Maciej Rybczynski, Zbigniew Wlodarczyk, Grzegorz Wilk
In this talk we present a possible explanation of the presence of high muon multiplicity events registered recenty by CERN ALICE experiment in its dedicated cosmic ray run.
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We discuss the relation between remnant fragmentation in inelastic high-energy hadronic interactions and muon production in extensive cosmic ray air showers. Using a newly developed tool, a simple and flexible hadronic event generator, we analyze the forward region of hadronic interactions. We show that measurements of the Feynman-x distribution in the beam fragmentation region at LHCf will be key to understanding muon production in air showers quantitatively.
We consider two new aspects of Extensive Air Shower development universality allowing to make accurate estimation of muon and electromagnetic (EM) shower contents in two independent ways. In the first case, to get muon (or EM) signal in water Cherenkov tanks or in scintillator detectors it is enough to know the vertical depth of shower maximum and the total signal in the ground detector. In the second case, the EM signal can be calculated from the primary particle energy and the zenith angle. In both cases the parametrizations of muon and EM signals are almost independent on primary particle n…
An analysis of the differences introduced by the hadronic interaction event generators during the development of the showers is presented. We have generated proton and nuclei induced air showers with energies up to $10^{20.5}$ eV, ``herded up'' by the code aires + sibyll/ qgsjet. The most relevant observables are taken into account for the comparison.
How uncertain are model predictions for the muon content of extensive air showers
研究了大气簇射中缪子含量预测与强子-空气相互作用特性之间的关系，并利用新的宇宙射线相互作用蒙特卡洛生成器QGSb详细探讨了特定相互作用机制对预测缪子数的影响，同时讨论了加速器测量对约束的影响。
The discovery of the Higgs boson marks a key ingredient to establish the electroweak structure of the Standard Model. Its non-abelian gauge structure gives rise to, yet unobserved, non-perturbative baryon and lepton number violating processes. We propose to use cosmic ray air showers, as measured at the Pierre Auger Observatory, to set a limit on the hadronic production cross section of sphalerons. We identify several observables to discriminate between sphaleron and QCD induced air showers.
Since recent RHIC data and the development of new theories for small x physics, a new interest appeared for forward physics. At LHC, a correct description of multiple parton interactions will be crucial to understand all the results. On the other hand, forward particle production and multiple interactions are the key points of air shower development. That's why air shower measurements done by precise experiments like KASCADE can help to understand high energy interactions, using hadronic models which are able to reproduce both accelerator and air shower data. In the framework of the EPOS model…
The objective of this work is to report on the modifications in air shower development due to muon bremsstrahlung and muonic pair production. In order to do that we have implemented new muon bremsstrahlung and muonic pair production procedures in the AIRES air shower simulation system, and have used it to simulate ultra high energy showers in different conditions. The influence of the mentioned processes in the global development of the air shower is important for primary particles of large zenith angles, while they do not introduce significant changes in the position of the shower maximum.
{}From the study of the multiple muon events in deep underground detectors, it is possible to extract information about the spectrum and composition of the primary cosmic rays. In this work the number of TeV muons produced by a primary cosmic ray of a given energy and zenith angle is computed using analytic and montecarlo methods, for a family of simplified models as description of the properties of hadronic interactions. The effects of the uncertainties in our knowledge of the hadronic cross sections in the calculation of TeV muons are discussed.
It has been proposed recently that, within the framework of split Supersymmetry, long lived gluinos generated in astrophysical sources could be detected using the signatures of the air showers they produce, thus providing a lower bound for their lifetime and for the scale of SUSY breaking. We present the longitudinal profile and lateral spread of $G$-hadron induced extensive air showers and consider the possibility of measuring them with a detector with the characteristics of the Pierre Auger Observatory.
The Sydney University Giant Air-shower Recorder (SUGAR) measured the muon component of extensive air showers with a unique array of muon detectors. The SUGAR data allow us to reconstruct the empirical dependence of muon density on the distance from the axis of the shower, the lateral distribution function (LDF). We compare the shape of this function with the predictions of hadronic-interaction models, QGSJET-II-04 and EPOS-LHC, in the energy range 10^17.6 - 10^18.6 eV. We find a difference between the observed data and the simulation: the observed muon density falls faster with the increased c…
We demonstrate that the shower-to-shower fluctuations of the muon content of extensive air showers correlate with the fluctuations of a variable of the first interaction of Ultra High Energy Cosmic Rays, which is computed from the fraction of energy carried by the hadrons that sustain the hadronic cascade. The influence of subsequent stages of the shower development is found to play a sub-dominant role. As a consequence, the shower-to-shower distribution of the muon content is a direct probe of the hadron energy spectrum of interactions beyond 100 TeV center of mass energies.
In this article we identify the key elements that govern the propagation of muons from the production in extensive air showers to ground. We describe a model based on simple assumptions that propagates the muons starting from the few relevant distributions at production. We compare the results to the ground distributions given by a full air shower Monte Carlo. This study is motivated by the need of modeling the muon component in extensive air showers with the goal of experimentally reconstructing their distributions at production, which act as a footprint of the hadronic cascade.
The objective of this work is to report on the influence of muon interactions on the development of air showers initiated by astroparticles. We make a comparative study of the different theoretical approaches to muon bremsstrahlung and muonic pair production interactions. A detailed algorithm that includes all the relevant characteristics of such processes has been implemented in the AIRES air shower simulation system. We have simulated ultra high energy showers in different conditions in order to measure the influence of these muonic electromagnetic interactions. We have found that during the…
In extensive air shower experiments, the number of muons crossing a detector at a given position, as well as their arrival time, arrival direction, and energy, are determined by a more fundamental 3-dimensional distribution linked to the hadronic core of the shower. Muons are produced high up in the atmosphere after the decay of mesons in the hadronic cascade. The distributions of production depth, energy, and transverse momentum of muons are enough to fully predict the muon component of air showers in any particular observational condition. By using air-shower simulations with the state-of-th…
Inspired by recent astrophysical observations of leptonic excesses measured by satellite experiments, we consider the impact of some general models of the dark sector on the muon production in extensive air showers. We present a compact approximative expression for the bremsstrahlung of a massive photon from an electron and use it within Monte Carlo simulations to estimate the amount of weakly interacting photon-like massive particles that could be produced in an extensive air shower. We find that the resulting muon production is by many orders of magnitude below the average muon count in a sh…
Extensive Air Showers are complex macroscopic objects initiated by single ultra-high energy particles. They are the result of millions of high energy reactions in the atmosphere and can be described as the superposition of hadronic and electromagnetic cascades. The hadronic cascade is the air shower backbone, and it is mainly made of pions. Decays of neutral pions initiate electromagnetic cascades, while the decays of charged pions produce muons which leave the hadronic core and travel many kilometers almost unaffected. Muons are smoking guns of the hadronic cascade: the energy, transverse mom…
In this paper the longitudinal profile of muon production along the shower axis is studied. The characteristics of this distribution is investigated for different primary masses, zenith angles, primary energies, and different high energy hadronic models. It is found that the shape of this distribution displays universal features similarly to what is known for the electromagnetic profile. The relation between the muon production distribution and the longitudinal electromagnetic evolution is also discussed.
Measurements of the muon content of extensive air showers at the highest energies show discrepancies compared to simulations as large as the differences between proton and iron. This so-called muon puzzle is commonly attributed to a lack of understanding of the hadronic interactions in the shower development. Furthermore, measurements of the fluctuations of muon numbers suggest that the discrepancy is likely a cumulative effect of interactions of all energies in the cascade. A feature of the air shower simulation code CORSIKA 8 allows us to access all previous generations of final-state muons …
We present the results of FLUKA simulations of the propagation of cosmogenic muons in a 20 kton spherical liquid scintillator detector underneath 700 to 900 meters of rock. A showering muon is one which deposits at least 3 GeV in the detector in addition to ionization energy. We find that 20 percent of muons are showering and a further 10 percent of muon events are muon bundles of which more than one muon enters the detector. In this range the showering and bundle fractions are robust against changes in the depth and topography, thus the total shower and bundle rate for a given experiment can …
The Sydney University Giant Air-shower Recorder (SUGAR) measured the energy spectrum of ultra-high-energy cosmic rays reconstructed from muon-detector readings, while the Pierre Auger Observatory, looking at the same Southern sky, uses the calorimetric fluorescence method for the same purpose. Comparison of their two spectra allows us to reconstruct the empirical dependence of the number of muons in the shower on the primary energy for energies between $10^{17}$ and $10^{18.5}$ eV. We compare this dependence with the predictions of hadronic interaction models \mbox{QGSJET-II-04} and \mbox{EPOS…
The production of very high energy muons inside an extensive air shower is observable at $ν$ telescopes and sensitive to the composition of the primary cosmic ray. Here we discuss five different sources of these muons: pion and kaon decays; charmed hadron decays; rare decays of unflavored mesons; photon conversion into a muon pair; and photon conversion into a $J/ψ$ vector meson decaying into muons. We solve the cascade equations for a $10^{10.5}$ GeV proton primary and find that unflavored mesons and gamma conversions are the two main sources of $E\ge 10^{8.5}$ GeV muons, while charm decays d…
A report on the characteristics of ultra-high energy air showers simulated with the AIRES program is presented. The AIRES system includes a fast simulating program which is an improved version of the well-known MOCCA program. The AIRES algorithms are briefly described and a series of results coming from the simulations are analyzed.
Sibyll$^\bigstar$: ad-hoc modifications for an improved description of muon data in extensive air showers
本研究针对超高能宇宙线空气簇射模拟中μ子含量与实验数据不符的问题，通过特设修改Sibyll 2.3d事件的末态以增加重子、$ρ^0$和奇异粒子的产生，发现这些修改能改善模拟与观测的μ子含量的匹配度，但需进一步研究以确认其物理现实性。
Most calculations of air shower development have been based on the Bethe-Heitler cross sections for bremsstrahlung and pair production. However, for energetic enough particles, a number of different external factors can reduce these cross sections drastically, slowing shower development and lengthening the showers. Four mechanisms that can suppress bremsstrahlung and pair production cross sections are discussed, and their effect on extremely high energy air showers considered. Besides lengthening the showers, these mechanisms greatly increase the importance of fluctuations in shower developmen…
A report on the characteristics of ultra-high energy air showers simulated with the current version of the AIRES program is presented. The AIRES system includes a fast simulating program, originally designed on the basis of the well-known MOCCA program, and progressively improved and tested. The AIRES algorithms are briefly described and some results coming from the simulations are analyzed.
Hadronic cross sections at ultra-high energy have a significant impact on the development of extensive air shower cascades. Therefore the interpretation of air shower data depends critically on hadronic interaction models that extrapolate the cross section from accelerator measurements to the highest cosmic ray energies. We discuss how extreme scenarios of cross section extrapolations can affect the interpretation of air shower data. We find that the theoretical uncertainty of the extrapolated proton-air cross section at ultra-high energies is much larger than suggested by the existing spread …
Studies of the nature of cosmic ray particles at the highest energies are based on the measurement of extensive air showers. Most cosmic ray properties can therefore only be obtained from the interpretation of air shower data and are thus depending on predictions of hadronic interaction models at ultra-high energies. We discuss different scenarios of model extrapolations from accelerator data to air shower energies and investigate their impact on the corresponding air shower predictions. To explore the effect of different extrapolations by hadronic interaction models we developed an ad hoc mod…
In order to examine a muon excess observed by the Pierre Auger Observatory, detailed Monte Carlo simulations were carried out for primary protons, iron nuclei and strangelets (hypothetical stable lumps of strange quark matter). We obtained a rough agreement between the simulations and the data for ordinary nuclei without any contribution of strangelets in primary flux of cosmic rays. Our simulations suggest that the shower observables are dominated by details of hadronic interaction models.
Reconstructing Air-Shower Observables using a Universality-Based Model at the Pierre Auger Observatory
本文利用基于级联方程解的普适性模型，结合强子成分，重建超高能宇宙射线空气簇射的可观测量，如簇射最大深度和μ子数，并在模拟和奥格天文台数据中验证性能。
A procedure is suggested for systematically narrowing the choice of possible primaries for (UHECR) air showers with energies beyond the Greisen-Zatsepin-Kuz'min cut-off of $4 \times 10^{19} eV$.
Pythia 8 as hadronic interaction model in air shower simulations
本研究将强子相互作用模型 Pythia 8 集成到空气簇射模拟框架 CORSIKA 8 中，发现其预测的更高截面导致簇射发展显著变浅。
We find that the ratio r_{mu e} of the muon to the electromagnetic component of an extended air shower at the ground level provides an indirect measure of the depth X_{max} of the shower maximum. This result, obtained with the air-shower code AIRES, is independent of the hadronic model used in the simulation. We show that the value of r_{mu e} in a particular shower discriminates its proton or iron nature with a 98% efficiency. We also show that the eventual production of forward heavy quarks inside the shower may introduce anomalous values of r_{mu e} in isolated events.
We propose to extract the charge information of high energy muons in very inclined extensive air showers by analyzing their relative lateral positions in the shower transverse plane. We calculate the muon lateral deviation under the geomagnetic field and compare it to dispersive deviations from other causes. By our criterion of resolvability, positive and negative muons with energies above $10^4$ GeV will be clearly separated into two lobes if the shower zenith angle is larger than $70^\circ$. Thus we suggest a possible approach to measure the $μ^+ / μ^-$ ratio for high energy muons.
QGSJET-III: predictions for extensive air shower characteristics and the corresponding uncertainties
本文介绍QGSJET-III模型对广延大气簇射特性的预测，并与其他模型比较，分析了增强μ子含量或延迟簇射发展的不确定性。
Sensitivity of seasonal variations of the muon energy spectrum in air showers to hadronic interaction models and the cosmic-ray mass composition
本文利用MCEq研究空气簇射中高能μ子数量季节变化对原初宇宙线能量、质量及强子相互作用模型的依赖，并提出结合地面阵列与深地下探测器测量该变化以探测宇宙线成分和强子相互作用的新方法。
Azimuthal fluctuations and number of muons at the ground in muon-depleted proton air showers at PeV energies
本研究提出基于$LCm$变量的新型判别方法，在PeV能量下实现更高的质子排斥水平，优于传统muon计数方法。
Whereas air shower simulations are very valuable tools for interpreting cosmic ray data, there is a long standing problem: is seems to be impossible to accommodate at the same time the longitudinal development of air showers and the number of muons measured at ground. Using a new hadronic interaction model (EPOS) in air shower simulations produces considerably more muons, in agreement with results from the HiRes-MIA experiment. We find that this is mainly due to a better description of baryon-antibaryon production in hadronic interactions. This is a new aspect of air shower physics which has n…
A simulation study of the energy released by extensive air showers in the form of MHz radiation is performed using the CoREAS simulation code. We develop an efficient method to extract this radiation energy from air-shower simulations. We determine the longitudinal profile of the radiation energy release and compare it to the longitudinal profile of the energy deposit by the electromagnetic component of the air shower. We find that the radiation energy corrected for the geometric dependence of the geomagnetic emission scales quadratically with the energy in the electromagnetic component of the…
Some general properties of extensive air showers are discussed. The main focus is put on the longitudinal development, in particular the energy flow, and on the lateral distribution of different air shower components. The intention of the paper is to provide a basic introduction to the subject rather than a comprehensive review.
We calculate contained and upward muon flux and contained shower event rates from neutrino interactions, when neutrinos are produced from annihilation of the dark matter in the Galactic Center. We consider model-independent direct neutrino production and secondary neutrino production from the decay of taus, W bosons and bottom quarks produced in the annihilation of dark matter. We illustrate how muon flux from dark matter annihilation has a very different shape than the muon flux from atmospheric neutrinos. We also discuss the dependence of the muon fluxes on the dark matter density profile an…
We discuss air shower simulations based on the EPOS hadronic interaction model. A remarkable feature is the fact that the number of produced muons is considerably larger compared to other interaction models. We show that this is due to an improved treatment of baryon-antibaryon production.
At high energy, cosmic rays can only be studied by measuring the extensive air showers they produce in the atmosphere of the Earth. Although the main features of air showers can be understood within a simple model of successive interactions, detailed simulations and a realistic description of particle production are needed to calculate observables relevant to air shower experiments. Currently hadronic interaction models are the main source of uncertainty of such simulations. We will study the effect of using different hadronic models available in CORSIKA and CONEX on extensive air shower predi…
We present a microscopic computation of the radio emission from air showers initiated by ultra-high energy cosmic rays in the atmosphere. The strategy adopted is to compute each secondary particle contribution of the electromagnetic component and to construct the total signal at any location. SELFAS2 is a code which doesn't rely on air shower generators like AIRES or CORSIKA and it is based on the concept of air shower universality which makes it completely autonomous. Each positron and electron of the air shower is generated randomly following relevant distributions and tracking them along th…
We study the role new gauge interactions in extensions of the standard model play in air showers initiated by ultrahigh-energy cosmic rays. Hadron-hadron events remain dominated by quantum chromodynamics, while projectiles and/or targets from beyond the standard model permit us to see qualitative differences arising due to the new interactions.
Amplified Tau-airshower at horizons may well open a novel powerful windows, at PeV-EeV energy, to Neutrino Astronomy. Neutrino induced air-showering astronomy rise because of neutrino masses, their mixing and the consequent replenishment of tau flavor during neutrino flight into spaces; Tau-Air-Showers escaping the Earth are the main traces amplified by its millions muon, billions gamma and thousand billions photon secondaries. Earth edges and its sharp shadows is the huge beam-dump detector for UHE neutrino and the almost noise-free screen for tau air-showers (as well as for PeVs anti-neutrin…
Readdressing the contribution of photonuclear reactions to the muon content of extensive air showers: a heuristic approach
本文提出一种启发式方法，考虑光核反应对缪子生成的贡献，以提高对扩展大气簇射中缪子数量的估计精度，减少系统误差。
We review some of the properties of extensive cosmic ray air showers and describe a simple model of the radio-frequency radiation generated by shower electrons and positrons as they bend in the Earth's magnetic field. We perform simulations by calculating the trajectory and radiation of a few thousand charged shower particles. The results are then transformed to predict the strength and polarization of the electromagnetic radiation emitted by the whole shower.
Double Extensive Air Showers and aligned events were discovered at energies E {\gtsim} 1016 eV over fourth century back. But up to now there is no sufficiently identical explanation of their nature. In this paper it is expected that both types of events are the result of breakup of the string formed in the collisions of super high energy particles.
We present a macroscopic calculation of coherent electro-magnetic radiation from air showers initiated by ultra-high energy cosmic rays, based on currents obtained from Monte Carlo simulations of air showers in a realistic geo-magnetic field. We can clearly relate the time signal to the time dependence of the currents. We find that the the most important contribution to the pulse is related to the time variation of the currents. For showers forming a sufficiently large angle with the magnetic field, the contribution due to the currents induced by the geo-magnetic field is dominant, but neither…
The AIRES (AIR-shower Extended Simulations) system is a set of programs and subroutines to realistically simulate particle showers produced after the incidence of high energy cosmic rays on the Earth's atmosphere, and to manage all the related output data. The current version includes a series of improvements with respect to previous releases that are explained in detail in this manual and/or the web site aires.fisica.unlp.edu.ar from where the software can be downloaded. Among such improvements, it is worth mentioning: (i) High energy hadronic collisions can be simulated usign the the well-kn…
High-energy cosmic rays are observed indirectly by detecting the extensive air showers initiated in Earth's atmosphere. The interpretation of these observations relies on accurate models of air shower physics, which is a challenge and an opportunity to test QCD under extreme conditions. Air showers are hadronic cascades, which eventually decay into muons. The muon number is a key observable to infer the mass composition of cosmic rays. Air shower simulations with state-of-the-art QCD models show a significant muon deficit with respect to measurements; this is called the Muon Puzzle. The origin…
In the sub-TeV regime, the most widely used hadronic interaction models disagree significantly in their predictions of particle spectra from cosmic ray induced air showers. We investigate the nature and impact of model uncertainties, focussing on air shower primaries with energies around the transition between high and low energy hadronic interaction models, where the dissimilarities are largest and which constitute the bulk of the interactions in air showers.
We present an introductory lecture on general features of cosmic rays, for non-experts, and some recent developments concerning cascade equations for air shower developments.
Production of muon pairs by high-energy photons in electromagnetic and hadronic showers in atmosphere has been calculated. The effect of muon pair production in hadronic Extensive Air Showers (EAS) is unlikely to be seen by next generation detectors. Applications of muon pair production process in electromagnetic showers to the very high energy gamma-ray astronomy is discussed. It is shown that, although this process dominates over conventional pion and kaon decay above a few TeV in photon-initiated showers and provides a distinctive signature of photon-induced event (muon pair), it is practic…
The muon tagging is an essential tool to distinguish between gamma and hadron-induced showers in wide field-of-view gamma-ray observatories. In this work, it is shown that an efficient muon tagging (and counting) can be achieved using a water Cherenkov detector with a reduced water volume and 4 PMTs, provided that the PMT signal spatial and time patterns are interpreted by an analysis based on Machine Learning (ML). The developed analysis has been tested for different shower and array configurations. The output of the ML analysis, the probability of having a muon in the WCD station, has been u…
Cerenkov Telescopes and Scintillators set on a Crown-like arrays facing the Horizons may reveal far Cosmic Rays Showers, nearer Anti-Neutrino-Electron + Electron --> W- shower in air and upgoing Tau Neutrino + N--> tau + X, --> Shower, Earth-Skimming tau air-showers. Even UHE SUSY Chi + e--> Selectron--> Chi + e at tens PeVs-EeV energy may blaze at Horizons, as anti-neutrino electron at Glashow peak - Burst shower. We show first estimate on down and up-going Horizontal Showers traces for present and future Magic-like Crown Arrays and their correlated Scintillator-like twin Crown Arrays. The on…
Forward hadron production in proton-air collisions above LHC energies through the fluctuations of extensive air showers
通过研究质子-空气碰撞中扩展大气簇射的波动，揭示高能范围内强子生产的新的探测方法。
The understanding of the basic properties of the ultra - high energy extensive air showers is strongly dependent on the description of the hadronic interactions in a energy range beyond that probed by the LHC. One of the uncertainties present in the modeling of the air showers is the treatment of diffractive interactions, which are dominated by non - perturbative physics and usually described by phenomenological models. These interactions are expect to affect the development of the air showers, since they provide a way of transporting substantial amounts of energy deep in the atmosphere, modif…
A Model of the Response of Surface Detectors to Extensive Air Showers Based on Shower Universality
基于簇射普适性，提出适用于水切伦科夫和闪烁体表面探测器的响应模型，可精确重建簇射极大深度和缪子数。
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