Evidences for strangelet presence in Primary Cosmic Rays

The recent results of experiment “Hadron” which was carried out at Tien-Shan Station in 1985–91 are discussed. The combining of extensive air shower array and large emulsion chamber has permitted to receive new experimental data on sharp scaling violation at energies ≥10¹⁵ eV (1 PeV). Data show strong hardness of hadron energy spectra in EAS cores for primary energies ≥3 PeV. The EAS electron lateral distribution function also exhibits the same energy dependence in interval 1–10 PeV. The EAS muon component also shows changing of energy dependence at 10 PeV. These data permit to discuss a model in which sharp scaling violation is connected with EAS spectrum “knee”. A hypothesis of strangelet presence in PCR is discussed. The flow of strangelet component is estimated to be about 1 m^?2 · year^?1.     

Radio emission of extensive air showers as a method for detecting ultra-high energy cosmic rays

Recording radio emission from extensive air showers (EASs) is considered now as a new promising method for detecting ultra-high energy (E ₀ > 5 × 10¹⁶ eV) cosmic rays. The results of calculation of EAS radio emission at frequencies from 40 to 80 MHz in the EAS energy range E ₀ = 10¹⁴–10¹⁷ eV are reported here, and the possibilities of determining EAS parameters from the radio emission lateral distribution are discussed.     

Macroscopic calculation of air shower radio emission

Two patterns of calculation of radio emission from extensive air showers (EAS), the so-called microapproach and macroapproach, are considered. The predictions of these approaches are compared by calculating the spatial distribution of the 40 MHz radio emission at the EAS energy 10¹⁶ eV.     

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.     

Heavy decaying dark matter and large-scale anisotropy of high-energy cosmic rays

We examine the role of the large-scale anisotropy of the high-energy cosmic ray distribution in a search for the heavy decaying dark matter (DM) signal. Using recent anisotropy measurements from the extensive air shower (EAS) observatories, we constrain the lifetime of the DM particles with masses 10⁷ ≤ M _X ≤ 10¹⁶ GeV. These constraints appear to be weaker than that obtained with the high-energy gamma-ray limits. We also estimate the desired precision level for the anisotropy measurements to discern the decaying DM signal marginally allowed by the gamma-ray limits and discuss the prospects of the DM search with the modern EAS facilities.     

The beam propagation factor and far-field distribution of Bessel-modulated Gaussian beams

The explicit expressions for the beam propagation factor (M ² factor) and far-field distribution of Bessel-Modulated Gaussian beams with quadratic radial dependence are derived. The results are analyzed with numerical example.     

Radio signals from extensive air showers with the energies <Emphasis Type="Italic">E</Emphasis> <Subscript>0</Subscript> ≥ 10<Superscript>19</Superscript> eV according to data from the Yakutsk extensive air shower array

A radio instrument and results obtained from the measurements of the 32-MHz radio signal from particles of extensive air showers (EASs) with energies E₀ ≥ 1×10¹⁹ eV are reported in brief. The data were obtained at the Yakutsk EAS array in 1987–1989 (the first series of measurements) and in 2009–2014 (new series of measurements). The radio signal from EASs with energies above 10²⁰eV was detected at the Yakutsk EAS array for the first time, including the shower with the record energy of ~2×10²⁰ eV for the Yakutsk EAS array.     

Measurement of multi-muon events in a flash chamber tracking calorimeter at sea level

Summary The rate and angular distribution of multi-muons events in extensive air showers (EAS) are measured at sea level by a high-efficiency flash chamber calorimeter with an angular resolution of about 0.5°. Data are compared with the predictions of the low-energy composition model (LEC) of the primary cosmic-rays energy spectrum in the range (10¹⁴”10¹⁶) eV and agreement has been found. The measured time correlation between multi-muons events is also discussed. No anomaly has been found. Partially supported by Ministero della Pubblica Istruzione. Marcello Conversi died on September 27, 1988. The present paper is dedicated to his memory.     

Methodological Issues of Gamma-Ray and Neutrino Searches at the Yakutsk Array

The method used to perform searches for extensive air showers (EAS) generated by neutral particles, such as high-energy gamma rays and astrophysical neutrinos, and the results of such searches are presented. A comprehensive analysis of relevant data, including those on EAS electrons, muons, and Cherenkov light and their time responses in scintillation and Cherenkov detectors, is performed for this purpose. An upper limit on the gamma-ray flux at the energies of 3 × 10¹⁸, 10¹⁹, and 3 × 10¹⁹ eV is set. A multivariate analysis of EAS properties of neutrino-induced air showers does not reveal neutrino-induced showers.     

Radio emission from extensive air showers as a method for cosmic-ray detection

At the present time, radio emission from extensive air showers (EASs) is being considered as a new promising method for detecting cosmic rays of energy in the region E ₀ > 5 × 10¹⁶ eV. Radio emission from an EAS whose development is simulated by the Monte Carlo method is calculated here. The field of radio emission from an EAS is calculated on the basis of two representations of a shower: that as a set of individual particles and that as a continuous set of currents. The sensitivity of radio emission to EAS parameters in the frequency range 10–100 MHz is investigated. The results can be used to analyze experiments that being presently performed (CODALEMA and LOPES) and those that are being planned for the future.     

Spatial distribution of EAS radio emission at 32 MHz

The results of the reprocessing of the experimental data on radio emission from extensive air showers (EAS) earlier obtained at the EAS facility (Moscow State University) are reported. The maximum depth distribution of showers is found from analysis of the width of the spatial distribution of radio emission. The average maximum depth is X _max = 655 ± 8 g/cm² for the primary particle energy E ₀ ～ (3–4) × 10¹⁷ eV. The normalized field strength at E ₀ = 10¹⁷ eV is 3.2 ± 0.6 and 2.8 ± 0.4 μV/(m MHz) at distances of 50 and 100 m from the axis, respectively. The accuracy of E ₀ determination from the radio emission field strength at 50 m from the axis is about 20%.     

Deuterons from 300 GeV proton collisions calculated from the Lund model

We present an alternative approach to describe deuteron production in high energy particle collisions. The phenomenological Lund-model has been used to give the number and momentum distribution of secondary nucleons produced in 300 GeV proton-proton collisions. Deuterons are assumed to be produced in a final state interaction between the nucleons inNN d reactions inside a volume of 1 F³. The results are compared to experimental data.Data became available for antideuteron production in e⁺e^– annihilation. * A Lund Monte Carlo calculation for the production of secondary nucleons in e⁺e^– collisions exist. The results from a final state interaction were too small by a factor 10³. A calculation for a coalescent model which uses the overlap of the proton-neutron momentum distribution with a distribution from a Hulthen wave function is in good agreement with the data. The coalescent model works well in this case. It is because the relative momentum of the coalescent nucleons produced for 10 GeV cm energy in e⁺e^– collisions is very much smaller than the relative momentum of the nucleons produced in 300 GeV fixed target energy ofpp collisions.     

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.     

The mass composition of cosmic rays according to the data obtained using the TUNKA-25 setup

The data obtained using the Cherenkov TUNKA-25 extensive air shower (EAS) installation and the refined method were used to obtain the energy dependence of the average EAS depth maximum. The EAS distributions over the depth of the maximum were obtained for the energies of 5 × 10¹⁵ and 2 × 10¹⁶ eV. An analysis of the shape of distributions indicates that the model of interaction of the nuclei that yields the highest position of the maximum (QGSJET-01) is preferable. If this model is used to account for the maximum’s position, one finds that 〈InA〉 = 1.9±0.2 and helium is dominant in the mass composition at the energy of 5 × 10¹⁵ eV. A sharp increase in the mean mass of the composition is observed at energies in excess of 10¹⁶ eV.     

Search for anisotropy in arrival directions of ultrahigh-energy cosmic rays by using the marr wavelet on the equatorial sphere

The arrival direction distribution of cosmic rays for energies E>10¹⁸ eV detected at the Yakutsk EAS array is analyzed using the Marr wavelet. Deviation from the isotropic distribution of 361 showers above 10¹⁹ eV is found at a significance level of 0.007, which corroborates previous evidence of the cosmic ray anisotropy in this energy range. In contrast to the previous methods, the wavelet analysis makes it possible to localize both a celestial-sphere domain containing a supposed source of excess cosmic ray flux and the scale parameter of the two-dimensional wavelet.     

On the angular distribution of extensive air showers

Angular distributions of extensive air showers with different number of charged particles in the range 2.5 × 10⁵–4 × 10⁷ are derived using the experimental data obtained with the EAS MSU array. Possible approximations of the obtained distributions with different empiric functions available in literature, are analyzed. It is shown that the exponential function provides the best approximation of the angular distributions in the sense of the χ² criterion.     

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.     

Method for mass analysis of primary cosmic ray particles with the SPHERE-2 system

The results of simulation showing the possibility of mass analysis of primary cosmic-ray particles in the energy range 10¹⁶–10¹⁸ eV with the use of the SPHERE-2 balloon system are reported. The system is lifted by a tethered balloon at an altitude of 1 km. It has almost continuous sensitivity at an area of about 1 km² that is viewed by 109 photoelectron multipliers. This property makes it possible to analyze in detail the spatial distribution of Cherenkov light in extensive air showers both in the immediate vicinity of the EAS core and at large distances from it.     

Testing calculation results of Cherenkov radiation flux from extensive air showers using CORSIKA

This paper presents computational results of the spatiotemporal characteristics of Cherenkov light from particles of extensive air showers (EASs) induced by ultra-high-energy cosmic rays (UHECR). These results were obtained by simulating EAS events with the CORSIKA software package. Events were induced by UHECR particles, i.e., protons and iron nuclei with energies of 10¹⁵ and 10¹⁶ eV. The computational results were compared with experimental data obtained at the Yakutsk EAS array; possible causes of the discrepancy between them are discussed.     

Exact solution of N-dimensional radial Schrödinger equation for the fourth-order inverse-power potential

Radial Schrödinger equation in N-dimensional Hilbert space with the potential V(r)=ar^-1+br^-2+cr^-3+dr^-4 is solved exactly by power series method via a suitable ansatz to the wave function with parameters those also exist in the potential function possibly for the first time. Exact analytical expressions for the energy spectra and potential parameters are obtained in terms of linear combinations of known parameters of radial quantum number n, angular momentum quantum number l, and the spatial dimensions N. Expansion coefficients of the wave function ansatz are generated through the two-term recursion relation for odd/even solutions.