J. van Buren

Bio: J. van Buren is an academic researcher from Karlsruhe Institute of Technology. The author has contributed to research in topics: KASCADE & Cosmic ray. The author has an hindex of 10, co-authored 16 publications receiving 372 citations.

Large-Scale Cosmic-Ray Anisotropy with KASCADE

Abstract: We present the results of an analysis of the large-scale anisotropy of cosmic rays in the PeV range. The Rayleigh formalism is applied to the right ascension distribution of extensive air showers measured by the KASCADE (Karlsruhe Shower Core and Array Detector) experiment. The data set contains about 108 extensive air showers in the energy range 0.7-6 PeV. No hints of anisotropy are visible in the right ascension distributions in this energy range. This accounts for all showers, as well as for subsets containing showers induced by predominantly light or heavy primary particles, respectively. Upper flux limits for Rayleigh amplitudes are determined to be between 10-3 at a primary energy of 0.7 PeV and 10-2 at 6 PeV.

KASCADE-Grande: a large acceptance, high-resolution cosmic-ray detector up to 1018 eV

Abstract: We describe the main features of the extensive air-shower array devoted to the study of cosmic-ray primaries and their interactions at primary energies 10 PeV – 1 EeV which is starting operation at Forschungszentrum Karlsruhe. It exploits the existing KASCADE multi-detector facilities, and two new detectors: Grande and Piccolo, with the respective aims of providing a large acceptance area (0.5 km 2 ) and a prompt trigger signal.

Search for Cosmic-Ray Point Sources with KASCADE

Abstract: A survey of the northern hemisphere for astrophysical point sources with continuous emission of high-energy cosmic rays is presented Around 47 × 107 extensive air showers with primary energies above ≈300 TeV measured by the KASCADE detector field are selected for this analysis Besides the sky survey, a search for signal excess in the regions of the Galactic plane and of selected point-source candidates has been performed There is no evidence for any significant excess This is valid for an analysis of all recorded showers, as well as for a data set enhanced by γ-ray-induced showers An upper flux limit of around 3 × 10-10 m-2 s-1 for a steady point source that transits the zenith is obtained Additionally, the distribution of the arrival directions of extensive air showers with energies above 80 PeV was studied by an autocorrelation analysis

The Primary proton spectrum of cosmic rays measured with single hadrons at ground level

Abstract: The flux of cosmic-ray‐induced single hadrons near sea level has been measured with the large hadron calorimeter of the KASCADE experiment. The measurement corroborates former results obtained with detectors of smaller size if the enlarged veto of the 304 m 2 calorimeter surface is accounted for. The program CORSIKA/ QGSJET is used to compute the cosmic-ray flux above the atmosphere. Between E0 ¼ 300 GeV and 1 PeV the primaryprotonspectrumcanbedescribedwithapowerlawparameterizedasdJ =dE0 ¼ (0:15 � 0:03)E � 2:78� 0:03 0 m � 2 s � 1 sr � 1 TeV � 1 . At the lower energy end the proton flux compares well with the results from recent direct measurements. Subject headingg cosmic rays

Test of interaction models up to 40 PeV by studying hadronic cores of EAS

Abstract: The interpretation of extensive air shower measurements often requires a comparison with shower simulations in the atmosphere. These calculations rely on hadronic interaction models which have to extrapolate into kinematical and energy regions not explored by present-day collider experiments. The KASCADE experiment with its large hadron calorimeter and the detector array for the electromagnetic and muonic components provides experimental data to check such interaction models. For the simulations the program CORSIKA is used, which has several hadronic event generators embedded. For high-energy interactions (E_{\rm{lab}}\gtrsim100 \ {\rm{GeV}}) the models DPMJET, \{\sc NEX{\sc US}} , QGSJET and SIBYLL have been used. Low-energy interactions have been treated by GHEISHA and FLUKA. Different hadronic observables are investigated as well as their correlations with the electromagnetic and muonic shower components up to primary energies of about 40 PeV. Although the predictions of the more recent models are to a large extent compatible with the measured data within the range given by proton and iron primary particles, there are still significant differences between the individual models.

About these proceedings

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The Astrophysics of Ultrahigh-Energy Cosmic Rays

Abstract: The origin of the highest energy cosmic rays is still unknown. The discovery of their sources is expected to reveal the workings of the most energetic astrophysical accelerators in the Universe. Current observations show a spectrum consistent with an origin in extragalactic astrophysical sources. Candidate sources range from the birth of compact objects to explosions related to gamma-ray bursts or to events in active galaxies. We discuss the main effects of propagation from cosmologically distant sources, including interactions with cosmic background radiation and magnetic fields. We examine possible acceleration mechanisms leading to a survey of candidate sources and their signatures. New questions arise from an observed hint of sky anisotropies and an unexpected evolution of composition indicators. Future observations may reach the necessary sensitivity to achieve charged particle astronomy and to observe ultrahigh-energy photons and neutrinos, which may further illuminate the workings of the Universe a...

Detection and imaging of atmospheric radio flashes from cosmic ray air showers

Abstract: The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 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 gamma-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.

On the knee in the energy spectrum of cosmic rays

Abstract: Results from direct and indirect measurements of cosmic rays are reviewed. Emphasis is given to the understanding of the knee in the energy spectrum. The data are compared to contemporary models for the knee. Implications on the present understanding of the origin of galactic cosmic rays are discussed.