arXiv subjects

D. Heck

Publications and source records attributed to D. Heck.

69 records · Page 4Linked to original sources

arXiv2005

Lateral width of shower image in the Auger fluorescence detector

The impact of the lateral distribution of light in extensive air showers on the detection and reconstruction of shower profiles is investigated for the Auger fluorescence telescopes. Based on three-dimensional simulations, the capability of the Auger telescopes to measure the lateral distribution of light is evaluated. The ability to infer the actual lateral distribution is confirmed by the comparison of detailed simulations with real data. The contribution of pixels located far from the axis of the shower image is calculated and the accepted signal is rescaled in order to reconstruct a correct shower profile. The analysis presented here shows that: (a) the Auger telescopes are able to observe the lateral distribution of showers and (b) the energy corrections to account for the signal in outlying pixels can exceed 10%, depending on shower geometry.

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arXiv2005

Upper limit on the photon fraction in highest-energy cosmic rays from AGASA data

A new method to derive an upper limit on photon primaries from small data sets of air showers is developed which accounts for shower properties varying with the primary energy and arrival direction. Applying this method to the highest-energy showers recorded by the AGASA experiment, an upper limit on the photon fraction of 51% (67%) at a confidence level of 90% (95%) for primary energies above 1.25 * 10^20 eV is set. This new limit on the photon fraction above the GZK cutoff energy constrains the Z-burst model of the origin of highest-energy cosmic rays.

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arXiv2005

Universal lateral distribution of energy deposit in air showers and its application to shower reconstruction

The light intensity distribution in a shower image and its implications to the primary energy reconstructed by the fluorescence technique are studied. Based on detailed CORSIKA energy deposit simulations, a universal analytical formula is derived for the lateral distribution of light in the shower image and a correction factor is obtained to account for the fraction of shower light falling into outlying pixels in the detector. The expected light profiles and the corresponding correction of the primary shower energy are illustrated for several typical event geometries. This correction of the shower energy can exceed 10%, depending on shower geometry.

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arXiv2004

First Results of Fast One-dimensional Hybrid Simulation of EAS Using CONEX

A hybrid simulation code is developed that is suited for fast one-dimensional simulations of shower profiles, including fluctuations. It combines the Monte Carlo simulation of high energy interactions with a fast numerical solution of cascade equations for the resulting distributions of secondary particles. Results obtained with this new code, called CONEX, are presented and compared to CORSIKA predictions.

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arXiv2004

On a possible photon origin of the most-energetic AGASA events

In this work the ultra high energy cosmic ray events recorded by the AGASA experiment are analysed. With detailed simulations of the extensive air showers initiated by photons, the probabilities are determined of the photonic origin of the 6 AGASA events for which the muon densities were measured and the reconstructed energies exceeded 10^20 eV. On this basis a new, preliminary upper limit on the photon fraction in cosmic rays above 10^20 eV is derived and compared to the predictions of exemplary top-down cosmic-ray origin models.

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arXiv2004

On the primary particle type of the most energetic Fly's Eye event

The longitudinal profile of the 320 EeV event observed by the Fly's Eye experiment is analysed. A method of testing the hypothesis of a specific primary particle type is described. Results for different particle types are summarized. For hadronic primaries between proton and iron nuclei, the discrepancy between observed and simulated profiles is in the range of 0.6-1.0 sigma for two different hadronic interaction models investigated. For primary photons, the discrepancy is 1.5sigma assuming a standard extrapolation of the photonuclear cross-section with energy. Larger values of the cross-section at highest energies make primary photon showers more similar to hadron-initiated events. The influence of varying the extrapolation of the photonuclear cross-section is studied.

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arXiv2004

Low Energy Hadronic Interaction Models

Different interaction models treating hadronic collisions below E_lab < 100 GeV in air shower simulations are compared within the frame of the CORSIKA program. Their behaviour is studied in isolated collisions of protons or pions with light-mass targets in comparison with experimental data. It is discussed how model properties influence air-shower parameters like the longitudinal profile or the lateral distribution of particles arriving at ground.

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arXiv2004

Was the Highest Energy Cosmic Ray a Photon?

The hypothetical photonic origin of the most energetic air shower detected by the Fly's Eye experiment is discussed. The method used for the analysis is based on Monte Carlo simulations including the effect of precascading of ultra-high energy (UHE) photons in the geomagnetic field. The application of this method to data expected from the Pierre Auger Observatory is discussed. The importance of complementing the southern Auger location by a northern site for UHE photon identification is pointed out.

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arXiv2004

Simulation of air shower image in fluorescence light based on energy deposits derived from CORSIKA

Spatial distributions of energy deposited by an extensive air shower in the atmosphere through ionization, as obtained from the CORSIKA simulation program, are used to find the fluorescence light distribution in the optical image of the shower. The shower image derived in this way is somewhat smaller than that obtained from the NKG lateral distribution of particles in the shower. The size of the image shows a small dependence on the primary particle type.

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arXiv2004

Simulation of Ultra-High Energy Photon Propagation in the Geomagnetic Field

The identification of primary photons or specifying stringent limits on the photon flux is of major importance for understanding the origin of ultra-high energy (UHE) cosmic rays. We present a new Monte Carlo program allowing detailed studies of conversion and cascading of UHE photons in the geomagnetic field. The program named PRESHOWER can be used both as an independent tool or together with a shower simulation code. With the stand-alone version of the code it is possible to investigate various properties of the particle cascade induced by UHE photons interacting in the Earth's magnetic field before entering the Earth's atmosphere. Combining this program with an extensive air shower simulation code such as CORSIKA offers the possibility of investigating signatures of photon-initiated showers. In particular, features can be studied that help to discern such showers from the ones induced by hadrons. As an illustration, calculations for the conditions of the southern part of the Pierre Auger Observatory are presented.

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arXiv2003

Simulation of Atmospheric Muon and Neutrino Fluxes with CORSIKA

The fluxes of atmospheric muons and neutrinos are calculated by a three dimensional Monte Carlo simulation with the air shower code CORSIKA using the hadronic interaction models DPMJET, VENUS, GHEISHA, and UrQMD. For the simulation of low energy primary particles the original CORSIKA has been extended by a parametrization of the solar modulation and a microscopic calculation of the directional dependence of the geomagnetic cut-off functions. An accurate description for the geography of the Earth has been included by a digital elevation model, tables for the local magnetic field in the atmosphere, and various atmospheric models for different geographic latitudes and annual seasons. CORSIKA is used to calculate atmospheric muon fluxes for different locations and the neutrino fluxes for Kamioka. The results of CORSIKA for the muon fluxes are verified by an extensive comparison with recent measurements. The obtained neutrino fluxes are compared with other calculations and the influence of the hadronic interaction model, the geomagnetic cut-off and the local magnetic field on the neutrino fluxes is investigated.

hep-ph↗

arXiv2002

Comparison of Hadronic Interaction Models at Auger Energies

The three hadronic interaction models DPMJET 2.55, QGSJET 01, and SIBYLL 2.1, implemented in the air shower simulation program CORSIKA, are compared in the energy range of interest for the Pierre Auger experiment. The model dependence of relevant quantities in individual hadronic interactions and air showers is investigated.

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arXiv2002

Extensive Air Shower Simulations at the Highest Energies

Air shower simulation programs are essential tools for the analysis of data from cosmic ray experiments and for planning the layout of new detectors. They are used to estimate the energy and mass of the primary particle. Unfortunately the model uncertainties translate directly into systematic errors in the energy and mass determination. Aiming at energies $> 10^{19}$ eV, the models have to be extrapolated far beyond the energies available at accelerators. On the other hand, hybrid measurement of ground particle densities and calorimetric shower energy, as will be provided by the Pierre Auger Observatory, will strongly constrain shower models. While the main uncertainty of contemporary models comes from our poor knowledge of the (soft) hadronic interactions at high energies, also electromagnetic interactions, low-energy hadronic interactions and the particle transport influence details of the shower development. We review here the physics processes and some of the computational techniques of air shower models presently used for highest energies, and discuss the properties and limitations of the models.

astro-ph↗

arXiv2001

Extensive Air Shower Simulations with CORSIKA and the Influence of High-Energy Hadronic Interaction Models

When high-energy cosmic rays (gamma's, protons, or heavy nuclei) impinge onto the Earth's atmosphere, they interact at high altitude with the air nuclei as targets. By repeated interaction of the secondaries an `extensive air shower' (EAS) is generated with huge particle numbers in the maximum of the shower development. Such cascades are quantitatively simulated by the Monte Carlo computer program CORSIKA. The most important uncertainties in simulations arise from modeling of high-energy hadronic interactions: a) The inelastic hadron-air cross sections. b) The energies occurring in EAS may extend far above the energies available in man-made accelerators, and when extrapolating towards higher energies one has to rely on theoretical guidelines. c) In collider experiments which are used to adjust the interaction models the very forward particles are not accessible, but just those particles carry most of the hadronic energy, and in the EAS development they transport a large energy fraction down into the atmosphere. CORSIKA is coupled alternatively with 6 high-energy hadronic interaction codes (DPMJET, HDPM, neXus, QGSJET, SIBYLL, VENUS). The influence of those interaction models on observables of simulated EAS is discussed.

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arXiv1999

Comparison of AGASA data with CORSIKA simulation

An interpretation of AGASA (Akeno Giant Air Shower Array) data by comparing the experimental results with the simulated ones by CORSIKA (COsmic Ray SImulation for KASCADE) has been made. General features of the electromagnetic component and low energy muons observed by AGASA can be well reproduced by CORSIKA. The form of the lateral distribution of charged particles agrees well with the experimental one between a few hundred metres and 2000 m from the core, irrespective of the hadronic interaction model studied and the primary composition (proton or iron). It does not depend on the primary energy between 10^17.5 and 10^20 eV as the experiment shows. If we evaluate the particle density measured by scintillators of 5 cm thickness at 600 m from the core (S_0(600), suffix 0 denotes the vertically incident shower) by taking into account the similar conditions as in the experiment, the conversion relation from S_0(600) to the primary energy is expressed as E [eV] = 2.15 x 10^17 x S_0(600)^1.015, within 10% uncertainty among the models and composition used, which suggests the present AGASA conversion factor is the lower limit. Though the form of the muon lateral distribution fits well to the experiment within 1000 m from the core, the absolute values change with hadronic interaction model and primary composition. The slope of the rho_mu(600) (muon density above 1 GeV at 600 m from the core) vs. S_0(600) relation in experiment is flatter than that in simulation of any hadronic model and primary composition. Since the experimental slope is constant from 10^15 eV to 10^19 eV, we need to study this relation in a wide primary energy range to infer the rate of change of chemical composition with energy. keywords: cosmic ray, extensive air shower, simulation, primary energy estimation PACS number ; 96.40.De, 96.40.Pq

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