High Energy Hadronic Interactions Research Articles

High Energy Cosmic Ray Interactions - an Overview

The status of present theoretical description of very high energy hadronic interactions is reviewed. The impact of new results of accelerator and cosmic ray experiments on hadronic interaction model constructions is discussed in detail. Special attention is payed to remaining uncertainties in model extrapolations into the ultra-high energy domain, in particular, concerning model predictions for the muon component of extensive air showers. New promising theoretical approaches are outlined and future experimental prospects are discussed.

Nonlinear screening effects in high energy hadronic interactions

Non-linear effects in hadronic interactions are treated by means of enhanced pomeron diagrams, assuming that pomeron-pomeron coupling is dominated by soft partonic processes. It is shown that the approach allows to resolve a seeming contradiction between realistic parton momentum distributions, measured in deep inelastic scattering experiments, and the energy behavior of total proton-proton cross section. Also a general consistency with both ``soft'' and ``hard'' diffraction data is demonstrated. An important feature of the proposed scheme is that the contribution of semi-hard processes to the interaction eikonal contains a significant non-factorizable part. On the other hand, the approach preserves the QCD factorization picture for inclusive high p_t jet production.

QGSJET-II: towards reliable description of very high energy hadronic interactions

Since a number of years the QGSJET model has been successfully used by different groups in the field of high energy cosmic rays. Current work is devoted to the first general update of the model. The key improvement is connected to an account for non-linear interaction effects which are of crucial importance for reliable model extrapolation into ultra-high energy domain. The proposed formalism allows to obtain a consistent description of hadron-hadron cross sections and hadron structure functions and to treat non-linear effects explicitely in individual hadronic and nuclear collisions. Other ameliorations concern the treatment of low mass diffraction, employment of realistic nuclear density profiles, and re-calibration of model parameters using a wider set of accelerator data.

Experimentally guided Monte Carlo calculations of the atmospheric muon and neutrino flux

The WILLI detector upgraded with the possibility to detect muons from different zenith and azimuthal angles of incidence is used to measure the charge ratio of low energy atmospheric muons, in particular the East -West effect. The results of Monte Carlo simulations with the CORSIKA code can be fairly well understood if the solar modulation, the geomagnetic cut-off and the local magnetic field are taken into account by the simulations. The data can be used to scrutinize the high-energy hadronic interaction models used as generators in the Monte Carlo program CORSIKA, and they shed some light on the models DPMJET, VENUS, UrQMD, currently in vogue. Via this procedure, having refined and calibrated the ingredients of the CORSIKA code, atmospheric muon and neutrino fluxes have been calculated and compared with recent measurements of the atmospheric muon flux and other calculations of the neutrino flux for various sites of different geomagnetic coordinates. Additionally, based on our simulations of the muon flux with CORSIKA, semi-analytical approximations used to calculate the muon flux for different applications, can be checked.

Sensitivity of Pamir emulsion chamber data to test high-energy hadronic interaction models

Emulsion experiments placed at high mountain altitudes register hadrons and high energy γ-rays with an energy threshold in the TeV region. These secondary shower particles are produced in the forward direction of interactions of mainly primary protons and alpha particles in the Earth's atmosphere. Therefore the measurements are sensitive to the physics of high-energy hadronic interaction models, e.g. as implemented in the Monte-Carlo air shower simulation program CORSIKA. Including detailed simulations for the Pamir detector the measured observables are compared with predictions from various hadronic interaction models which leads to the exclusion of some of the current models. In this context, general problems of the measurement technique by emulsion chambers like the large intrinsic shower fluctuations are discussed.

ALIGNED EVENTS OBSERVED BY EMULSION CHAMBERS IN THE KNEE REGION

The coplanar emission of very high energy secondary cosmic rays was observed at stratospheric altitudes by the X-ray emulsion chamber experiments ECHOS-Concorde and RUNJOB. This paper treats the physical relevancy of the experimental observations using Monte Carlo calculations carried out with the help of the CORSIKA program. Different high energy hadronic interaction models have been used to study the possible dependence of this effect upon the primary particle mass number.

Comparison of measured and simulated lateral distributions for electrons and muons with KASCADE

Lateral distributions for electrons and muons in extensive air showers measured with the array of the KASCADE experiment are compared to results of simulations based on the high-energy hadronic interaction models QGSJet and SIBYLL. It is shown, that the muon distributions are well described by both models. Deviations are found for the electromagnetic component, where both models predict a steeper lateral shape than observed in the data. For both models the observed lateral shapes of the electron component indicate a transition from a light to a more heavy composition of the cosmic ray spectrum above the knee.

Geometric structures in hadronic cores of extensive air showers observed by KASCADE

The geometric distribution of high-energy hadrons >100 GeV in shower cores measured with the KASCADE calorimeter is analyzed. The data are checked for sensitivity to hadronic interaction features and indications of new physics as discussed in the literature. The angular correlation of the most energetic hadrons and in particular the fraction of events with hadrons being aligned are quantified by means of the commonly used parameter lambda_4. The analysis shows that the observed lambda_4 distribution is compatible with that predicted by simulations and is not linked to an angular correlation from hadronic jet production at high energy. Another parameter, d_4^max, describing distances between hadrons measured in the detector, is found to be sensitive both to the transverse momenta in secondary hadron production and the primary particle type. Transverse momenta in high-energy hadron interactions differing by a factor two or more from what is assumed in the standard simulations are disfavoured by the measured d_4^max distribution.

Coplanar emission in very high energy cosmic ray interactions

The alignment of very high energy secondary cosmic rays, implying coplanar emissions, was observed at both stratospheric and mountain altitudes by several x-ray emulsion chamber experiments. This paper investigates the physical relevance of the experimental observations through detailed Monte Carlo calculations carried out with the CORSIKA program combining different models of high energy hadronic interaction. The physical factors likely to induce or to influence this phenomenon are discussed.

Collective behavior in nuclear interactions and shower development

The mechanism of hadronic interactions at very high energies is still unclear. Available accelerator data constrain weakly the forward rapidity region which determines the development of atmospheric showers. This ignorance is one of the main sources of uncertainty in the determination of the energy and composition of the primary in hadron-induced atmospheric showers. In this paper we examine the effect on the shower development of two kinds of collective effects in high-energy hadronic interactions which modify the production of secondary particles. The first mechanism, modeled as string fusion, affects strongly the central rapidity region but only slightly the forward region and is shown to have very little effect on the shower development. The second mechanism implies a very strong stopping; it affects modestly the profile of shower maximum but broadens considerably the number distribution of muons at ground. For the latter mechanism, the development of air showers is faster mimicking a heavier projectile. On the other hand, the number of muons at ground is lowered, resembling a shower generated by a lighter primary.

On sensitivity of Cherenkov radiation to the dynamics of high-energy cosmic ray interactions

A simulation study of the effects resulting from creation of quark–gluon plasma in high-energy collisions of cosmic iron nuclei with the air has been carried out. The Cherenkov light emission has been found to reveal some features of the dynamics of high-energy hadronic interactions.

Reanalysis of GU miniarray data using CORSIKA

The GU miniarray is a ultra high energy cosmic ray (UHECR) detector consisting of eight plastic scintillators of carpet area 2m2, each viewed by fast PMTs. It is used to detect Giant EAS by the method of time spread measurement of secondary particles produced in the atmosphere. The energies of the air showers have been reestimated using CORSIKA program. As in the original analysis the Cosmic Ray energy was determined via its relation to the ground level parameter Ns, the shower size. This relation was obtained previously through a best fit relation in agreement with QGS model and Yakutsk data. In this work we use CORSIKA code with QGSJET model of high energy hadronic interactions to simulate miniarray data leading to a modified relation between primary energy and shower size. A revised energy spectrum is reported for 1017–1019eV primary energy.

Determination of the calorimetric energy in extensive air showers

The contribution of different components of an air shower to the total energy deposit in the atmosphere, for different angles and primary particles, was studied using the CORSIKA air shower simulation code. The amount of missing energy, parameterized in terms of the calorimetric energy, was calculated. The results show that this parameterization varies less than 1% with angle or observation level. The dependence with the primary mass is less than 5% and, with the high energy hadronic interaction model, less than 2%. The systematic error introduced by the use of just one parameterization of the missing energy correction function, for an equal mixture of proton and iron at 45°, was calculated to be below 3%. We estimate the statistical error due to shower-to-shower fluctuations to be about 1%.

High-energy hadronic interactions (20 years of the Quark-Gluon Strings Model)

The approach to high-energy hadronic interactions based on the 1/N expansion in QCD and the string model of hadrons is reviewed. The Quark-Gluon Strings Model (QGSM) is discussed in detail. Applications of the QGSM to the multiparticle production at high energies are considered. It is shown that the model gives a perfect description of many aspects of hadronic interactions: diffractive processes, multiplicity distributions, correlations, and inclusive spectra of different particles in a broad energy region. It is pointed out that predictions of the model are in good agreement with data from hadronic colliders. Recent applications of the approach to small-x physics and heavy-ion collisions are reviewed.

Test of high-energy hadronic interaction models with high-altitude cosmic-ray data

Emulsion experiments placed at high mountain altitudes register hadrons and high-energy γ-rays with an energy threshold in the TeV region. These secondary shower particles are produced in the forward direction of interactions of mainly primary protons and alpha-particles in the Earth's atmosphere. Single γ's and hadrons are mainly produced by the interactions of the primary cosmic-ray nuclei of primary energy below 10 15 eV. Therefore the measurements are sensitive to the physics of high-energy hadronic interaction models, e.g., as implemented in the Monte Carlo air shower simulation program CORSIKA. By use of detailed simulations invoking various different models for the hadronic interactions we compare the predictions for the single-particle spectra with data of the Pamir experiment. For higher primary energies characteristics of so-called gamma-ray families are used for the comparisons. Including detailed simulations for the Pamir detector we found that the data are incompatible with the HDPM and SIBYLL 1.6 models, but are in agreement with QGSJET, NEXUS, and VENUS.

Test of high-energy hadronic interaction models with KASCADE — Particle physics with air shower detectors

Multi-component measurements of extensive air showers are used to study details of hadronic interactions at high energies. Results of the KASCADE experiment are summarized and limitations of the interpretation of the measurements are pointed out. In addition, requirements are discussed for new measurements of interaction properties by accelerator experiments.

Importance of forward interactions for cosmic ray air shower simulations

Collider data covering the very forward directions at the highest attainable energies are most important for improving high-energy hadronic interaction models which are used in extensive air shower simulation programs like CORSIKA.

Osobennost' Pomeranchuka i vzaimodeistviya adronov pri vysokikh energiyakh

Osobennost' Pomeranchuka i vzaimodeistviya adronov pri vysokikh energiyakh

The information from muon arrival time distributions of high-energy EAS as measured with the KASCADE detector

Using the facilities of the KASCADE Central Detector extensive air showers (EAS) muon arrival time distributions, observed with reference to the arrival time of the first locally registered muon, and their correlations with other EAS observables have been experimentally investigated. The variation of adequately defined time parameters with the distance R μ from the EAS axis has been measured. The experimental data enable a study of the sensitivity of such local arrival time distributions, which characterise the structure of the shower disc, to the mass composition of cosmic rays in the energy region around the knee. For that purpose, non-parametric multivariate even-by-event analyses have been performed for an estimate of the mass composition specified by three different mass groups, invoking detailed Monte Carlo simulations of the EAS development. It turns out that local muon arrival time distributions, without information on the curvature of the shower disc, display a minor sensitivity to the mass of the EAS inducing particle, at least for distances from the shower axis R μ<100 m. The measurements comprise a subset of all EAS events registered by KASCADE due to the observation conditions of the arrival time distributions, with a threshold of the muon energy E th=2.4 GeV and a minimum multiplicity n th for being accepted in the observed data samples. This subset is sensitive to variations of the integral EAS muon energy spectrum. By studying the event acceptance in the registered samples on basis of Monte Carlo simulations a test of the consistency of the Monte Carlo simulations with the data is enabled, comparing the results inferred from observations at different R μ and different n th values. Within the present uncertainties the results of such a test show a remarkable agreement of the experimental findings with the Monte Carlo simulations, using the QGSJET model as generator of the high-energy hadronic interactions.

Test and analysis of hadronic interaction models with KASCADE event rates

Based on the KASCADE multi-detector system with its large hadron calorimeter and using the CORSIKA simulation program with the implemented high-energy hadronic interaction models QGSJET, VENUS, DPMJET, SIBYLL, and HDPM, a method for the test of models by comparing event rates is described. Preliminary results show differences of the model predictions both among each other and when confronted with measurements. The rates are strongly influenced by the inelastic cross sections and the elasticity, especially by the contribution of diffractive dissociation. The discrepancy to measurements at primary energies below ⋍ 3 · 10 13 eV can be reduced by increasing the non-diffractive inelastic cross section.