S. Over

Publications (62)85.98 Total impact

• Article: The spectrum of high-energy cosmic rays measured with KASCADE-Grande

  The KASCADE-Grande Collaboration: W. D. Apel, J. C. Arteaga-Velazquez, K. Bekk, M. Bertaina, J. Bluemer, H. Bozdog, I. M. Brancus, P. Buchholz, E. Cantoni, A. Chiavassa, [......], H. Schieler, F. G. Schroeder, O. Sima, G. Toma, G. C. Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: The energy spectrum of cosmic rays between 10**16 eV and 10**18 eV, derived from measurements of the shower size (total number of charged particles) and the total muon number of extensive air showers by the KASCADE-Grande experiment, is described. The resulting all-particle energy spectrum exhibits strong hints for a hardening of the spectrum at approximately 2x10**16 eV and a significant steepening at c. 8x10**16 eV. These observations challenge the view that the spectrum is a single power law between knee and ankle. Possible scenarios generating such features are discussed in terms of astrophysical processes that may explain the transition region from galactic to extragalactic origin of cosmic rays.
  06/2012;
• Source

  Available from: H. J. Mathes

  Article: KASCADE-Grande - Contributions to the 32nd International Cosmic Ray Conference, Beijing, August, 2011

  W D Apel, J. C. Arteaga-Velazquez, K. Bekk, M. Bertaina, J. Bluemer, H. Bozdog, I. M. Brancus, P. Buchholz, E. Cantoni, A. Chiavassa, [......], H. Schieler, F. G. Schroeder, O. Sima, G. Toma, G C Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: Contributions of the KASCADE-Grande Collaboration to the 32nd International Cosmic Ray Conference, Beijing, August, 2011.
  11/2011;
• Source

  Available from: H. J. Mathes

  Article: Kneelike structure in the spectrum of the heavy component of cosmic rays observed with KASCADE-Grande.

  W D Apel, J C Arteaga-Velázquez, K Bekk, M Bertaina, J Blümer, H Bozdog, I M Brancus, P Buchholz, E Cantoni, A Chiavassa, [......], H Schieler, F G Schröder, O Sima, G Toma, G C Trinchero, H Ulrich, A Weindl, J Wochele, M Wommer, J Zabierowski
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  ABSTRACT: We report the observation of a steepening in the cosmic ray energy spectrum of heavy primary particles at about 8×10(16) eV. This structure is also seen in the all-particle energy spectrum, but is less significant. Whereas the "knee" of the cosmic ray spectrum at 3-5×10(15) eV was assigned to light primary masses by the KASCADE experiment, the new structure found by the KASCADE-Grande experiment is caused by heavy primaries. The result is obtained by independent measurements of the charged particle and muon components of the secondary particles of extensive air showers in the primary energy range of 10(16) to 10(18) eV. The data are analyzed on a single-event basis taking into account also the correlation of the two observables.
  Physical Review Letters 10/2011; 107(17):171104. · 7.37 Impact Factor
• Source

  Available from: Victor Vladimirovich Alekseenko

  Article: The East-West method: an exposure-independent method to search for large scale anisotropies of cosmic rays

  R Bonino, V. V. Alekseenko, O. Deligny, P. L. Ghia, M. Grigat, A. Letessier-Selvon, H. Lyberis, S. Mollerach, S. Over, E. Roulet
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  ABSTRACT: The measurement of large scale anisotropies in cosmic ray arrival directions at energies above 10^13 eV is performed through the detection of Extensive Air Showers produced by cosmic ray interactions in the atmosphere. The observed anisotropies are small, so accurate measurements require small statistical uncertainties, i.e. large datasets. These can be obtained by employing ground detector arrays with large extensions (from 10^4 to 10^9 m^2) and long operation time (up to 20 years). The control of such arrays is challenging and spurious variations in the counting rate due to instrumental effects (e.g. data taking interruptions or changes in the acceptance) and atmospheric effects (e.g. air temperature and pressure effects on EAS development) are usually present. These modulations must be corrected very precisely before performing standard anisotropy analyses, i.e. harmonic analysis of the counting rate versus local sidereal time. In this paper we discuss an alternative method to measure large scale anisotropies, the "East-West method", originally proposed by Nagashima in 1989. It is a differential method, as it is based on the analysis of the difference of the counting rates in the East and West directions. Besides explaining the principle, we present here its mathematical derivation, showing that the method is largely independent of experimental effects, that is, it does not require corrections for acceptance and/or for atmospheric effects. We explain the use of the method to derive the amplitude and phase of the anisotropy and we demonstrate its power under different conditions of detector operation.
  06/2011;
• Article: The cosmic ray energy spectrum in the range 1016-1018 eV measured by KASCADE-Grande

  M. Bertaina, W. D. Apel, J. C. Arteaga-Velázquez, K. Bekk, J. Blümer, H. Bozdog, I. M. Brancus, P. Buchholz, E. Cantoni, A. Chiavassa, [......], H. Schieler, F. Schröder, O. Sima, G. Toma, G. C. Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: The KASCADE-Grande experiment, located at Campus North of the Karlsruhe Institute of Technology (Germany) is a multi-component extensive air-shower experiment devoted to the study of cosmic rays and their interactions at primary energies 1014-1018 eV. One of the main goals of the experiment is the measurement of the all particle energy spectrum in the 1016-1018 eV range, i.e. extending the range accessible by KASCADE alone. The Grande detector samples the charged component (Nch) of the air shower while the original KASCADE array provides in addition a measurement of the muon component (Nμ). The combined information of Nch and Nμ is used to estimate the energy on an event-by-event basis and to derive the all-particle energy spectrum. Since the calibration of the observables in terms of the primary energy depends on Monte Carlo simulations, three different methods with partially different sources of uncertainties, have been considered and compared to each other to derive the systematics on the energy spectrum. The different methods employed to derive the spectrum and their uncertainties, as well as the implications of the obtained result, are discussed in detail.
  Astrophysics and Space Sciences Transactions 05/2011; 7:229-234.
• Source

  Available from: H. J. Mathes

  Article: Longitudinal EAS-Development Studies in the Air-Shower Experiment KASCADE-Grande

  P. Doll, W D Apel, J. C. Arteaga-Velázquez, K. Bekk, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, P. Buchholz, E. Cantoni, [......], H. Schieler, F. G. Schröder, O. Sima, G. Toma, G C Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: A large area (128 m^2) Muon Tracking Detector (MTD), located within the KASCADE experiment, has been built with the aim to identify muons (E_mu > 0.8 GeV) and their directions in extensive air showers by track measurements under more than 18 r.l. shielding. The orientation of the muon track with respect to the shower axis is expressed in terms of the radial- and tangential angles. By means of triangulation the muon production height H_mu is determined. By means of H_mu, a transition from light to heavy cosmic ray primary particle with increasing shower energy Eo from 1-10 PeV is observed. Muon pseudorapidity distributions for the first interactions above 15 km are studied and compared to Monte Carlo simulations. Comment: Presented at the XVI International Symposium on Very High Energy Cosmic Ray Interactions (ISVHECRI 2010), Batavia, IL, USA (28 June 2 July 2010). 4 pages, 3 figures
  10/2010;
• Source

  Available from: H. J. Mathes

  Article: Sensitivity of KASCADE-Grande data to hadronic interaction models

  D. Kang, W D Apel, J. C. Arteaga-Velázquez, K. Bekk, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, P. Buchholz, E. Cantoni, [......], H. Schieler, F. G. Schröder, O. Sima, G. Toma, G C Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: KASCADE-Grande is a large detector array dedicated for studies of high-energy cosmic rays in the primary energy range from 100 TeV to 1 EeV. The multi-detector concept of the experimental set-up offers the possibility to measure simultaneously various observables related to the electromagnetic, muonic, and hadronic air shower components. The experimental data are compared to predictions of CORSIKA simulations using high-energy hadronic interaction models (e.g. QGSJET or EPOS), as well as low-energy interaction models (e.g. FLUKA or GHEISHA). This contribution will summarize the results of such investigations. In particular, the validity of the new EPOS version 1.99 for EAS with energy around 100 PeV will be discussed. Comment: Talk given at XVI International Symposium on Very High Energy Cosmic Ray Interactions ISVHECRI 2010, Batavia, IL, USA (28 June 2 July 2010). 4 pages, 4 figures
  09/2010;
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  Available from: H. J. Mathes

  Article: The KASCADE-Grande experiment: measurements of the all-particle energy spectrum of cosmic rays

  J. C. Arteaga-Velázquez, W D Apel, K. Bekk, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, P. Buchholz, E. Cantoni, A. Chiavassa, [......], H. Schieler, F Schröder, O. Sima, G. Toma, G C Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: The all-particle energy spectrum as measured by the KASCADE-Grande experiment for E = 10^{16} - 10^{18} eV is presented within the framework of the QGSJET II/FLUKA hadronic interaction models. Three different methods were applied based on the muon size and the total number of charged particles individually and in combination. From the study it is found that the spectrum cannot be completely described by a smooth power law due to the presence of characteristic features. Comment: Invited talk given at XVI International Symposium on Very High Energy Cosmic Ray Interactions ISVHECRI 2010, Batavia, IL, USA (28 June 2 July 2010). 6 pages, 8 figures
  09/2010;
• Article: Primary Energy Spectrum as Reconstructed from S(500) Measurements by KASCADE‐Grande

  G. Toma, W. D. Apel, J. C. Arteaga, F. Badea, K. Bekk, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, M. Brüggemann, [......], H. Schieler, F. Schröder, O. Sima, M. Stümpert, G. C. Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: In cosmic ray investigations by observations of extensive air showers (EAS) the general question arises how to relate the registered EAS observables to the energy of the primary particle from the cosmos entering into the atmosphere. We present results on the reconstruction of the primary energy spectrum of cosmic rays from the experimentally recorded S(500) observable using the KASCADE‐Grande detector array. The KASCADE‐Grande experiment is installed in Forschungszentrum Karlsruhe, Germany, and driven by an international collaboration. Previous EAS investigations have shown that for a fixed energy the charged particle density becomes independent of the primary mass at certain distances from the shower core. This feature can be used as an estimator for the primary energy. The particular radial distance from the shower core where this effect shows up is a characteristic of the detector. For the KASCADE‐Grande experiment it was shown to be around 500 m, hence a notation S(500). Extensive simulation studies have shown that S(500) is mapping the primary energy. The constant intensity cut (CIC) method is applied to evaluate the attenuation of the S(500) observable with the zenith angle. An attenuation correction is applied and all recorded S(500) values are corrected for attenuation. A calibration of S(500) values with the primary energy has been worked out by simulations and was used for conversion providing the possibility to obtain the primary energy spectrum (in the energy range accessible to KASCADE‐Grande 1010–1018 eV). The systematic uncertainties induced by different factors are considered.
  AIP Conference Proceedings. 01/2010; 1203(1):145-150.
• Source

  Available from: H. J. Mathes

  Article: Lateral Distribution of the Radio Signal in Extensive Air Showers Measured with LOPES

  LOPES Collaboration, W D Apel, J. C. Arteaga, T. Asch, A. F. Badea, L. Baehren, K. Bekk, M. Bertaina, P. L. Biermann, J. Bluemer, [......], O. Sima, K. Singh, G. Toma, G C Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski, J. A. Zensus
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  ABSTRACT: 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. Comment: accepted by Astroparticle Physics
  10/2009;
• Article: New method to measure the attenuation of hadrons in extensive air showers

  W. D. Apel, J. C. Arteaga, F. Badea, K. Bekk, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, M. Brüggemann, P. Buchholz, [......], M. Stümpert, G. Toma, G. C. Trinchero, H. Ulrich, J. van Buren, W. Walkowiak, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: Extensive air showers are generated through interactions of high-energy cosmic rays impinging the Earth’s atmosphere. A new method is described to infer the attenuation of hadrons in air showers. The numbers of electrons and muons, registered with the scintillator array of the KASCADE experiment, are used to estimate the energy of the shower inducing primary particle. A large hadron calorimeter is used to measure the hadronic energy reaching observation level. The ratio of energy reaching ground level to the energy of the primary particle is used to derive an attenuation length of hadrons in air showers. In the energy range from 106 to 3×107 GeV the attenuation length obtained increases from 170 to 210 g/cm2. The experimental results are compared to predictions of simulations based on contemporary high-energy interaction models.
  Phys. Rev. D. 07/2009; 80(2).
• Source

  Available from: H. J. Mathes

  Article: Cosmic Ray Measurements with the KASCADE-Grande Experiment

  KASCADE-Grande Collaboration: W. D. Apel, J. C. Arteaga, F. Badea, K. Bekk, M. Bertaina, J. Bluemer, H. Bozdog, I. M. Brancus, M. Brueggemann, P. Buchholz, [......], F. Schroeder, O. Sima, M. Stuempert, G. Toma, G C Trinchero, H. Ulrich, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: 14 KASCADE-Grande reports submitted to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009 Comment: Contributions to the 31st International Cosmic Ray Conference, Lodz, Poland, July 2009
  06/2009;
• Article: The KASCADE‐Grande Experiment

  V. de Souza, W. D. Apel, J. C. Arteaga, F. Badea, K. Bekk, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, M. Brüggemann, [......], M. Stümpert, G. Toma, G. C. Trinchero, H. Ulrich, J. van Buren, W. Walkowiak, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski
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  ABSTRACT: KASCADE‐Grande is a multi‐component detector located at Karlsruhe, Germany. It was optimized to measure cosmic ray air showers with energies between 5×1016 and 1018 eV. Its capabilities are based on the use of several techniques to measure the electromagnetic and muon components of the shower in an independent way which allows a direct comparison to hadronic interaction models and a good estimation of the primary cosmic ray composition.
  AIP Conference Proceedings. 04/2009; 1123(1):211-216.
• Source

  Available from: Janusz Zabierowski

  Article: A test of the hadronic interaction model EPOS with air shower data

  W D Apel, J C Arteaga, F Badea, K Bekk, M Bertaina, J Blümer, H Bozdog, I M Brancus, M Brüggemann, P Buchholz, [......], M Stümpert, G Toma, G C Trinchero, H Ulrich, J van Buren, W Walkowiak, A Weindl, J Wochele, M Wommer, J Zabierowski
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  ABSTRACT: Predictions of the hadronic interaction model EPOS 1.61 as implemented in the air shower simulation program CORSIKA are compared to observations with the KASCADE experiment. The investigations reveal that the predictions of EPOS are not compatible with KASCADE measurements. The discrepancies seen are most likely due to use of a set of inelastic hadronic cross sections that are too high.
  Journal of Physics G Nuclear and Particle Physics 02/2009; 36(3):035201. · 4.18 Impact Factor
• Conference Proceeding: Detecting radio pulses from air showers

  A. Horneffer, W.D. Apel, J.C. Arteaga, T. Asch, J. Auffenberg, F. Badea, L. Bahren, K. Bekk, M. Bertaina, P.L. Biermann, [......], M. Stumpert, G. Toma, G.C. Trinchero, H. Ulrich, W. Walkowiak, A. Weindl, J. Wochele, M. Wommer, J. Zabierowski, J.A. Zensus
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  ABSTRACT: Cosmic rays are energetic particles from outside the earth’s atmosphere. When a high energy cosmic ray hits the atmosphere it triggers a cascade of secondary particles produced in nuclear interactions, an air shower. Up to now the established methods of measuring air showers are detection of the particles that reach the ground level or optical observation of the Cherenkov or fluorescent light.
  Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE; 11/2008
• Article: Air shower radio detection with LOPES

  J Blümer, W D Apel, J C Arteaga, T Asch, J Auffenberg, F Badea, L Bähren, K Bekk, M Bertaina, P L Biermann, [......], M Stümpert, G Toma, G C Trinchero, H Ulrich, J van Buren, W Walkowiak, A Weindl, J Wochele, J Zabierowski, J A Zensus
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  ABSTRACT: LOPES is an array of 30 radio antenna co-located with the KASCADE-Grande extensive air shower detector in Karlsruhe, Germany. It is designed as a digital radio interferometer for the detection of radio emission from extensive air showers. LOPES features high bandwidth and fast data processing. A unique asset is the concurrent operation with KASCADE-Grande. We report about the progress in understanding the radio signals measured by LOPES. In addition, the status and further perspectives of LOPES and the large scale application of this novel detection technique are sketched.
  Journal of Physics Conference Series 07/2008; 120(6):062012.
• Article: Radio Emission in Atmospheric Air Showers: First Measurements with LOPES-30

  P G Isar, S Nehls, W D Apel, T Asch, F Badea, L Bähren, K Bekk, A Bercuci, M Bertaina, P L Biermann, [......], G Toma, G C Trinchero, H Ulrich, J van Buren, W Walkowiak, A Weindl, J Wochele, J Zabierowski, J A Zensus, D Zimmermann
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  ABSTRACT: 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.
  Journal of Physics Conference Series 10/2007; 81(1):012006.
• Article: Radio Emission in Atmospheric Air Showers: Results of LOPES-10

  A Haungs, W D Apel, T Asch, F Badea, L Bähren, K Bekk, A Bercuci, M Bertaina, P L Biermann, J Blümer, [......], G Toma, G C Trinchero, H Ulrich, J van Buren, W Walkowiak, A Weindl, J Wochele, J Zabierowski, J A Zensus, D Zimmermann
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  ABSTRACT: 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.
  Journal of Physics Conference Series 10/2007; 81(1):012005.
• Article: The knee of cosmic rays — news from KASCADE

  H. Ulrich, W. D. Apel, J. C. Arteaga, A. F. Badea, K. Bekk, A. Bercuci, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, [......], H. Schieler, O. Sima, M. Stümpert, G. Toma, G. C. Trinchero, J. van Buren, W. Walkowiak, A. Weindl, J. Wochele, J. Zabierowski
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  ABSTRACT: The energy spectrum of cosmic rays, following over large energy ranges a simple power law, steepens at energies around 4 PeV. This so‐called knee is believed to be an imprint of corresponding steepenings or even cut‐offs in the energy spectra of single cosmic ray elements, thus implying a change of composition in the range between 1 PeV and 100 PeV. One of the sophisticated experiments aiming at detailed measurements in the knee region is the KASCADE experiment and its successor, KASCADE‐Grande. In the following, existing data on the knee and their limitations are briefly discussed. Concluding, an update on the KASCADE composition analysis is presented. © 2007 American Institute of Physics
  AIP Conference Proceedings. 08/2007; 928(1):31-38.
• Article: Results and status of KASCADE‐Grande

  H. Ulrich, W. D. Apel, A. F. Badea, K. Bekk, A. Bercuci, M. Bertaina, J. Blümer, H. Bozdog, I. M. Brancus, M. Brüggemann, [......], O. Sima, M. Stümpert, G. Toma, G. C. Trinchero, J. van Buren, W. Walkowiak, A. Weindl, J. Wochele, J. Zabierowski, D. Zimmermann
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  ABSTRACT: The KASCADE‐Grande experiment measures extensive air showers induced by cosmic rays in the knee region (with energies between 0.5 PeV and 1 EeV). The principal task of the experiment is to measure precisely the energy and chemical composition of primary cosmic rays to clarify the origin of the knee. The data of the original KASCADE experiment have been used in a composition analysis, which shows the knee is caused by a steepening of the element spectra. The limitations to these conclusions due to the dependence on the high energy hadronic interaction models used in the simulations are also presented. © 2006 American Institute of Physics
  AIP Conference Proceedings. 11/2006; 870(1):186-189.