Using a large set of simulated extensive air showers, we investigate universality features of electron and positron distributions in very-high-energy cosmic-ray air showers. Most particle distributions depend only on the depth of the shower maximum and the number of particles in the cascade at this depth. We provide multi-dimensional parameterizations for the electron-positron distributions in terms of particle energy, vertical and horizontal momentum angle, lateral distance, and time distribution of the shower front. These parameterizations can be used to obtain realistic electron-positron distributions in extensive air showers for data analysis and simulations of Cherenkov radiation, fluorescence signal, and radio emission.
We present two new aspects of Extensive Air Shower (EAS) 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 detectors it is enough to know the vertical depth of shower maximum and the total signal. In the second case, the EM signal can be calculated from the primary particle energy and the zenith angle. In both cases the parameterizations of muon and EM signals are almost independent on primary particle nature, energy and zenith angle.
It is shown, that highly accurate estimation of muon shower content can be performed on the basis of knowledge of only vertical depth of shower maximum and total signal in ground detector. The estimate is almost independent on primary energy and particle type and on zenith angle. The study is performed for 21500 showers, generated with CORSIKA~6.204 from spectrum $E^{-1}$ in the energy range $\log10(E)$ [eV]=18.5--20 and uniformly in $\cos^2θ$ in zenith angle interval $θ=0^\circ-65^\circ$ for QGSJET II/Fluka interaction models.
Scaling properties of nuclei- and photon-initiated air showers are examined in wide primary energy range ($10^{14}÷10^{22}$~eV) taking into account Landau-Pomeranchuk-Migdal and geomagnetic field effects. It is shown that the invariance in lateral distribution and also the universal dependence between shower age and root mean square radius of electron component exist up to the highest energies. The implications of shower universality for reanalysis, cross-checking and validation of the results of different experiments together with decreasing of the influence of hadronic model uncertainties ar…
Based on extensive air shower simulations it is shown that the electron distributions with respect to the two angles, determining electron direction at a given shower age, for a fixed electron energy and lateral distance, are universal. It 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, of the lateral distance (integrated over a…
It is shown that the shape of any electron distribution in a high energy air shower is the same in all such showers, if taken at the same age, independently of the primary energy, mass and thus, of the interaction model.
We present the first results of the application of the recently found universality of behavior of muon signal to electromagnetic (EM) signal ratio with respect to the vertical depth of showers maximum for mass composition and hadronic interaction studies. Making use of the fact that for zenith angles above 45 degrees the dependence of the ratio on the vertical depth of shower maximum is very similar for QGSJET II and EPOS 1.99 we show that this provides the possibility to estimate muon shower content in almost interaction model independent way. To evaluate the excess of signal in the data in r…
The development of cosmic ray air showers can be influenced by atmospheric electric fields. Under fair weather conditions these fields are small, but the strong fields inside thunderstorms can have a significant effect on the electromagnetic component of a shower. Understanding this effect is particularly important for radio detection of air showers, since the radio emission is produced by the shower electrons and positrons. We perform Monte Carlo simulations to calculate the effects of different electric field configurations on the shower development. We find that the electric field becomes i…
The High-Altitude Water Cherenkov (HAWC) Observatory records the air showers produced by cosmic rays and gamma rays at a rate of about 20 kHz. While the events observed by HAWC are 99.9% hadronic cosmic rays, this background can be strongly suppressed using topological cuts that preferentially select electromagnetic air showers. Using this capability of HAWC, we can create a sample of air showers dominated by gamma rays and cosmic electrons and positrons. HAWC is one of the few operating observatories capable of measuring showers produced by electron and positron primaries above 1 TeV, and can…
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…
Accurate prediction of the radio emission from cosmic ray air showers relies on computationally demanding Monte Carlo simulations such as CoREAS. We aim to expedite this process via a semi-analytical synthesis model while maintaining high accuracy by using simulated radio pulses as templates. We present our key concept for template processing focusing on the development of the particle cascade and its empirical effect on the locally produced radio signal. In this context the universality of the radio emission from small sections of an air shower also becomes important where most previous studi…
We study the azimuthal distributions of Cherenkov photons in Extensive Air Showers (EASs) initiated by $γ$-ray, proton and iron primaries of different energies incident at various zenith angles over a high altitude observation level. The azimuthal distributions of electrons and positrons along with their asymmetric behaviour have also been studied here to understand the feature of azimuthal distributions of Cherenkov photons in EASs. The main motivation behind this study is to see whether the azimuthal distribution of Cherenkov photons can provide any means to distinguish the $γ$-ray initiated…
On the basis of the scaling approach and CORSIKA simulations data the radial scale factor of lateral distribution of electrons in extensive air showers is confirmed as potentially effective primary mass estimator, and its sensitivity to hadronic interaction model is investigated. It is shown that improved composition results both on average and event-by-event basis can be achieved taking into account the universality property of air shower development expressed by the relation between radial scale factor and longitudinal age parameter. The enhancements of such a theoretically motivated tool fo…
The reconstruction of cosmic-ray-induced extensive air showers with a non-imaging Cherenkov detector array requires knowledge of the Cherenkov yield of any given air shower for a given set of shower parameters. Although air showers develop in a stochastic cascade, certain characteristics of the particles in the shower have been shown to come from universal probability distributions, a property known as shower universality. Both the energy and the angular distributions of charged particles within a shower have been parameterized. One can use these distributions to calculate the Cherenkov photon…
In this work, the effects of the extensive air showers (EAS) were described by estimating the lateral distribution function (LDF) at very high energies of various cosmic ray particles. LDF was simulated for charged particles such as the electron and positron pair production, gamma, muons and all charged particles at very high energies 10^16, 10^18 and 10^19 eV. The simulation was performed using air shower simulator system (AIRES) version 2.6.0. The effect of primary particles, energies, thinning energy and zenith angle on the charged LDF particles produced in the EAS was taken into account. T…
Using the simulation code SELFAS2, we present predictions of the radio signal emitted by extensive air showers (EAS) during their development in the atmosphere. The radio emission in the MHz range coming from air showers is the superposition of two mechanisms: the variation of the transverse current due to the systematic opposite drift of electrons and positrons in the Earth's magnetic field and the variation of the charge excess due to the electrons in excess in the shower front. In this paper, we stress particularly the effect of the realistic air refractive index on the radio signal predict…
New analysis of lateral distributions (LD) of electrons, muons and charged particles in extensive air showers generated by $10^{15}-10^{19}$ eV cosmic rays has been made with respect to the scaling formalism for LD and air shower universality paradigm. It is found that lateral distributions of electrons and muons, when considered separately, are well described by one-parametric scaling functions, while for the charged particles mixture distributions the scaling description is not accurate in radial distance range where electrons and muons give a comparable contribution to the local particle de…
Monte Carlo simulations are performed to study the correlation between the ground cosmic ray intensity and near-earth thunderstorms electric field at YBJ (4300 m a.s.l., Tibet, China). The variations of the secondary cosmic ray intensity are found to be highly dependent on the strength and polarity of the electric field. In negative fields and in positive fields greater than 600 V/cm, the total number of ground comic ray positrons and electrons increases with increasing electric field strength. And these values increase more obviously when involving a shower with lower primary energy or a high…
Extensive air showers (EAS) are a cascade of electromagnetic radiation and ionized particles that produced in the atmosphere through the interaction of a primary cosmic ray with the atom of nucleus in the air producing a huge amount of secondary particles such as X-ray, electrons, neutrons, muons, alpha particles, etc. In this work, EAS effects were demonstrated by estimating the lateral distribution function (LDF) at ultrahigh energies of the various cosmic ray particles. The LDF of charged particles such as electron and positron pair production, gamma and muons particles was simulated at ult…
We consider a theory with isotropic nonbirefringent Lorentz violation in the photon sector and explore the effects on the development of the electromagnetic component of extensive air showers in the Earth atmosphere. Specifically, we consider the case of a "fast" photon with a phase velocity larger than the maximum attainable velocity of a massive Dirac fermion (this case corresponds to a negative Lorentz-violating parameter $κ$ in the action). Shower photons with above-threshold energies decay promptly into electron-positron pairs, instead of decaying by the conventional production of electro…
Charged particles of extensive air showers (EAS), mainly electrons and positrons, initiate the emission of fluorescence light in the Earth's atmosphere. This light provides a calorimetric measurement of the energy of cosmic rays. For reconstructing the primary energy from an observed light track of an EAS, the fluorescence yield in air has to be known in dependence on atmospheric conditions, like air temperature, pressure, and humidity. Several experiments on fluorescence emission have published various sets of data covering different parts of the dependence of the fluorescence yield on atmosp…
Radio detection of cosmic-ray-induced air showers has come to a flight the last decade. Along with the experimental efforts, several theoretical models were developed. The main radio-emission mechanisms are established to be the geomagnetic emission due to deflection of electrons and positrons in Earth's magnetic field and the charge-excess emission due to a net electron excess in the air shower front. It was only recently shown that Cherenkov effects play an important role in the radio emission from air showers. In this article we show the importance of these effects to extract quantitatively…
We describe the characteristics of a new radio signal, generated by the secondary electrons and positrons of the shower front when they reach the ground. The very fast deceleration of these particles induces the coherent emission of an electric field at frequencies smaller than 20 MHz. We show, using simulations with the code SELFAS, that this sudden death signal should be detectable with a simple dedicated antenna and could provide many informations on the shower, in particular the nature of the primary cosmic ray. We also show that this signal permits to estimate the atmospheric depth of max…
The Cherenkov radio pulse emitted by hadronic showers in ice is calculated for showers of energies in the EeV range. This is obtained with three dimensional simulations of both shower development and the coherent radio pulse emitted as the excess charge develops in the shower. A Monte Carlo, ZHAireS, has been developed for this purpose combining the high energy hadronic interaction capabilities of AIRES, and the dense media propagation capabilities of TIERRAS, with the precise low energy tracking and specific algorithms developed to calculate the radio emission in ZHS. A thinning technique is …
In recent years, the freely available Monte Carlo code REAS for modelling radio emission from cosmic ray air showers has evolved to include the full complexity of air shower physics. However, it turned out that in REAS2 and all other time-domain models which calculate the radio emission by superposing the radiation of the single air shower electrons and positrons, the calculation of the emission contributions was not fully consistent. In this article, we present a revised implementation in REAS3, which incorporates the missing radio emission due to the variation of the number of charged partic…
The composition of ultra-high energy cosmic rays is still poorly known and constitutes a very important topic in the field of high-energy astrophysics. Detection of ultra-high energy cosmic rays is carried out via the extensive air showers they create after interacting with the atmosphere constituents. The secondary electrons and positrons within the showers emit a detectable electric field in the kHz-GHz range. It is possible to use this radio signal for the estimation of the atmospheric depth of maximal development of the showers \xmax, with a good accuracy and a duty cycle close to $100\%$.…
CoREAS is a Monte Carlo code for the simulation of radio emission from extensive air showers. It implements the endpoint formalism for the calculation of electromagnetic radiation directly in CORSIKA. As such, it is parameter-free, makes no assumptions on the emission mechanism for the radio signals, and takes into account the complete complexity of the electron and positron distributions as simulated by CORSIKA. In this article, we illustrate the capabilities of CoREAS with simulations carried out in different frequency ranges from tens of MHz up to GHz frequencies, and describe in particular…
At energies above a few TeV, no measurements of the cosmic-ray electron spectrum exist yet. By considering the similarity of air showers induced by electrons and gamma rays as seen by ground-based arrays, we use published limits on isotropic gamma-ray fluxes to place first constraints on the >10 TeV electron spectrum. We demonstrate that, due the proximity of known sources, the flux of such electrons (and positrons) can be large. We show how these smoothly connect to lower-energy positrons measured by PAMELA and relate to exciting new indications from Fermi.
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…
The energy spectrum of cosmic rays in the range 10^15 eV to 6*10^19 eV has been studied using the air Cherenkov light detectors of the Yakutsk array. The total flux of photons produced by relativistic electrons (including positrons as well, hereafter) of extensive air showers in the atmosphere is used as the energy estimator of the primary particle initiating a shower. The resultant differential flux of cosmic rays exhibits, in accordance with previous measurements, a knee and ankle features at energies 3*10^15 and ~10^19 eV, respectively. A comparison of observational data with simulations is…
Since 2002, the CODALEMA experiment located within the Nançay Radio Observatory studies the ultra-high energy cosmic rays (above 10^{17} eV) arriving in the Earth atmosphere. These cosmic rays interact with the component of the atmosphere, inducing an extensive air shower (EAS) composed mainly of charged particles (electrons and positrons). During the development of the shower in the atmosphere, these charged particles in movement generate a fast electric field transient (a few nanoseconds to a few tens of ns), detected at ground by CODALEMA with dedicated radio antennas over a wide frequency …
The angular distribution of Cherenkov light in an air shower is closely linked to that of the shower electrons and positrons. As charged particles in extensive air showers are deflected by the magnetic field of the Earth, a deformation of the angular distribution of the Cherenkov light, that would be approximately symmetric about the shower axis if no magnetic field were present, is expected. In this work we study the variation of the Cherenkov light distribution as a function of the azimuth angle in the plane perpendicular to shower axis. It is found that the asymmetry induced by the geomagne…
The radio intensity and polarization footprint of a cosmic-ray induced extensive air shower is determined by the time-dependent structure of the current distribution residing in the plasma cloud at the shower front. In turn, the time dependence of the integrated charge-current distribution in the plasma cloud, the longitudinal shower structure, is determined by interesting physics which one would like to extract such as the location and multiplicity of the primary cosmic-ray collision or the values of electric fields in the atmosphere during thunderstorms. To extract the structure of a shower …
The radio detection method for cosmic rays relies on coherent emission from electrons and positrons which is beamed in a narrow cone along the shower axis. Currently the only mod- els to reproduce this emission with sufficient accuracy are Monte Carlo based simulations of the particle and radio emission physics, which require large investments of computation time. The work presented here focuses on condensing the simulation results into a semi-analytical model. This relies on building a framework based on theoretical predictions of radio emission, but instead of calculating the radio signal di…
Forward hadron production in proton-air collisions above LHC energies through the fluctuations of extensive air showers
Departamento de Física, Instituto Superior Técnico (IST), Universidade de Lisboa（里斯本大学高等理工学院物理系）；Laboratório de Instrumentação e Física Experimental de Partículas (LIP)（粒子实验与仪器实验室）；Technische Universität Dortmund（多特蒙德工业大学）
High-energy cosmic rays, impinging on the atmosphere of the Earth initiate cascades of secondary particles, the extensive air showers. The electrons and positrons in the air shower emit electromagnetic radiation. This emission is detected with the LOFAR radio telescope in the frequency range from 10 to 240 MHz. The data are used to determine the properties of the incoming cosmic rays. The radio technique is now routinely used to measure the arrival direction, the energy, and the particle type (atomic mass) of cosmic rays in the energy range from $10^{17}$ to $10^{18}$ eV. This energy region is…
In this study, the necessity of the simulation study for exploring the interactions of ultra-high energy particles cosmic rays was examined. Different hadronic interaction models such as (SIBYLL, QGSJET, and EPOS) were simulated by using air showers simulation AIRES system (version 19.04.00). Also, the charged particle density of Extensive Air Showers (EAS) was calculated by estimating the lateral distribution function (LDF). Moreover, the LDF simulation of the two primary particles (proton and iron nuclei) was performed, taking into account their primary energies effect and the zenith angle o…
Cosmic rays have extremely high particle energies (up to $10^{20} \; \text{eV}$) and can be used to search for violations of Lorentz invariance. We consider isotropic nonbirefringent Lorentz violation in the photon sector for the case of a photon velocity larger than the maximum attainable velocity of the standard fermions. Up to now, Earth-based bounds on this type of Lorentz violation have been determined from observations of TeV gamma rays. Here, we elaborate on a novel approach to test Lorentz invariance with greatly improved sensitivity. This approach is based on investigating extensive a…
Cosmic ray air showers emit radio pulses at MHz frequencies, which can be measured with radio antenna arrays - like LOPES at the Karlsruhe Institute of Technology in Germany. To improve the understanding of the radio emission, we test theoretical descriptions with measured data. The observables used for these tests are the absolute amplitude of the radio signal, and the shape of the radio lateral distribution. We compare lateral distributions of more than 500 LOPES events with two recent and public Monte Carlo simulation codes, REAS 3.11 and CoREAS (v 1.0). The absolute radio amplitudes predic…
The Pierre Auger Observatory is the world's largest detector for observation of ultra-high-energy cosmic rays (UHECRs) (above the energy of $10^{17}$ eV). It consists of a Fluorescence Detector (FD) and an array of particle detectors known as the Surface Detector (SD). Observations of extensive air showers by the Observatory can be used to probe hadronic interactions at high energy, in a kinematic and energy region inaccessible to experiments at man-made accelerators and to measure the muon component of the shower. Air showers induced by different primaries have different muon contents. With i…
Current experimental data on cosmic-ray charged leptons are briefly reviewed including measurements of the positron fraction, electron and positron spectra and inclusive electron+positron data. Precision measurements by PAMELA and AMS-02 of the positron spectrum and its striking difference from the electron spectrum have prompted several theoretical speculations. In order to discriminate among different interpretations of the 'positron anomaly', a major step is needed to achieve an accurate direct measurement of the shape of the inclusive electron spectrum beyond 1 TeV. Ongoing efforts along t…
Recent measurements of the cosmic-ray electron (e-) and positron (e+) fluxes show apparent excesses compared to the spectra expected by standard cosmic-ray (CR) propagation models in our galaxy. These excesses may be related to particle acceleration in local astrophysical objects, or to dark matter annihilation/decay. The e+/e- ratio (measured up to ~100 GeV) increases unexpectedly above 10 GeV and this may be connected to the excess measured in all-electron flux at 300-800 GeV. Measurement of this ratio at higher energies is a key parameter to understand the origin of these spectral anomalies…
It is generally assumed that for energy injection before recombination, all of the injected energy is dissipated as heat in the baryon-photon plasma, giving rise to the $y$-type, $i$-type, and $μ$-type distortions in the CMB spectrum. We show that this assumption is incorrect when the energy is injected in the form of energetic (i.e. energy much greater than the background CMB temperature) particles. We evolve the electromagnetic cascades, from the injection of high energy particles, in the expanding Universe and follow the non-thermal component of CMB spectral distortions resulting from the i…
