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R. Engel

Publications and source records attributed to R. Engel.

At least 289 records · Page 16Linked to original sources
arXiv2013

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 $E = 10^{16.92 \pm 0.10} \, \mathrm{eV}$, 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 $10^{16.3} \, \mathrm{eV}$ to $10^{18} \, \mathrm{eV}$. 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 $E = 10^{17.08 \pm 0.08} \, \mathrm{eV}$ with a change of the power law index from $-3.25 \pm 0.05$ to $-2.79 \pm 0.08$.

astro-ph.HE↗
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↗
arXiv2012

Pion emission from the T2K replica target: method, results and application

The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at the CERN SPS using a replica of the T2K graphite target. In this paper details of the experiment, data taking, data analysis method and results from the 2007 pilot run are presented. Furthermore, the application of the NA61/SHINE measurements to the predictions of the T2K initial neutrino flux is described and discussed.

hep-ex↗
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

Measurement of Production Properties of Positively Charged Kaons in Proton-Carbon Interactions at 31 GeV/c

Spectra of positively charged kaons in p+C interactions at 31 GeV/c were measured with the NA61/SHINE spectrometer at the CERN SPS. The analysis is based on the full set of data collected in 2007 with a graphite target with a thickness of 4% of a nuclear interaction length. Interaction cross sections and charged pion spectra were already measured using the same set of data. These new measurements in combination with the published ones are required to improve predictions of the neutrino flux for the T2K long baseline neutrino oscillation experiment in Japan. In particular, the knowledge of kaon production is crucial for precisely predicting the intrinsic electron neutrino component and the high energy tail of the T2K beam. The results are presented as a function of laboratory momentum in 2 intervals of the laboratory polar angle covering the range from 20 up to 240 mrad. The kaon spectra are compared with predictions of several hadron production models. Using the published pion results and the new kaon data, the K+/π+ ratios are computed.

hep-ex↗
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

Measurements of Cross Sections and Charged Pion Spectra in Proton-Carbon Interactions at 31 GeV/c

Interaction cross sections and charged pion spectra in p+C interactions at 31 GeV/c were measured with the large acceptance NA61/SHINE spectrometer at the CERN SPS. These data are required to improve predictions of the neutrino flux for the T2K long baseline neutrino oscillation experiment in Japan. A set of data collected during the first NA61/SHINE run in 2007 with an isotropic graphite target with a thickness of 4% of a nuclear interaction length was used for the analysis. The measured p+C inelastic and production cross sections are 257.2 +- 1.9 +- 8.9 mb and 229.3 +- 1.9 +- 9.0 mb, respectively. Inclusive production cross sections for negatively and positively charged pions are presented as a function of laboratory momentum in 10 intervals of the laboratory polar angle covering the range from 0 up to 420 mrad. The spectra are compared with predictions of several hadron production models.

hep-ex↗
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↗
arXiv2011

Hadron-Hadron and Cosmic-Ray Interactions at multi-TeV Energies

The workshop on "Hadron-Hadron and Cosmic-Ray Interactions at multi-TeV Energies" held at the ECT* centre (Trento) in Nov.-Dec. 2010 gathered together both theorists and experimentalists to discuss issues of the physics of high-energy hadronic interactions of common interest for the particle, nuclear and cosmic-ray communities. QCD results from collider experiments -- mostly from the LHC but also from the Tevatron, RHIC and HERA -- were discussed and compared to various hadronic Monte Carlo generators, aiming at an improvement of our theoretical understanding of soft, semi-hard and hard parton dynamics. The latest cosmic-ray results from various ground-based observatories were also presented with an emphasis on the phenomenological modeling of the first hadronic interactions of the extended air-showers generated in the Earth atmosphere. These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting.

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↗