Energy Spectrum Of Primary Cosmic Rays Research Articles

EAS Cherenkov LDF Analysis: CORSIKA Simulations for Tunka-133 and Chacaltaya Arrays

This study leverages CORSIKA simulations to analyze the Lateral Distribution Function (LDF) of Cherenkov photons in Extensive Air Showers (EAS) within the knee region of the cosmic ray energy spectrum (10^15 - 10^16 eV). Focusing on primary particles like helium, proton, oxygen, and iron nuclei at varying zenith angles (0˚, 20˚, and 45˚), we aimed to reconstruct Cherenkov photons' LDF using an Exponential Function model, tailored as a function of primary energy. Our approach involved a comparative analysis of simulated LDFs with experimental data from the Tunka-133 and Chacaltaya arrays. The results exhibit a high degree of concordance between simulated and observed data, affirming the validity of our method. We developed a set of approximation functions for different primary particles and zenith angles, enhancing our ability to identify the particle type in EAS events and accurately determine its energy. The primary contribution of our work lies in its potential to rapidly compile a comprehensive LDF pattern library, instrumental for analyzing real EAS array events and reconstructing the mass composition and primary cosmic ray energy spectrum. This advancement in CORSIKA-based simulation methods marks a significant stride in cosmic ray research, offering a robust tool for detailed EAS analysis.Highlights : Validation of Simulation Accuracy: Demonstrated high concordance between CORSIKA simulated LDFs and experimental data from Tunka-133 and Chacaltaya arrays. Enhanced Particle Identification: Development of approximation functions for various primary particles and zenith angles, improving accuracy in identifying particle types in EAS events. Advancement in Cosmic Ray Research: Potential to create a comprehensive LDF pattern library, significantly aiding in the reconstruction of mass composition and primary cosmic ray energy spectrum. Keywords : CORSIKA Simulations, Cherenkov LDF, EAS Analysis, Cosmic Ray Spectrum, Particle Identification

Primary cosmic ray energy spectrum and mean mass composition using data from the TAIGA astrophysical complex

The corrected dependence of the mean depth of the EAS maximum X_{max}Xmax on the energy was obtained from the data of the Tunka-133 array for 7 years and the TAIGA-HiSCORE array for 2 years. The parameter \langle\ln A\rangle⟩lnA⟪, characterizing the mean mass compositon was derived from these results. The differential energy spectrum of primary cosmic rays in the energy range of 2\cdot 10^{14}2⋅1014 – 2\cdot 10^{16}2⋅1016 eV was reconstructed using the new parameter Q_{100}Q100 the Cherenkov light flux at the core distance 100 m. Change of the parameter for the energy reconstuction for the TAIGA-HiSCORE from Q_{200}Q200 to Q_{100}Q100 provides a decreasing energy threshold for the spectrum to about 200 TeV.

Evidence of fresh cosmic ray in galactic plane based on DAMPE measurement of B/C and B/O ratios

More and more experiments have identified that the energy spectra of both primary and secondary cosmic-rays exhibit a hardening above ∼ 200 GV. More recently, the DAMPE experiment has reported a hardening of boron-to-carbon ratio at 200 GV. These signs call for modifications of the conventional cosmic-ray (CR) picture. In this work, we propose that the plethoric secondary cosmic rays, for example, boron, antiprotons, originate from the hadronic interactions of freshly accelerated cosmic rays with the interstellar gas near the sources. We find that secondary-to-primary ratios, for example, boron-to-carbon, boron-to-oxygen and antiproton-to-proton ratios, can be well described. The measurements of electrons and positrons can also be accounted for.

Universal properties of primary and secondary cosmic ray energy spectra

Atomic nuclei appearing in cosmic rays (CRs) are typically classified as primary or secondary. However, a better understanding of their origin and propagation properties is still necessary. We analyse the flux of primary (He, C, O) and secondary nuclei (Li, Be, B) detected with rigidity (momentum/charge) between 2 GV and 3 TV by the alpha magnetic spectrometer on the International Space Station. We show that q-exponential distribution functions, as motivated by generalized versions of statistical mechanics with temperature fluctuations, provide excellent fits for the measured flux of all nuclei considered. Primary and secondary fluxes reveal a universal dependence on kinetic energy per nucleon for which the underlying energy distribution functions are solely distinguished by their effective degrees of freedom. All given spectra are characterized by a universal mean temperature parameter ∼200 MeV which agrees with the Hagedorn temperature. Our analysis suggests that QCD scattering processes together with nonequilibrium temperature fluctuations imprint universally onto the measured CR spectra, and produce a similar shape of energy spectra as high energy collider experiments on the Earth.

Primary Cosmic Ray Energy Spectrum Above the ‘‘Knee’’ Measured with PRISMA-32 Array

PRISMA-32 (PRImary Spectrum Measurement Array) is working since 2012 in the Scientific & Educational Center NEVOD (NRNU ‘‘MEPhI’’, Moscow). Array area is $${\sim}500$$ m $${}^{2}$$ . PRISMA-32 consists of 32 specially developed electron–neutron detectors capable to measure simultaneously electronic and hadronic components of the extensive air showers with energies above $$10^{14}$$ eV. This feature is very important because hadronic component is a ‘‘skeleton’’ of the shower, and one can use measurements of hadron number along with simulations to recalculate primary energy spectrum independently or/and together with commonly used EAS size. Detailed Monte-Carlo simulation with CORSIKA and GEANT4 was performed and dependence of hadronic number on primary energy was obtained. Experimental data were processed and analyzed. Primary energy spectrum was recalculated from neutron number spectrum and it is in agreement with some other experiments at energies above $$10^{16}$$ eV. The results of the analysis are presented.

The primary cosmic-ray energy spectrum measured with the Tunka-133 array

The EAS Cherenkov light array Tunka-133, with ~ 3 km2 geometric area, is taking data since 2009.The array permits a detailed study of energy spectrum and mass composition of cosmic rays in the energy range from 6 · 1015 to 1018 eV. We describe the methods of time and amplitude calibration of the array and the methods of EAS parameters reconstruction. We present the all-particle energy spectrum, based on 7 seasons of operation.

EAS Phenomenology and Cosmic Ray Spectrum Ground Based Measurements

Primary cosmic ray energy spectrum around and above 1 PeV is of great interest due to its non-power-law behavior (“knee”) in PeV region found many years ago using the indirect EAS (Extensive Air Shower) method. The method is based on secondary particles measuring on Earth’s surface under a thick atmosphere. Traditionally, people use detectors sensitive to ionization produced mostly by secondary electromagnetic component and therefore any found changes in EAS size spectrum correspond to secondary components, which have to be recalculated to primary spectrum. Recently some new “knees” were claimed by high altitude experiments: at ∼45 TeV for all-particle spectrum (HAWC), for primary protons and helium: at ∼400 TeV (Tibet ASγ) and at ∼700 TeV (ARGO-YBJ) thus widening the “knee” region from ∼0.045 to 5 PeV. The natural explanation of such a strange spectrum behavior in a wide energy range could be found in the EAS phenomenological approach to the knee problem.

The Search for Diffuse Gamma Rays Using Data from the Tunka-Grande Experiment

The Tunka-Grande array is part of an experimental complex located in the Tunka Valley (Republic of Buryatia, Russia) about 50 km from Lake Baikal. This complex also contains the Tunka-133 and Tunka-Rex arrays. The aim of this complex is to study the primary cosmic ray energy spectrum and mass composition in the energy range of 1016–1018 eV, and to search for diffuse gamma rays in the energy range of 5 × 1016–5 × 1017 eV. The design of the Tunka-Grande array and the procedure for reconstructing the parameters of extensive air showers (EASes) are described, and preliminary results are presented from the search for diffuse gamma rays with energies of more than 5 × 1016 eV.

On the cosmic ray energy spectrum “knees”

Primary cosmic ray energy spectrum around and above 1 PeV is of great interest due to its non-power law behavior found many years ago using the indirect EAS (Extensive Air Shower) method. The method is based on secondary particles measuring on Earth’s surface under a thick atmosphere. Traditionally people use detectors sensitive to ionization produced mostly by electromagnetic component and so called “knee” was found for EAS size spectrum many years ago. Later it was assigned to a steepening of cosmic ray spectrum at 3-5 PeV. Recently some new “knees” were claimed by high altitude experiments, for primary protons and helium: at ∼200-300 TeV (Tibet ASγ) and at ∼700 TeV (ARGO-YBJ) thus widening the “knee” region from ∼0.2 to 5 PeV and demonstrating disagreement with the existing experimental data. The natural explanation of such a strange spectrum behavior can be found in the phenomenological approach to the knee problem.

Energy spectrum of primary cosmic rays at energies of 2 × 1013 to 5 × 1017 eV, according to Tien Shan data

The primary cosmic ray energy spectrum at energies of 1015 to 5 × 1017 eV is presented using the results from observations by the Tien Shan HADRON array. The spectrum was obtained from the spectrum of showers according to the number of electrons using a new way of determining the parameter of spatial distribution function S of electrons. The energy spectrum can be extended to low energies up to 2 × 1013 eV using data from separate experiments at the former Tien Shan array. Conclusions are drawn regarding changes in the form of the spectrum and its chemical composition at energies over 1016 eV. The spectrum is compared to the results from the TUNKA installation.

Properties of the difference method for searching for anisotropy of primary cosmic rays

Methodical properties and features of the original difference method for searching for the anisotropy in the knee region of the primary cosmic ray energy spectrum are analyzed. It is shown that the method in which properties of particle fluxes, rather than intensities, are studied is stable to randomexperimental errors andmakes it possible to separate anomalies associatedwith the laboratory coordinate system from anomalies in the celestial coordinates. The method uses multiple scattering of charged particles in galactic magnetic fields for studying the entire celestial sphere, including sky regions beyond the installation line of sight.

Sharp knee phenomenon of primary cosmic ray energy spectrum

Primary energy spectral models are tested in the energy range of 1-200 PeV using standardized extensive air shower responses from BASJE-MAS, Tibet, GAMMA and KASCADE scintillation shower arrays. Results point towards the two-component origin of observed cosmic ray energy spectra in the knee region (GAPS spectral model) consisting of a pulsar component superimposed upon rigidity-dependent power law diffuse galactic flux. The two-component energy spectral model accounts for both the sharp knee shower spectral phenomenon and observed irregularity of all-particle energy spectrum in the region of 50-100 PeV. Alternatively, tested multi-population primary energy spectra predicted by non-linear diffusive shock acceleration (DSA) models describe observed shower spectra in the knee region provided that the cutoff magnetic rigidities of accelerating particles are 6.0+/-0.3 PV and 45+/-2 PV for the first two populations respectively. Both tested spectral models confirm the predominant H-He primary nuclei origin of observed shower spectral knee. The parameters of tested energy spectra are evaluated using solutions of inverse problem on the basis of the corresponding parameterizations of energy spectra for primary H, He, O-like and Fe-like nuclei, standardized shower size spectral responses in the 550-1085 g/cm^2 atmospheric slant depth range and near vertical muon truncated size spectra detected by the GAMMA array.

Extensive Air Showers’ Arrival Direction Distribution by TBS Array

Arrival zenith angle distribution for the Extensive Air Showers (EAS) with a wide range of number of charged particles is studied using the experimental data obtained using the EAS 4-detector array TBS in Tbilisi. The station is a part of the GELATICA net in Georgia (GEorgian Large-area Angle and Time Coincidence Array). This experiment is devoted to the study of possible correlations in the arrival times and directions of separate EAS events over large distances and to the Primary Cosmic Ray energy spectrum investigation at very high energies. It is shown that the distribution function with the exponential dependence of showers’ flux on absorbing atmospheric depth provides a good approximation for the angular distribution despite the existing azimuth anisotropy of array. The dependence of the EAS absorption path estimation on the angular measure cutoff boundary is studied.

Cosmic ray physics with the ARGO-YBJ experiment

The main scientific goals of the ARGO-YBJ ex- periment are -ray astronomy with a few hundreds GeV en- ergy threshold and cosmic ray physics below and around the knee of the primary energy spectrum (10 12 10 16 eV), where the transition from direct to indirect measurement techniques takes place. The ARGO-YBJ experiment, located at the Cos- mic Ray Observatory of Yangbajing (Tibet, P.R. of China, 4 300 m a.s.l.), is an unconventional Extensive Air Shower ar- ray of about 6,700 m 2 of active area, the only one exploiting the full-coverage technique at very high altitude currently in operation. The detector space-time granularity, performance and location offer a unique chance to make a detailed study of the structure of cosmic ray showers, in particular of the hadronic component. In this work we will focus on the main experimental results concerning cosmic ray and hadronic in- teraction physics: primary cosmic ray energy spectrum, an- tiproton over proton ratio, anisotropy in the cosmic ray flux and proton-air cross-section. Moreover, the possible data analysis improvements based on the use of all detailed infor- mation on the shower front (curvature, time width, rise time, ..), as well as the extension of the investigable energy range, allowed by the analog RPC readout, will be pointed out. nique at very high altitude presently in data taking. Location and detector features make ARGO-YBJ capable of investi- gating a wide range of fundamental issues in Cosmic Ray and Astroparticle Physics at relatively low energy threshold: - very high energy -ray astronomy, with an energy thresh- old of a few hundreds GeV; - search for emission of gamma ray bursts in the full GeV - TeV energy range; - study of cosmic rays (spectrum, composition, p/p ra- tio measurement, shower space-time structure, ...) starting at TeV energies; - Sun and heliosphere physics above Eth 1 GeV. In following sections, after a brief description of the detec- tor and its performance, the main results achieved on several items of cosmic ray physics will be presented and discussed.

Cosmic ray physics with the ARGO-YBJ experiment

Cosmic ray physics in the 10 12–10 15 eV primary energy range is among the main scientific goals of the ARGO-YBJ experiment. The detector, located at the Cosmic Ray Observatory of Yangbajing (Tibet, P.R. China) at 4300 m a.s.l., is a full coverage Extensive Air Shower array consisting of a carpet of Resistive Plate Chambers of about 6000 m 2. The apparatus layout, performance and location offer a unique possibility to make a deep study of several characteristics of the hadronic component of the cosmic ray flux in an energy window marked by the transition from direct to indirect measurements. In this work we will focus on the experimental results concerning the measurements of the primary cosmic ray energy spectrum and of the proton-air cross-section. The all-particle spectrum has been measured, by using a bayesian unfolding technique, in the 1–100 TeV energy region. The proton-air cross-section has been measured at the same energies, by exploiting the cosmic ray flux attenuation for different atmospheric depths (i.e. zenith angles). The total proton–proton cross-section has then been estimated at center of mass energies between 70 and 500 GeV, where no accelerator data are currently available.

Primary cosmic ray energy spectrum in terms of the GAMMA muon data

The energy spectrum of the primary cosmic rays is obtained by conversion from the truncated muon size spectrum of EAS studied with the GAMMA array. The previously observed dependence of E 0 on N μ tr at various zenith angles is used. It is shown that the present spectrum has the same structure (“bump”) as the spectrum determined by another independent multi-parametric energy estimation method confirming that the “bump” structure is not produced by uncertainties in our methods.

Hybrid approach to the primary cosmic ray composition

In this work we discuss the advantage of combining a classical extensive air shower array with an Imaging Atmospheric Cherenkov Telescope having the ability to detect Direct Cherenkov (DC) light like H.E.S.S. experiment which derived using this technique the spectrum for cosmic iron nuclei in the energy range 50-200 TeV. Such a hybrid detector will offer a unique opportunity to test the different criteria used for the identification of primary cosmic ray particles (muon electron abundance, hadron content and lateral profiles), and then to approach the elemental composition around the knee of the primary cosmic ray energy spectrum when validated criteria are extended beyond the present DC energy window.

An all-particle primary energy spectrum in the 3–200 PeV energy range

We present an all-particle primary cosmic-ray energy spectrum in the 3 × 106–2 × 108 GeV energy range obtained by a multi-parametric event-by-event evaluation of the primary energy. The results are obtained on the basis of an expanded EAS data set detected at mountain level (700 g cm−2) by the GAMMA experiment. The energy evaluation method has been developed using the EAS simulation with the SIBYLL interaction model taking into account the response of GAMMA detectors and reconstruction uncertainties of EAS parameters. Nearly unbiased (<5%) energy estimations regardless of a primary nuclear mass with an accuracy of about 15–10% in the 3 × 106–2 × 108 GeV energy range respectively are attained. An irregularity (‘bump’) in the spectrum is observed at primary energies of ∼7.4 × 107 GeV. This bump exceeds a smooth power-law fit to the data by about 4 standard deviations. By not rejecting the stochastic nature of the bump completely, we examined the systematic uncertainties of our methods and conclude that they cannot be responsible for the observed feature.

Direct stratospheric measurements of charges and energies of Primary Cosmic Rays in the range of 1013 − 1015 eV (CROSS Project)

The CROSS (Cosmic Rays Over Spectrum Steepening) experiment is aimed at direct measurements of masses and energies of primary cosmic ray (PCR) nuclei in the range of 1013 − 1015 eV near the break in the PCR energy spectrum. The experimental equipment includes a balloon ionization spectrometer consisting of X-ray transition radiation generators interlaid with thin-wall proportional chambers.

Experiment SPHERE status – 2006 and CR composition determination by means of Cherenkov light LDF

The modern status of the SPHERE experiment and the method to determine the primary energy and the kind of the primary nuclear particles is presented. The SPHERE experiment is based on A.E.Chudakov's suggestion to use a new method for investigating the ultra high energy primary cosmic ray energy spectrum [A.E. Chudakov, Trudy conf. po cosm. lutcham, (in Russian), p.69, Yakutsk, 1972]. A small device lifted above the snow surface of the Earth detects the Cherenkov light of extensive air showers reflected from the surface. The relatively simple detector SPHERE-2 (spherical mirror 1.5m diameter and retina of 100 pixels) is presented. The next plan of the SPHERE experiment is to start measurements of the cosmic ray spectrum in the energy range 10 16 – 10 18 eV above the snow surface of Lake Baikal.