Simulation of muon-induced air showers affecting CMS tracking detectors

We study the propagation of energetic muons produced by ultrahigh energy cosmic rays which could penetrate the cavern of a giant experiment called Compact Muon Solenoid (CMS) at CERN. The present work is based on our previous simulation model proposed in [1]. We have improved this model by (1) eliminating the ambiguity via adding Landau-Pomeranchuk-Migdal effect to the Monte-Carlo code, (2) using different incidence angles of the simulated air showers, (3) defining the actual contents of the CMS cavern concrete. We estimate the energy spectrum of muons produced by air showers of primary protons and photons, which could be detected as a background in the CMS tracking detectors. Our results show that muons produced by air showers within the energy range 10¹⁷–10²⁰ eV injected to the CMS site could penetrate the cavern with cutoff energy 36.5 GeV. The article is published in the original.     

Studying the muon and hadron components of extensive air showers with the Carpet-2 array

The method of separating muons and hadrons recorded by the Muon Detector of the Carpet-2 air shower array of Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) is described. The results of studying characteristics of the muon and hadron components of extensive air showers (EAS) with N _e ≥ 10⁵ are presented. For the range of distances 40–55 m from shower axes the numbers of hadrons with energies higher than 30 GeV and muons with energies above 1 GeV are obtained as functions of the shower size N _e .     

Multiple penetrating particles with narrow separation associated with extensive air showers (EAS)

An experiment has been carried out at a vertical depth of 580 m.w.e. at Kolar Gold Fields, to investigate various characteristics of energetic muons (E _mln ⋍ 150 GeV) associated with extensive air showers (EAS). Double parallel penetrating particles with narrow separations (<1m) have an exponential decoherence distribution withe-folding separation of ⋍ 25 cm.     

Cascade showers in the NEVOD Cherenkov water detector

A technique for measuring the cascade shower energy in the NEVOD Cherenkov water detector with a spatial lattice of quasi-spherical modules is discussed. The technique allows the number of cascade particles that move near the shower axis to be reconstructed on the basis of analysis of response amplitudes of triggered photomultiplier tubes. The technique of cascade-curve reconstruction was applied to cascade showers generated by near-horizontal high-energy muons extracted by means of the DECOR coordinate-tracking detector arranged around the Cherenkov water detector. The first results of measuring the energy spectrum of cascade showers of 10–1000 GeV are presented.     

Search for heavy mass particles in extensive air showers

A large multiplate cloud chamber with fast timing scintillators inside is being operated with the extensive air shower array at Ootacamund to further elucidate the time structure of high energy hardons in air showers. The major interest in the present investigation is to understand the nature of the large delay (>20 ns) high energy (>40 GeV) events that appeared as strong cndidates for heavy mass particles in an earlier experiment carried out with a total absorption spectrometer. Two events observed during one year’s operation of the experiment are discussed. Now deceased.     

Observation of double extensive air showers

Double extensive air showers were studied at the Tien Shan high-mountain scientific station of the Lebedev Physical Institute using two different installations. One measured the electron-photon shower component, the other measured Cherenkov radiation. Double showers separated by a time interval of ～100 ns were detected by both setups. The frequency of the occurrence of such showers in each setup is analyzed. It is shown that these frequencies are identical when observing vertical showers (the zenith angle ? < 60°).     

Portion of muons with a threshold energy above 1 GeV in extensive air showers with ultra-high energies,according to the Yakutsk EAS array data

Characteristics of the muon component in extensive air showers and the fluctuations of muons are considered. In this work, we compare experimental data with computations performed for various models of the hadron interactions of protons and iron nuclei. The aim of this analysis is to obtain information on the mass composition of cosmic rays in an ultra-high energy region.     

Production of high-energy muons in gamma showers

We have calculated the number of high-energy muons in gamma showers generated by photoproduction and by muon pair creation. The prompt muons have flatter energy spectrum than the muons, which come from photoproduction and contribute significant fraction of the total muon rates for E_μ ? 1 TeV. The total rate of high-energy muons in gamma showers is, however, very low.     

Test of hadron interaction models in the most important energy range of secondary particles in spectra of atmospheric muons

A simple method has been proposed for testing hadron interaction models, which are used to simulate extensive air showers, in observed spectra of atmospheric muons. It has been shown that muon flux intensities in the energy range of 10²–10⁴ GeV that are calculated within the SIBYLL 2.1, QGSJETII-04, and QGSJET01 models exceed the data of the classical experiments L3 + Cosmic, MACRO, and LVD on the spectra of atmospheric muons by a factor of 1.5–2. It has been concluded that these tested models overestimate the generation of secondary particles with the highest energies in elementary events of interaction between hadrons in agreement with the LHCf and TOTEM accelerator experiments.     

Possible observations of new physics in ultrahigh-energy cosmic rays

The muon lateral structure functions in giant air showers induced by primary photons have been simulated with the help of original codes. Particularly, the densities of muons with energies above 0.5 and 1 GeV at a distance of 1000 m from the shower core have been estimated for gamma-induced showers of various energies. A comparison with the results of calculations for hadronic showers shows a considerable deficit of muons in the gamma-induced showers. The density of muons at a distance of 1000 m from the shower core happened to be ≳ 10 times larger for the hadronic showers. Some possible constraints of the source models with superheavy-dark-matter particles and topological defects are discussed. The text was submitted by the authors in English.     

Spatial distribution of Čerenkov light from extensive air showers

The spatial distribution function of Čerenkov radiation from particles of extensive air showers with energies in the interval 10¹²–10¹⁷ eV calculated by the computer code CORSIKA and the approximation constructed on the basis of this calculation have allowed us to reconstruct the events, that is, to reconstruct the type and energy of the particle that generated extensive air shower from signal amplitudes of Čerenkov light registered with the Tunka-25 facility. The calculated spatial distribution function of Čerenkov light is in good agreement with the fitting function constructed in [1–4] to reconstruct the parameters of extensive air showers registered with the Tunka-25 facility. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 43–48, July, 2006.     

Networks in extensive air showers

Extensive air showers are produced when high energy cosmic rays or γ$\gamma$-rays enter from the top of the atmosphere. Extensive air showers are multi-fractal in nature and in this paper we explore the topological properties of these showers. We show that the topology of extensive air showers has an exponential distribution which may arise due to the inherent tree structure character of its passage in the atmosphere.     

Variable composition of cosmic rays with E 0 ≥ 1017 eV according to the data from the muon detectors of the Yakutsk EAS array

The lateral distribution of muons with the threshold E _μ ≈ 1.0 secθ GeV (where θ is the zenith angle) in extensive air showers (EASs) with the energy E ₀ ≈ 10^17–19 eV in various observation periods from November 1987 to June 2013 has been analyzed. The experimental data have been compared to the calculations within various models of the development of EASs from the CORSIKA package. The experimental data are in the best agreement with the QGSJET II-04 model. The mass composition of cosmic rays with E ₀ < 2 × 10¹⁸ eV before 1996 was much lighter than that in a later time interval.     

Electrons and muons in extensive air showers of energies E 0≥3×1017 eV: Yakutsk array data and QGSJET model

The results obtained from an analysis of the 1974–1998 Yakutsk array data on muons with threshold energy E _μ ≈ 1.0 × secθ GeV and on all charged particles (electrons and muons) in extensive air showers (EAS) are reported and compared with the results of calculations based on the model of quark-gluon strings with jets. For energies of E ₀≤3×10¹⁸ eV and zenith angles of θ≤45°, the results of the model calculations are consistent with the measured properties of the showers, while, for higher energy EASs, there are considerable discrepancies, which are probably due to the change in the development of the shower cascade in the region E ₀≥3×10¹⁸ eV.     

Nonstationary phenomena in cosmic rays with <Emphasis Type="Italic">E</Emphasis><Subscript>0</Subscript> ≤ 10<Superscript>18</Superscript> eV according to the data of the Yakutsk EAS array

The energy spectrum of cosmic rays and the fraction of muons with the threshold 1.0secθ GeV in the total number of charged particles in extensive air showers with energy E ₀ ≥ 10¹⁷ eV according to Yakutsk array data collected during 35 years of its continuous operation in 1978–2012 have been analyzed. It has been shown that these characteristics are noticeably different in different time periods. Before 1996, the integral intensity of the spectrum at E ₀ = 10¹⁷ eV varied near one stable position and then began to increase. It increased by (45 ± 5)% in seven years and, then, began to decrease. This phenomenon was accompanied a similar change in the fraction of muons and was caused by a significant increase in the average weight of the chemical composition of cosmic rays after 1996 as compared to preceding years.     

Properties of giant air showers and the problem of estimating the primary-particle energy

The main errors in energy estimation in individual events detected at the Yakutsk EAS array are analyzed. The data on the fraction of muons are considered. For inclined showers with energies exceeding 10¹⁹ eV, it is much larger than the value given by approximation at lower energies. This difference may be due to new processes arising upon interaction between particles with such energies, which leads to a significant increase in the muon component in the total primary-particle energy.     

MARTA: a high-energy cosmic-ray detector concept for high-accuracy muon measurement

A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.     

Mass Composition of Cosmic Rays with Energies above 1017 eV According to the Data from the Muon Detectors of the Yakutsk EAS Array

The lateral distribution of muons in extensive air showers with energies above 1017 eV detected by underground scintillation detectors with a threshold of 1.0 GeV at the Yakutsk array in 1986–2016 has been analyzed. The experimental data on the muon flux density at a distance of 300 m from the shower axis have been compared to the calculations within various models of hadron interactions at ultrahigh energies. The experimental data are in the best agreement with the QGSJet01 and QGSJet II-04 models. The mass composition of cosmic rays in the energy range of (1–30) × 10¹⁷ eV changes from middle nuclei to a purely proton composition.

     

Estimate of the mass composition of cosmic rays with E 0 ≤ 1018 eV according to the data from a new muon detector at the Yakutsk EAS array

The lateral distribution function of muons with the threshold E _μ ≈ 0.5secθ GeV (θ is the zenith angle) in extensive air showers with energy E ₀ ≥ 10¹⁷ eV has been examined using a new detector located at a distance of 180 m from the center of the Yakutsk array. This detector has been operating since autumn 2012 and consists of 27 autonomous scintillator counters with an area of 2 m². The experimental data have been compared to the calculations within the QGSJET-01 model with the CORSIKA air shower simulator. Agreement between the experimental data and calculations is achieved for the mixed composition of cosmic rays with the average atomic number satisfying the condition 〈lnA〉 ≈ 2.84 ± 0.08.     

Increase in the absorption length of inclined extensive air showers

The dependence of the number of extensive air showers with an energy above 10¹⁸ eV on the zenith angle θ is obtained in groups with a constant solid-angle step. The number of showers first decreases with an increase in the zenith angle and then, after reaching ～5°, increases strongly. With increasing energy, the kink on the dependence of the number of showers on θ is displaced towards larger angles, i.e., in the direction corresponding to the shift of the depth of the cascade-curve maximum.