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  • Other Sources  (13)
  • Kosmische Elektrodynamik {Astrophysik}  (8)
  • Experimentelle Mineralogie  (5)
  • Univ. Bochum  (9)
  • Univ. Siegen  (4)
  • Wiley
  • 2010-2014  (13)
  • 2000-2004
  • 1980-1984
  • 1925-1929
Collection
  • Other Sources  (13)
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Publisher
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  • 2010-2014  (13)
  • 2000-2004
  • 1980-1984
  • 1925-1929
Year
  • 1
    Publication Date: 2020-10-07
    Description: In cosmic ray experiments the arrival directions, among other properties, of cosmic ray particles from detected air shower events are reconstructed. The question of uniformity in the distribution of arrival directions is of large importance for models that try to explain cosmic radiation. In this thesis, methods for the reconstruction of parameters of a dipole-like flux distribution of cosmic rays from a set of recorded air shower events are studied. Different methods are presented and examined by means of detailed Monte Carlo simulations. Particular focus is put on the implications of spurious experimental effects. Modifications of existing methods and new methods are proposed. The main goal of this thesis is the development of the horizontal Rayleigh analysis method. Unlike other methods, this method is based on the analysis of local viewing directions instead of global sidereal directions. As a result, the symmetries of the experimental setup can be better utilised. The calculation of the sky coverage (exposure function) is not necessary in this analysis. The performance of the method is tested by means of further Monte Carlo simulations. The new method performs similarly good or only marginally worse than established methods in case of ideal measurement conditions. However, the simulation of certain experimental effects can cause substantial misestimations of the dipole parameters by the established methods, whereas the new method produces no systematic deviations. The invulnerability to certain effects offers additional advantages, as certain data selection cuts become dispensable.
    Description: thesis
    Keywords: 523 ; TFE 000 ; Kosmische Elektrodynamik {Astrophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 177 S.
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  • 2
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 523 ; TCE 500 ; TFE 000 ; TVM 610 ; TVB 420 ; Sonstige Instrumente {Astronomische Instrumente} ; Kosmische Elektrodynamik {Astrophysik} ; Luftelektrische Beobachtungs- und Meßverfahren {Meteorologie} ; Aeronomie {Meteorologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 165 S.
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  • 3
    Publication Date: 2021-03-29
    Description: We have investigated the implications of isotropically distributed interstellar magnetohydrodynamic plasma waves on the scattering mean free path and the spatial anisotropy of high-energy cosmic rays. We demonstrate a drastic modification of the energy dependence of both cosmic ray transport parameters compared to previous calculations that have assumed that the plasma waves propagate only parallel or antiparallel to the ordered magnetic field (slab turbulence).
    Description: thesis
    Keywords: 539.7223 ; 523 ; 550 ; TFE 000 ; TFG 000 ; Kosmische Elektrodynamik {Astrophysik} ; Magnetohydrodynamik und Plasma-Astrophysik
    Language: English
    Type: monograph , publishedVersion
    Format: 91 S.
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  • 4
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    Univ. Siegen
    Publication Date: 2021-03-29
    Description: The CosmoALEPH experiment, located underground at the LEP e+e? storage ring at CERN at a depth of 320 m water equivalent, was used to study the chemical composition of primary cosmic rays up to 10 PeV energies from the measurement of high energy muons, created in extensive air showers by interactions of primary nuclei in the atmosphere. The Time Projection Chamber (TPC) and the Hadron Calorimeter of the ALEPH detector and six scintillator stations located at distances up to 1 km from each other were used to analyse the decoherence curve, multiplicity and transverse momentum distributions of energetic cosmic muons. The experimental data were compared with predictions from different Monte Carlo (MC) models and mass composition approaches. From a comparison between the measured decoherence distribution with CosmoALEPH and the MC predicted decoherence curves for proton, helium and iron, a primary composition of (77±11) % protons and (23±11) % iron nuclei with a ?2 - probability of 84 % was determined, based on the predictions of the VENUS model with the constant mass composition approach. The analysis of the decoherence curve, with consideration of correlations between the measured CosmoALEPH parameters, leads to a composition of (88 ± 8) % protons and (12 ± 8) % iron nuclei for cosmic rays with a ?2 -probability of 53 % ...
    Description: thesis
    Keywords: 523 ; TFE 000 ; Kosmische Elektrodynamik {Astrophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 191 S.
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  • 5
    Publication Date: 2021-03-29
    Description: In the present work analytical solutions of the transport equation for hadronic cosmic rays are calculated. With these, it is possible for the first time to fit the energy spectra of the cosmic protons measured at the position of the earth. A focus lies on the investigation of the spatial diffusion of the galactic cosmic ray nuclei and their stochastic reacceleration by plasma waves superimposed on the interstellar medium. A realistic spatial distribution of supernova remnants as primary sources of the galactic cosmic rays and, as an additional process, the solar modulation are taken into account. Different fit parameters are obtained. Additionally, analytical approximations of the momentum solution for a power law injection spectrum for small and large momenta are calculated for the case without and for the case with spallation losses.
    Description: thesis
    Keywords: 523 ; TFE 000 ; Kosmische Elektrodynamik {Astrophysik}
    Language: English
    Type: monograph , publishedVersion
    Format: 192 S.
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  • 6
    Publication Date: 2021-03-29
    Description: Die vorliegende Arbeit untersucht den Einfluß von thermisch verteiltem Plasma auf die Strahlungsemission in den Jets von aktiven galaktischen Kernen. Zur Bestimmung der Heiz- und Strahlungsproduktionsraten wird die Strahlungstransportgleichung für einige einfache Geometrien exakt gelöst und anschließend der maximale Fehler abgeschätzt, der aus der Unkenntnis der exakten Geometrien folgt. Es wird eine analytische Abschätzung hergeleitet, welcher Prozeß die Heizrate dominiert. Schließlich wird untersucht, welche Bedingungen an experimentelle Daten gestellt werden müssen, um die Parameter des Modells eindeutig fitten zu können.
    Description: thesis
    Keywords: 523 ; TFG 000 ; TFE 000 ; Magnetohydrodynamik und Plasma-Astrophysik ; Kosmische Elektrodynamik {Astrophysik}
    Language: German
    Type: monograph , publishedVersion
    Format: 129 S.
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  • 7
    Publication Date: 2021-03-29
    Description: Triaxial compression experiments were performed on the synthesized samples and Fe-bearing clinopyroxenite in a solid medium apparatus at a confining pressure of 0.75 to 2.5 GPa, temperatures 900 to 1175oC, and strain rates between 1.1x10-6 s-1 to 8.5x 10-5 s-1. Samples of calcic compositions deformed at high differential stresses reveal abundant mechanical (100)[001] twins, whereas jadeite aggregates deformed at low differential stress show well developed subgrain boundaries. Combining the mechanical data and observed microstructures for deformed synthetic samples reveal that the deformation of diopside aggregates is controlled by dislocation glide, while the kinetics of dislocation climb controls the deformation of jadeite aggregates. The variation in strength with composition obeys scaling by the dependence of melting temperature and shear modulus on composition. In contrast to climb-controlled deformation, glide-controlled deformation should be insensitive to impurity concentrations.
    Description: thesis
    Keywords: 549 ; TQL 000 ; VAE 140 ; VGF 300 ; Sonstige Verfahren {Geophysik} ; Gesteinsdeformation {Strukturgeologie} ; Experimentelle Mineralogie
    Language: English
    Type: monograph , publishedVersion
    Format: 99 S.
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  • 8
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    Univ. Bochum
    Publication Date: 2021-03-29
    Description: Löslichkeitsdaten gesteinsbildender Minerale unter hohen Drücken sind für unser Verständnis von Fluideigenschaften und Massentransport von Mineralen in der Erdkruste und oberen Mantel von großer Wichtigkeit. In dieser Arbeit wurden neue in situ Masseverlust Methoden entwickelt um Löslichkeiten zu bestimmen, die dann in einer hydrothermalen Diamant Stempel Zelle getestet wurden. In der ersten Methode wird die Tendenz von Kristallen ausgenutzt während eines Experiments eine idiomorphe Form anzunehmen. Die zweite Methode basiert auf Messung und Analyse der Doppelbrechung eines Kristalls um dessen Dicke zu bestimmen. Masseverluste von wenigen æg können so bestimmt werden. Beide Methoden sind bis in den ppm Bereich anwendbar. Die Ergebnisse dieser Arbeit tragen sowohl zu unserem technischen Verständnis von Hockdruck/Hochtemperatur Equipment bei als auch zu unserem allgemeinen Verständnis der chemischen Eigenschaften von Fluiden in Hochdruck Umgebungen wie z.B. in Subduktionszonen.
    Description: thesis
    Keywords: 549 ; TQL 000 ; VGF 300 ; VAE 140 ; Sonstige Verfahren {Geophysik} ; Experimentelle Mineralogie ; Gesteinsdeformation {Strukturgeologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 232 S.
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  • 9
    Publication Date: 2021-03-29
    Description: thesis
    Keywords: 549 ; 552.4 ; VGF 300 ; TQL 000 ; VKB 291 ; Experimentelle Mineralogie ; Sonstige Verfahren {Geophysik} ; Metamorphe Komplexe, Alpen {Petrologie}
    Language: German
    Type: monograph , publishedVersion
    Format: 441 S.
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  • 10
    Publication Date: 2021-03-29
    Description: 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. KASCADE-Grande is a ground based detector array to study extensive air showers generated by primary cosmic ray particles in the energy range from 10^14 eV to 10^18 eV. Approximately 290,000 air showers measured between January 2005 and Febuary 2006 are used to generate arrival time distributions of electrons and muons for 13 intervals of the distance R to the shower center. The particle arrival times are reconstructed by unfolding detector signal pulses sampled by a Flash-ADC based data acquisition system connected to the electron and muon detectors of eight detector stations of the KASCADE detector array. For distances R〉200 m particles of the a muonic shower component arrive on average earlier at observation level than particles of the electromagnetic shower component. This difference in arrival time is used to determine a cut on the particle arrival time as a function of the distance from the shower center. This cut is intended to be used by experiments with time resolving detectors for the separation of electrons and muons according to their arrival times relative to the arrival time of the shower core. Particles with arrival times smaller than the cut are considered as muons. Due to the large spread of the arrival time distributions the number of muons reconstructed in this way will contain a contribution from the electromagnetic shower component ...
    Description: thesis
    Keywords: 539.7223 ; 523 ; 550 ; TFE 000 ; TVM 000 ; Kosmische Elektrodynamik {Astrophysik} ; Verschiedene Phänomene und Einflüsse {Meteorologie}
    Language: English
    Type: monograph , publishedVersion
    Format: 162 S.
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  • 11
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    Univ. Bochum
    Publication Date: 2021-03-29
    Description: Zur Untersuchung der Rheologie der Mischkristallreihe Jadeit-Diopsid wurden experimentelle Untersuchungen am Endglied Jadeit durchgeführt. Polykristalline Jadeit Proben wurden aus einem Glas in einer Stempel-Zylinder-Apparatur synthetisiert. Diese Proben wurden in einer modifizierten Griggs-Apparatur bei einem Umschließungsdruck von 2.5 GPa bei verschiedenen Temperaturen und Verformungsraten in axialer Richtung deformiert. Parameter für ein Fließgesetz für Versetzungskriechen wurden abgeleitet. Deformation im Regime des Versetzungskriechens konnte aus einer Analyse der Mikrogefüge abgeleitet werden. Die erzeugten Mikrostrukturen wurden mit denen von natürlichen, deformierten Omphaziten verglichen. Anwendung des Fließgesetzes erlaubt eine Abschätzung von Spannungsmagnituden in der Eklogitschicht in Subduktionszonen. Aus Experimenten an natürlichen Proben wurde die kritische Scherspannung für mechanische Zwillingsbildung in Jadeit abgeleitet.
    Description: thesis
    Keywords: 549 ; VAE 140 ; VGF 300 ; VAE 130 ; Gesteinsdeformation {Strukturgeologie} ; Experimentelle Mineralogie ; Geomechanik
    Language: English
    Type: monograph , publishedVersion
    Format: 162 S.
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  • 12
    Publication Date: 2021-03-29
    Description: In dieser Arbeit wird die inverse Comptonstreuung behandelt. Bei diesem Prozess streuen Elektronen niederenergetische Photonen zu höheren Energien; für die Anwendung auf die Jets aktiver galaktischer Kerne wird der sogenannte SSC--Prozess, bei dem die Elektronen die von ihnen selbst erzeugten Synchrotronphotonen streuen, untersucht. In der vorliegenden Arbeit wird für diesen Prozess erstmals eine analytische Lösung unter Berücksichtigung aller Beschränkungen der Verteilungen der Streupartner hergeleitet. Darüber hinaus wird im Rahmen des sogenannten Modells der relativistischen Stoßfront erstmalig der SSC--Prozess und die Auswirkung der elektrostatischen Turbulenz auf die Multifrequenzspektren untersucht.
    Description: thesis
    Keywords: 523 ; TFE 000 ; Kosmische Elektrodynamik {Astrophysik}
    Language: German
    Type: monograph , publishedVersion
    Format: 167 S.
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  • 13
    Publication Date: 2021-03-29
    Description: Diese experimentelle Studie untersucht Fluide in natürlichen Gesteinszusammensetzungen unter UHP-metamorphen Bedingungen. Die UHP-Fluide werden quantifiziert, ihre chemische Zusammensetzung und ihre Verteilung im Kornmaßstab beschrieben, sowie Schlüsse hinsichtlich ihrer Eigenschaften unter Versuchsbedingungen und ihrem Verhalten beim Abschrecken gezogen. Mikrogefüge und Phasenparagenesen werden in Abhängigkeit von Druck, Temperatur, Versuchszeit, Wassergehalt und Gesteinstyp charakterisiert.
    Description: thesis
    Keywords: VGF 300 ; VKB 200 ; VJC 400 ; Experimentelle Mineralogie ; Petrologie der Metamorphite ; Fluid-Gestein-Wechselwirkungen {Geochemie}
    Language: English
    Type: monograph , publishedVersion
    Format: 269 S.
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