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 (
>
10
20
eV). Emphasis is put on observational results, their interpretation, and the global picture of cosmic rays that has emerged during the last decade.
At energies greater than 10
15
eV, cosmic-ray particles can be measured only indirectly by detecting the extensive showers of secondary particles they create in the Earth's atmosphere. A detailed ...simulation of these particle showers is needed to reconstruct the properties of the primary particles. Key to understanding extensive air showers is the modeling of hadronic multiparticle production at energies from the particle-production threshold up to 10
20
eV—far beyond the reach of man-made accelerators. In this article, we introduce the relation between extensive air showers and hadronic interactions at high energy. We review air shower predictions of commonly used interaction models and discuss their uncertainties. Finally, we illustrate the importance of accelerator measurements for air shower simulation and, complementarily, the information that can be obtained from air showers on particle production.
An efficient method for calculating inclusive conventional and prompt atmospheric leptons fluxes is presented. The coupled cascade equations are solved numerically by formulating them as matrix ...equation. The presented approach is very flexible and allows the use of different hadronic interaction models, realistic parametrizations of the primary cosmic-ray flux and the Earth's atmosphere, and a detailed treatment of particle interactions and decays. The power of the developed method is illustrated by calculating lepton flux predictions for a number of different scenarios.
► In this work we compare results on inclusive particle production at center-of-mass (c.m.) energies sqrt (s)
=
0.9, 2.36, and 7
TeV measured in proton–proton collisions at the CERN Large Hadron ...Collider to the predictions of various hadronic Monte Carlo (MC) models (QGSJET, EPOS and SIBYLL) used commonly in ultra-high-energy cosmic-ray physics. ► As a benchmark with standard collider physics hadronic models we also show data-theory comparisons using the PYTHIA and PHOJET MCs with various parameter settings. ► While reasonable overall agreement is found for some of the MC, none of them reproduces consistently the sqrt (s) evolution of all the inclusive hadron observables. ► We discuss implications of the new LHC data for the description of cosmic-ray interactions at the highest energies measured on Earth.
The determination of the primary energy and mass of ultra-high-energy cosmic-rays (UHECR) generating extensive air-showers in the Earth’s atmosphere, relies on the detailed modeling of hadronic multiparticle production at center-of-mass (c.m.) collision energies up to two orders of magnitude higher than those studied at particle colliders. The first Large Hadron Collider (LHC) data have extended by more than a factor of three the c.m. energies in which we have direct proton–proton measurements available to compare to hadronic models. In this work we compare LHC results on inclusive particle production at energies
s
=
0.9
,
2.36
, and 7
TeV to predictions of various hadronic Monte Carlo (MC) models used commonly in cosmic-ray (CR) physics (
qgsjet,
epos and
sibyll). As a benchmark with a standard collider physics model we also show
pythia (and
phojet) predictions with various parameter settings. While reasonable overall agreement is found for some of the MC, none of them reproduces consistently the
s
evolution of all the observables. We discuss implications of the new LHC data for the description of cosmic-ray interactions at the highest energies.
We review open questions and prospects for progress in ultrahigh-energy cosmic ray (UHECR) research, based on a series of discussions that took place during the “The High-Energy Universe: Gamma-Ray, ...Neutrino, and Cosmic-ray Astronomy” MIAPP workshop in 2018. Specifically, we overview open questions on the origin of the bulk of UHECRs, the UHECR mass composition, the origin of the end of the cosmic-ray spectrum, the transition from Galactic to extragalactic cosmic rays, the effect of magnetic fields on the trajectories of UHECRs, anisotropy expectations for specific astrophysical scenarios, hadronic interactions, and prospects for discovering neutral particles as well as new physics at ultrahigh energies. We also briefly overview upcoming and proposed UHECR experiments and discuss their projected science reach.
A large scientific community depends on the precise modeling of complex processes in particle cascades in various types of matter. These models are used most prevalently in cosmic ray physics, ...astrophysical-neutrino physics, and gamma ray astronomy. In this white paper, we summarize the necessary steps to ensure the evolution and future availability of optimal simulation tools. The purpose of this document is not to act as a strict blueprint for next-generation software, but to provide guidance for the vital aspects of its design. The topics considered here are driven by physics and scientific applications. Furthermore, the main consequences of implementation decisions on performance are outlined. We highlight the computational performance as an important aspect guiding the design, since future scientific applications will heavily depend on an efficient use of computational resources.
We study neutrons produced in simulations of extensive air showers. By using the Monte Carlo simulation package Fluka, our examination is able to extend from the highest energy neutrons, produced in ...hadronic interactions, all the way down to thermal energies. The energy spectra, arrival times, and lateral distributions of neutrons at the ground are compared for different primary species, as are the longitudinal profiles of the neutron fluence. Direct comparisons are drawn with the analogous distributions for muons.
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