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T. Huege

Publications and source records attributed to T. Huege.

At least 127 records · Page 7Linked to original sources
arXiv2013

Simulating radio emission from air showers with CoREAS

CoREAS is a Monte Carlo code for the simulation of radio emission from extensive air showers. It implements the endpoint formalism for the calculation of electromagnetic radiation directly in CORSIKA. As such, it is parameter-free, makes no assumptions on the emission mechanism for the radio signals, and takes into account the complete complexity of the electron and positron distributions as simulated by CORSIKA. In this article, we illustrate the capabilities of CoREAS with simulations carried out in different frequency ranges from tens of MHz up to GHz frequencies, and describe in particular the emission characteristics at high frequencies due to Cherenkov effects arising from the varying refractive index of the atmosphere.

astro-ph.HE↗
arXiv2012

Radar reflection off extensive air showers

We investigate the possibility of detecting extensive air showers by the radar technique. Considering a bistatic radar system and different shower geometries, we simulate reflection of radio waves off the static plasma produced by the shower in the air. Using the Thomson cross-section for radio wave reflection, we obtain the time evolution of the signal received by the antennas. The frequency upshift of the radar echo and the power received are studied to verify the feasibility of the radar detection technique.

astro-ph.HE↗
arXiv2012

The spectrum of high-energy cosmic rays measured with KASCADE-Grande

The energy spectrum of cosmic rays between 10**16 eV and 10**18 eV, derived from measurements of the shower size (total number of charged particles) and the total muon number of extensive air showers by the KASCADE-Grande experiment, is described. The resulting all-particle energy spectrum exhibits strong hints for a hardening of the spectrum at approximately 2x10**16 eV and a significant steepening at c. 8x10**16 eV. These observations challenge the view that the spectrum is a single power law between knee and ankle. Possible scenarios generating such features are discussed in terms of astrophysical processes that may explain the transition region from galactic to extragalactic origin of cosmic rays.

astro-ph.HE↗
arXiv2012

Experimental evidence for the sensitivity of the air-shower radio signal to the longitudinal shower development

We observe a correlation between the slope of radio lateral distributions, and the mean muon pseudorapidity of 59 individual cosmic-ray-air-shower events. The radio lateral distributions are measured with LOPES, a digital radio interferometer co-located with the multi-detector-air-shower array KASCADE-Grande, which includes a muon-tracking detector. The result proves experimentally that radio measurements are sensitive to the longitudinal development of cosmic-ray air-showers. This is one of the main prerequisites for using radio arrays for ultra-high-energy particle physics and astrophysics.

astro-ph.IM↗
arXiv2011

Kneelike structure in the spectrum of the heavy component of cosmic rays observed with KASCADE-Grande

We report the observation of a steepening in the cosmic ray energy spectrum of heavy primary particles at about $8 \times 10^{16}$ eV. This structure is also seen in the all-particle energy spectrum, but is less significant. Whereas the `knee' of the cosmic ray spectrum at $3-5 \times 10^{15}$ eV was assigned to light primary masses by the KASCADE experiment, the new structure found by the KASCADE-Grande experiment is caused by heavy primaries. The result is obtained by independent measurements of the charged particle and muon components of the secondary particles of extensive air showers in the primary energy range of $10^{16}$ to $10^{18}$ eV. The data are analyzed on a single-event basis taking into account also the correlation of the two observables.

astro-ph.HE↗
arXiv2011

First results of the CROME experiment

It is expected that a radio signal in the microwave range is produced in the atmosphere due to molecular bremsstrahlung initiated by extensive air showers. The CROME (Cosmic-Ray Observation via Microwave Emission) experiment was built to search for this microwave signal. Radiation from the atmosphere is monitored in the extended C band (3.4--4.2 GHz) in coincidence with showers detected by the KASCADE-Grande experiment. The detector setup consists of several parabolic antennas and fast read-out electronics. The sensitivity of the detector has been measured with different methods. First results after half a year of data taking are presented.

hep-ex↗
arXiv2010

Longitudinal EAS-Development Studies in the Air-Shower Experiment KASCADE-Grande

A large area (128 m^2) Muon Tracking Detector (MTD), located within the KASCADE experiment, has been built with the aim to identify muons (E_mu > 0.8 GeV) and their directions in extensive air showers by track measurements under more than 18 r.l. shielding. The orientation of the muon track with respect to the shower axis is expressed in terms of the radial- and tangential angles. By means of triangulation the muon production height H_mu is determined. By means of H_mu, a transition from light to heavy cosmic ray primary particle with increasing shower energy Eo from 1-10 PeV is observed. Muon pseudorapidity distributions for the first interactions above 15 km are studied and compared to Monte Carlo simulations.

astro-ph.HE↗
arXiv2010

Sensitivity of KASCADE-Grande data to hadronic interaction models

KASCADE-Grande is a large detector array dedicated for studies of high-energy cosmic rays in the primary energy range from 100 TeV to 1 EeV. The multi-detector concept of the experimental set-up offers the possibility to measure simultaneously various observables related to the electromagnetic, muonic, and hadronic air shower components. The experimental data are compared to predictions of CORSIKA simulations using high-energy hadronic interaction models (e.g. QGSJET or EPOS), as well as low-energy interaction models (e.g. FLUKA or GHEISHA). This contribution will summarize the results of such investigations. In particular, the validity of the new EPOS version 1.99 for EAS with energy around 100 PeV will be discussed.

astro-ph.HE↗
arXiv2010

The KASCADE-Grande experiment: measurements of the all-particle energy spectrum of cosmic rays

The all-particle energy spectrum as measured by the KASCADE-Grande experiment for E = 10^{16} - 10^{18} eV is presented within the framework of the QGSJET II/FLUKA hadronic interaction models. Three different methods were applied based on the muon size and the total number of charged particles individually and in combination. From the study it is found that the spectrum cannot be completely described by a smooth power law due to the presence of characteristic features.

astro-ph.HE↗
arXiv2010

On noise treatment in radio measurements of cosmic ray air showers

Precise measurements of the radio emission by cosmic ray air showers require an adequate treatment of noise. Unlike to usual experiments in particle physics, where noise always adds to the signal, radio noise can in principle decrease or increase the signal if it interferes by chance destructively or constructively. Consequently, noise cannot simply be subtracted from the signal, and its influence on amplitude and time measurement of radio pulses must be studied with care. First, noise has to be determined consistently with the definition of the radio signal which typically is the maximum field strength of the radio pulse. Second, the average impact of noise on radio pulse measurements at individual antennas is studied for LOPES. It is shown that a correct treatment of noise is especially important at low signal-to-noise ratios: noise can be the dominant source of uncertainty for pulse height and time measurements, and it can systematically flatten the slope of lateral distributions. The presented method can also be transfered to other experiments in radio and acoustic detection of cosmic rays and neutrinos.

astro-ph.IM↗
arXiv2010

Prospects for determining air shower characteristics through geosynchrotron emission arrival times

Using simulations of geosynchrotron radiation from extensive air showers, we present a relation between the shape of the geosynchrotron radiation front and the distance of the observer to the maximum of the air shower. By analyzing the relative arrival times of radio pulses at several radio antennas in an air shower array, this relation may be employed to estimate the depth of maximum of an extensive air shower if its impact position is known, allowing an estimate for the primary particle's species. Vice versa, the relation provides an estimate for the impact position of the shower's core if an external estimate of the depth of maximum is available. In realistic circumstances, the method delivers reconstruction uncertainties down to 30 g/cm^2 when the distance to the shower core does not exceed 7 km. The method requires that the arrival direction is known with high precision.

astro-ph.HE↗
arXiv2010

Simulation of radio emission from air showers in atmospheric electric fields

We study the effect of atmospheric electric fields on the radio pulse emitted by cosmic ray air showers. Under fair weather conditions the dominant part of the radio emission is driven by the geomagnetic field. When the shower charges are accelerated and deflected in an electric field additional radiation is emitted. We simulate this effect with the Monte Carlo code REAS2, using CORSIKA-simulated showers as input. In both codes a routine has been implemented that treats the effect of the electric field on the shower particles. We find that the radio pulse is significantly altered in background fields of the order of ~100 V/cm and higher. Practically, this means that air showers passing through thunderstorms emit radio pulses that are not a reliable measure for the shower energy. Under other weather circumstances significant electric field effects are expected to occur rarely, but nimbostratus clouds can harbor fields that are large enough. In general, the contribution of the electric field to the radio pulse has polarization properties that are different from the geomagnetic pulse. In order to filter out radio pulses that have been affected by electric field effects, radio air shower experiments should keep weather information and perform full polarization measurements of the radio signal.

astro-ph.HE↗
arXiv2010

New method for the time calibration of an interferometric radio antenna array

Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect high-energy cosmic rays via the radio emission from atmospheric extensive air showers. LOPES is an array of dipole antennas placed within and triggered by the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology, Germany. The antennas are digitally combined to build a radio interferometer by forming a beam into the air shower arrival direction which allows measurements even at low signal-to-noise ratios in individual antennas. This technique requires a precise time calibration. A combination of several calibration steps is used to achieve the necessary timing accuracy of about 1 ns. The group delays of the setup are measured, the frequency dependence of these delays (dispersion) is corrected in the subsequent data analysis, and variations of the delays with time are monitored. We use a transmitting reference antenna, a beacon, which continuously emits sine waves at known frequencies. Variations of the relative delays between the antennas can be detected and corrected for at each recorded event by measuring the phases at the beacon frequencies.

astro-ph.IM↗
arXiv2009

Monte Carlo simulations of air showers in atmospheric electric fields

The development of cosmic ray air showers can be influenced by atmospheric electric fields. Under fair weather conditions these fields are small, but the strong fields inside thunderstorms can have a significant effect on the electromagnetic component of a shower. Understanding this effect is particularly important for radio detection of air showers, since the radio emission is produced by the shower electrons and positrons. We perform Monte Carlo simulations to calculate the effects of different electric field configurations on the shower development. We find that the electric field becomes important for values of the order of 1 kV/cm. Not only can the energy distribution of electrons and positrons change significantly for such field strengths, it is also possible that runaway electron breakdown occurs at high altitudes, which is an important effect in lightning initiation.

astro-ph.HE↗
arXiv2009

Lateral Distribution of the Radio Signal in Extensive Air Showers Measured with LOPES

The antenna array LOPES is set up at the location of the KASCADE-Grande extensive air shower experiment in Karlsruhe, Germany and aims to measure and investigate radio pulses from Extensive Air Showers. The coincident measurements allow us to reconstruct the electric field strength at observation level in dependence of general EAS parameters. In the present work, the lateral distribution of the radio signal in air showers is studied in detail. It is found that the lateral distributions of the electric field strengths in individual EAS can be described by an exponential function. For about 20% of the events a flattening towards the shower axis is observed, preferentially for showers with large inclination angle. The estimated scale parameters R0 describing the slope of the lateral profiles range between 100 and 200 m. No evidence for a direct correlation of R0 with shower parameters like azimuth angle, geomagnetic angle, or primary energy can be found. This indicates that the lateral profile is an intrinsic property of the radio emission during the shower development which makes the radio detection technique suitable for large scale applications.

astro-ph.HE↗
arXiv2009

Radio detection of cosmic rays in the Pierre Auger Observatory

In small-scale experiments such as CODALEMA and LOPES, radio detection of cosmic rays has demonstrated its potential as a technique for cosmic ray measurements up to the highest energies. Radio detection promises measurements with high duty-cycle, allows a direction reconstruction with very good angular resolution, and provides complementary information on energy and nature of the cosmic ray primaries with respect to particle detectors at ground and fluorescence telescopes. Within the Pierre Auger Observatory, we tackle the technological and scientific challenges for an application of the radio detection technique on large scales. Here, we report on the results obtained so far using the Southern Auger site and the plans for an engineering array of radio detectors covering an area of ~20 km^2.

astro-ph.IM↗