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In the presented analysis of air shower data measured with the KASCADE experiment energy spectra for five mass groups are reconstructed. The results show a change of composition towards heavier elements across the knee but also demonstrate an insufficient description of the data by the used hadronic interaction models QGSJet and SIBYLL. [ABSTRACT FROM AUTHOR]

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?-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. [ABSTRACT FROM AUTHOR]

LOFAR is a new digital radio interferometer that is being build in The Netherlands. By sampling the radio waves with fast ADCs it can digitally store the whole waveform information and analyze transient events like air showers after they have been recorded. To demonstrate its ability to measure air showers we are building LOPES (a LOFAR PrototypeStation) at the site of an existing air shower array (KASCADE-Grande). The first phase consisting of 10 antennas is already running. It has demonstrated how digital interference suppression and beamforming can overcome the problem of radio interference and pick out air shower events. [ABSTRACT FROM AUTHOR]

Anisotropies in the arrival directions of cosmic rays reflect their source distribution and propagation properties. In the presented analysis extensive air shower measurements with KASCADE are analyzed with respect to large and small scale anisotropies. The resulting upper limits on large scale anisotropy amplitudes of 10-3 to 10-2 restrict the parameter space of several propagation models. No cosmic ray point sources could be found in a sky survey of the northern hemisphere. Typical upper flux limits for point sources are around 10-10m-2s-1. [ABSTRACT FROM AUTHOR]

The KASCADE-Grande experiment extends the existing extensive air shower experiment KASCADE by an array of 37 detector stations spread over an area of 0.5 km2. The new Grande array measures the charged component of the showers. To reconstruct the mass composition of the cosmic rays, additional information from the muon component of air showers is required. Using observables from the new Grande array together with the muon detectors of the original KASCADE array provides a possibility to reconstruct also the total muon number of each air shower. The quality of reconstruction based on comparison with simulated data, as well as first results of a reconstructed muon size spectrum are presented. [ABSTRACT FROM AUTHOR]

KASCADE (KArlsruhe Shower Core and Array DEtector) is determining flux spectra for different primary mass groups to disentangle the knee feature of the primary cosmic-ray energy spectrum. The energy spectra of the light element groups result in a knee-like bending and a steepening above the knee. The topology of the individual knee positions suggests a rigidity dependence. To proof the rigidity dependence the KASCADE array is now extended by a factor 10 in area. The major goal of KASCADE-Grande is the observation of the ’iron-knee’ in the cosmic-ray spectrum at around 100 PeV which is expected following the KASCADE observations. PACS: 98.70.Sa Cosmic rays [ABSTRACT FROM AUTHOR]

Abstract: The muon detection facilities of the Central Detector of the cosmic ray experiment KASCADE(-Grande) have been extended by a system of limited streamer tube (LST) detectors, recently brought into operation. This detector system improves the efficiency and the multiplicity resolution of the high-energy muon detection by the setup of large-area position sensitive wire proportional chambers (MWPC) of the Central Detector, currently used in extensive air showers (EAS) investigations of KASCADE. The present work describes the technical layout and operation of the LST system, the methods and procedures for studying the characteristics and performance of this detector component, and the reconstruction of basic EAS observables: the total number, the density and the spatial distributions of EAS particles registered with the LST system. Special emphasis is put on the discussion of the uncertainties. Average number of hits as well as muon number (for ) and density spectra are presented for illustrating the operation of the LST. The information about the spatial pattern is parameterized in terms of fractal moments. The information content of the EAS observables of the LST system is demonstrated using Monte Carlo simulations with the program CORSIKA. [Copyright &y& Elsevier]

The evolution of the muon content of very high energy air showers (EAS) in the atmosphere is investigated with data of the KASCADE-Grande observatory. For this purpose, the muon attenuation length in the atmosphere is obtained to Λ μ = 1256 ± 85 − 232 + 229 ( syst ) g/cm 2 from the experimental data for shower energies between 10 16.3 and 10 17.0  eV. Comparison of this quantity with predictions of the high-energy hadronic interaction models QGSJET-II-02, SIBYLL 2.1, QGSJET-II-04 and EPOS-LHC reveals that the attenuation of the muon content of measured EAS in the atmosphere is lower than predicted. Deviations are, however, less significant with the post-LHC models. The presence of such deviations seems to be related to a difference between the simulated and the measured zenith angle evolutions of the lateral muon density distributions of EAS, which also causes a discrepancy between the measured absorption lengths of the density of shower muons and the predicted ones at large distances from the EAS core. The studied deficiencies show that all four considered hadronic interaction models fail to describe consistently the zenith angle evolution of the muon content of EAS in the aforesaid energy regime. [ABSTRACT FROM AUTHOR]

The KASCADE-Grande large area (128 m 2 ) Muon Tracking Detector has been built with the aim to identify muons ( E μ thr = 800 MeV) in Extensive Air Showers by track measurements under 18 r.l. shielding. This detector provides high-accuracy angular information (approx. 0.3 ° ) for muons up to 700 m distance from the shower core. In this work we present the lateral density distributions of muons in EAS measured with the Muon Tracking Detector of the KASCADE-Grande experiment. The density is calculated by counting muon tracks in a muon-to-shower-axis distance range from 100 m to 610 m from showers with reconstructed energy of 10 16 – 10 17 eV and zenith angle θ < 18 ° . In the distance range covered by the experiment, these distributions are well described by functions phenomenologically determined already in the fifties (of the last century) by Greisen. They are compared also with the distributions obtained with the KASCADE scintillator array ( E μ thr = 230 MeV) and with distributions obtained using simulated showers. [ABSTRACT FROM AUTHOR]

We report the first direct measurement of the overall characteristics of microwave radio emission from extensive air showers. Using a trigger provided by the KASCADE-Grande air shower array, the signals of the microwave antennas of the Cosmic-Ray Observation via Microwave Emission experiment have been read out and searched for signatures of radio emission by high-energy air showers in the GHz frequency range. Microwave signals have been detected for more than 30 showers with energies above 3×1016 eV. The observations presented in this Letter are consistent with a mainly forward-directed and polarized emission process in the GHz frequency range. The measurements show that microwave radiation offers a new means of studying air showers at E⩾1017 eV. [ABSTRACT FROM AUTHOR]

Abstract: Previous results obtained by KASCADE-Grande using the QGSjetII-02 hadronic interaction model have shown that the energy spectrum of cosmic rays between eV and eV exhibits a significant hardening at approximately eV and a slight but statistically significant steepening close to eV. Moreover, the analysis with QGSjetII-02 suggests that the break observed around eV is caused by the heavy component of primary cosmic rays. In this paper, we report on the results of similar analyses performed using the SIBYLL 2.1 and EPOS 1.99 hadronic interaction models to interpret the data. The present results confirm qualitatively the previous findings. However, the intensity of the all-particle spectrum, the positions of the hardening and steepening of the spectrum, as well as the relative abundance of the heavy and light mass groups depend on the hadronic interaction model used to interpret the data. [Copyright &y& Elsevier]

Abstract: The KASCADE-Grande experiment operated at KIT from January 2004 to November 2012, measuring EAS generated by primary cosmic rays in the 1016–1018 eV energy range. The experiment detected, for each single event, with a high resolution, the total number of charged particles (N ch ) and of muons ( ). In this contribution we present the latest results about: [(i)] The measurement of the all particle energy spectrum, discussing the influence of the hadronic interaction model used to derive the energy calibration of the experimental data. [(ii)] The energy spectra derived separating the events according to the ratio. This technique allowed us to unveil a steepening of the spectrum of heavy primaries at and a hardening of the spectrum of light primaries at . [(iii)] The elemental spectra (for five mass groups) obtained applying a detailed unfolding analysis technique. [(iv)] A search for large scale anisotropies. [Copyright &y& Elsevier]

Highlights: [•] We compare LOPES radio lateral distributions of air showers with simulations. [•] Absolute amplitude is reproduced by REAS 3.11 simulations, but lower for CoREAS. [•] Slope of measured lateral distributions is reproduced by both simulation programs. [•] Rarely measured rising lateral distributions are likely due to refractive index of air. [•] The lateral distribution is sensitive to energy and mass of the primary particle. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: The KASCADE–Grande experiment, located at Karlsruhe Institute of Technology (Germany) is a multi-component extensive air-shower experiment devoted to the study of cosmic rays and their interactions at primary energies 1014–1018 eV. Main goals of the experiment are the measurement of the all-particle energy spectrum and mass composition in the 1016–1018 eV range by sampling charged (N ch ) and muon () components of the air shower. The method to derive the energy spectrum and its uncertainties, as well as the implications of the obtained result, is discussed. An overview of the analyses performed by KASCADE–Grande to derive the mass composition of the measured high-energy comic rays is presented as well. [Copyright &y& Elsevier]

We report the observation of a steepening in the cosmic ray energy spectrum of heavy primary particles at about 8 x 1016 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 x 1015 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 1016 to 1018 eV. The data are analyzed on a single-event basis taking into account also the correlation of the two observables. [ABSTRACT FROM AUTHOR]

Abstract: Relativistic, charged particles present in extensive air showers (EAS) 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. [Copyright &y& Elsevier]

Abstract: The reconstruction of Extensive Air Showers (EAS) observed by particle detectors at the ground is based on the characteristics of observables like the lateral particle density and the arrival times. The lateral densities, inferred for different EAS components from detector data, are usually parameterised by applying various lateral distribution functions (LDFs). The LDFs are used in turn for evaluating quantities like the total number of particles or the density at particular radial distances. Typical expressions for LDFs anticipate azimuthal symmetry of the density around the shower axis. The deviations of the lateral particle density from this assumption arising from various reasons are smoothed out in the case of compact arrays like KASCADE, but not in the case of arrays like Grande, which only sample a smaller part of the azimuthal variation. KASCADE-Grande, an extension of the former KASCADE experiment, is a multi-component Extensive Air Shower (EAS) experiment located at the Karlsruhe Institute of Technology (Campus North), Germany. The lateral distributions of charged particles are deduced from the basic information provided by the Grande scintillators – the energy deposits – first in the observation plane, then in the intrinsic shower plane. In all steps azimuthal dependences should be taken into account. As the energy deposit in the scintillators is dependent on the angles of incidence of the particles, azimuthal dependences are already involved in the first step: the conversion from the energy deposits to the charged particle density. This is done by using the Lateral Energy Correction Function (LECF) that evaluates the mean energy deposited by a charged particle taking into account the contribution of other particles (e.g. photons) to the energy deposit. By using a very fast procedure for the evaluation of the energy deposited by various particles we prepared realistic LECFs depending on the angle of incidence of the shower and on the radial and azimuthal coordinates of the location of the detector. Mapping the lateral density from the observation plane onto the intrinsic shower plane does not remove the azimuthal dependences arising from geometric and attenuation effects, in particular for inclined showers. Realistic procedures for applying correction factors are developed. Specific examples of the bias due to neglecting the azimuthal asymmetries in the conversion from the energy deposit in the Grande detectors to the lateral density of charged particles in the intrinsic shower plane are given. [Copyright &y& Elsevier]

Abstract: A new method is explored to detect extensive air showers: the measurement of radio waves emitted during the propagation of the electromagnetic shower component in the magnetic field of the Earth. Recent results of the pioneering experiment LOPES are discussed. It registers radio signals in the frequency range between 40 and 80MHz. The intensity of the measured radio emission is investigated as a function of different shower parameters, such as shower energy, angle of incidence, and distance to shower axis. In addition, new antenna types are developed in the framework of LOPESstar and new methods are explored to realize a radio self-trigger algorithm in real time. [Copyright &y& Elsevier]

Abstract: The properties of galactic cosmic rays are investigated with the KASCADE-Grande experiment in the energy range between 1014 and 1018 eV. Recent results are discussed. They concern mainly the all-particle energy spectrum and the elemental composition of cosmic rays. [Copyright &y& Elsevier]

Abstract: A large area (128m2) muon tracking detector, located within the KASCADE experiment, has been built with the aim to identify muons (E μ >0.8GeV) and their angular correlation in extensive air showers by track measurements under 18 r.l. shielding. Orientation of the muon track with respect to the shower axis is expressed in terms of the radial and tangential angles, which are the basic tools for all muon investigations with the tracking detector. By means of triangulation the muon production height is determined. Distributions of measured production heights are compared to CORSIKA shower simulations. Analysis of these heights reveals a transition from light to heavy cosmic ray primary particles with increasing shower energy in the energy region of the ‘Knee’ of the cosmic ray spectrum [Copyright &y& Elsevier]

Abstract: KASCADE-Grande is the enlargement of the KASCADE extensive air shower detector, realized to expand the cosmic ray studies from the previous 1014–1017 eV primary energy range to 1018 eV. This is performed by extending the area covered by the KASCADE electromagnetic array from 200×200 to 700×700m2 by means of 37 scintillator detector stations of 10m2 area each. This new array is named Grande and provides measurements of the all-charged particle component of extensive air showers (N ch ), while the original KASCADE array particularly provides information on the muon content . Additional dense compact detector set-ups being sensitive to energetic hadrons and muons are used for data consistency checks and calibration purposes. The performance of the Grande array and its integration into the entire experimental complex is discussed. It is demonstrated that the overall observable resolutions are adequate to meet the physical requirements of the measurements, i.e. primary energy spectrum and elemental composition studies in the primary cosmic ray energy range of 1016–1018 eV. [Copyright &y& Elsevier]

Abstract: The KASCADE experiment measures extensive air showers induced by cosmic rays in the energy range around the so-called knee. The data of KASCADE have been used in a composition analysis showing the knee at 3–5PeV to be caused by a steepening in the light-element spectra [T. Antoni et al., (KASCADE Coll.), Astropart. Phys. 24 (2005) 1–25]. Since the applied unfolding analysis depends crucially on simulations of air showers, different high-energy hadronic interaction models (QGSJet and SIBYLL) were used. The results have shown a strong dependence of the relative abundance of the individual mass groups on the underlying model. In this update of the analysis we apply the unfolding method with a different low energy interaction model (FLUKA instead of GHEISHA) in the simulations. While the resulting individual mass group spectra do not change significantly, the overall description of the measured data improves by using the FLUKA model. In addition data in a larger range of zenith angle are analysed. The new results are completely consistent, i.e. there is no hint to any severe problem in applying the unfolding analysis method to KASCADE data. [Copyright &y& Elsevier]

Abstract: On basis of the theorem of a universal shower development stating that a hadronically generated extensive air shower is completely described by the primary energy, the position of the shower maximum and a parameter related to the total muon number, the so-called correlation curve method is developed and applied to KASCADE data. Correlation information of the muon and electron content of showers measured by the KASCADE experiment are used for the reconstruction of energy and mass of primary cosmic rays. Systematic uncertainties of the method and the results are discussed in detail. It is shown that by this method general tendencies in spectrum and composition indeed can be revealed, but the absolute normalization in energy and mass scale requires much more detailed simulations. [Copyright &y& Elsevier]

Abstract: Extensive air showers measured by the KASCADE–Grande experiment at the Forschungszentrum Karlsruhe are studied with respect to the arrival times of electrons and muons at observation level. The mean and the spread of the arrival time distributions have been used to determine the average time profile of the electromagnetic and muonic shower disk. For core distances particles of the muonic shower component arrive on average earlier at observation level than particles of the electromagnetic shower component. The difference increases with the core distance from at to at , where the width of the muonic and electromagnetic shower disks are comparable. This difference in arrival time is used to separate the electrons and muons dependent on the distance from the shower center. This is intended to be used by experiments with time resolving detectors. [Copyright &y& Elsevier]

Abstract: Radio pulses are emitted during the development of air showers, where air showers are generated by ultra-high energy cosmic rays entering the Earth''s atmosphere. These nano-second short pulses are presently investigated by various experiments for the purpose of using them as a new detection technique for cosmic particles. For an array of 30 digital radio antennas (LOPES experiment) an absolute amplitude calibration of the radio antennas including the full electronic chain of the data acquisition system is performed, in order to estimate absolute values of the electric field strength for these short radio pulses. This is mandatory, because the measured radio signals in the MHz frequency range have to be compared with theoretical estimates and with predictions from Monte Carlo simulations to reconstruct features of the primary cosmic particle. A commercial reference radio emitter is used to estimate frequency dependent correction factors for each single antenna of the radio antenna array. The expected received power is related to the power recorded by the full electronic chain. Systematic uncertainties due to different environmental conditions and the described calibration procedure are of order 20%. [Copyright &y& Elsevier]