Composition Of Primary Cosmic Rays Research Articles

Summary of the main results of the KASCADE and KASCADE-Grande experiments

The KASCADE and KASCADE-Grande experiments operated in KIT-Campus North, Karlsruhe (Germany) from 1993 to 2012. The two experiments studied primary cosmic rays in the energy range from 1014 eV to 1018 eV, investigating the change of slope of the spectrum detected at 2 - 4 × 1015 eV, the so called knee. We briefly review the performance of the experiments and then the main results obtained in the operation of both experiments: the test of hadronic interaction models, the all particle primary spectrum, the elemental composition of primary cosmic rays (with the first claim of a knee-like feature of the heavy primaries spectrum) and the search for large scale anisotropies.

Helium flux and elemental composition of galactic Cosmic Rays with the DAMPE space mission

DAMPE (DArk Matter Particle Explorer) is a space mission project promoted by the Chinese Academy of Sciences (CAS), in collaboration with Universities and Institutes from China, Italy and Switzerland. The detector is collecting data in a stable sun-synchronous orbit lasting 95 minutes at an altitude of about 500 km. It has been launched in December 17th, 2015, from the Jiuquan Satellite Launch Center, in the Gobi Desert. The main goals of the mission are: indirect search for Dark Matter, looking for signatures in the electron and photon spectra with energies up to 10 TeV; analysis of the flux and composition of primary Cosmic Rays with energies up to hundreds of TeV; high energy gamma-ray astronomy. Preliminary results about the Helium flux and Cosmic Ray composition will be presented and discussed.

Study of muons in extensive air showers from ultra-high energy cosmic rays measured with the Telescope Array experiment

The origin of ultra-high energy cosmic rays (UHECRs) has been a long-standing mystery. One of the uncertainties in UHECR observation derives from the hadronic interaction model used for air shower Monte-Carlo (MC) simulations. The number of muons observed at ground level from UHECR induced air showers is expected to depend upon the composition of primary cosmic rays. The MC prediction also depends on hadronic interaction models. One may test the hadronic interaction models by comparing the measured number of muons with the MC prediction. The Telescope Array (TA) is the largest experiment in the northern hemisphere observing UHECR in Utah, USA. It aims to reveal the origin of UHECR by studying the energy spectrum, mass composition and anisotropy of cosmic rays by utilizing an array of surface detectors (SDs) and fluorescence detectors. We studied muon densities in the UHE extensive air showers by analyzing the signal of TA SD stations for highly inclined showers which should have high muon purity. A high muon purity condition is imposed that requires the geometry of the shower and relative position of the given station and implies that muons dominate the signal. On condition that the muons contribute about 65% of the total signal, the number of particles from air showers is typically 1.88 ± 0.08(stat:) ± 0.42(syst:) times larger than the MC prediction with the QGSJET II-03 model for protons. The same feature was also obtained for other hadronic models, such as QGSJET II-04.

The Pierre Auger Observatory: Review of Latest Results and Perspectives

The Pierre Auger Observatory is the world’s largest operating detection system for the observation of ultra high energy cosmic rays (UHECRs), with energies above 10 17 eV. The detector allows detailed measurements of the energy spectrum, mass composition and arrival directions of primary cosmic rays in the energy range above 10 17 eV. The data collected at the Auger Observatory over the last decade show the suppression of the cosmic ray flux at energies above 4 × 10 19 eV. However, it is still unclear if this suppression is caused by the energy limitation of their sources or by the Greisen–Zatsepin–Kuzmin (GZK) cut-off. In such a case, UHECRs would interact with the microwave background (CMB), so that particles traveling long intergalactic distances could not have energies greater than 5 × 10 19 eV. The other puzzle is the origin of UHECRs. Some clues can be drawn from studying the distribution of their arrival directions. The recently observed dipole anisotropy has an orientation that indicates an extragalactic origin of UHECRs. The Auger surface detector array is also sensitive to showers due to ultra high energy neutrinos of all flavors and photons, and recent neutrino and photon limits provided by the Auger Observatory can constrain models of the cosmogenic neutrino production and exotic scenarios of the UHECRs origin, such as the decays of super heavy, non-standard-model particles. In this paper, the recent results on measurements of the energy spectrum, mass composition and arrival directions of cosmic rays, as well as future prospects are presented.

Estimation of mass composition of high energy cosmic rays via modeling a relation between lateral distribution parameters and shower age

Lateral distribution function of extensive air showers of energetic cosmic rays, indicate how secondary particles spread over a surface detectors. There are many different universal formulas between lateral distribution parameters and shower age parameter which can be used to infer about maximum development of extensive air shower (which is a key parameter to estimate the mass composition of primary cosmic rays). At present work, an estimated percent of mass composition of ultra-high energy cosmic rays is investigated by comparison between Ivanov et al. modeling of simulated data, which has been done by CoRSiKa, and Yakutsk experimental data.

EAS thermal neutron detection with the PRISMA-LHAASO-16 experiment

EAS (extensive air shower) thermal neutron measurement gives advantages to study energy and mass composition of primary cosmic rays especially in the knee region. After the success of the PRISMA-YBJ experiment, we build a new EAS thermal neutron detection array at Tibet University, Lhasa, China (3700 m a.s.l.) in March, 2017. This prototype array so called "PRISMA-LHAASO-16" consists of 16 EAS EN-detectors ("EN" is abbreviation for electron and neutron) measuring two main EAS components: hadronic and electromagnetic ones. Different from PRISMA-YBJ, these detectors use a thin layer of a novel type of ZnS(Ag) scintillator alloyed with natural boron compound for thermal neutron capture. PRISMA-LHAASO-16 will be moved to the LHAASO site in the near future. In this paper, we introduce principle of the detection technique, deployment of the array, and the test results of the array.

EAS age determination from the study of the lateral distribution of charged particles near the shower axis with the ARGO-YBJ experiment

The ARGO-YBJ experiment, a full coverage extensive air shower (EAS) detector located at high altitude (4300 m a.s.l.) in Tibet, China, has smoothly taken data, with very high stability, since November 2007 to the beginning of 2013. The array consisted of a carpet of about 7000 m2 Resistive Plate Chambers (RPCs) operated in streamer mode and equipped with both digital and analog readout, providing the measurement of particle densities up to few particles per cm2. The unique detector features (full coverage, readout granularity, wide dynamic range, ..) and location (very high altitude) allowed a detailed study of the lateral density profile of charged particles at ground very close to the shower axis and its description by a proper lateral distribution function (LDF). In particular, the information collected in the first 10 m from the shower axis have been shown to provide a very effective tool for the determination of the shower development stage (“age”) in the energy range 50 TeV - 10 PeV. The sensitivity of the age parameter to the mass composition of primary Cosmic Rays is also discussed.

The Tunka-Grande experiment

The investigation of energy spectrum and mass composition of primary cosmic rays in the energy range 1016–1018 eV and the search for diffuse cosmic gamma rays are of the great interest for understanding mechanisms and nature of high-energy particle sources, the problem of great importance in modern astrophysics. Tunka-Grande scintillator array is a part of the experimental complex TAIGA (Tunka Advanced Instrument for Cosmic Ray and Gamma Astronomy) which is located in the Tunka Valley, about 50 km from Lake Baikal. The purpose of this array is the study of diffuse gamma rays and cosmic rays of ultra-high energies by detecting extensive air showers. We describe the design, specifications of the read-out, data acquisition (DAQ) and control systems of the array.

An anomaly in the properties of primary cosmic rays from the Vela cluster

Based on experimental data obtained by the GAMMA array for the knee energy region, an anomaly is found in the mass composition of primary cosmic rays arriving from the region of the Vela cluster. An original difference method is used that offers high sensitivity, protection against accidental experimental errors, and the ability to separate anomalies associated with the laboratory coordinate system from those in celestial coordinates. Allowing for the multiple scattering of charged particles in the galactic magnetic fields allows parts of the sky not directly visible from the array to be studied.

The prototype SPHERE-Antarctica station and the possibility of using silicon PMTs to detect the Cherenkov and fluorescent light of EASes

The design for a balloon instrument to study the energy spectrum and mass composition of primary cosmic rays at energies exceeding 1018 eV is presented. It is planned to conduct the experiment during Antarctica’s polar night. The equipment allows the separate registration of fluorescent light (FL) and Cherenkov radiation (CR) in each event. The advantages of the experiment over existing ground-based installations and future orbiting stations are discussed. A way of separating FL from CR with light filters and optical silicon detectors is described.

Probing the cosmic ray mass composition in the knee region through TeV secondary particle fluxes from solar surroundings

The possibility of estimating the mass composition of primary cosmic rays above the knee of its energy spectrum through the study of high energy gamma rays, muons and neutrinos produced in the interactions of cosmic rays with the solar ambient matter and radiation has been explored. It is found that the theoretical fluxes of TeV gamma rays, muons and neutrinos from a region around $15^{o}$ of the Sun are sensitive to mass composition of cosmic rays in the PeV energy range. The experimental prospects for detection of such TeV gamma rays/neutrinos by future experiments are discussed.

A proposed method for measurement of cosmic-ray mass composition based on geomagnetic spectroscopy

The effect of the geomagnetic Lorentz force on the muon component of extensive air shower (EAS) has been studied in a Monte Carlo generated simulated data sample. This geomagnetic field affects the paths of muons in an EAS, causing a local contrast or polar asymmetry in the abundance of positive and negative muons about the shower axis. The asymmetry can be approximately expressed as a function of transverse separation between the positive and negative muons barycentric positions in the EAS through opposite quadrants across the shower core in the shower front plane. In the present study, it is found that the transverse muon barycenter separation and its maximum value obtained from the polar variation of the parameter are higher for Iron primaries than protons for highly inclined showers. Hence, in principle, these parameters can be exploited to the measurement of primary cosmic-ray chemical composition. Possibility of practical realization of the proposed method in a real experiment is briefly discussed.

The search of the anisotropy of the primary cosmic radiation by the difference method

On the basis of experimental data obtained in the knee energy region with the GAMMA array an anomaly has been found in the mass composition of primary cosmic rays coming from the region of the VELA cluster. We used an original difference method which has high sensitivity, stability against accidental experimental errors and the possibility to separate anomalies connected with the laboratory coordinate system from anomalies observed in the celestial coordinates. The multiple scattering of the charged particles in the galactic magnetic fields makes it possible to study regions of the sky outside the direct visibility of the array.

Detection and analysis of atmospheric muons using the ALICE detector at the LHC

ALICE is a general purpose experiment designed to investigate nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC). Located 52 meters underground, with 28 meters of overburden rock, it has also been used to detect the muonic component of the extensive air showers produced by cosmic-ray interactions in the upper atmosphere. A program of cosmic-ray data taking, with specific triggers for atmospheric muons, was started in 2010 in periods when there is no beam circulating in the LHC. Several million events have been recorded to date. The large size and excellent tracking capability of the ALICE Time Projection Chamber are exploited to detect and reconstruct these muons. In this paper the analysis of the multiplicity distribution of the atmospheric muons detected by ALICE between 2010 and 2013 is presented, along with the comparison with Monte Carlo simulations. Special emphasis is given to the study of high multiplicity events containing more than 100 reconstructed muons. The comprehension of the frequency of these events was an unsolved problem since the pioneering studies performed by ALEPH and DELPHI experiments at LEP. In our work the ALICE measurements show that such high multiplicity events demand primary cosmic rays with energy above 1016 eV. Their frequency can be successfully described by assuming a heavy mass composition of primary cosmic rays above this energy and using the most recent interaction models to describe the development of the air shower resulting from the primary interaction.

Detection and analysis of atmospheric muons using the ALICE detector at the LHC

ALICE is a general purpose experiment designed to investigate nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC). Located 52 meters underground, with 28 meters of overburden rock, it has also been used to detect the muonic component of the extensive air showers produced by cosmic-ray interactions in the upper atmosphere. A program of cosmic-ray data taking, with specific triggers for atmospheric muons, was started in 2010 in periods when there is no beam circulating in the LHC. Several million events have been recorded to date. The large size and excellent tracking capability of the ALICE Time Projection Chamber are exploited to detect and reconstruct these muons. In this paper the analysis of the multiplicity distribution of the atmospheric muons detected by ALICE between 2010 and 2013 is presented, along with the comparison with Monte Carlo simulations. Special emphasis is given to the study of high multiplicity events containing more than 100 reconstructed muons. The comprehension of the frequency of these events was an unsolved problem since the pioneering studies performed by ALEPH and DELPHI experiments at LEP. In our work the ALICE measurements show that such high multiplicity events demand primary cosmic rays with energy above 1016 eV. Their frequency can be successfully described by assuming a heavy mass composition of primary cosmic rays above this energy and using the most recent interaction models to describe the development of the air shower resulting from the primary interaction.

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.

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.

Measurement of the TeV atmospheric muon charge ratio with the full OPERA data set

The OPERA detector, designed to search for νμ→ντ oscillations in direct appearance mode, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale cosmic rays. Given the large rock depth and the detector's wide acceptance, the apparatus was used to measure the atmospheric muon charge ratio in the TeV energy region. The muon charge ratio, defined as the number of positive over negative charged muons, provides an understanding of the mechanism of multiparticle production in the atmosphere in kinematic regions not accessible to accelerators, as well as information on the primary cosmic ray composition. We present the results obtained with the full statistics collected by OPERA from 2008 to 2012. The combination of two data sets with opposite magnet polarities allows minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region are obtained.

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.