A Search for gamma-ray emission from the galactic plane in the longitude range between 37 degrees and 43 degrees

title: Observations at large zenith angles
abstract: Cherenkov telescope observations at zenith angles >70° are capable of providing large collection areas for high energy γ-induced air showers. In order to provide a full Monte Carlo simulation of the large zenith angle observations the air shower simulation code CORSIKA was modified to treat particles in a curved geometry. First results of studies with the stand alone telescope HEGRA CT1 are presented.

title: Rejection of the hypothesis that Mkn-501 TeV photons are pure Bose – Einstein condensates
abstract: The TeV energy spectrum of the Blazar type galaxy Mkn-501 as measured by the HEGRA air Cherenkov telescopes extends beyond 16 TeV and constitutes the most energetic photons observed from an extragalactic object. A fraction of the emitted spectrum is possibly absorbed in interactions with low energy photons of the diffuse extragalactic infrared radiation, which in turn offers the unique possibility to measure the diffuse infrared radiation density by exact TeV spectroscopy. The upper limit on the density of the extragalactic infrared radiation derived from the TeV observations imposes constraints on models of galaxy formation and stellar evolution. One of the recently published ideas to reduce the absorption of TeV photons is based upon the assumption Max-Planck-Institut für Kernphysik, Postfach 103980, D-69029 Heidelberg, Germany Max-Planck-Institut für Physik, Föhringer Ring 6, D-80805 München, Germany Universidad Complutense, Facultad de Ciencias F́isicas, Ciudad Universitaria, E-28040 Madrid, Spain Universität Hamburg, II. Institut für Experimentalphysik, Luruper Chaussee 149, D-22761 Hamburg, Germany Universität Kiel, Institut für Experimentelle und Angewandte Physik, Leibnizstraße 15-19, D-24118 Kiel, Germany Universität Wuppertal, Fachbereich Physik, Gaußstr.20, D-42097 Wuppertal, Germany Yerevan Physics Institute, Alikhanian Br. 2, 375036 Yerevan, Armenia On leave from Altai State University, Dimitrov Street 66, 656099 Barnaul, Russia Corresponding author: Dieter Horns Dieter.Horns@desy.de

title: Recent Additions to the Extensive Air Shower Simulation Code CORSIKA
abstract: The Monte Carlo program CORSIKA simulates the evolution of extensive air showers in the atmosphere initiated by photons, hadrons or nuclei. Besides the already available 5 models DPMJET, HDPM, QGSJET, SIBYLL, and VENUS describing hadronic interactions at high energies we have added the new model NEXUS. Based on the universality hypothesis of the behavior of high energy interactions, NEXUS in its unified approach combines Gribov-Regge theory and perturbative QCD, including Reggeons, soft Pomerons, semi-hard Pomerons as a QCD-evolution of soft Pomerons, and parton-parton scattering. A further CORSIKA addition is the ‘curved’ option which allows a correct treatment of showers incident at large zenith angles > 70. At those angles a deviation from a planar atmosphere caused by the curvature of the Earth’s surface must be taken into account. The new extensions and features of CORSIKA are described.

title: Cherenkov light based measurement of extensive air showers around the knee with the HEGRA experiment
abstract: Data of the wide angle atmospheric Cherenkov light detector array AIROBICC and the scintillator matrix of the HEGRA air shower detector complex are combined to determine the energy spectrum and coarse composition of charged cosmic rays in the energy interval from 300 TeV to 10 PeV.

title: Energy spectrum and chemical composition of cosmic rays between 0.3 and 10 PeV determined from the Cherenkov-light and charged-particle distributions in air showers
abstract: Measurements of the lateral distribution of Cherenkov photons with the wide-angle atmospheric Cherenkov light detector array AIROBICC and of the charged particle lateral distribution with the scintillator matrix of the HEGRA air-shower detector complex in air showers are reported. They are used in conjunction to determine the energy spectrum and coarse chemical composition of charged cosmic rays in the energy interval from 0.3 PeV to 10 PeV. With the atmospheric shower-front sampling technique these detectors measure the electromagnetic component of an extensive air shower via the lateral density distribution of the shower particles and of the Cherenkov photons. The data are compared with events generated with the CORSIKA program package with the QGSJET hadronic-event generator. Consistency checks performed with primary energy-reconstruction methods based on different shower observables indicate satisfactory agreement between these extensive air shower simulations and the experimental data. This permits to derive results concerning the energy spectrum and composition of charged cosmic rays. The energy spectrum features a so called "knee" at

title: Primary Energy Spectrum as Reconstructed from S(500) Measurements by KASCADE‐Grande
abstract: In cosmic ray investigations by observations of extensive air showers 
(EAS) the general question arises how to relate the registered EAS observables to the energy of the primary particle from the cosmos entering into the atmosphere. We present results on the reconstruction of the primary energy 
spectrum of cosmic rays from the experimentally recorded S(500) observable using the KASCADE‐Grande detector array. The KASCADE‐Grande experiment is installed in Forschungszentrum Karlsruhe, Germany, and driven by an international collaboration. Previous EAS investigations have shown that for a fixed energy the charged particle density becomes independent of the primary mass at certain distances from the shower core. This feature can be used as an estimator for the primary energy. The particular radial distance from the shower core where this effect shows up is a characteristic of the detector. For the KASCADE‐Grande experiment it was shown to be around 500 m, hence a notation S(500). Extensive simulation studies have shown that S(500) is mapping the primary energy. The constant intensity cut (CIC) method is applied to evaluate the attenuation of the S(500) observable with the zenith angle. An attenuation correction is applied and all recorded S(500) values are corrected for attenuation. A calibration of S(500) values with the primary energy has been worked out by simulations and was used for conversion providing the possibility to obtain the primary energy 
spectrum (in the energy range accessible to KASCADE‐Grande 
10
10
–10
18
 
eV
).
The systematic uncertainties induced by different factors are considered.

title: Results from KASCADE–Grande
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 10 14 –10 18  eV. Main goals of the experiment are the measurement of the all-particle energy spectrum and mass composition in the 10 16 –10 18  eV range by sampling charged ( N ch ) and muon ( N μ ) 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.

title: Ultrahigh Energy Neutrinos at the Pierre Auger Observatory
abstract: The observation of ultrahigh energy neutrinos (UHE nu s) has become a priority in experimental astroparticle physics. UHE nu s can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going nu) or in the Earth crust (Earth-skimming nu), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHE nu s in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHE nu s in the EeV range and above.

title: The KASCADE‐Grande Experiment
abstract: The KASCADE-Grande experiment measures extensive air showers induced by primary cosmic rays in the energy range 1014 – 1018 eV. The major motivation for KASCADE-Grande is the investigation of the so called ”knee” in the energy spectrum of cosmic rays and its presumed rigidity dependence. A short overview of the experimental setup with focus on the Grande array and its new data acquisition system is given. As an example of analysis the reconstruction of the total muon number is presented.