O. Sima

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

Progress in air shower radio measurements: Detection of distant events

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

Amplified radio emission from cosmic ray air showers in thunderstorms

, 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

The wavefront of the radio signal emitted by cosmic ray air showers

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

Frequency spectra of cosmic ray air shower radio emission measured with LOPES

to

On noise treatment in radio measurements of cosmic ray air showers

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

Comparing LOPES measurements of air-shower radio emission with REAS 3.11 and CoREAS simulations

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

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

Radio emission of highly inclined cosmic ray air showers measured with LOPES

with a change of the power law index from