Particles In Extensive Air Showers Research Articles

Changes in the chemical composition of primary cosmic radiation at ultrahigh energies

The signals from particles of extensive air showers in the energy region of 1017–1020 eV in both the surface and underground scintillation detectors of the Yakutsk array are calculated using the CORSIKA 6.616 and GEANT4 software packages and compared with experimental data. It is shown that a transition from a heavy primary composition to proton primaries at energies (1–2.6) × 1018 eV and from primary protons again to heavy primaries at energies above 1.3 × 1019 eV might be observed.

Measurements of high energy cosmic rays above 10 PeV with KASCADE-Grande

In the present work, different aspects of the measurement and reconstruction of extensive air showers generated by cosmic rays in the energy range between 10 16 eV and 10 18 eV are investigated. KASCADE-Grande detects charged particles of extensive air showers at ground level. From the energy deposits and the arrival times of the particles in the detector stations, the main parameters of the extensive air showers are reconstructed: the impact point, the direction of the shower axis, the total number of electrons (N e ), and the total number of muons (Nμ) of the shower at observation level. The nurnbers of electrons and muons are related to the mass and energy of the primary particle and are the basis for further analysis. The shape of the electron number spectrum reflects the shape of the cosmic ray energy spectrum. Knowing the reconstruction accuracies, the N e spectrum of the KASCADE- Grande data is studied in order to identify possible spectral features. It is found, that observed structures are consistent with the detector resolution and the reconstruction uncertainties. On the basis of the correlation between the total number of muons in the showers and the total number of charged particles, a composition estimation is carried out. A k Nearest Neighbours (kNN) classification procedure is developed: a measured air shower is classified as proton-like or iron-like by finding its nine nearest neighbours in the parameter space of the selected mass sensitive observables. The total number of charged particles (N ch ) and the total number of muons (N μ ) are found to be suitable observables for this purpose. The parameter space is populated by a set of simulated proton and iron induced air showers and an air shower is assigned to the class most common among its neighbours. The misclassification errors, as obtained in the training phase, are taken into account. An increase of the relative number of iron-like induced air showers is observed between 10 16 eV and 3.2·10 16 eV, which could be associated with the decrease of the cosmic ray light component (He, CNO group) due to the break in its energy spectrum. Above 3.2·10 16 eV, about 70% of the events result to be iron-like and ≈ 30% proton-like. At the highest observed energies an increase of light primaries is indicated. The results presented in this work constitute a first attempt to carry out composition analysis with KASCADE-Grande data.

Estimation of the proton energy spectrum in knee region by analog read-out of ARGO-YBJ experiment**Supported by National Natural Science Foundation of China (10120130794)

Based on the six months data set of ARGO-YBJ experiment with analog read-out and its Monte Carlo simulation, we study the difference between different primaries induced showers by using the space-time information of the charged particles in Extensive Air Showers. With five parameters which can efficiently pick out primary proton induced showers as inputs of an artificial neural network, the proton spectrum from 100 TeV to 10 PeV can be obtained.

On absorption of the hadron component of EAS cores in a large lead calorimeter at ‘knee’-range energies

The absorption of the core particles of extensive air showers (EAS) in the large 36 m2 lead ionization calorimeter (at the Tien-Shan mountain station) is analyzed in comparison with full Monte Carlo simulations. The EAS development in the atmosphere is simulated in the framework of CORSIKA+QGSJET code whereas the passage of hadrons and muons through the calorimeter has been simulated using the FLUKA transport code. It is shown that in EAS with energies of a few PeV the value of absorption length, Λ, of core hadron energy increases with energy much faster than that expected from simulations. This effect may be connected with the appearance of a small (a few per cent) excess of abnormal EAS cores with large ionization deposited in the lower layers of the calorimeter. It is shown that the shape of ionization curves in the lead calorimeter observed in abnormal EAS resembles that of high-energy muon groups. This effect cannot be explained by the increase of heavy nuclei in the PCR in the knee region. The hypothesis of prompt muons originated in the interaction of particles with atomic nuclei in the atmosphere also cannot explain the excess of abnormal absorption even at large values of charmed particle production cross sections.

Simulation study on number of secondary particles in extensive air showers using CORSIKA code

We have simulated more than ${10}^{5}$ extensive air showers (EAS) by CORSIKA code, with a proton as the primary particle. The range of energy for primary particles was selected from 50 TeV to 5 PeV, with differential flux given by $dN/dE\ensuremath{\propto}{E}^{\ensuremath{-}2.7}$. Using the secondary charged particles produced of these EASs, we obtained the function $d{N}_{\mathrm{sp}}(\ensuremath{\theta},X)/d\ensuremath{\theta}$, where ${N}_{\mathrm{sp}}(\ensuremath{\theta},X)$ is the number of secondary charged particles in EASs as a function of atmosphere depth, $X$, and zenith angle, $\ensuremath{\theta}$. A $\mathrm{sin}\ensuremath{\theta}{cos}^{n(X)}\ensuremath{\theta}$ distribution was obtained for zenith angle distribution of the number of secondary charged particles, where power index, $n(X)$, is a function of atmosphere depth, $X$. We obtained $n(X)=3.02+0.003X\mathrm{ln}X\ensuremath{-}8.28\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}{X}^{3}\ensuremath{-}1.35\mathrm{ln}X$. We have compared our results with the experimental data of various observatories.

Cosmic ray spectrum obtained from the energy scattered by the particles of extensive air showers in the atmosphere and the galactic model

The differential energy spectrum of cosmic rays that is obtained on the basis of the measurements of Cherenkov radiation from extensive air showers in an energy range of 1015–1020 eV is compared with the model of the propagation of primary particles in the interstellar medium with fractal properties. It is found that the shape of the experimental spectrum is in good agreement with the shape of the calculated spectrum of “all particles” at 1015–1018 eV. The average mass composition of cosmic rays that is calculated on the basis of five components does not contradict the average mass composition obtained from the experimental data for several parameters in this energy range.

On the choice of the lateral distribution function for EAS charged particles

Knowledge of the lateral distribution function (LDF) of charged particles in extensive air showers (EASs) is necessary for adequate determination of both the total number Ne of particles and other parameters used to classify the showers selected for analysis. Many researchers continue to actively use the Nishimura-Kamata-Greisen LDF despite that fact that it was obtained theoretically within a fairly rough approximation of electromagnetic cascade theory. In this study, the dependence of the shape of the EAS spectrum over the number of particles on the type of LDF used to treat experimental data is investigated. The Nishimura-Kamata-Greisen function and the scaling function are analyzed [5]. Major attention is given to the data obtained at the Moscow State University EAS array.

Spatial distribution of Čerenkov light from extensive air showers

The spatial distribution function of Cerenkov 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 Cerenkov light registered with the Tunka-25 facility. The calculated spatial distribution function of Cerenkov 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.

Modeling and parameterization of the spatial distribution of Čerenkov light from extensive air showers

Spatial distribution of Cerenkov radiation of extensive air shower particles with energies 1013–1016 eV is simulated by the CORSIKA code for conditions and configuration of the Tunka-25 facility. Based on the calculated results, sets of approximating functions are constructed for different primary particles and zenith angles. A comparison of the calculated spatial distribution functions of Cerenkov light with the functions measured on the Tunka-25 facility demonstrates the feasibility of identification of the particle initiating the shower and determination of its energy in the vicinity of the bend point of the cosmic ray spectrum.

Application of bidimensional power spectrum properties of extensive air shower particle distributions to γ–proton discrimination

High-energy interactions of cosmic γ rays and protons with the earth atmosphere have been simulated by means of the CORSIKA Monte Carlo code, and the secondary particle density distributions at ground level in the resulting extensive air showers have been studied. It is shown that the power spectrum of the bidimensional particle density fluctuations have features typical of a 1/ f noise in the bidimensional frequency domain, and is found to have different features for different primary cosmic rays. This property is applied to the separation of electromagnetic from proton simulated extensive air showers and it is proposed as a new discrimination method that can be used experimentally for real-time γ–proton separation. A cutting parameter related to the bidimensional power spectrum is calculated and the efficiency of the cutting procedure for γ–proton separation is evaluated.

Radio-Frequency Radiation Induced by Transverse Current of Charged Particles of Extensive Air Shower

Radio-Frequency Radiation Induced by Transverse Current of Charged Particles of Extensive Air Shower

Anomalous time structure of extensive air shower particle flows in the knee region of primary cosmic ray spectrum

We observe the new phenomenon of anomalous prolonged time distributions of neutron intensity using the 18NM64-type neutron monitor operating together with the shower installation of the Tian-Shan mountain cosmic ray station. We observe anomalous events in the core region of extensive air showers (EAS) with the size Ne > 106. The threshold of their generation coincides with the ‘knee’ in the energy spectrum of primary cosmic rays (about 3 × 1015 eV). The prolonged neutron events are accompanied by the flows of EAS electrons and γ-quanta having time distributions similar to those of the neutrons. The discovered phenomenon may be a reason to make a principal change in the usual procedure of EAS exploration.

Monte Carlo study of the arrival time distribution of particles in extensive air showers in the energy range 1–100 TeV

A detailed simulation of vertical showers in atmosphere produced by primary gammas and protons, in the energy range 1–100 TeV, has been performed by means of the FLUKA Monte Carlo code, with the aim of studying the time structure of the shower front at different detector heights. It turns out that the time delay distribution can be fitted using few parameters coincident with the distribution central moments. Such parameters exhibit a smooth behaviour as a function of energy. These results can be used both for detector design and for the interpretation of the existing measurements. Differences in the time structure between gamma and proton induced showers are found and explained in terms of the nonrelativistic comonent of extensive air showers.

Operation and performance of the Cosmic Ray Tracking (CRT) detector system

The cosmic ray tracking (CRT) detectors consist of two drift chambers of the TPC type and an iron plate as a muon filter between the two chambers. CRT detectors are designed to detect and identify secondary cosmic ray particles in extensive air showers. Each detector has a local electronics box with a readout, trigger, and monitoring system. The local computers at the detector stations are used for hit and track finding in parallel to the detector readout. Detector stations are permanently calibrated online, using the cosmic ray data. The online software, including data processing and calibration procedures, are presented in this paper. Ten detectors are in operation at the site of the HEGRA air shower array. The detector performance has been evaluated using data from these detectors and the HEGRA array as well as by Monte Carlo simulations. The spatial resolution has been found to be about 1 mm both in drift and in wire direction. The corresponding angular resolution is about 0.4° in each projection for a single track. Muons are usually identified if scattered by less than 2.5° in the iron plate, corresponding to energies above about 1 GeV. In HEGRA-triggered showers an overall muon identification efficiency of 87% is achieved, with a fraction of only 0.07% of the electrons being misidentified as muons.

The Cosmic Ray Tracking (CRT) detector system

The Cosmic Ray Tracking (CRT) project represents a study on the use of tracking detectors of the time projection chamber type to detect secondary cosmic ray particles in extensive air showers. In reconstructing the arrival direction of the primary cosmic ray particles, the CRT detectors take advantage of the angular correlation of secondary particles with the cosmic rays leading to these air showers. In this paper, the detector hardware including the custom-designed electronics system is described in detail. A CRT detector module provides an active area of 2.5 m 2 and allows to measure track directions with a precision of 0.4°. It consists of two circular drift chambers of 1.8 m diameter with six sense wires each, and a 10cm thick iron plate between the two chambers. Each detector has a local electronics box with a readout, trigger, and monitoring system. The detectors can distinguish penetrating muons from other types of charged secondaries. A large detector array could be used to search for γ-ray point sources at energies above several TeV and for studies of the cosmic-ray composition. Ten detectors are in operation at the site of the HEGRA air shower array.

Total inelasticity in p14N interactions at 103-104 TeV

A number of characteristics of groups of the highest energy particles in extensive air showers (so-called gamma h-families) measured in the cosmic ray Pamir experiment and the data from the Tian-Shan extensive air shower experiment were compared with those simulated using three different h14N interaction models distinguished mainly by the dependence of the total inelasticity on energy: namely increasing, constant and decreasing. The chemical composition of the primary cosmic rays varied from so-called normal to extremely enriched by heavy nuclei. The detection of gamma h-families in emulsion chambers was also simulated. On the basis of the comparison, we conclude that the total inelasticity in h14N interactions up to laboratory energy of 104 TeV is greater than 0.55, and that an energy-independent value of 0.55 is in contradiction with the data we consider at any cross-section which is consistent with the cosmic ray experimental data and for any composition of primary cosmic rays from so-called normal to super-heavy. The quark gluon string model with ktot increasing up to 0.84 at 104 TeV and the inelastic charge-exchange probability of 0.3-0.5 fits well the data used.

Measurement of the angular distributions of particles in air showers.

Using a scintillator air shower array to determine the direction, size, and core position of extensive air showers and a large-volume drift chamber to track individual shower particles, we have measured the angular distributions of charged particles in extensive air showers at sea level. The distributions are sharply peaked around the shower axis, with characteristic widths of a few degrees. Particles at large distances from the shower axis tend to point towards the axis as their origin. Monte Carlo models of air showers reproduce the measured distributions rather well.

Afterpulses and decay times of fast scintillation counters for extensive air shower experiments

Abstract A fast scintillation counter system to observe the arrival time distribution of relativistic particles in extensive air showers has been developed. The generation rate of afterpulses observed by a ternary plastic scintillator counter of a fast-time-response photomultiplier were studied in detail. It was found that the effect of afterpulses generated in the photomultiplier and scintillation process was negligibly small compared with that of afterpulses produced by delayed particles in the shower. It was also found that long decay components in the scintillator output can be explained as being due to afterpulses.

Transition effect of air shower particles in the thin absorder

The response of plastic scintillators to the flux of particles in extensive air showers of various sizes was measured at various distances from the core. One scintillator was placed above the other, and thin iron absorber was inserted between them, varying its thickness. The ratio of the particle density measured by the lower scintillator ϱlower to that measured by the upper one ϱupper, ϱlower/ϱupper, was found to decrease with the core distance and to be almost independent of the shower size. In case of iron absorber of 1 mm thickness, the ratio was found to be ∼1.2 forr≤1.5 m, and decrease to ∼1.0 forr≥10 m, wherer is the distance from the core. The empirical formulae for the transition effect were obtained. Modification of shower parameters due to the transition effect was investigated, using these formulae. A theoretical estimate of the transition effect was carried out, and it was shown that the observed transition effect could be explained by the cascade of the electromagnetic components of air shower within the scintillator and absorber.

Proportional counter for air shower observation

About a thousand proportional counters of 500 cm × 10 cm × 10 cm have been constructed and are now in operation for the observation of cosmic ray particles in extensive air showers at Akeno EAS Array. The method of mass production, the dynamic characteristics and the estimated deterioration life time of the proportional counter are described and discussed.