C. Grupen

Detection and imaging of atmospheric radio flashes from cosmic ray air showers.

The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >1020 eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within ∼50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or γ-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.

Ankle-like feature in the energy spectrum of light elements of cosmic rays observed with KASCADE-Grande

Recent results of the KASCADE-Grande experiment provided evidence for a mild knee-like structure in the all-particle spectrum of cosmic rays at

A test of the hadronic interaction model EPOS with air shower data

E = 10^{16.92 \pm 0.10} \, \mathrm{eV}

Cosmic ray measurements with LOPES: Status and recent results

, which was found to be due to a steepening in the flux of heavy primary particles. The spectrum of the combined components of light and intermediate masses was found to be compatible with a single power law in the energy range from

Revised absolute amplitude calibration of the LOPES experiment

10^{16.3} \, \mathrm{eV}

Comparison of lopes measurements with coreas and reas 3.11 simulations

to

LOPES — Recent Results and Open Questions on the Radio Detection of Air Showers

10^{18} \, \mathrm{eV}

Reconstructing energy and Xmax of cosmic ray air showers using the radio lateral distribution measured with LOPES

. In this paper, we present an update of this analysis by using data with increased statistics, originating both from a larger data set including more recent measurements and by using a larger fiducial area. In addition, optimized selection criteria for enhancing light primaries are applied. We find a spectral feature for light elements, namely a hardening at

A limit on the diffuse gamma-rays measured with KASCADE-Grande

E = 10^{17.08 \pm 0.08} \, \mathrm{eV}

Radio emission of highly inclined cosmic ray air showers measured with LOPES - possibility for neutrino detection

with a change of the power law index from