Extensive Air Shower Simulations Research Articles

Air showers and hadronic interactions with CORSIKA 8

The CORSIKA 8 project is a collaborative effort aiming to develop a versatile C++ framework for the simulation of extensive air showers, intended to eventually succeed the long-standing FORTRAN version. I present an overview of its current capabilities, focusing on aspects concerning the hadronic and muonic shower components. In particular, I demonstrate the “cascade lineage” feature and its application to quantify the importance of certain phase-space regions in hadronic interactions for muon production. Additionally, I show first results using Pythia 8.3, which as of late is usable as interaction model in cosmic-ray applications and is currently being integrated into CORSIKA 8.

CORSIKA 8 - the next-generation air shower simulation framework

For more than 20 years, the community has heavily relied on CORSIKA for the simulation of extensive air showers, their Cherenkov light emission and their radio signals. While tremendously successful, the Fortran-based monolithic design of CORSIKA up to version 7 limits adaptation to new experimental needs, for example, in complex scenarios where showers transition from air into dense media, and to new computing paradigms such as the use of multi-core and GPU parallelization. With CORSIKA 8, we have reimplemented the core functionality of CORSIKA in a modern, modular, C++-based simulation framework, and successfully validated it against CORSIKA 7. Here, we discuss the philosophy of CORSIKA 8, showcase some example applications, and present the current state of implementation as well as the plans for the future.

Neutrons in simulations of extensive air showers

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.

Hadronic Interactions Studies at the LHC

The deficit of muons in the simulation of extensive air showers is a long-standing problem and the origin of large uncertainties in the reconstruction of the mass of the high-energy primary cosmic rays. Hadronic interaction models re-tuned after early LHC data have a more consistent description of the muon content among them but still disagree with the data. Furthermore, some inconsistencies are also visible in the electromagnetic component. Ten years after the first LHC-tuned model release, much more detailed data are available both from LHC, SPS and hybrid air shower measurements, allowing for the understanding of some deficiencies in the model which could lead to a change in both Xmax and the muon production by air showers. A better treatment of the core-corona approach according to LHC data has important consequences on the muon production while an update of diffraction and nuclear fragmentation is changing the Xmax distribution. An updated version of EPOS LHC will be presented addressing the main issues of this model.

Pythia 8 as hadronic interaction model in air shower simulations

Hadronic interaction models are a core ingredient of simulations of extensive air showers and pose the major source of uncertainties of predictions of air shower observables. Recently, Pythia 8, a hadronic interaction model popular in accelerator-based high-energy physics, became usable in air shower simulations as well. We have integrated Pythia 8 with its new capabilities into the air shower simulation framework CORSIKA 8. First results show significantly shallower shower development, which we attribute to higher cross-section predictions by the new simplified nuclear model of Pythia.

Study of identified particle ratios using cosmic rays Monte-Carlo models in [formula omitted] collisions at [formula omitted] and 7 TeV

Cosmic rays with high energies can be studied only by measuring the extensive air showers of particles produced in the upper atmosphere. A complete simulation is required to know the primary particle properties, which is possible by studying the modeling of hadronic particle production at the generator level. In this connection, we report the yield ratios π−/π+, K−/K+, p̄/p (same particles ratio), p/π, p/K, and K/π (different particles ratio) with pseudorapidity (η) in pp collisions at s = 0.9 and 7 TeV using models being used for extensive air shower simulation. The ratios were measured at the following transverse momentum (pT) regions; low pT; 0 < pT< 0.8 GeV/c, intermediate pT; 0.8 < pT< 1.2 GeV/c and high pT; pT> 1.2 GeV/c and at different pseudorapidity (η) range of 3.0 < η< 4.5 and 2.5 < η< 4.5. These results are then compared with the data from the LHCb experiment. The ratio of π−/π+ from various model predictions agrees with the measurements at both energies at almost all pT and η regions. There is a reasonable agreement in K−/K+ and p̄/p ratios of model and experimental data at s = 900 GeV except few pT and η regions, in which the models do not describe the experimental data adequately. However, almost all the models fully describe the K−/K+ and p̄/p ratios at s = 7 TeV except few pT and η regions. Moreover, none of the models completely reproduce the different particle ratios at s = 900 GeV, with Pythia and EPOS producing better results. On the other hand, in most cases, the models’ predictions for the different particle ratios are consistent with experimental data s = 7 TeV. These kinds of studies will certainly help tune the Monte-Carlo generators being used for the studies of the hadron productions at various energies.

Explaining the characteristics of lateral shower age of cosmic ray extensive air showers

A simple analytical argument is proposed for a possible explanation of the characteristics of the lateral shower age (s) of proton (p)/nuclei-initiated showers. The argument states that the lateral density distribution (LDD) of electrons of a p-initiated shower is due to the superposition of several electromagnetic (EM) sub-showers developed at a very early stage in the atmosphere from the decay of neutral pions ( $$\pi ^{0}$$ s). Thanks to the superposition property of the electron LDD in a p shower, a plausible analytical parametrisation has been worked out by giving a well represented lateral density function for the electron LDDs of p- and $$\pi ^{0}$$ -initiated showers. Based on cosmic ray extensive air shower simulations, we have validated how the various characteristics of s can be understood in the context of the proposed argument. The s parameter of a p shower and its correlations with the shower ages of electron- and $$\pi ^{0}$$ -initiated showers support the idea that the result of superposition of several EM sub-showers initiated by $$\pi ^{0}$$ s with varied energies at a very early stage might produce the LDD of electrons of a p shower. It is also noticed with the simulated data that the present conjecture works well relating to the notion of the local shower age parameter.

A modular telescope facility to investigate the cosmic ray decoherence curve

This paper describes the use of a set of small cosmic ray detectors for the measurement of the decoherence curve, i.e. the probability of observing coincidence events between pairs of particles from an extensive air shower as a function of the separation distance between them. Individual detection modules were arranged into 15 telescopes located in various positions, such as to cover nominal separation distances between 0.5 and about 25 m with a fine mesh. A measurement of the decoherence curve has been carried out during a period of approximately 24 days at an altitude close to the sea level, with the detectors located in a large lecture hall of the Physics Department, below a concrete roof. Results were also compared to theoretical simulations of extensive air showers based on Corsika. Performance of the method is discussed, with possible extension of this technique to provide a low-cost facility for the investigation of the decoherence curve at even larger distances.

On the estimation of the depth of maximum of extensive air showers using the steepness parameter of the lateral distribution of Cherenkov radiation

Using Monte Carlo simulation of extensive air showers, we showed that the maximum depth of showers, Xmax can be estimated using P=Q(100)∕Q(200), the ratio of Cherenkov photon densities at 100 and 200 meters from the shower core, which is known as the steepness parameter of the lateral distribution of Cherenkov radiation on the ground. A simple quadratic model has been fitted to a set of data from simulated extensive air showers, relating the steepness parameter and the shower maximum depth. Then the model has been tested on another set of simulated showers. The average difference between the actual maximum depth of the simulated showers and the maximum depth obtained from the lateral distribution of Cherenkov light is about 9 g/cm2. In addition, possibility of a more direct estimation of the mass of the initial particle from P has been investigated. An exponential relation between these two quantities has been fitted. Applying the model to another set of showers, we found that the average difference between the estimated and the actual mass of primary particles is less than 0.5 atomic mass unit.

PROPOSAL: A library to propagate leptons and high energy photons

PROPOSAL is a Monte Carlo simulation library, usable both in C++ and via a python wrapper, used to describe the propagation of highly energetic particles. Originally designed to provide a precise description of muon and tau propagation, recent updates introduced both photon propagation as well as a more precise implementation of electron and positron propagation. Due to its modular code structure, the user can either use the complete propagation routine provided by PROPOSAL to easily simulate all secondaries created during particle propagation or extract individual parts of the propagation routine to use them in specific applications. Examples of applications of PROPOSAL are its usage in the simulation chain of the IceCube Neutrino Observatory as well as its implementation as an electromagnetic shower model in the upcoming eighth version of the extensive air shower simulation framework CORSIKA. This talk provides a general overview of the functionalities and possibilities of PROPOSAL.

Optimizing Cherenkov Photons Generation and Propagation in CORSIKA for CTA Monte–Carlo Simulations

CORSIKA (COsmic Ray SImulations for KAscade) is a program for detailed simulation of extensive air showers initiated by high energy cosmic ray particles in the atmosphere, and is used today by almost all the major instruments that aim at measuring primary and secondary cosmic rays on the ground. The Cherenkov telescope array (CTA), currently under construction, is the next-generation instrument in the field of very-high-energy gamma-ray astronomy. Detailed CORSIKA Monte Carlo simulations will be regularly performed in parallel to CTA operations to estimate the instrument response functions, necessary to extract the physical properties of the cosmic sources from the measurements during data analysis. The estimated CPU time associated with these simulations is very high, of the order of 200 million HS06 hours per year. Code optimization becomes a necessity towards fast productions and limited costs. We propose in this paper multiple code transformations that aim to facilitate automatic vectorization done by the compiler, ensuring minimal external libraries requirement and high hardware portability.

On the Problem of Ultrahigh Energy Cosmic Ray Mass Composition Evaluation from Lateral Distributions of EAS Charged Particles Measured at Different Ranges of Radial Distances

The results of the analysis of simulations of extensive air showers (EAS) generated by ultrahigh energy cosmic rays are presented. The analysis was performed within the framework of the scaling approach developed by the authors to describe the lateral distribution functions of electrons and muons of EAS. We discuss a method to evaluate the mass composition of cosmic rays from the experimental data of existing ground-based hybrid experiments with consideration of the potential of their forthcoming extensions as well as the next generation experiments. The discussed method allows minimizing the influence of the uncertainty of nuclear interaction model, instrumental and methodical biases on physical conclusions with respect to the type of primary particle.&#x0D; It is shown that the use of the scale parameters of the lateral distributions as an indicator of primary particle, as well as the universal relationship between the scale parameters of the lateral distribution and the (longitudinal) age of the cascade, provides improving mass composition estimations on both the average and event-by-event basis by a single method in a wide primary energy range.

Hadronic interaction model sibyll2.3cand inclusive lepton fluxes

Muons and neutrinos from cosmic ray interactions in the atmosphere originate from decays of mesons in air-showers. Sibyll-2.3c aims to give a precise description of hadronic interactions in the relevant phase space for conventional and prompt leptons in light of new accelerator data, including that from the LHC. Sibyll is designed primarily as an event generator for use in simulation of extensive air showers. Because it has been tuned for forward physics as well as the central region, it can also be used to calculate inclusive fluxes. The purpose of this paper is to describe the use of Sibyll-2.3c for calculation of fluxes of atmospheric leptons.

Extensive Air Shower beyond GZK cutoff

Nowadays, ultrahigh energy cosmic rays are subject to intense research of great interest. The existence of such rays with an energy above 1020 eV is contradicted by the limit GZK due to photopion production, or by nuclei photodisintegration, in the interaction of UHECR with the cosmic microwave background. Many current UHECR experimental investigations, Auger observatory, Telescope Array (TA) and soon Extreme Universe Space Observatory on Japanese Experiment Module (JEM-EUSO) try to answer some relevant questions. What are ultrahigh energy cosmic rays? Where do they come from? How do they acquire such colossal energies? In this work detailed simulations of extensive air showers have been carried out with the help of CONEX program in order to evaluate the shower maximum depth longitudinal profile, Xmax. This parameter and its fluctuations are very sensitive to the primary particle mass.

CORSIKA 8 – Towards a modern framework for the simulation of extensive air showers

Current and future challenges in astroparticle physics require novel simulation tools to achieve higher precision and more flexibility. For three decades the FORTRAN version of CORSIKA served the community in an excellent way. However, the effort to maintain and further develop this complex package is getting increasingly difficult. To overcome existing limitations, and designed as a very open platform for all particle cascade simulations in astroparticle physics, we are developing CORSIKA 8 based on modern C++ and Python concepts. Here, we give a brief status report of the project.

The hadronic interaction model Sibyll 2.3c and muon production in extensive air-showers

One of the applications of the hadronic interaction model Sibyll is the simulation of extensive air showers of ultra-high energy cosmic rays. In recent years it has become more and more clear that simulations do not agree with measurements when it comes to observables related to muons in air showers. We discuss the processes in Sibyll that are directly related to muon production in extensive air showers and describe their relation to shower observables.

Universality of Electron Distributions in Extensive Air Showers

Abstract Based on extensive air shower simulations, it is shown that electron distributions with respect to two angles determining the electron direction at a given shower age, for a fixed electron energy and lateral distance, are universal. This means that the distributions do not depend on the primary particle energy or mass (thus, neither on the interaction model), shower zenith angle, or shower to shower fluctuations, if they are taken at the same shower age. Together with previous work showing the universality of the distributions of the electron energy, lateral distance (integrated over angles), and angle (integrated over lateral distance) for fixed electron energy, this paper completes a full universal description of the electron states at various shower ages. Analytical parametrizations of the full electron states are given. It is also shown that some distributions can be described by a number of variables smaller than five, with the new ones being products of old ones raised to some power. The accuracy of the present parametrization is sufficiently good to apply to showers with a primary energy uncertainty of 14% (as is the case at the Pierre Auger Observatory). The shower fluctuations in the chosen bins of the multidimensional variable space are about 6%, determining the minimum uncertainty needed for the parametrization of the universal distributions. An analytical way of estimating the effect of the geomagnetic field is given. Thanks to the universality of the electron distribution in any shower, a new method of shower reconstruction can be worked out from the data from observatories using the fluorescence technique. The light fluxes (both fluorescence and Cherenkov) for any shower age can be exactly predicted for a shower with any primary energy and shower maximum depth, so that the two quantities can be obtained by best fitting the predictions to the measurements.

Testing hadronic interactions with the Pierre Auger Observatory

The most energetic particles in the universe – ultra-high energy cosmic rays – interact with the atmosphere, creating air showers whose characteristics are sensitive to the primary mass composition and hadronic interaction properties. Currently, these showers are our only window to test the properties of collisions at energies beyond the reach of human-made accelerators. The Pierre Auger Observatory provides the largest data sample of cosmic ray events with energy above 1018 eV. Being a hybrid detector, it allows us to independently measure two different shower components: the profile of the electromagnetic particles crossing the atmosphere, and a sample of all particles that reach the ground,from which we can retrieve the muon number and the muon production depth profile. It will be shown that none of the hadronic interaction models used for simulations of extensive air showers, which were updated after the LHC data, is able to consistently describe all these measured shower observables.

Atmospheric Cosmic-Ray Variation and Ambient Dose Equivalent Assessments Considering Ground Level Enhancement Thanks to Coupled Anisotropic Solar Cosmic Ray and Extensive Air Shower Modeling.

This work investigates the impact of Forbush decrease (FD) and ground-level enhancement (GLE) in the atmosphere, based on solar and galactic cosmic-ray models and the extensive air shower simulations. This approach gives the possibility to investigate both the dynamic behavior of neutron monitors (NM) (using response function) and the flight dose. The ambient dose equivalent during quiet solar activity and solar events (i.e., FDs and GLEs) were investigated for realistic flight plans issued from the Eurocontrol Demand Data Repository. The calculated ambient dose equivalents were compared with flight measurements in quiet solar conditions; comparisons are relevant and demonstrate the ability to estimate the dose level. The GLE model was validated for the GLEs 5 and 69 using the cosmic-ray variation recorded by NMs. The GLE model was applied to flight dose calculations. All of these results show that dose values vary drastically with the route path (latitude, longitude and altitude) and with the delay between the flight departure and the solar event occurrence. Doses induced by extreme GLE events were investigated specifically for London to New York flights, and resulting additional doses are a few hundred or 1,000 μSv, impacting significantly the annual effective dose. This highlights the importance of monitoring extreme solar events and using realistic semi-empirical and particle transport methods for reliable calculation of dose levels.

Mass discrimination of cosmic rays by topological multi-parametric patterns

This paper discusses an effective classification method for primary mass of cosmic rays (CRs) to give a comprehensive view about different properties of near vertical Extensive Air Showers (EASs) at Alborz-1 array (35°43′N51°20′E, 1200 m a.s.l corresponding to an average atmospheric depth of 890 gcm−2) observation level. The method is based on the analysis of topological multi-parametric patterns which have been produced by simulated EASs. Iron, Oxygen, and proton were selected as primary CRs. Muon and electron multiplicities in specified distances of shower core as well as muon and electron sizes, as mass-sensitive observables of a common EAS, were selected to make the patterns. Primary energies are 100 TeV, 500 TeV, 1 PeV, 5 PeV, 10 PeV and a continuous energy spectrum from 200 TeV to 1 PeV with a spectral index of γ=2.7. Three sets of EASs were simulated and applied to the patterns to examine the method. This investigation have been carried out for showers simulated by QGSjet II-04 + GHEISHA and also SIBYLL + GHEISHA interaction models. The obtained results show that the primary mass discrimination determined by this method, strongly depends on the distance from sampling area to the showers core and also we observed that the results obtained by QGSjet II-04 and SIBYLL are almost identical. Moreover, the results demonstrate the effectiveness of the method.