Mass Composition Of Cosmic Rays Research Articles

Xmaxreconstruction from amplitude information with AERA

The standard method to estimate the mass of a cosmic ray is the measurement of the atmospheric depth of the shower maximum ($X_\text{max}$). This depth is strongly correlated with the mass of the primary because it depends on the interaction cross section of the primary with the constituents of the atmosphere. Measuring the electric field, emitted by the secondary particles of an extensive air shower (EAS), with the Auger Engineering Radio Array (AERA) in the 30-80 MHz band allows the determination of the depth of shower maximum on the basis of the good understanding of the radio emission mechanisms. The duty cycle of radio detectors is close to 100\%, making possible the statistical determination of the cosmic-ray mass composition through the study of a large number of cosmic rays above 10$^{17}$ eV. In this contribution, $X_\text{max}$ reconstruction methods based on the study of the radio signal with AERA are detailed.

Measurement of the Muon Content of Air Showers with IceTop

IceTop, the surface component of the IceCube detector, has measured the energy spectrum of cosmic ray primaries in the range between 1.6 PeV and 1.3 EeV. IceTop can also be used to measure the average density of GeV muons in the shower front at large radial distances (> 300 m) from the shower axis. Wei present the measurement of the muon lateral distribution function for primary cosmic rays with energies between 1.6 PeV and about 0.1 EeV, and compare it to proton and iron simulations. We also discuss how this information can be exploited in the reconstruction of single air shower events. By combining the information on the muon component with that of the electromagnetic component of the air shower, we expect to reduce systematic uncertainties in the inferred mass composition of cosmic rays arising from theoretical uncertainties in hadronic interaction models.

Cosmic ray spectrum and composition from three years of IceTop and IceCube

IceTop is the surface component of the IceCube Observatory, composed of frozen water tanks at the top of IceCube’s strings. Data from this detector can be analyzed in different ways with the goal of measuring cosmic ray spectrum and composition. The shower size S125 from IceTop alone can be used as a proxy for primary energy, and unfolded into an all-particle spectrum. In addition, S125 from the surface can be combined with high-energy muon energy loss information from the deep IceCube detector for those air showers which pass through both. Using these coincident events in a complementary analysis, both the spectrum and mass composition of primary cosmic rays can be extracted in parallel using a neural network. Both of these analyses have been performed on three years of IceTop and IceCube data. Both all-particle spectra as well as individual spectra for elemental groups are presented.

New approach to cosmic ray investigations above the knee

It is assumed that at energies around the knee the nucleus-nucleus interaction is drastically changed due to production of blobs of quark-gluon matter with very large orbital momentum. This approach allows explain all so-called unusual events observed in cosmic rays and gives a new connection between results of EAS investigations and energy spectrum and mass composition of primary cosmic rays. To check this approach, the experiments in cosmic rays and at LHC are proposed.

Measurement of the mass composition of ultra-high energy cosmic rays with the Pierre Auger Observatory

The understanding of the nature of ultra-high energy cosmic rays is one of the most intriguing open questions for current and future observatories. With its hybrid design and huge exposure, the Pierre Auger Observatory provides valuable statistical measurements of the chemical composition of cosmic rays with energies above 1017 eV, including the search for neutral primaries such as neutrinos and photons. We report on the most recent results which are based on the accurate measurement of the depth of the shower maximum, Xmax, by the fluorescence telescopes and on the shape of the signals recorded by the water-Cherenkov detectors. The interpretation of these results in terms of mass composition is also discussed related to the hadronic interaction models used to describe the development of air showers.

Study of muon bundles from extensive air showers with the ALICE detector at CERN LHC

ALICE is one of four large experiments at the CERN Large Hadron Collider, specially designed to study particle production in ultra-relativistic heavy-ion collisions. Located 52 meters underground with 28 meters of overburden rock, it has also been used to detect muons produced by cosmic-ray interactions in the upper atmosphere. The large size and excellent tracking capability of the ALICE Time Projection Chamber are exploited to study the muonic component of extensive air showers. We present the multiplicity distribution of these atmospheric muons and its comparison with Monte Carlo simulations. The latest version of the QGSJET hadronic interaction model was used to simulate the development of the resulting air showers. High multiplicity events containing more than 100 reconstructed muons were also studied. Similar events have been studied in previous underground experiments such as ALEPH and DELPHI at LEP without satisfactory explanations for the frequency of the highest multiplicity events. We demonstrate that the high muon-multiplicity events observed in ALICE stem from primary cosmic rays with energies above 1016 eV and that the frequency of these events can be successfully described by assuming a heavy mass composition of primary cosmic rays in this energy range.

Results and perspectives of cosmic ray mass composition studies with EAS arrays in the Tunka Valley

The study of the cosmic ray mass composition in the energy range 1016 - 1018 eV is one of the main aims of Tunka-133. This EAS Cherenkov array started data acquisition in the Tunka Valley (50 km from Lake Baikal) in autumn 2009. Tunka-133 provides a measurement of the EAS maximum depth (Xmax) with an accuracy of about 30 g/cm2. Further mass composition analyses at the highest energies (1017 - 1018 eV) will be based on the comparison of primary energy measured by the radio method and the densities of charged particles measured by shielded and unshielded detectors. The high duty cycle of the common operation of the new scintillation array (Tunka-Grande) and the radio extension of the experiment (Tunka-REX) will provide a high statistics of events.

Azimuthal asymmetry in the risetime of the surface detector signals of the Pierre Auger Observatory

The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, $(\sec \theta)_\mathrm{max}$, sensitive to the mass composition of cosmic rays above $3 \times 10^{18}$ eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modelling that must be resolved before the mass composition can be inferred from $(\sec \theta)_\mathrm{max}$.

A large light-mass component of cosmic rays at 10(17)-10(17.5) electronvolts from radio observations.

Cosmic rays are the highest-energy particles found in nature. Measurements of the mass composition of cosmic rays with energies of 10(17)-10(18) electronvolts are essential to understanding whether they have galactic or extragalactic sources. It has also been proposed that the astrophysical neutrino signal comes from accelerators capable of producing cosmic rays of these energies. Cosmic rays initiate air showers--cascades of secondary particles in the atmosphere-and their masses can be inferred from measurements of the atmospheric depth of the shower maximum (Xmax; the depth of the air shower when it contains the most particles) or of the composition of shower particles reaching the ground. Current measurements have either high uncertainty, or a low duty cycle and a high energy threshold. Radio detection of cosmic rays is a rapidly developing technique for determining Xmax (refs 10, 11) with a duty cycle of, in principle, nearly 100 per cent. The radiation is generated by the separation of relativistic electrons and positrons in the geomagnetic field and a negative charge excess in the shower front. Here we report radio measurements of Xmax with a mean uncertainty of 16 grams per square centimetre for air showers initiated by cosmic rays with energies of 10(17)-10(17.5) electronvolts. This high resolution in Xmax enables us to determine the mass spectrum of the cosmic rays: we find a mixed composition, with a light-mass fraction (protons and helium nuclei) of about 80 per cent. Unless, contrary to current expectations, the extragalactic component of cosmic rays contributes substantially to the total flux below 10(17.5) electronvolts, our measurements indicate the existence of an additional galactic component, to account for the light composition that we measured in the 10(17)-10(17.5) electronvolt range.

Study of the energy spectrum and mass composition of primary cosmic rays in the energy range of 1018–1020 eV using a balloon setup in antarctica (SPHERE-antarctica project)

An Antarctic balloon experiment for measuring the energy spectrum and elemental composition of cosmic rays in the ultrahigh-energy range (1018–1020) eV is proposed. Scientific equipment will measure fluorescence caused by an extensive air shower formed in the atmosphere by an ultrahigh energy particle and Cherenkov light of this shower reflected from a snow surface. It is assumed that the balloon will fly in the circumpolar orbit in Antarctica at a height of ~25 km for (2–3) winter (in the Southern Hemisphere)months. For this time, ~3000 events caused by particles with energies above 1018 eV and (200–300) events caused by particles with energies above 1019 eV will be detected.

Study of cosmic ray events with high muon multiplicity using the ALICE detector at the CERN Large Hadron Collider

ALICE is one of four large experiments at the CERN Large Hadron Collider near Geneva, specially designed to study particle production in ultra-relativistic heavy-ion collisions. Located 52 meters underground with 28 meters of overburden rock, it has also been used to detect muons produced by cosmic ray interactions in the upper atmosphere. In this paper, we present the multiplicity distribution of these atmospheric muons and its comparison with Monte Carlo simulations. This analysis exploits the large size and excellent tracking capability of the ALICE Time Projection Chamber. A special emphasis is given to the study of high multiplicity events containing more than 100 reconstructed muons and corresponding to a muon areal density ρμ > 5.9 m−2. Similar events have been studied in previous underground experiments such as ALEPH and DELPHI at LEP. While these experiments were able to reproduce the measured muon multiplicity distribution with Monte Carlo simulations at low and intermediate multiplicities, their simulations failed to describe the frequency of the highest multiplicity events. In this work we show that the high multiplicity events observed in ALICE stem from primary cosmic rays with energies above 1016 eV and that the frequency of these events can be successfully described by assuming a heavy mass composition of primary cosmic rays in this energy range. The development of the resulting air showers was simulated using the latest version of QGSJET to model hadronic interactions. This observation places significant constraints on alternative, more exotic, production mechanisms for these events.

Radio signal correlation at 32 MHz with extensive air showers parameters

The paper presents correlations of radio signals measured at the Yakutsk array with air shower parameters: the shower energy E0 and the depth of maximum Xmax. It is shown that from radio emission measurements of air showers one can obtain individual shower parameters and hence, the mass composition of cosmic rays. In addition, we also derived a generalized formula for calculating the primary energy of the air showers.

Mass Composition of Cosmic Rays at Ultra High Energies by Yakutsk Data

The paper describes methods for the analysis of cosmic rays mass composition and results for over a large time span. The data were obtained at Small Cherenkov array over 20 year period of continuous observation and 40 - years of observations at the main Yakutsk array. The experimental data indicates changes in the MC in the energy range 1016 - 1018 eV which confirmed by results obtained by other EAS arrays.

Estimating of Cherenkov Radiation in Extensive Air Showers Using CORSIKA Code for Tunka133 EAS Cherenkov Array

The simulation of Cherenkov light Lateral distribution function (LDF) in Extensive Air Showers (EAS) initiated primary particles such as primary calcium, argon, proton iron nuclei, neutron and nitrogen have been performed using CORSIKA program for conditions and configurations of Tunka133 EAS Cherenkov array. The simulation was fulfilled at the high energy range 1014-1016eV for four different zenith angles 0o, 10o, 15oand 30o. The results of the simulated Cherenkov light LDF are compared with the measurements of Tunka133 EAS array for the same particles and energy range mentioned above. This comparison may give the good ability to reconstruct the energy spectrum and mass composition of the primary cosmic ray particles in EAS. The main feature of the given approach consists of the possibility to make a library of Cherenkov light LDF samples which could be utilized for analysis of real events which can be detected with different EAS arrays and reconstruction of the primary cosmic rays energy spectrum and mass composition of EAS particles.

Mass composition of ultrahigh-energy cosmic rays, according to data from the Pierre Auger Collaboration: A statistical investigation using the Copula function

The mass composition of cosmic rays with ultrahigh energies (2 × 10182–5 × 1019 eV) is studied using the publicly accessible data of the Pierre Auger Collaboration as of January 1, 2014. Employing tools for describing intrinsic relations inside multidimensional distribution (the Copula function) at 3 × 1018–3 × 1019 eV, the investigation reveals a mass composition weight of a complex nature.

Mass composition of cosmic rays with energy E 0 ≥ 1017 eV, according to surface detectors of the Yakutsk EAS array

The lateral distribution of charged particles is investigated in extensive air showers (EASes) with energy E0 ≥ 1017 eV at the Yakutsk array using surface scintillation detectors over the period 1977–2013. Experimental values are compared to calculations made by different models of EAS development contained in the CORSICA software package. The best agreement between theory and experiment is observed with the QGSJET-01-d and QGSJET-II-04 models. A change in the mass composition of cosmic rays in the direction of purely proton is observed in the energy range of 1–20 × 1017 eV.

The promise of the Tunka-Grande scintillation experiment for studying the mass composition of primary cosmic rays

A description of the project of the Tunka-Grande scintillation complex is provided. The prospects of studying the energy spectrum and mass composition of the primary cosmic rays during simultaneous registration of the Cherenkov, electron, and muon components of extensive air showers are discussed.

Correlation between radio signals at a frequency of 32 MHz and the parameters of extensive air showers, using data from measurements at the Yakutsk EAS array

The correlation between radio signals and the parameters of extensive air showers (EASes), particularly shower energy E0 and maximum depth Xmax of EAS development. It is shown that we can estimate the parameters of individual showers and analyze the mass composition of cosmic rays by measuring EAS radio emissions.

Energy spectrum and mass composition of cosmic rays, by the data of the Tunka-133 array

The Tunka-133 Cherenkov light array for the detection of extensive air showers (EAS) acquires data over the five winters from 2009 to 2014. The direction of arrival, the shower core coordinates on the plane of observation, the primary energy, and the depth of the shower maximum are reconstructed for each EAS. A differential all-particle energy spectrum is obtained in the energy range of 6 × 1015–3 × 1018 eV over 1540 h, along with the energy dependence of the average depth of the shower maximum in the range of 6 × 1016–3 × 1018 eV. Based on this dependence, the variation in the average composition of the primary cosmic rays is estimated as a function of energy.

Spectra of cosmic-ray protons and nuclei from 1010 to 1020 eV within the galactic origin scenario of cosmic rays

Results from calculating the cosmic ray energy spectrum within the Galactic origin scenario are presented. Key elements of the approach are the assumed existence of Galactic sources that accelerate particles up to ∼1011 GeV and a highly inhomogeneous (fractal type) distribution of matter and magnetic fields in the Galaxy that leads to large free paths for particles (Levy flights), along with an overwhelming contribution to the cosmic ray fluxes observed in the energy range of 109–1011 GeV from particles reaching the Solar System without scattering. It is shown that the proposed scenario allows us to describe the main features of the observed cosmic ray spectrum from 1010 to 1020 eV. The behavior of the cosmic ray mass composition in the ultra-high energy region is discussed.