Component Of Extensive Air Showers Research Articles

Universality of the muon component of extensive air showers

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-the-art hadronic interaction models, the mentioned distributions at production are analyzed as a function of zenith angle, primary mass, and hadronic interaction model, and their level of universality is studied and assessed in an exhaustive manner for the first time.

Optimizing the zenith angle dependence of cosmic ray muons from Charm particles in the knee region: simulation study

The muonic component of air showers is one of the most abundant component of charged particles arriving at the Earth’s surface, and able to penetrate deeply underground, and is very sensitive to the primary mass and energy of the initial cosmic particle. Atmospheric muons are produced in the propagation of different components of extensive air showers. Therefore, variations in the muon ratio, defined as the number of positive over negative charged muons, must be well understood. In this paper, we study the variation of the muon charge ratio of cosmic muons at different zenith angles, and we study the contribution of charm particles in producing atmospheric muons using Monte Carlo showers initiated by two cosmic primaries, proton and iron, with four energies [10 PeV, 100 PeV, 1 EeV, 10 EeV], in the zenith range of [0° to 60°].

AugerPrime status and prospects

The Pierre Auger Collaboration started a few years ago the AugerPrime project to increase the Surface Detector (SD) performance of the Pierre Auger Observatory. It aims to address the still open questions on the origin and composition of the highest energy cosmic rays by allowing a better identification of the nature of the primaries. The key element of this major upgrade is the capability of measuring the different components of extensive air showers, which will be significantly improved by the addition of a Surface Scintillator Detector (SSD) on each water-Cherenkov detector (WCD) constituting the SD. Moreover, the dynamic range of measurement is extended through an additional small photomultiplier tube inside the WCD. New electronics is processing the signals from the WCD and the SSD with higher sampling frequency and enhanced resolution. The scintillator module deployment started in 2019, and the new electronics in December 2020. The collected data allow for the evaluation of the first performances of the upgraded array and to adapt the whole data acquisition chain necessary for an efficient and sustainable operation of the Observatory. After the recall of the motivations for the upgrade, the main characteristics of the new detection setup are reviewed, as well as the status of its deployment and commissioning. The expected prospects are also discussed.

On the mystery of the multi-muon flux at the TeV cosmic-ray energy range

Current Monte Carlo simulations do not provide a good description of the muon component of extensive air showers. Many air shower experiments report discrepancies between their data and Monte Carlo predictions, ranging from the TeV scale up to the highest energies. In these proceedings, we address the seasonal variation of the multi-muon events observed by the NOvA Near Detector (ND). For our studies, we use the general-purpose Monte Carlo code FLUKA to treat the transport and interaction of the air-shower particles in the atmosphere and other media. Our design considers a multilayered atmosphere and a layered underground approximated to match the NOvA ND location and detector geometry. Our atmospheric model uses air densities for winter and summer calculated from the temperature and geopotential information for the pressure levels given by the European Center for Medium-Range Weather Forecasts (ECMWF) datasets in situ. Understanding the multi-muon flux at the cosmic ray high-energy range may lead to a better description of the muon production mechanisms in ultra-high-energy extensive air showers. In addition, it can help to improve future Monte Carlo codes or hint at new physics processes or interactions.

Auger@TA: Deploying an independent Pierre Auger Observatory SD micro-array at the Telescope Array Project

The Pierre Auger Observatory (Auger) and the Telescope Array Project (TA) are the two largest ultra-high-energy cosmic ray observatories in the world. They operate in the Southern and Northern hemispheres, respectively, at similar latitudes but with different surface detector (SD) designs. This difference in detector design changes their sensitivity to the various components of extensive air showers. The over-arching goal of the Auger@TA working group is to cross-calibrate the SD arrays of the two observatories in order to identify or rule out systematic causes for the apparent differences in the flux measured at Auger and TA. The project itself is divided into two phases. Phase-I finished in 2020 and consisted of a station-level comparison facilitated by the deployment of two Auger stations, one prototype station with a single central PMT and a standard Auger station, in the middle of the TA SD near the Central Laser Facility, along with a modified TA station to provide external triggers from the TA SD. This provided the opportunity to observe the same extensive air showers with both Auger and TA detectors to directly compare their measurements. Phase-II of Auger@TA is currently underway and aims at building a self-triggering micro-Auger-array inside the TA array. This micro-array consists of eight Auger stations, seven of which use a 1-PMT prototype configuration and form a single hexagon with a traditional 1.5 km Auger spacing. The 8th station is of the standard Auger 3-PMT configuration and is placed at the center of the hexagon, along with a TA station to form a triplet. Each Auger station will also be outfitted with an AugerPrime Surface Scintillator Detector. A custom communication system using readily available components will be used to provide communication between the stations and remote access to each station via a central communications station. The deployment of the micro-array took place at the end of September 2022. A simulation study was carried out to gauge the expected performance of the Auger@TA micro-array and to derive trigger effi ciencies and event rates.

Status of the AugerPrime upgrade of the Pierre Auger Observatory

The Pierre Auger Observatory consists of a detector system to study ultrahigh-energy cosmic rays. These cosmic rays can be detected only through the observation of extensive air showers. The hybrid detection of air showers at the Observatory is based on the Surface Detector (SD) – an array of about 1660 water-Cherenkov detectors, and the Fluorescence Detector, with 27 telescopes overlooking the SD. Recently, an upgrade of the Observatory was initiated, called AugerPrime. The main purpose of the upgrade is to improve the mass composition sensitivity of the SD through precise measurements of the muonic and electromagnetic components of extensive air showers. For this purpose, additional scintillator and radio detectors are being installed on top of SD stations. The upgrade also includes updated SD electronics, and underground muon detectors. In this talk, the motivation and the current status of the upgrade will be reviewed.

Muon lateral distribution function of extensive air showers: Results of the Sydney University Giant Air-shower Recorder versus modern Monte Carlo simulations

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 core distance than it is predicted in simulations. This observation may be important for interpretation of the energy-dependent discrepancies in the simulated and observed numbers of muons in air showers, known as the "muon excess".

Study of the spatiotemporal structure of extensive air showers at high energies

In a series of works carried out at the Tien-Shan High Altitude Science Station (TSHASS), a penetrating component of extensive air showers (EAS) caused by cosmic rays (CR) with energy of the primary particle above 1 PeV was discovered. The local increase in the energy of secondary hadrons in the EAS cores in the region of the CR spectrum slope change around energy of 3 PeV, the so-called “knee”. The problem of knee formation currently is one of the currently still open mysteries in astrophysics. The studies carried out at the TSHASS show that more information on the knee region can be obtained by studying the characteristics of the EAS cores. At present, a large installation with an area of several hundred square meters is being constructed at the station to study the EAS cores in the “knee” region. The installation is located at an altitude of 3330 meters above sea level near the city of Almaty, Kazakhstan.

The Complex of Experimental Facilities for the Cosmic Ray Investigation at the Tien Shan Mountain Station

The study describes the experimental complex of the station located in the Tien Shan mountains at an elevation of 3340 m above sea level. The complex consists of detectors of different types scattered across the station area, such as scintillation particles detectors, Cherenkov detectors, radio emission detectors for the measurement of the electron component of extensive air showers (EAS) created by the (1–1000) PeV cosmic ray particles, an ionization calorimeter and neutron detectors for the study of the nuclear-active component of EAS cores, and the underground particle detectors for the detection of cosmic ray muons. The data acquisition system allows the simultaneous recording of parameters from various stand-alone detectors registering an EAS, and storage of the acquired data in the database. As an illustration of research capability, the results of the EAS study are presented here which were obtained during the last few years at the different experimental set-ups constituting the Tien Shan complex.

The NEVOD-EAS air-shower array

The Experimental complex NEVOD includes several different setups for studying various components of extensive air showers (EAS) in the energy range from 1010 to 1018eV. The NEVOD-EAS array for detection of the EAS electron–photon component began its data taking in 2018. It is a distributed system of scintillation detectors installed over an area of about 104 m2. A distinctive feature of this array is its cluster organization with different-altitude layout of the detecting elements. The main goal of the NEVOD-EAS array is to obtain an estimation of the primary particle energy for events measured by various detectors of the Experimental complex NEVOD. This paper describes the design, operation principles and data processing of the NEVOD-EAS array. The criteria for the event selection and the accuracy of the EAS parameters reconstruction obtained on the simulated events are discussed. The results of the preliminary analysis of experimental data obtained during a half-year operation are presented.

Status of the Yakutsk Air Shower Array and Future Plans

The Yakutsk Extensive Air Shower Array has been continuously operating for more than 50 years (since 1970) and up until recently it has been one of world's largest ground-based instruments aimed at studying the properties of cosmic rays in the ultra-high energy domain. In this report we discuss results recently obtained at the array - on cosmic rays energy spectrum, mass composition and directional anisotropy - and how they fit into the world data. Special attention is paid to the measurements of muonic component of extensive air showers. Theoretical results of particle acceleration at shocks are also briefly reviewed. Future scientific and engineering plans on the array modernization are discussed.

The rise of muon content in extensive air showers after the 3 PeV knee of the primary cosmic ray spectrum according to data of the Tien Shan mountain installation

We put together the experimental results on muon component of extensive air showers (EAS) which were gained with various techniques at the detector complex of the Tien Shan mountain station. According to this comparison, the problem of the EAS muon content in the range of primary cosmic ray energies (1–100)PeV seems to be more complicated than it was usually supposed. Generally, from the models of nuclear interaction it follows that the EAS which have produced gamma-hadron families in the Tien Shan X-ray emulsion chamber did preferably originate from interaction of the light cosmic ray nuclei, such that their muon abundance must be ∼1.5 times below an average calculated over all showers. In contrary, the experimental muon counts in the EAS with families demonstrate a (1.5–2)-fold excess above the average, and this difference starts to be observable in the showers with the energy above the 3PeV knee of the primary cosmic ray spectrum. Later on, the rise of muon production in EAS after the knee was confirmed at Tien Shan by another experiment on detection of the neutrons stemmed from interaction of cosmic ray muons. Thus, the results obtained by the two completely different methods do mutually agree with each other but contradict to the common models of hadron interaction.

Extraction of the muon signals recorded with the surface detector of the Pierre Auger Observatory using recurrent neural networks

The Pierre Auger Observatory, at present the largest cosmic-ray observatory ever built, is instrumented with a ground array of 1600 water-Cherenkov detectors, known as the Surface Detector (SD). The SD samples the secondary particle content (mostly photons, electrons, positrons and muons) of extensive air showers initiated by cosmic rays with energies ranging from 1017eV up to more than 1020eV. Measuring the independent contribution of the muon component to the total registered signal is crucial to enhance the capability of the Observatory to estimate the mass of the cosmic rays on an event-by-event basis. However, with the current design of the SD, it is difficult to straightforwardly separate the contributions of muons to the SD time traces from those of photons, electrons and positrons. In this paper, we present a method aimed at extracting the muon component of the time traces registered with each individual detector of the SD using Recurrent Neural Networks. We derive the performances of the method by training the neural network on simulations, in which the muon and the electromagnetic components of the traces are known. We conclude this work showing the performance of this method on experimental data of the Pierre Auger Observatory. We find that our predictions agree with the parameterizations obtained by the AGASA collaboration to describe the lateral distributions of the electromagnetic and muonic components of extensive air showers.

Development and validation of the signal simulation for the underground muon detector of the Pierre Auger Observatory

The underground muon detector of the Pierre Auger Observatory is aimed at attaining direct measurements of the muonic component of extensive air showers produced by cosmic rays with energy from 1016.5 eV up to the region of the ankle (around 1018.7 eV). It consists of two nested triangular grids of underground scintillators with 433 m and 750 m spacings, and a total of 71 positions, each with 192 scintillator strips (30 m2) deployed 2.3 m underground. The light produced by impinging muons in the scintillators is propagated with optical fibers towards an array of silicon photomultipliers. In this work, we present the development, validation, and performance of an end-to-end tool for simulating the response of the underground muon detector to single-muon signals, which constitutes the basis for further simulations of the whole array. Laboratory data and simulation outcomes are found consistent, showing that with the underground muon detector we can measure single muons, with an efficiency of 99%, up to about 1050 particles arriving at exactly the same time in 30 m2 of scintillator.

Studying Characteristics of the Neutron Component of Extensive Air Showers Using Data from the URAN Array

Studying Characteristics of the Neutron Component of Extensive Air Showers Using Data from the URAN Array

On the Origin of the Knee in the Cosmic Ray Energy Spectrum

It is analytically shown that the total absorption of the hadron component of extensive air showers and the transition to the pure electromagnetic cascade cannot cause the observed sharp knee in the cosmic ray energy spectrum. This fact and the absence of proved nuclear models allow the conclusion that the knee origin is astrophysical.

Monitoring the long term stability of civil buildings through the MRPC telescopes of the EEE Project

Cosmic ray muons are a penetrating component of extensive air showers created in the Earth atmosphere by the interaction of highly energetic primary particles, mostly protons, which continuously bombard our Planet. The secondary cosmic radiation is the result of the complex interplay between the production cross section and the interaction mechanisms with the atmosphere (including the energy loss, multiple scattering and particle decay). Cosmic muons have been considered since several decades as a powerful probe to exploit our environment, from muography of volcanoes to absorption radiography of possible hidden rooms inside large structures, such as Pyramids, to the detection of high-Z illicit nuclear materials inside containers and many other applications of social interest.This paper discusses the possibility to employ the Multigap Resistive Plate Chambers (MRPC) of the Extreme Energy Events (EEE) Project as muon tracking detectors to monitor the long term stability of civil buildings and structures when used in conjunction with additional detectors. For this application the average direction of the cosmic muon tracks passing through the MRPC telescope and an additional detector located some distance apart in the same building may be reconstructed with good precision and any small variation over long time acquisition periods may be monitored. The performance of such setup is discussed and experimental results from first coincidence measurements obtained with a 40 × 60 cm2 scintillator detector operated in the same building with one of the EEE telescopes, at about 15 m vertical distance from it, are presented. Simple Monte Carlo and GEANT simulations were also carried out to evaluate typical acceptance values for the operating conditions employed so far, to extrapolate to other geometrical configurations, and to evaluate multiple scattering effects.

Reconstruction of Characteristics of Extensive Air Showers Detected with the NEVOD-EAS Array

In 2018, the creation of the central part of the NEVOD-EAS cluster-type array aimed at detection of the electron-photon component of extensive air showers in the energy range from 1015 to 1017 eV was completed. At present, a continuous data taking is being performed at the array. The results of the reconstruction of registered extensive air showers using the methods developed within the framework of the cluster approach to experimental data analysis are presented.

Study on the detection efficiency and uniformity of a Water Cherenkov Detector based on Geant4

The Water Cherenkov Detector (WCD) is an important and widely used detector in cosmic ray physics, mainly used to measure the electromagnetic component of extensive air showers. Generally, a full detector simulation based on Geant4 for large arrays would require too much computing time and memory, because it would be a very CPU-intensive job to track all the Extensive Air Shower particles (mainly electrons and photons) hitting a very large area WCD detector. Therefore we developed a code simulating the behavior of muons, gamma-rays and electrons crossing a cell of a full WCD array. The results of this simulation can be collected in look-up table that can be used by fast simulation codes for large arrays. In this note we describe the results obtained simulating a single cell of cubic geometry (5×5×5 m3). The code we have developed for this particular geometry can easily be adapted to other detector designs. Firstly, the parameters in simulation are determined analysing the properties of the WCDs. Then, we calculate the most probable value (MPV) and sigma of the Landau function describing the distribution of the photoelectron numbers detected by the WCD photomultipliers. The results of the simulation are tested by a comparison with experimental results available in the literature: the relative error between their MPVs is only 1.37% for vertical muon- signal. We show that photoelectron distributions do not only depend on particle types and energies, but also on the incidence zenith angles and on the distance between the particle impact position and the center of the cell (i.e. the photomultiplier).

Dependence of the Energy Deposit of Muon Bundles on Local Muon Density and Zenith Angle

Energy characteristics of the muon component of extensive air showers (EASes) are investigated at the NEVOD experimental complex in order to solve the problem of a detected excess of muons in EASes at ultrahigh energies, relative to simulation results. The dependences of the energy deposit of muon bundles on the zenith angle and the local muon density are obtained for primary energies of 10–1000 PeV. The results from comparing the data to simulations performed with the CORSIKA program are presented.