Author name code: kuijpers ADS astronomy entries on 2022-09-14 author:"Kuijpers, Jan M.E." ------------------------------------------------------------------------ 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. Bibcode: 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. 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 Bibcode: 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. 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 Bibcode: 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 $X_\mathrm{max}$. 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 Bibcode: 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. 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. Bibcode: 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. Title: Electric Current Circuits in Astrophysics Authors: Kuijpers, Jan; Frey, Harald U.; Fletcher, Lyndsay Bibcode: 2016mssf.book....3K Altcode: No abstract at ADS 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. Bibcode: 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. Title: Electric Current Circuits in Astrophysics Authors: Kuijpers, Jan; Frey, Harald U.; Fletcher, Lyndsay Bibcode: 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. 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 Bibcode: 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 (Xmax) of 13% and 50 g /cm2, 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. 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. Bibcode: 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 1017 eV and zenith angles smaller than 45̂, 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 2. But the simulations indicate that under better conditions this method might yield an accuracy for the atmospheric depth of the shower maximum, Xmax, better than 30 g/c 2. 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. 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. Bibcode: 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. 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. Bibcode: 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. Title: Reconstructing energy and Xmax 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. Bibcode: 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 Xmax. 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 Xmax 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, Xmax values are reconstructed with the LOPES measurements with a resolution of 90 g/cm2. A precision on Xmax better than 30 g/cm2 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. Bibcode: 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, Xmax, 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 Xmax 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 Xmax 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. Bibcode: 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. Bibcode: 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. Bibcode: 2013JPhCS.409a2075S Altcode: LOPES is a digital antenna array for the radio measurement of cosmic-ray air showers at energies around 1017 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 Xmax 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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.
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.
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.
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.
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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 (≳1016 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. Bibcode: 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 LOPESstar 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. Bibcode: 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 2 when the distance to the shower core does not exceed 7 km. The method requires that the arrival direction is known with high precision. Title: Simulation of radio emission from air showers in atmospheric electric fields Authors: Buitink, S.; Huege, T.; Falcke, H.; Kuijpers, J. Bibcode: 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. Bibcode: 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 Bibcode: 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=2.6×10-3) 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 Bibcode: 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 R0, describing the slope of the lateral profiles range between 100 and 200 m. No evidence for a direct correlation of R0 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. Bibcode: 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. Bibcode: 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 Bibcode: 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) 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. Bibcode: 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. Bibcode: 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. Bibcode: 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.
Aims: A study of anisotropies in the energy range between 100 and 500 GeV is performed. This energy range is not yet well explored.
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.
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 10-4. 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. Bibcode: 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 (1017 eV).
Methods: We observe short radio pulses in a broad frequency band with the dipole-interferometer LOPES (LOFAR Prototype Station), which is triggered by a particle detector array named Karlsruhe Shower Core and Array Detector (KASCADE). LOFAR is the Low Frequency Array. For this analysis, 23 strong air shower events are selected using parameters from KASCADE. The radio data are digitally beam-formed before the spectra are determined by sub-band filtering and fast Fourier transformation.
Results: The resulting electric field spectra fall off to higher frequencies. An average electric field spectrum is fitted with an exponential Eν=K\cdotexp (ν/MHz/β) and β=-0.017±0.004, or alternatively, with a power law ɛν=K\cdotνα 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.
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.

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. Bibcode: 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.
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.
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.
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. Bibcode: 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.
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.
Methods: Detailed computational models of the disintegration and deflection processes for a wide range of cosmic ray primaries in the energy range of 1016 to 1020 eV were combined with sophisticated detector models to calculate realistic detection rates.
Results: The fraction of Gerasimova-Zatsepin events is found to be approximately 10-5 of the cosmic ray flux, implying an intrinsic event rate of around 0.07 km-2 sr-1 yr-1 in the defined energy range. Event rates in any real experiment, whether existing or under construction, will probably not exceed 10-2 yr-1. 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. Bibcode: 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. Bibcode: 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 1016--1020.5 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. Bibcode: 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 (>105 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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.
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.
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.
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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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.
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.
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.
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 Bibcode: 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 PSR B0031-07 Authors: Smits, J. M.; Mitra, D.; Stappers, B. W.; Kuijpers, J.; Weltevrede, P.; Jessner, A.; Gupta, Y. Bibcode: 2007A&A...465..575S Altcode: 2007astro.ph..1893S Context: PSR B0031-07 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.
Aims: Using the results of an analysis of simultaneous multifrequency observations of PSR B0031-07, 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 PSR B0031-07 at each emission frequency for driftmodes A and B.
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.
Results: The model reproduces the observed polarisation and intensity characteristics, suggesting that diffuse emission plays an important role in the emission properties of PSR B0031-07. 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 1019 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. Bibcode: 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 1019 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. Bibcode: 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. Bibcode: 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. Bibcode: 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.
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.
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.
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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 Ne, muon number Nµ, 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. Bibcode: 2006JPhCS..39..463H Altcode: 2005astro.ph.11649H The origin of high-energy cosmic rays in the energy range from 1014 to 1018 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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.

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. Bibcode: 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. Bibcode: 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 (P3) 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. Bibcode: 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. Bibcode: 2005Natur.435..313F Altcode: 2005astro.ph..5383F The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >1020eV 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 2005ICRC....8...45N Altcode: 2005ICRC...29h..45N No abstract at ADS Title: Gravitational Wave Interactions with Magnetized Plasmas Authors: Moortgat, Joachim; Kuijpers, Jan Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 1013 W, which corresponds with brightness temperature of 1030 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;nGJ(r*) where nGJ(r*) is the Goldreich-Julian density at a stellar radius r*, and finally, at large altitude where the background magnetic field is low B0 ≤ 10-2;T.

Appendix A is only available in electronic form at

http://www.edpsciences.org Title: Gravitational waves in magnetized relativistic plasmas Authors: Moortgat, J.; Kuijpers, J. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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 1000m3 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. Bibcode: 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. Bibcode: 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 (S0, 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 Bibcode: 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. Bibcode: 1999ESASP.448..859P Altcode: 1999mfsp.conf..859P; 1999ESPM....9..859P No abstract at ADS Title: Magnetodipole Oven Authors: Istomin, Ya. N.; Kuijpers, J. Bibcode: 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. Bibcode: 1998Zenit..25..196K Altcode: No abstract at ADS Title: The Coriolis Effect and the Origin of Prominences Authors: Kuijpers, J.; Mestel, L. Bibcode: 1998ESASP.417..247K Altcode: 1998cesh.conf..247K No abstract at ADS Title: A Solar Prominence Model Authors: Kuijpers, Jan Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1996ASPC...93..182A Altcode: 1996ress.conf..182A No abstract at ADS Title: Particle Acceleration Authors: Kuijpers, J. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 (7×1011 2×1012 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. Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1993SSRv...63..191P Altcode: No abstract at ADS Title: Book Review: Transition radiation and transition scattering / Adam Hilger, 1990 Authors: Kuijpers, J. Bibcode: 1993SSRv...63..195K Altcode: 1993SSRv...63..195G No abstract at ADS Title: Pulsar core emission and double layers Authors: Volwerk, M.; Kuijpers, J. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1992ASIC..377..537V Altcode: 1992xrb..work..537V No abstract at ADS Title: Physics of Flares in Stars and Accretion Disks Authors: Kuijpers, J. Bibcode: 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. Bibcode: 1991SSRv...57..189H Altcode: No abstract at ADS Title: Flaring interactions between accretion disk and neutron star magnetosphere. Authors: Aly, J. J.; Kuijpers, J. Bibcode: 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. Bibcode: 1990ppsa.conf..227K Altcode: No abstract at ADS Title: Coherent Radiation from Electrostatic Double Layers. Authors: Kuijpers, J. Bibcode: 1990ppsa.conf...17K Altcode: No abstract at ADS Title: Magnetic Flares in Close Binaries Authors: Kuijpers, J. Bibcode: 1990ASIC..319..761K Altcode: 1990acb..proc..761K No abstract at ADS Title: Coherent Radiation from Electrostatic Double Layers Authors: Kuijpers, Jan Bibcode: 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 Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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 vc/rc where the infall velocity vc of the cloud is taken to be subalfvénic and rc is the radius of the cloud. The efficiency of wave-excitation is calculated and turns out to be of order 0.1 (ρc0)(vc/cA)3 for the Alfvén mode and of order 1.8 (ρc0)(vc/cA)7 for the fast mode (cA is the Alfvén speed, ρc is the mass density inside the cloud and ρ0 that of the ambient atmosphere). Title: On the Controversy Concerning Turbulent Bremsstrahlung Authors: Melrose, D. B.; Kuijpers, J. Bibcode: 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. Bibcode: 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 Bibcode: 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 1011 cm−3, a temperature of 5 × 108 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 ≈ 1027 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 2.5×107K. 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 1.4×1031ergs s-1. The peak temperature was 6×107K, with an iron K line confirming the thermal character of the emission. Title: Solar VLBI. Authors: Tapping, K. F.; Kuijpers, J. Bibcode: 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. Bibcode: 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. Bibcode: 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 σ2CrB (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. Bibcode: 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. Bibcode: 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. Bibcode: 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 × 107 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 × 1031 erg s-1 and a total duration of 8 hours. The peak temperature was 5.0 keV with an emission measure of 9.4 × 1053 cm-3. 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. Bibcode: 1985NTNA...51...21K Altcode: No abstract at ADS Title: Radio Observable Processes in Stars (Invited Paper) Authors: Kuijpers, J. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1984SSRv...37..399O Altcode: No abstract at ADS Title: Diffusion of high energy electrons in the solar corona Authors: Achterberg, A.; Kuijpers, J. Bibcode: 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. Bibcode: 1984SSRv...38..385F Altcode: No abstract at ADS Title: Book-Review - Highlights of Astronomy V.6 Authors: West, R. M.; Kuijpers, J. Bibcode: 1984SSRv...37..404W Altcode: No abstract at ADS Title: Radial white dwarf accretion. Authors: Kuijpers, J.; Pringle, J. E. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1983SSRv...35..293W Altcode: No abstract at ADS Title: Very long baseline interferometry of solar flares Authors: Kuijpers, J.; Tapping, K. F.; Graham, D. Bibcode: 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. Bibcode: 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. Bibcode: 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/Ec approximately equal to 0.1 (Ec 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. Bibcode: 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. Bibcode: 1981Zenit...8...28F Altcode: No abstract at ADS Title: Book reviews Authors: Verbunt, Frank; Kleczek, J.; Bleeker, J. A. M.; Kuijpers, Jan; Dommanget, J. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1980SSRv...27..216K Altcode: No abstract at ADS Title: The active radio sun. Authors: Fokker, A. D.; Kuijpers, J. M. E. Bibcode: 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. Bibcode: 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. Bibcode: 1980Zenit...7..436F Altcode: No abstract at ADS Title: Theory of type IV DM bursts Authors: Kuijpers, J. Bibcode: 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. Bibcode: 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 Bibcode: 1978SSRv...21..469P Altcode: No abstract at ADS Title: Type IV dm bursts: onset and sudden reductions. Authors: Benz, A. O.; Kuijpers, J. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1975UtrOv.301.....K Altcode: No abstract at ADS Title: Collective wave-particle interactions in solar type IV radio sources Authors: Kuijpers, J. M. E. Bibcode: 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 Bibcode: 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. Bibcode: 1974cesra...4..133K Altcode: No abstract at ADS Title: A possible generating mechanism for intermediate drift bursts Authors: Kuijpers, J. Bibcode: 1972cesra...3..130K Altcode: No abstract at ADS