Jörg R. Hörandel

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The Knee in the Energy Spectrum of Cosmic Rays

Jörg R. Hörandel

NATO Science Series II: Mathematics, Physics and Chemistry > Neutrinos and Explosive Events in the Universe > Energetic Particles: From the Heliosphere to the Galaxy and Beyond > 365-376

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.

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A parameterization for the radio emission of air showers as predicted by CoREAS simulations and applied to LOFAR measurements

Anna Nelles, Stijn Buitink, Heino Falcke, Jörg R. Hörandel, more

Astroparticle Physics > 2015 > 60 > C > 13-24

Measuring radio emission from air showers provides excellent opportunities to directly measure all air shower properties, including the shower development. To exploit this in large-scale experiments, a simple and analytic parameterization of the distribution of the radio signal at ground level is needed. Data taken with the Low-Frequency Array (LOFAR) show a complex two-dimensional pattern of pulse...

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Nearby supernova remnants and the cosmic ray spectral hardening at high energies

Satyendra Thoudam, Jörg R. Hörandel

Monthly Notices of the Royal Astronomical Society > 421 > 2 > 1209 - 1214

Recent measurements of cosmic ray spectra of several individual nuclear species by the CREAM, TRACER and ATIC experiments indicate a change in the spectral index of the power laws at TeV energies. Possible explanations among others include non‐linear diffusive shock acceleration of cosmic rays, different cosmic ray propagation properties at higher and lower energies in the Galaxy and the presence...

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On the point‐source approximation of nearby cosmic ray sources

Satyendra Thoudam, Jörg R. Hörandel

Monthly Notices of the Royal Astronomical Society > 419 > 1 > 624 - 637

In this paper, we check in detail the validity of the widely adopted point‐source approximation for nearby cosmic ray (CR) sources. Under an energy‐independent escape model for CRs from the sources, we show that for young nearby sources, the point‐source approximation breaks down at lower energies and the CR spectrum depends on the size and the morphology of the source. When applied to the nearby...

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A possible correlation between the high‐energy electron spectrum and the cosmic ray secondary‐to‐primary ratios

Satyendra Thoudam, Jörg R. Hörandel

Monthly Notices of the Royal Astronomical Society > 414 > 2 > 1432 - 1438

Recent observations of high‐energy cosmic ray electrons by the Fermi‐Large Area Telescope (LAT) and the High Energy Stereoscopic System (HESS) experiments between 20 GeV and 5 TeV have found that the energy spectrum closely follows a broken power law with a break at around 1 TeV. On the other hand, measurements of cosmic ray secondary‐to‐primary ratios like the boron‐to‐carbon ratio seem to indicate...

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Cosmic rays at the highest energies

Jörg R. Hörandel

Progress in Particle and Nuclear Physics > 2010 > 64 > 2 > 351-359

Cosmic rays at the highest energies are observed with the Pierre Auger Observatory. Recent results are discussed and the properties of high-energy cosmic rays are reviewed.

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Cosmic rays from the knee to the highest energies

Johannes Blümer, Ralph Engel, Jörg R. Hörandel

Progress in Particle and Nuclear Physics > 2009 > 63 > 2 > 293-338

This review summarizes recent developments in the understanding of high-energy cosmic rays. It focuses on galactic and presumably extragalactic particles in the energy range from the knee (10 ¹⁵ eV ) up to the highest energies observed (>1020 eV). Emphasis is put on observational results, their interpretation, and the global picture of cosmic rays that has emerged during the last decade.

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Air fluorescence relevant for cosmic-ray detection—Summary of the 5th fluorescence workshop, El Escorial 2007

Fernando Arqueros, Jörg R. Hörandel, Bianca Keilhauer

Nuclear Inst. and Methods in Physics Research, A > 2008 > 597 > 1 > 1-22

High-energy cosmic rays with energies exceeding 1017eV are frequently observed by measurements of the fluorescence light induced by air showers. A major contribution to the systematic uncertainties of the absolute energy scale of such experiments is the insufficient knowledge of the fluorescence light yield of electrons in air. The aim of the 5th Fluorescence Workshop was to bring together experimental...

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Air fluorescence relevant for cosmic-ray detection—Review of pioneering measurements

Fernando Arqueros, Jörg R. Hörandel, Bianca Keilhauer

Nuclear Inst. and Methods in Physics Research, A > 2008 > 597 > 1 > 23-31

Cosmic rays with energies exceeding 1017eV are frequently registered by measurements of the fluorescence light emitted by extensive air showers. The main uncertainty for the absolute energy scale of the measured air showers is coming from the fluorescence light yield of electrons in air. The fluorescence light yield has been studied in laboratory experiments. Pioneering measurements between 1954 and...

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The origin of galactic cosmic rays

Jörg R. Hörandel

Nuclear Inst. and Methods in Physics Research, A > 2008 > 588 > 1-2 > 181-188

The origin of galactic cosmic rays is one of the most interesting unsolved problems in astroparticle physics. Experimentally, the problem is attacked by a multi-disciplinary effort, namely by direct measurements of cosmic rays above the atmosphere, by air shower observations, and by the detection of TeV γ rays. Recent experimental results are presented and their implications on the contemporary understanding...

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Cosmic-ray composition and its relation to shock acceleration by supernova remnants

Jörg R. Hörandel

Advances in Space Research > 2008 > 41 > 3 > 442-463

An overview is given on the present status of the understanding of the origin of galactic cosmic rays. Recent measurements of charged cosmic rays and photons are reviewed. Their impact on the contemporary knowledge about the sources and acceleration mechanisms of cosmic rays and their propagation through the Galaxy is discussed. Possible reasons for the knee in the energy spectrum and scenarios for...

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Propagation of super-high-energy cosmic rays in the Galaxy

Jörg R. Hörandel, Nikolai N. Kalmykov, Aleksei V. Timokhin

Astroparticle Physics > 2007 > 27 > 2-3 > 119-126

The propagation of high-energy cosmic rays in the Galaxy is investigated. Solutions of a diffusion model are combined with numerically calculated trajectories of particles. The resulting escape path length and interaction path length are presented and energy spectra obtained at Earth are discussed. It is shown that the energy spectra for heavy elements should be flatter as compared to light ones due...

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On the mean logarithmic mass of cosmic rays derived from measurements of the average depth of the maximum of extensive air showers

Jörg R. Hörandel

Nuclear Physics B (Proceedings Supplements) > 2006 > 151 > 1 > 75-78

The impact of properties of individual hadronic interactions like the inelastic cross section and the elasticity on the development of extensive air showers is investigated. Simulations of air showers are performed, their predictions are compared to measured values of integral muon multiplicities and the average depth of the shower maximum. Effects on the mean logarithmic mass derived from the measurements...

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Cosmic-ray abundances and energy spectra at high energies: Measurements with TRACER and KASCADE

Jörg R. Hörandel

Advances in Space Research > 2006 > 38 > 7 > 1549-1557

Galactic cosmic rays are investigated with complementary techniques above the atmosphere and on ground. Recent results of two experiments, the TRACER balloon experiment and the KASCADE air-shower detector are discussed.

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Search results for: Jörg R. Hörandel

The Knee in the Energy Spectrum of Cosmic Rays

A parameterization for the radio emission of air showers as predicted by CoREAS simulations and applied to LOFAR measurements

Nearby supernova remnants and the cosmic ray spectral hardening at high energies

On the point‐source approximation of nearby cosmic ray sources

A possible correlation between the high‐energy electron spectrum and the cosmic ray secondary‐to‐primary ratios

Cosmic rays at the highest energies

Cosmic rays from the knee to the highest energies

Air fluorescence relevant for cosmic-ray detection—Summary of the 5th fluorescence workshop, El Escorial 2007

Air fluorescence relevant for cosmic-ray detection—Review of pioneering measurements

The origin of galactic cosmic rays

Cosmic-ray composition and its relation to shock acceleration by supernova remnants

Propagation of super-high-energy cosmic rays in the Galaxy

On the mean logarithmic mass of cosmic rays derived from measurements of the average depth of the maximum of extensive air showers

Cosmic-ray abundances and energy spectra at high energies: Measurements with TRACER and KASCADE

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