Calibrating the absolute amplitude scale for air showers measured at LOFAR
Abstract
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.
Keywords
Cite
@article{arxiv.1507.08932,
title = {Calibrating the absolute amplitude scale for air showers measured at LOFAR},
author = {A. Nelles and J. R. Hörandel and T. Karskens and M. Krause and S. Buitink and A. Corstanje and J. E. Enriquez and M. Erdmann and H. Falcke and A. Haungs and R. Hiller and T. Huege and R. Krause and K. Link and M. J. Norden and J. P. Rachen and L. Rossetto and P. Schellart and O. Scholten and F. G. Schröder and S. ter Veen and S. Thoudam and T. N. G. Trinh and K. Weidenhaupt and S. J. Wijnholds and J. Anderson and L. Bähren and M. E. Bell and M. J. Bentum and P. Best and A. Bonafede and J. Bregman and W. N. Brouw and M. Bruüggen and H. R. Butcher and D. Carbone and B. Ciardi and F. de Gasperin and S. Duscha and J. Eislöffel and R. A. Fallows and W. Frieswijk and M. A. Garrett and M. P. van Haarlem and G. Heald and M. Hoeft and A. Horneffer and M. Iacobelli and E. Juette and A. Karastergiou and J. Kohler and V. I. Kondratiev and M. Kuniyoshi and G. Kuper and J. van Leeuwen and P. Maat and R. McFadden and D. McKay-Bukowski and E. Orru and H. Paas and M. Pandey-Pommier and V. N. Pandey and R. Pizzo and A. G. Polatidis and W. Reich and H. Röttgering and D. Schwarz and M. Serylak and J. Sluman and O. Smirnov and C. Tasse and M. C. Toribio and R. Vermeulen and R. J. van Weeren and R. A. M. J. Wijers and O. Wucknitz and P. Zarka},
journal= {arXiv preprint arXiv:1507.08932},
year = {2015}
}
Comments
34 pages, 10 figures