arXiv subjects

C. Rühle

Publications and source records attributed to C. Rühle.

27 records · Page 2Linked to original sources

arXiv2013

LOPES 3D reconfiguration and first measurements

The Radio detection technique of high-energy cosmic rays is based on the radio signal emitted by the charged particles in an air shower due to their deflection in the Earth's magnetic field. The LOPES experiment at Karlsruhe Institute of Technology, Germany with its simple dipoles made major contributions to the revival of this technique. LOPES is working in the frequency range from 40 to 80 MHz and was reconfigured several times to improve and further develop the radio detection technique. In the current setup LOPES consists of 10 tripole antennas which measure the complete electric field vector of the radio emission from cosmic rays. LOPES is the first experiment measuring all three vectorial components at once and thereby gaining the full information about the electric field vector and not only a two-dimensional projection. Such a setup including also measurements of the vertical electric field component is expected to increase the sensitivity to inclined showers and help to advance the understanding of the emission mechanism. We present the reconfiguration and calibration procedure of LOPES 3D and discuss first measurements.

astro-ph.IM↗

arXiv2013

LOPES 3D - vectorial measurements of radio emission from cosmic ray induced air showers

LOPES 3D is able to measure all three components of the electric field vector of the radio emission from air showers. This allows a better comparison with emission models. The measurement of the vertical component increases the sensitivity to inclined showers. By measuring all three components of the electric field vector LOPES 3D demonstrates by how much the reconstruction accuracy of primary cosmic ray parameters increases. Thus LOPES 3D evaluates the usefulness of vectorial measurements for large scale applications.

astro-ph.HE↗

arXiv2013

Thunderstorm Observations by Air-Shower Radio Antenna Arrays

Relativistic, charged particles present in extensive air showers lead to a coherent emission of radio pulses which are measured to identify the shower initiating high-energy cosmic rays. Especially during thunderstorms, there are additional strong electric fields in the atmosphere, which can lead to further multiplication and acceleration of the charged particles and thus have influence on the form and strength of the radio emission. For a reliable energy reconstruction of the primary cosmic ray by means of the measured radio signal it is very important to understand how electric fields affect the radio emission. In addition, lightning strikes are a prominent source of broadband radio emissions that are visible over very long distances. This, on the one hand, causes difficulties in the detection of the much lower signal of the air shower. On the other hand the recorded signals can be used to study features of the lightning development. The detection of cosmic rays via the radio emission and the influence of strong electric fields on this detection technique is investigated with the LOPES experiment in Karlsruhe, Germany. The important question if a lightning is initiated by the high electron density given at the maximum of a high-energy cosmic-ray air shower is also investigated, but could not be answered by LOPES. But, these investigations exhibit the capabilities of EAS radio antenna arrays for lightning studies. We report about the studies of LOPES measured radio signals of air showers taken during thunderstorms and give a short outlook to new measurements dedicated to search for correlations of lightning and cosmic rays.

astro-ph.HE↗

arXiv2013

LOPES-3D, an antenna array for full signal detection of air-shower radio emission

To better understand the radio signal emitted by extensive air-showers and to further develop the radio detection technique of high-energy cosmic rays, the LOPES experiment was reconfigured to LOPES-3D. LOPES-3D is able to measure all three vectorial components of the electric field of radio emission from cosmic ray air showers. The additional measurement of the vertical component ought to increase the reconstruction accuracy of primary cosmic ray parameters like direction and energy, provides an improved sensitivity to inclined showers, and will help to validate simulation of the emission mechanisms in the atmosphere. LOPES-3D will evaluate the feasibility of vectorial measurements for large scale applications. In order to measure all three electric field components directly, a tailor-made antenna type (tripoles) was deployed. The change of the antenna type necessitated new pre-amplifiers and an overall recalibration. The reconfiguration and the recalibration procedure are presented and the operationality of LOPES-3D is demonstrated.

astro-ph.IM↗

arXiv2013

Cosmic Ray Measurements with LOPES: Status and Recent Results (ARENA 2012)

LOPES is a digital antenna array at the Karlsruhe Institute of Technology, Germany, for cosmic-ray air-shower measurements. Triggered by the co-located KASCADE-Grande air-shower array, LOPES detects the radio emission of air showers via digital radio interferometry. We summarize the status of LOPES and recent results. In particular, we present an update on the reconstruction of the primary-particle properties based on almost 500 events above 100 PeV. With LOPES, the arrival direction can be reconstructed with a precision of at least 0.65°, and the energy with a precision of at least 20 %, which, however, does not include systematic uncertainties on the absolute energy scale. For many particle and astrophysics questions the reconstruction of the atmospheric depth of the shower maximum, Xmax, is important, since it yields information on the type of the primary particle and its interaction with the atmosphere. Recently, we found experimental evidence that the slope of the radio lateral distribution is indeed sensitive to the longitudinal development of the air shower, but unfortunately, the Xmax precision at LOPES is limited by the high level of anthropogenic radio background. Nevertheless, the developed methods can be transferred to next generation experiments with lower background, which should provide an Xmax precision competitive to other detection technologies.

astro-ph.HE↗

arXiv2013

Tunka-Rex: a Radio Antenna Array for the Tunka Experiment (ARENA 2012)

Tunka-Rex, the Tunka radio extension, is an array of 20 antennas at the Tunka experiment close to Lake Baikal in Siberia. It started operation on 08 October 2012. The antennas are connected directly to the data acquisition of the Tunka main detector, a 1 square-km large array of 133 non-imaging photomultipliers observing the Cherenkov light of air showers in dark and clear nights. This allows to cross-calibrate the radio signal with the air-Cherenkov signal of the same air showers - in particular with respect to the energy and the atmospheric depth of the shower maximum, Xmax. Consequently, we can test whether in rural regions with low radio background the practically achievable radio precision comes close to the precision of the established fluorescence and air-Cherenkov techniques. At a mid-term perspective, due to its higher duty-cycle, Tunka-Rex can enhance the effective observing time of Tunka by an order of magnitude, at least in the interesting energy range above 100 PeV. Moreover, Tunka-Rex is very cost-effective, e.g., by using economic Short Aperiodic Loaded Loop Antennas (SALLAs). Thus, the results of Tunka-Rex and the comparison to other sophisticated radio arrays will provide crucial input for future large-scale cosmic-ray observatories, for which measurement precision as well as costs per area have to be optimized. In this paper we shortly describe the Tunka-Rex setup and discuss the technical and scientific goals of Tunka-Rex.

astro-ph.IM↗

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↗

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↗

arXiv2009

Study of leakage currents in pCVD diamonds as function of the magnetic field

pCVD diamond sensors are regularly used as beam loss monitors in accelerators by measuring the ionization of the lost particles. In the past these beam loss monitors showed sudden increases in the dark leakage current without beam losses and these erratic leakage currents were found to decrease, if magnetic fields were present. Here we report on a systematic study of leakage currents inside a magnetic field. The decrease of erratic currents in a magnetic field was confirmed. On the contrary, diamonds without erratic currents showed an increase of the leakage current in a magnetic field perpendicular to the electric field for fields up to 0.6T, for higher fields it decreases. A preliminary model is introduced to explain the observations.

physics.ins-det↗