Radio measurements of the energy and the depth of the shower maximum of cosmic-ray air showers by Tunka-Rex

Journal of cosmology and astroparticle physics 1601(01), 052 (2016). doi:10.1088/1475-7516/2016/01/052
We reconstructed the energy and the position of the shower maximum of air showers with energies E gtrsim 100 PeV applying a method using radio measurements performed with Tunka-Rex. An event-to-event comparison to air-Cherenkov measurements of the same air showers with the Tunka-133 photomultiplier array confirms that the radio reconstruction works reliably. The Tunka-Rex reconstruction methods and absolute scales have been tuned on CoREAS simulations and yield energy and X(max) values consistent with the Tunka-133 measurements. The results of two independent measurement seasons agree within statistical uncertainties, which gives additional confidence in the radio reconstruction. The energy precision of Tunka-Rex is comparable to the Tunka-133 precision of 15%, and exhibits a 20% uncertainty on the absolute scale dominated by the amplitude calibration of the antennas. For X(max), this is the first direct experimental correlation of radio measurements with a different, established method. At the moment, the X(max) resolution of Tunka-Rex is approximately 40 g/cm(2). This resolution can probably be improved by deploying additional antennas and by further development of the reconstruction methods, since the present analysis does not yet reveal any principle limitations.
Published by IOP, London