1 / 16

Andreas Horneffer for the LOPES Collaboration

Radboud University Nijmegen. Experimental. Results from LOPES, an Overview. Andreas Horneffer for the LOPES Collaboration. Radio Emission from Air Showers. Air showers emit short, intense radio pulses Radiation due to geomagnetic emission process e.g. geosynchrotron

helen
Download Presentation

Andreas Horneffer for the LOPES Collaboration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Radboud University Nijmegen Experimental Results from LOPES, an Overview Andreas Horneffer for the LOPES Collaboration

  2. Radio Emission from Air Showers • Air showers emit short, intense radio pulses • Radiation due to geomagnetic emission process e.g. geosynchrotron • Coherent emission at low frequencies • Measuring the radio emission from air showers could give several benefits: • Higher duty cycle than fluorescence telescopes • Effective RFI suppression allows measuring in polluted (populated) areas • Data integrated over the shower evolution, can be complementary to particle detectors • High angular resolution possible

  3. LOPES(LOFAR PrototypeStation) • Set up at and working together with KASCADE-Grande • Frequency range of 40 – 80 MHz • Triggered by KASCADE or Grande large event trigger • 10 antennas in the first phase • 30 antennas in second phase • reconfigured for dual-polarization • plus LOPESSTAR antennas • Goals: • Develop techniques to measure the radio emission from air showers • Determine the radiation mechanism of air showers • Measure the properties of the radio emission from air showers • Calibrate the radio data with theoretical and experimental values from an existing air shower array

  4. First detection of CR radio pulse by LOPES • Strong coherent radio pulse coincident with air shower • Shows direct association of radio with air shower geometry • All-sky radio-only mapping • Imaging (AZ-EL) with time resolution of 12.5 ns • Total duration is ~200 ns • No cleaning was performed, side lobes still visible • Location of burst agrees with KASCADE location to within 0.5°. Falcke et al. (LOPES collaboration) 2005, Nature, 435, 313

  5. Radio Pulse Height Parametrisation Comparison with KASCADE data leads to parameterization formula: εEW=A·(B-cos(α))·cos(θ)·exp(R/R0) ·(E/1017eV)γ[μV/m MHz] With: A=11±1 B=1.16±0.025 R0=236±81 γ=0.95±0.04 E Horneffer et al. (LOPES coll.) ICRC(2007) Merida

  6. Lateral Behavior • Investigate the lateral behavior by: • Statistical analysis of many events • Analysis of single antennas in strong events R0=236 ±81 110 events single event

  7. Lateral BehaviorFlat Events & Simulations • Simulations predict systematically smaller scale parameters • R0,sim<100m • Some events show a “flat” behavior with large R0 • no flat distributions obtained in simulations S. Nehls, PhD-Thesis 2008 Uni Karlsruhe

  8. Lateral BehaviorFlat Events & Simulations • Possible explanation: flat inner region • Needs further study! S. Nehls, PhD-Thesis 2008 Uni Karlsruhe

  9. Frequency Spectrum • Spectrum of the radio pulse from two methods: • sub-band filtering • Fourier-transform of single pulses • Can be fit with a power law of slope: -1 • No dependence on direction, energy or distance found • Consistent with simulations power law slope: α=-1±0.3 Nigl et al. (LOPES coll.) A&A accepted

  10. Thunderstorm Effects • Measured clear radio excess during thunderstorms • For E>100 V/cm E-field force dominates B-field: • Fair weather: E=1 V/cm • Thunderstorms: E=1 kV/cm • Electric fields have two main effects depending on geometry: • Additional curvature of e± • Linear acceleration of e± • B-field effect dominates under normal conditions • >90% duty cycle possible Thunderstorm events control sample ‘perfect weather’ sample Buitink et al. (LOPES coll.) A&A 467(2007)385

  11. Polarization • Some events show strong polarization • In general: • Events from East or West have stronger NS component • Events from North or South have stronger EW component EW Component NS Component Isar et al. (LOPES coll.) ICRC(2007) Merida

  12. Preparing the Future • LOFAR: • High sensitivity • Excellent calibration • Radio@Auger • Development of autonomous antennas • Self triggering • Simulations!!!

  13. Summary • Radio signal depends on angle to geomagnetic field. • Confirmation of geomagnetic emission process. • Pulse height scales about linearly with primary energy. • Confirmation of coherent emission. • Pulse height scales with distance: ε~exp(R/R0) • Larger R0 value found than in simulations, flattening at the center? • Frequency spectrum is a decreasing power law or exponential. • Compatible with simulations • Amplified radio signal during thunderstorms. • Strong electric fields can influence the emission process. • Polarization shows azimuthal dependence. • Similar to simulations. • Not shown: • LOPES is more sensitive to inclined air showers than KASCADE. • The angular resolution of LOPES increases with primary energy.

  14. LOPES Collaboration ASTRON, The Netherlands H. Butcher G. de Bruyn C.M. de Vos G.W. Kant Y. Koopman H.J. Pepping G. Schoonderbeek W. van Capellen S. Wijnholds Dept of Astrophysics, Nijmegen, The Netherlands L. Bähren S. Buitink H. Falcke J.R. Hörandel A. Horneffer J. Kuijpers S. Lafèbre A. Nigl J. Petrovic K. Singh Dipartimento di Fisica Generale dell'Universita, Torino, Italy M. Bertaina A. Chiavassa F. Di Pierro G. Navarra Institut für Kernphysik, FZK, Germany W.D. Apel J.C. Arteaga A.F. Badea K. Bekk J. Blümer H. Bozdog K. Daumiller P. Doll R. Engel M. Finger A. Haungs D. Heck T. Huege P.G. Isar H.J. Mathes H.J. Mayer S. Nehls J. Oehlschläger T. Pierog H. Rebel M. Roth H. Schieler F. Schröder H. Ulrich A. Weindl J. Wochele M. Wommer Univ Wuppertal, Germany J. Auffenberg D. Fuhrmann R. Glasstetter K.H. Kampert J. Rautenberg Universität Siegen, Germany M. Brüggemann P. Buchholz C. Grupen D. Kickelbick Y. Kolotaev S. Over W. Walkowiak Max-Planck-Institut für Radio- astronomie, Bonn, Germany P.L. Biermann J.A. Zensus IPE, FZK, Germany T. Asch H. Gemmeke O. Krömer M. Manewald L. Petzold A. Schmidt Istituto di Fisica dello Spazio Interplanetario, Torino, Italy E. Cantoni P.L. Ghia C. Morello G.C. Trinchero National Inst of Physics and Nuclear Engineering Bucharest,Romania I.M. Brancus B. Mitrica M. Petcu A. Saftoiu O. Sima G. Toma Univ Karlsruhe, Germany F. Cossavella V. De Souza M. Ender D. Kang K. Link M. Ludwig M. Melissas N. Palmieri Soltan Institute for Nuclear Studies, Lodz, Poland P. Łuczak J. Zabierowski

  15. Positional Accuracy Particle Detectors vs. Radio Antennas Interferometry gives excellent position information! The radio emission from normal showers is directly associated with the particle shower within our beamsize. Air showers are amplified and modified in thunderstorm electric field! ~ averagebeamsize linear improvement with SNR Nigl 2007, PhD, RU Nijmegen

  16. Simulations:Extraction of Xmax Huege et al. (2008) Lafebre et al. (2008), in prep.

More Related