@article{38c813a0c15541e8b7bf6c3eb6a6a9f7,
title = "Measurement of the circular polarization in radio emission from extensive air showers confirms emission mechanisms",
abstract = "We report here on a novel analysis of the complete set of four Stokes parameters that uniquely determine the linear and/or circular polarization of the radio signal for an extensive air shower. The observed dependency of the circular polarization on azimuth angle and distance to the shower axis is a clear signature of the interfering contributions from two different radiation mechanisms, a main contribution due to a geomagnetically-induced transverse current and a secondary component due to the build-up of excess charge at the shower front. The data, as measured at LOFAR, agree very well with a calculation from first principles. This opens the possibility to use circular polarization as an investigative tool in the analysis of air shower structure, such as for the determination of atmospheric electric fields.",
author = "O. Scholten and Trinh, {T. N.G.} and A. Bonardi and S. Buitink and P. Correa and A. Corstanje and {Dorosti Hasankiadeh}, Q. and H. Falcke and H{\"o}randel, {J. R.} and P. Mitra and K. Mulrey and A. Nelles and Rachen, {J. P.} and L. Rossetto and P. Schellart and S. Thoudam and {Ter Veen}, S. and {De Vries}, {K. D.} and T. Winchen",
note = "Funding Information: The LOFAR cosmic ray key science project acknowledges funding from an Advanced Grant of the European Research Council (FP/2007-2013)/ERC Grant Agreement No. 227610. The project has also received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 640130). We furthermore acknowledge financial support from FOM, (FOM-project 12PR304) and the Flemish foundation of scientific research (FWO-12L3715N). A. N. is supported by the DFG (research fellowship NE 2031/1-1). LOFAR, designed and constructed by ASTRON, has facilities in several countries, that are owned by various parties (each with their own funding sources), and that are collectively operated by the International LOFAR Telescope foundation under a joint scientific policy. Publisher Copyright: {\textcopyright} 2016 American Physical Society.",
year = "2016",
month = nov,
day = "23",
doi = "10.1103/PhysRevD.94.103010",
language = "British English",
volume = "94",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Physical Society",
number = "10",
}