SUB> approximately equal to 0.1 (E<SUB>c</SUB>
is twice the Dreicer field) and the ratio of electron cyclotron to
plasma frequency is of order unity or larger.
---------------------------------------------------------
Title: Collisionless perpendicular shocks - Applications to solar
type II radio bursts and the Antares /alpha Sco/ radio emission
Authors: Klinkhamer, F. R.; Kuijpers, J.
1981A&A...100..291K Altcode:
A model of a collisionless perpendicular shock is proposed based
on (1) local marginal stability of ion-acoustic waves and (2) ion
heating in supercritical shocks by a beam of reflected ions behind
the shock proper. The mean turbulence energy density in the shock is
calculated. Type II radio bursts of the sun and their characteristic
fine structures lend themselves to explanation. The effective
temperature of the ion-sound waves is found to be substantially larger
than the observed radio brightness temperature. By using the turbulent
Bremsstrahlung mechanism for Langmuir waves, the radio luminosity can be
accounted for. In addition, the observed radio emission from the Antares
B companion star embedded in a stellar wind from the M supergiant is
considered. The available free energy in a single bow shock is found
to be far less than the observed radio luminosity. The estimated wind
from the B star itself, however, creates a secondary shock which is
sufficiently energetic to account for the observed emission.
---------------------------------------------------------
Title: Radioverschijnselen als boodschappers uit de zonnecorona (3)
continuüm-uitbarstingen en hun geheimentaal.
Authors: Fokker, A. D.; Kuijpers, J. M. E.
1981Zenit...8...28F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book reviews
Authors: Verbunt, Frank; Kleczek, J.; Bleeker, J. A. M.; Kuijpers,
Jan; Dommanget, J.
1980SSRv...27..215V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Comment on 'On the upconversion of ion sound to Langmuir
turbulence,' by L. Vlahos and K. Papadopoulos
Authors: Kuijpers, J.
1980ApJ...238L.165K Altcode:
It is shown that the production of Langmuir waves from ion sound
by the turbulent bremsstrahlung mechanism can be more effective
than the destruction of the Langmuir waves by the Dawson-Oberman
resistivity. Previous conclusions to the contrary are in error owing
to the neglect of the wave-number dependence of the ion-sound waves.
---------------------------------------------------------
Title: Turbulent bremsstrahlung of Langmuir waves
Authors: Kuijpers, J.
1980A&A....83..201K Altcode:
The turbulent bremsstrahlung process of Tsytovich et al. (1975) is
reconsidered. In this mechanism the electrons that are resonant with an
already existing nonthermal level of ion-sound waves radiate Langmuir
waves. The efficiency of the process is derived in an independent way
and corrections are found to the previous result. In particular it is
found that Langmuir waves can only be produced efficiently when the
ion-sound wave number is of the order of the Debye wave number. It
is shown that in this case the consumed total ion-sound wave energy
roughly equals the total amount of radiated Langmuir wave energy.
---------------------------------------------------------
Title: Book-Review - Galaxies and Quasars
Authors: Kaufmann, W. J., III; Kuijpers, J.
1980SSRv...27..216K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The active radio sun.
Authors: Fokker, A. D.; Kuijpers, J. M. E.
1980NTNA...46...26F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Radioverschijnselen als boodschappers uit de zonnecorona
(I). Het decor der radioverschijnselen.
Authors: Fokker, A. D.; Kuijpers, J. M. E.
1980Zenit...7..334F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Radioverschijnselen als boodschappers uit de zonnecorona
(2). Kennismaking met enkele radioverschijnselen.
Authors: Fokker, A. D.; Kuijpers, J. M. E.
1980Zenit...7..436F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Theory of type IV DM bursts
Authors: Kuijpers, J.
1980IAUS...86..341K Altcode:
It is noted that the study of fine structures in continuum radio
emission from the sun is of importance in order to probe the physics
of radio sources and of flares in particular. The existing fine
structure theories are reviewed and an application to a radio flare
is given. Attention is given to stationary magnetic traps including
discussion of high frequency electrostatic instability, and high
frequency electromagnetic instability. It is shown that the most
important high frequency instability in such traps in the solar corona
is the loss-cone instability of upper hybrid waves at the resonant
surfaces. In addition, the characteristics of the most important fine
structures in type IV dm bursts in the 160-320 MHz band as described
mainly by Slottje (1980) are presented and the type IV dm burst of
June 25, 1978 is examined.
---------------------------------------------------------
Title: Pulsed Acceleration in Solar Flares
Authors: Kuijpers, J.
1978A&A....69L...9K Altcode:
Summary It is shown that plasmaturbulence in solar flares may well
lead to periodic acceleration of particles. The periodicity of the
acceleration process is due to the intrinsic non-linearity of the
coupled rate equations describing the production of ion-sound and
Langmuir waves. Key words Solar flares, acceleration, plasma waves.
---------------------------------------------------------
Title: Book reviews
Authors: Plavec, Miroslav; Hoekstra, R.; de Jager, C.; Grygar, Jiři;
Otterman, J.; van den Dool, H. M.; Namba, O.; Gunsing, C. J. Th.;
Pecker, Jean-Claude; Kwee, K. K.; Perek, L.; Callebaut, D.; Kuijpers,
Jan; de Graaff, W.; Reijnen, G. C. M.; Swanenburg, B.; Grevesse,
N.; Kleczek, J.; Piquet, P.; Fokker, A. D.; van Bueren, H. G.; Page,
D. Edgar; van Duinen, R. J.; Pacini, Franco
1978SSRv...21..469P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Type IV dm bursts: onset and sudden reductions.
Authors: Benz, A. O.; Kuijpers, J.
1976SoPh...46..275B Altcode:
The effect of collisions of suprathermal electrons with a thermal
background plasma is investigated and is shown to cause flattening of a
monotonically descending velocity distribution of fast particles. As a
result flare-produced energetic electrons that are trapped in a coronal
magnetic arch and that are initially distributed in energy according to
a power-law, can give rise to an instability of Langmuir waves in the
background plasma and the subsequent emission of continuum radiation
as observed in type IV dm bursts.
---------------------------------------------------------
Title: Fiber burst concurrent with a weak noise storm.
Authors: Kuijpers, J.; Slottje, C.
1976SoPh...46..247K Altcode:
A new kind of radio burst is described and identified as quasi-fiber
burst according to some striking similarities with fiber bursts. Its
interpretation is discussed in terms of Kuijpers' whistler model and an
explanation for a broken variety of. the observed burst is given. The
derived magnetic field strength in the source is 4 G at a plasma level
of 300 MHz.
---------------------------------------------------------
Title: Generation of Intermediate Drift Bursts in Solar Type IV
Radio Continua Through Coupling of Whistlers and Langmuir Waves
Authors: Kuijpers, J.
1975SoPh...44..173K Altcode:
The possible generation of intermediate drift bursts in type IV dm
continua through coupling between whistler waves, traveling along the
magnetic field, and Langmuir waves, excited by a loss-cone instability
in the source region, is elaborated. We investigate the generation,
propagation and coupling of whistlers.
---------------------------------------------------------
Title: A unified explanation of solar type IV dm continua and zebra
patterns.
Authors: Kuijpers, J.
1975A&A....40..405K Altcode:
A unified mechanism is presented for the production of type IV dm
continuum radiation and zebra-pattern microstructure. It is shown that
both the continuum and zebra patterns can originate in plasma waves at
the upper hybrid frequency which are excited by a loss-cone distribution
of fast electrons superposed on the thermal background. The zebra
patterns will result from the electrostatic instability at source-region
surfaces with integer ratios of electron plasma frequency/electron
cyclotron frequency provided that the fraction of fast particles is
small and the frequency ratio is large. A continuum will be produced
under opposite conditions or in the same way as the zebra patterns if
the magnetic-field inhomogeneity makes the plasma frequency vary more
than a value equal to the average electron cyclotron frequency along
the different harmonic surfaces.
---------------------------------------------------------
Title: Collective wave-particle interactions in solar type IV radio
sources.
Authors: Kuijpers, J.
1975UtrOv.301.....K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Collective wave-particle interactions in solar type IV
radio sources
Authors: Kuijpers, J. M. E.
1975PhDT.........1K Altcode:
This thesis proposes a coherent emission mechanism for type IV
decimetric radio bursts, a unified explanation of solar type IV
decimetric continuum storms and zebra patterns, and a possible emission
mechanism for intermediate drift bursts. Observations of solar type
IV bursts, continuum storms, and fine structures are reviewed. The
fine structures and source regions are described, and velocity-space
instabilities are analyzed. It is suggested that type IV bursts are
produced by the induced conversion of coherently generated Cerenkov
plasma waves into electromagnetic waves. It is proposed that continuum
storms and zebra patterns originate in plasma waves excited at the
upper hybrid frequency by a loss-cone distribution of fast electrons
superposed on the ion background, that the patterns result when the
inverse fractional density of the fast electrons exceeds the ratio of
the electron plasma and cyclotron frequencies, and that the storms
occur in the opposite situation. It is shown that the coupling of
whistler solitons and Langmuir waves can produce intermediate drift
bursts when the phase velocity of the Langmuir waves is of the order
of the speed of light.
---------------------------------------------------------
Title: A Coherent Radiation Mechanism for Type IV dm Radio Bursts
Authors: Kuijpers, Jan
1974SoPh...36..157K Altcode:
An interpretation is presented of the decimetric type IV continuum with
fine structure on March 6, 1972 and of the corresponding source region,
in terms of Čerenkov plasma radiation and alternatively of synchrotron
radiation, both in case of coherent and incoherent generation. If
the magnetic field strength in the source region is a few gauss, in a
stationary situation a loss cone instability develops which generates
electron plasma waves coherently. The amount of energetic electrons
required for consecutive induced scattering of the plasma waves at
the thermal ions into electromagnetic waves is less than in case
of synchrotron radiation. It is concluded that the former mechanism
provides the explanation of type IV continua with fine structure such as
intermediate drift bursts and sudden reductions of the continuum level.
---------------------------------------------------------
Title: A Coherent Radiation Mechanism for Type IV dm Radio Bursts
Authors: Kuijpers, J.
1974cesra...4..133K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A possible generating mechanism for intermediate drift bursts
Authors: Kuijpers, J.
1972cesra...3..130K Altcode:
No abstract at ADS
