Calibrating the absolute amplitude scale for air showers measured at LOFAR

Air showers induced by cosmic rays create nanosecond pulses detectable at radio frequencies. These pulses have been measured successfully in the past few years at the LOw-Frequency ARray (LOFAR) and are used to study the properties of cosmic rays. For a complete understanding of this phenomenon and the underlying physical processes, an absolute calibration of the detecting antenna system is needed. We present three approaches that were used to check and improve the antenna model of LOFAR and to provide an absolute calibration of the whole system for air shower measurements. Two methods are based on calibrated reference sources and one on a calibration approach using the diffuse radio emission of the Galaxy, optimized for short data-sets. An accuracy of 19% in amplitude is reached. The absolute calibration is also compared to predictions from air shower simulations. These results are used to set an absolute energy scale for air shower measurements and can be used as a basis for an absolute scale for the measurement of astronomical transients with LOFAR.

M. J. Bentum | M. C. Toribio | R. A. M. J. Wijers | O. Smirnov | A. Corstanje | S. Buitink | J. E. Enriquez | H. Falcke | J. R. Horandel | P. Schellart | O. Scholten | S. ter Veen | M. Erdmann | S. J. Wijnholds | L. Bahren | A. Haungs | A. Horneffer | T. Huege | K. Link | F. G. Schroder | G. Heald | R. Krause | V. N. Pandey | R. Hiller | P. Maat | J. P. Rachen | M. E. Bell | J. Eisloffel | M. Kuniyoshi | P. Zarka | A. Nelles | K. Weidenhaupt | D. McKay-Bukowski | W. Reich | R. J. van Weeren | J. van Leeuwen | R. A. Fallows | W. Frieswijk | A. Bonafede | F. de Gasperin | M. Iacobelli | M. Pandey-Pommier | C. Tasse | W. N. Brouw | B. Ciardi | S. Duscha | A. Karastergiou | V. I. Kondratiev | R. McFadden | M. J. Norden | H. Paas | A. G. Polatidis | D. Schwarz | J. Sluman | O. Wucknitz | M. P. van Haarlem | M. A. Garrett | E. Juette | R. Pizzo | M. Serylak | T. N. G. Trinh | J. Anderson | P. Schellart | S. Buitink | A. Corstanje | J. Enriquez | H. Falcke | A. Nelles | S. Veen | H. Rottgering | O. Wucknitz | S. Wijnholds | K. Weidenhaupt | M. Erdmann | J. Leeuwen | J. Rachen | P. Zarka | J. Hörandel | L. Rossetto | R. Krause | B. Ciardi | O. Smirnov | J. Bregman | M. V. Haarlem | A. Haungs | T. Huege | F. Schroder | P. Best | M. Krause | H. Butcher | R. Vermeulen | R. Wijers | G. Heald | A. Horneffer | R. Pizzo | A. Bonafede | F. Gasperin | E. Orr̀u | H. Röttgering | C. Tasse | R. Hiller | V. Pandey | W. Frieswijk | O. Scholten | A. Karastergiou | M. Brüggen | M. Garrett | W. Reich | M. Bell | D. Carbone | J. Eisloffel | V. Kondratiev | M. Serylak | W. Brouw | R. Fallows | M. Iacobelli | M. Toribio | M. Norden | R. McFadden | R. V. Weeren | M. Pandey-Pommier | M. Hoeft | M. Bentum | M. Kuniyoshi | P. Maat | H. Paas | A. Polatidis | J. Sluman | G. Kuper | D. Schwarz | S. Duscha | E. Juette | J. Kohler | F. de Gasperin | D. McKay-Bukowski | J. Horandel | J. Eislöffel | F. Schröder | T. Trinh | K. Link | L. Bähren | L. Bahren | P. Best | M. Krause | E. Orru | T. Karskens | S. Thoudam | M. Bruuggen | J. Anderson | J. Bregman | M. Hoeft | G. Kuper | R. Vermeulen | L. Rossetto | H. R. Butcher | H. Rottgering | J. Kohler | T. Karskens | S. Thoudam | M. Bruuggen | D. Carbone | E. Orrú | R. Weeren

[1]  P. Schellart,et al.  Calibration of the LOFAR antennas , 2016 .

[2]  P. G. Isar,et al.  Energy estimation of cosmic rays with the Engineering Radio Array of the Pierre Auger Observatory , 2015, 1508.04267.

[3]  P. G. Isar,et al.  Improved absolute calibration of LOPES measurements and its impact on the comparison with REAS 3.11 and CoREAS simulations , 2015, 1507.07389.

[4]  P. Schellart,et al.  Measurement of the cosmic-ray energy spectrum above 1016 eV with the LOFAR Radboud Air Shower Array , 2015, 1506.09134.

[5]  N. Budnev,et al.  Measurement of cosmic-ray air showers with the Tunka Radio Extension (Tunka-Rex) , 2015, 1509.08624.

[6]  S. Fliescher.  Antenna Devices and Measurement of Radio Emission from Cosmic Ray induced Air Showers at the Pierre Auger Observatory , 2015 .

[7]  J. Anderson,et al.  Measuring a Cherenkov ring in the radio emission from air showers at 110-190 MHz with LOFAR , 2014, 1411.6865.

[8]  T. Karskens.  An absolute calibration of the antennas at LOFAR , 2015 .

[9]  P. Schellart,et al.  Method for high precision reconstruction of air shower Xmax using two-dimensional radio intensity profiles , 2014, 1408.7001.

[10]  P. Schellart,et al.  LORA : A scintillator array for LOFAR to measure extensive air showers , 2014, 1408.4469.

[11]  P. G. Isar,et al.  Reconstruction of the energy and depth of maximum of cosmic-ray air showers from LOPES radio measurements , 2014, 1408.2346.

[12]  N. T. Thao,et al.  Probing the radio emission from air showers with polarization measurements , 2014 .

[13]  N. Budnev,et al.  Tunka-Rex: Status and results of the first measurements , 2013, 1310.8477.

[14]  A. D. Jong,et al.  Detecting cosmic rays with the LOFAR radio telescope , 2013, 1311.1399.

[15]  T. Huege,et al.  Simulating radio emission from air showers with CoREAS , 2013, 1301.2132.

[16]  F. Schröder.  Radio detection of air showers with the Auger engineering radio array , 2013 .

[17]  N. T. Thao,et al.  Antennas for the detection of radio emission pulses from cosmic-ray induced air showers at the Pierre Auger Observatory , 2012, 1209.3840.

[18]  N. T. Thao,et al.  The rapid atmospheric monitoring system of the Pierre Auger Observatory , 2012, 1208.1675.

[19]  A. Scaife,et al.  A broad-band flux scale for low-frequency radio telescopes , 2012, 1203.0977.

[20]  K. D. Vries,et al.  A realistic treatment of geomagnetic Cherenkov radiation from cosmic ray air showers , 2012, 1201.4471.

[21]  W. Carvalho,et al.  Monte Carlo simulations of radio pulses in atmospheric showers using ZHAireS , 2011, 1107.1189.

[22]  M. C. Toribio,et al.  LOFAR: The LOw-Frequency ARray , 2013, 1305.3550.

[23]  Branko Kolundzija.  WIPL-D: From university software to company product , 2011, Proceedings of the 5th European Conference on Antennas and Propagation (EUCAP).

[24]  S. Wijnholds,et al.  In Situ Antenna Performance Evaluation of the LOFAR Phased Array Radio Telescope , 2011, IEEE Transactions on Antennas and Propagation.

[25]  P. G. Isar,et al.  Amplitude calibration of a digital radio antenna array for measuring cosmic ray air showers , 2008, 0802.4151.

[26]  Max Tegmark,et al.  A model of diffuse Galactic radio emission from 10 MHz to 100 GHz , 2008, 0802.1525.

[27]  Gijs Schoonderbeek,et al.  LOFAR Station Architectural Design Document , 2007 .

[28]  M. J. Norden.  RCU II Signal Analysis and Specification , 2007 .

[29]  Emil Polisensky,et al.  LFmap: A Low Frequency Sky Map Generating Program , 2007 .

[30]  S. Ellingson,et al.  Antennas for the next generation of low-frequency radio telescopes , 2005, IEEE Transactions on Antennas and Propagation.

[31]  S. Buitink,et al.  Detection and imaging of atmospheric radio flashes from cosmic ray air showers , 2005, Nature.

[32]  P. G. Isar,et al.  The Pierre Auger Cosmic Ray Observatory , 2015, 1502.01323.

[33]  R. Bansal,et al.  Antenna theory; analysis and design , 1984, Proceedings of the IEEE.

[34]  H. R. Allan.  Radio Emission from Extensive Air Showers , 1971, Nature.

[35]  I. Lerche,et al.  Radiation from cosmic ray air showers , 1966, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[36]  G. Askar’yan.  Coherent Radio Emission from Cosmic Showers in Air and in Dense Media , 1965 .

[37]  H.T. Friis,et al.  A Note on a Simple Transmission Formula , 1946, Proceedings of the IRE.