Polarized radio emission from extensive air showers measured with LOFAR

Abstract

We present LOFAR measurements of radio emission from extensive air showers. We find that this emission is strongly polarized, with a median degree of polarization of nearly $99\%$, and that the angle between the polarization direction of the electric field and the Lorentz force acting on the particles, depends on the observer location in the shower plane. This can be understood as a superposition of the radially polarized charge-excess emission mechanism, first proposed by Askaryan and the geomagnetic emission mechanism proposed by Kahn and Lerche. We calculate the relative strengths of both contributions, as quantified by the charge-excess fraction, for $163$ individual air showers. We find that the measured charge-excess fraction is higher for air showers arriving from closer to the zenith. Furthermore, the measured charge-excess fraction also increases with increasing observer distance from the air shower symmetry axis. The measured values range from $(3.3\pm 1.0)\%$ for very inclined air showers at $25\mathrm{m}$ to $(20.3\pm 1.3)\%$ for almost vertical showers at $225\mathrm{m}$. Both dependencies are in qualitative agreement with theoretical predictions.

22 pages, 14 figures, accepted for publication in JCAP

References in corpus (4)

• The shape of the radio wavefront of extensive air showers as measured with LOFAR
• LORA: A scintillator array for LOFAR to measure extensive air showers
• The air shower maximum probed by Cherenkov effects from radio emission
• Radiodetection of Cosmic Ray Extensive Air Showers

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