Small shower CORSIKA simulations

Extensive Air Showers (EAS) induced by cosmic ray particles of very low energies, owing to the significantly steep cosmic ray energy spectrum, dominate the secondary particle flux measured by single detectors and small shower arrays. Such arrays connected in extended networks can be used to determine potentially interesting spatial correlations between showers, which may shed new light on the nature of ultra high-energy cosmic rays. The quantitative interpretation of showers recorded by small local arrays requires a methodology that differs from that used by ordinary large EAS arrays operating in the "knee" region and above. We present "small EAS generator," a semi-analytical method for integrating cosmic ray spectra over energies of interest and summing over the mass spectra of primary nuclei in arbitrary detector configurations. Furthermore, we provide results on the EAS electron and muon fluxes and particle density spectra.     

Underground hadronic calorimeter for EAS studies

An innovative method for studying the properties of extensive air showers (EASes) that is based on the detection of thermal neutrons generated by high energy hadrons under a soil absorber of 500 g cm⁻² is proposed and tested. It is shown that underground hadronic calorimeter can be performed with special scintillation detectors developed by the authors. The method could be quite useful in gamma shower selection and investigations of EAS properties, primary cosmic ray mass composition, EAS core location, and so on.     

Muon Content of Extensive Air Showers: Comparison of the Energy Spectra Obtained by the Sydney University Giant Air-Shower Recorder and by the Pierre Auger Observatory

The Sydney University Giant Air-shower Recorder(SUGAR) measured the energy spectrum of ultra-high-energy cosmic rays reconstructed from muon detector reading. Comparison of their spectra SUGAR and Pierre Auger Observatory allows us to reconstruct the empirical dependence of the number of muons in a vertical shower on the primary energy for energies between 1017 and 1018 eV. We compared this dependence with the predictions of hadronic interaction models QGSJET-II-04, EPOS-LHC and SIBYLL-2.3c. In addition, we analyzed the response of the array of muon detectors in order to determine the slope of the muon lateral distribution function. It is important to understand how much the number of muons differs from the predictions of modeling at different distances from the shower axis.     

Investigating hadronic cores of exstensive air showers at the CARPET-2 array

Characteristics of the hadronic component of exstensive air shower (EAS) trunks are investigated at the CARPET-2 array of the Baksan Neutrino Observatory, Institute for Nuclear Research, Russian Academy of Sciences. In this work, we study showers with axes that located within its muon detector (MD). We discuss the procedure for selecting such showers in our experiment. The relationship between the number of thermal neutrons detected by heat detectors installed in the muon detector’s tunnel and the total energy of a cascade generated by hadrons in the magnetic detector’s absorbent matter is presented.     

The extensive air shower muon number spectrum beyond the knee in the cosmic-ray energy spectrum

The extensive air shower (EAS) muon number spectrum is obtained with increased statistics using the central muon detector of the EAS MSU array, which records muons with energies above 10 GeV. The dependence of the mass composition of primary cosmic rays on the energy is considered. The conclusion is confirmed that for energies from 3 × 10¹⁵ eV (the primary energy spectrum knee) up to 10¹⁷ eV a change in the composition associated with an increase in the proportion of heavy nuclei occurs; however, after the energy of 10¹⁷ eV, the proportion of heavy nuclei begins to decrease and the composition becomes lighter. A comparison with similar data from other experiments is conducted. The existence of an additional component of cosmic rays is confirmed; earlier an indication of its presence was derived from data on the EAS electron number spectrum.     

A proposed NEVOD-EAS installation for the detection of extensive air showers

A new installation is dedicated to the independent evaluation of extensive air shower (EAS) energies detected in the NEVOD-DECOR experiment in the knee region of the energy spectrum. The design for the measuring system of the shower installation is based on clusters of scintillation detectors that are located on the roofs of laboratory buildings at MEPhI (Moscow) and will detect the electromagnetic (for near-vertical showers) and muon (for large zenith angles) EAS components. Features of the measuring system, the system for data acquisition and processing, and the results from investigating the characteristics of a single detector are discussed, along with the algorithm for event formation by the data of separate clusters.     

Energy spectrum and mass composition of primary cosmic rays at energies 10<Superscript>15</Superscript>–10<Superscript>18</Superscript> eV

Data on muon and electron components of extensive air showers (EAS) (obtained with the EAS MSU array) were used to derive the primary cosmic ray (PCR) mass composition. It is shown that for energies beyond the knee at energy 3 × 10¹⁵ eV the abundance of heavy nuclei increases with energy. But at energies above 10¹⁷ eV the abundance of light nuclei starts to grow. The primary cosmic ray spectrum in the range 10¹⁵–10¹⁸ eV is analyzed. It is shown that at energies above 10¹⁷ eV the additional component appears and it differs from the bulk of Galactic cosmic rays generated by shocks in SN remnants.     

Determining the primary cosmic ray energy from the total flux of Cherenkov light measured at the Yakutsk EAS array

We present a method for determining the energy of the primary particle that generates an extensive air shower (EAS) of comic rays based on measuring the total flux of Cherenkov light from the shower. Applying this method to Cherenkov light measurements at the Yakutsk EAS array has allowed us to construct the cosmic ray energy spectrum in the range 10¹⁵ ? 3 × 10¹⁹ eV.     

Cosmic ray sea level muon spectrum at large zenith angle derived from the latest JACEE primary spectrum

The sea level cosmic ray muon spectrum at 89° has been estimated from the primary nucleon spectrum estimated after the latest JACEE measurements. The p-A collision cross section has been considered for hadronic energy moments calculations. The meson atmospheric diffusion equations after Bugaev et al. have been used in this analysis. The calculated large zenith angle muon spectrum is well in accord with the latest MUTRON data for cosmic ray muons arriving at zenith angles 86° to 90°.On leave from Indian Association for the cultivation of Science, Calcutta 700032, India.     

Atmospheric neutrino flux supported by recent muon experiments

We present a new one-dimensional calculation of low and intermediate energy atmospheric muon and neutrino fluxes, using up-to-date data on primary cosmic rays and hadronic interactions. We study several sources of uncertainties relevant to our calculations. A comparison with the muon fluxes and charge ratios measured in several modern balloon-borne experiments suggests that the atmospheric neutrino flux is essentially lower than one used for the standard analyses of the sub-GeV and multi-GeV neutrino induced events in underground detectors.     

On special features of the longitudinal development of extensive air showers and on the spectrum of cosmic rays

It is shown that, in the development of an extensive air shower (EAS) initiated by primary cosmic rays in the Earth’s atmosphere, there is a special feature that sterms from the violation of equilibrium between EAS components and whose inclusion requires revising both EAS phenomenology and the existing experimental data obtained by indirectly measuring the energy spectrum of cosmic rays by the EAS method.     

Expected energy spectrum of cosmic ray protons and helium below4 PeV measured by LHAASO

The Large High Altitude Air Shower Observatory(LHAASO) is a composite cosmic ray observatory consisting of three detector arrays: kilometer square array(KM2 A), which includes the electromagnetic detector array and muon detector array, water Cherenkov detector array(WCDA) and wide field-of-view Cherenkov telescope array(WFCTA). One of the main scientific objectives of LHAASO is to precisely measure the cosmic rays energy spectrum of individual components from 10~(14) eV to 10~(18) eV. The hybrid observation will be employed by the LHAASO experiment, in which the lateral and longitudinal distributions of extensive air shower can be observed simultaneously. Thus, many kinds of parameters can be used for primary nuclei identification. In this paper, high purity cosmic ray simulation samples of the light nuclei component are obtained using multi-variable analysis. The apertures of 1/4 LHAASO array for pure proton and mixed proton and helium(HHe) samples are 900 m~2 Sr and1800 m~2 Sr, respectively. Prospect of obtaining proton and HHe spectra from 100 TeV to 4 PeV is discussed.     

Atmospheric effects in the intensity of cosmic ray muon bundles

We analyze experimental data on cosmic ray muon bundles collected with a DECOR coordinate detector. Substantial variations in the intensity of the events are observed during the experiment. These variations are found to be caused by changes in atmospheric conditions. This study is the first to obtain experimental estimates of the temperature and barometric coefficients for muon bundles. It is shown that the observed effect can be explained by changes in the side distribution function of EAS muons.     

Muons in Extensive Air Showers with Energy above 10 17 eV According to the Long Standing Studies at the Yakutsk Array

lateral distribution of muons was studied in extensive air showers initiated by cosmic rays with energy above 1017 eV. The study is based on the experimental data of underground scintillation detectors with 1-GeV energy threshold collected during the continuous observational period lasting from 1986 to 2017. Experimentally measured values of muon density are compared to results of simulations performed for primary protons and iron nuclei within the framework of four ultra-high energy hadronic interaction models. The density of particles with 1-GeV threshold obtained in simulations was then converted to the signal of ground-shielded scintillation detectors of the array. Studying the features of the resulting muon lateral distribution has allowed us to reconstruct parameters of longitudinal development of extensive air showers.     

PLASTEX: the palermo-leeds air shower tracking experiment

Summary An experiment is described in which air shower measurement are carried out by means of a ?track detector? placed in a test location near the center of a conventional array telescope currently in use for gamma-ray astronomy. This array, consisting of scintillators (GREX, operated at Haverah Park (U.K.) by the Department of Physics of the University of Leeds), provides, in the usual way, for each shower it selects, its own estimates of shower direction and shower particle density at the test location. Estimates of the muon density at the test location are provided by a large muon detector in operation nearby. The scintillator array triggers this muon detector and it is able to provide flexibly tailored trigger signals for the track detector. This detector named PLASTEX (acronym for Palermo Leeds Air Shower Tracking Experiment), consisting of tracking chambers above and below a thin sheet of lead, designed to provide data on charged particles incident from the air, on the stopping, scattering and multiplication of these particles in the lead sheet and on charged particles created in the lead sheet by shower photons. From these data estimates are derived of the densities and directional properties of the electrons, photons and muons striking the track detector. These results are to be compared with those given by the conventional detectors and with theoretical predictions given by simulations that are being carried out. The objective is to develop and assess optimal procedures for employing clusters of PLASTEX-type detectors as telescopes for the observation of UHE cosmic rays, including cosmic gammarays, over a very wide energy range. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

High-energy cosmic ray muons in the Earth’s atmosphere

We present the calculations of the atmospheric muon fluxes at energies 10–10⁷ GeV based on a numerical-analytical method for solving the hadron-nucleus cascade equations. It allows the non-power-law behavior of the primary cosmic ray (PCR) spectrum, the violation of Feynman scaling, and the growth of the total inelastic cross sections for hadron-nucleus collisions with increasing energy to be taken into account. The calculations have been performed for a wide class of hadron-nucleus interaction models using directly the PCR measurements made in the ATIC-2 and GAMMA experiments and the parameterizations of the primary spectrum based on a set of experiments. We study the dependence of atmospheric muon flux characteristics on the hadronic interaction model and the influence of uncertainties in the PCR spectrum and composition on the muon flux at sea level. Comparison of the calculated muon energy spectra at sea level with the data from a large number of experiments shows that the cross sections for hadron-nucleus interactions introduce the greatest uncertainty in the energy region that does not include the knee in the primary spectrum.     

EMMA—a new underground cosmic-ray experiment

An experiment observing underground muons originating from cosmic-ray air showers is under preparation in the Pyhäsalmi mine, Finland. The aim is to cover an area of about 200–300 m², and the detector setup is capable of measuring the muon multiplicity and their lateral distribution. The detector is placed at a depth of about 85 m (corresponding about 240 m w.e.), which gives a threshold energy of muons of about 45 GeV. The detection of the multimuon events is motivated by partly unknown composition of the primary cosmic rays in the energy region of 10¹⁵–10¹⁶ eV, i.e., the knee region. In addition, by measuring only the higher energy muons of the air shower, the lowest energy muons being filtered out by the rock overburden, the data is sensitive also to the studies of the upper parts of the air shower. The experiment will be constructed mainly using drift chambers used previously in LEP detectors at CERN, but it can also be expanded using plastic scintillator detectors. The prototype detector is expected to be running in the beginning of 2006, and the full-size detector by the end of 2007.     

Forbush decreases recorded by the URAGAN muon hodoscope in 2006–2011

Variations in the cosmic ray muon flux on Earth’s surface during Forbush decreases (FD) recorded by the URAGAN muon hodoscope in 2006–2011 are investigated. The dependence of the rate of amplitude reduction on the primary particle energy in a range above 10 GeV at different phases of FD development is studied by analyzing the variations in the cosmic ray muon flux recorded with the hodoscope. Analytical data on the spatial and angular dynamics of the muon flux are used to estimate variations in the spatial anisotropy of the muon flux during FDs.     

Investigation of the PCR energy spectrum shape by the means of the local EAS muon density technique

The results of studying the primary cosmic radiation (PCR) flux in the energy range 10¹⁵–10¹⁸ eV at the NEVOD-DECOR experimental array using local muon density spectra are reported. The experimental distributions and the spectra obtained by simulation of EAS muon LDF using the CORSIKA code are compared. Possibilities of using a new method for analysis of muon bundle events on the basis of the primary energy estimator are discussed.     

Electron–Neutron Detector Array (ENDA)

Physics of Atomic Nuclei - By accurate measurement of components and energy spectrum in the knee region, problem of origin of cosmic ray can be solved. In one extensive air shower (EAS), high...