Cores Of Extensive Air Showers Research Articles

Dependence of normalized phase angle of cosmic ray radio signals on core location of an extensive air shower

High energy cosmic rays hitting the earth atmosphere induce extensive air showers propagating downward with a high gamma factor. Determining the core location of such air shower is a necessary step to measure other important characteristics of a cosmic ray such as the lateral distribution function. In this study and based on computer simulations and radio signal analyses we investigate the relation between normalized radio signal phase angle emitted from particles in an air shower to the position of a shower core. We perform a series of simulations based on CORSIKA and COREAS code for cosmic rays with different types of primary particles with an energy range from 0.1 to 1 EeV. The results show a direct relationship between the average slope of normalized radio signal phase angle as a function of frequency to the absolute distance from extensive air shower core location. We have calculated the normalized radio signal phase angle to have the absolute minimum value at close distances to a shower core location. We discuss a possible approach to estimate core location with different types of virtual radio arrays.

Fair Weather Neutron Bursts From Photonuclear Reactions by Extensive Air Shower Core Interactions in the Ground and Implications for Terrestrial Gamma‐ray Flash Signatures

AbstractWe report on anomalously long duration (2 ms) count rate bursts following the impact of cosmic ray showers near a 7.62 cm x⊘7.62 cm LaBr3 scintillation detector at the High Altitude Water Cherenkov array in Mexico, previously described by Stenkin et al. (2001), and termed “neutron bursts.” The largest burst produced 198 counts within 2 ms in our LaBr3 detector. We simulate the neutron burst albedo flux (that is, secondary emissions from an extensive air shower core impacting the ground), and show that (1) the characteristic spectra and count rates are well explained by neutron absorption in the ground and (2) any cosmic ray secondary that produces neutrons, either through hadron inelastic collisions, or photoneutron production by gamma‐rays, produces the same characteristic spectra. This implies that other natural phenomena that produce downward beams of gamma‐rays, like Terrestrial gamma ray flashes, should produce a similar “neutron burst” signature from the photoneutron reactions occurring in the soil.

Attenuation of Hadronic Cascades in Ionization Calorimeter and Long-Range Component

The propagation and detection of electron–nuclear cascades in an ionization calorimeter are considered, and it is shown that the attenuation length associated with ionization may differ strongly from the attenuation length for the energy flux. A possible reason for the hypothesis of a long-range component in detecting cores of extensive air showers is proposed.

Estimation of the $$\boldsymbol{p+\textrm{He}}$$ Fraction in the Mass Composition of Primary Cosmic Radiation the Energy Range of $$\boldsymbol{E_{0}=1}$$–100 PeV according to Gamma-Ray Families Featuring Halo

The present article reports on an analysis of the properties that gamma-ray families featuring a halo exhibit in the cores of extensive air showers (EAS). The events under analysis were obtained in the XREC (x-ray emulsion chambers) PAMIR experiment, and the properties of these events were studied at distances extending up to about 10 cm from the EAS axis with a resolution of approximately 30 $$\mu$$ m. The investigation of the parameters of events in EAS cores by the halo method permitted analyzing the mass composition of primary cosmic radiation (PCR) at $$E_{0}=10$$ PeV and assessing the fraction of light nuclei in PCR, which depend only slightly on the model of EAS propagation through the atmosphere. From an analysis of gamma-ray families featuring a halo and multicenter halos obtained in the PAMIR XREC, it was found that the fraction of the ( $$p+\textrm{He}$$ ) component of PCR was about 40 $${\%}$$ . The properties of proton-induced EAS events detected at the Tien-Shan high-mountain Scientific Station (TShSS) were studied along with the KASCADE-Grande experimental data. On the basis of studying the dependence of the EAS age and $$N_{\mu}$$ on $$N_{e}$$ in the TShSS EAS (EAS $$+$$ XREC TShSS) data, it is concluded that PCR mass composition becomes heavier in the range of $$E_{0}=1$$ –100 PeV.

On the Dominant Role of Charm Production in the Forward Kinematic Region According to Cosmic-Ray Experiments

A phenomenon of abnormally weak absorption of very-high-energy cosmic-ray hadrons in lead is discussed. This phenomenon was first observed in Tien-Shan high-altitude experiments in hadronic cores of extensive air showers and has encouraged to introduce the hypothesis of a so-called long-flying or penetrating cosmic-ray component. A similar effect was detected later with deep uniform lead X-ray emulsion chambers (XREC) at the Pamirs. Experiments, which are sensitive to the production of charmed hadrons in the forward kinematic region (xLab ≳ 0.1), have been carried out at the Tien-Shan and Pamirs with exposing two-storey XRECs with large air gaps to prove explanation of the experimental results with high charm production cross section $${\sigma _{pp \to c\bar c}} \sim 8$$ at xLab ≳ 0.1 at ⟨ELab⟩ ∼ 75 TeV. This $${\sigma _{pp \to c\bar c}}$$ value makes it possible to reproduce the experimental hadron-absorption curve observed with XRECs, including curve’s bending at a depth of ∼70 c.u.

Investigation of abnormal absorption of cosmic-ray hadrons in lead calorimeters

A phenomenon of abnormally weak absorption of very high energy cosmic ray hadrons in thick lead blocks is discussed. This phenomenon was first observed in a Tien Shan high altitude experiment to study hadronic cores of extensive air showers (EAS) with a deep ionization calorimeter and encouraged researchers to introduce the hypothesis of the so-called long-flying or penetrating cosmic ray component. A similar effect was detected later with deep uniform lead X-ray emulsion chambers (XREC) at the Pamirs, which we discuss in detail. To establish the nature of the phenomenon we are have carried out dedicated experiments at the Tien Shan and at the Pamirs by exposing two-storey XRECs with large air gaps. According to detailed simulation of the chamber response, these experiments are very sensitive to the production of charmed hadrons in the forward kinematic region and can prove a hypothesis that the phenomenon under study can be explained on the assumption of very high values of charm particle production cross section at 〈ELab〉 ~ 75 TeV in the forward kinematic region at xLab≳ 0.1 which are near the upper limit of recent results of collider experiments, i.e., σpp→c¯c~ 8 mb. The same factor makes it possible to fit all the features of the experimental hadron absorption curve observed by means of deep uniform lead XRECs, including its bending at a depth of ~ 70 c.u.

Exotic model of the cosmic ray spectrum

A detailed study of the cores of extensive air showers (EAS) at mountain level (Tien-Shan 690 g/cm2) was carried out in the hybrid experiment HADRON. An analysis of the fine structure of the EAS spectrum in the energy region1015- 1017(knee) showed that there are two breaks in the spectrum. Along with the previously known break at an energy of 3 · 1015eV, a change in the slope of the EAS spectrum is observed at an energy slightly below 1017eV. In addition the use of a large X-ray emulsion chamber (XREC) as a detector of EAS cores allowed us to obtain several new results. An abnormal scaling violation in hadron spectra for Ne~ 107(E0~ 1016eV) means the existence of a penetrating component of non-nuclear origin. The conclusion about the non-nuclear origin of the penetrating component in the primary radiation of CR is confirmed by the data about the excess of muons in the EAS containing hadrons of maximum energies. It is assumed that the mass composition of primary cosmic radiation varies sharply at energies of 1015- 1016eV, where quasi-nuclei (strangelets) appear instead of nuclei. A new model of the mass composition of cosmic rays in the region of ultrahigh energies is proposed on this basis .

Nuclear-Physics Model of the Knee in the EAS Spectrum

Spectra of the most energetic hadrons in cores of extensive air showers (EAS) were obtained for the first time in the HADRON hybrid experiment in Tien Shan mountains. The spectra in question exhibit a scaling violation, which requires invoking nontrivial effects in order to explain this circumstance. In the present article, unusual data on pp-interaction cross sections from recent experiments at the Large Hadron Collider are analyzed with this aim in view. A comparison with data at lower energies shows that the elastic cross section for pp interaction grows faster than the respective inelastic cross section. It would be natural to expect that a similar or a stronger effect is present in nucleus–nucleus interactions in cosmic rays. A possible change in the properties of nuclear cascades in the Earth’s atmosphere provides the possibility of discussing a new interpretation of the knee in the EAS spectrum and some exotic phenomena observed in cosmic-ray experiments. This interpretation is proposed for the first time. Particular attention is given to unique data from the HADRON hybrid experiment.

Investigation of EAS cores

The development of nuclear-electromagnetic cascade models in air in the late forties have shown informational content of the study of cores of extensive air showers (EAS). These investigations were the main goal in different experiments which were carried out over many years by a variety of methods. Outcomes of such investigations obtained in the HADRON experiment using an X-ray emulsion chamber (XREC) as a core detector are considered. The N e spectrum of EAS associated with γ-ray families, spectra of γ-rays (hadrons) in EAS cores and the N e dependence of the muon number, ⟨N μ ⟩, in EAS with γ-ray families are obtained for the first time at energies of 1015 –1017 eV with this method. A number of new effects were observed, namely, an abnormal scaling violation in hadron spectra which are fundamentally different from model predictions, an excess of muon number in EAS associated with γ-ray families, and the penetrating component in EAS cores. It is supposed that the abnormal behavior of γ-ray spectra and N e dependence of the muon number are explained by the emergence of a penetrating component in the 1st PCR spectrum ‘knee’ range. Nuclear and astrophysical explanations of the origin of the penetrating component are discussed. The necessity of considering the contribution of a single close cosmic-ray source to explain the PCR spectrum in the knee range is noted.

Imprint of the atmospheric attenuation process on electron distribution in EAS

The lateral density distribution (LDD) of shower particles in an extensive air shower (EAS) experiment is commonly approximated by a particular type of lateral density function (LDF). A standard perception is being used in air shower physics since long, according to which the LDD is assumed to be symmetric about the EAS axis, and the adopted LDF is adequate for the description of the LDD. However, the simulated electron density of a non-vertical EAS is asymmetric. In this work, such asymmetry in the LDD can be qualitatively explained as the atmospheric attenuation suffered by each shower particle. Quantitatively, the asymmetry can be roughly described in terms of a gap length (GL) between the EAS core and the center of the modified density pattern consisting of several equi-density ellipses. This study also validates the use of such a modeling of the atmospheric attenuation on the electromagnetic component in an EAS by investigating the so called GL in simulated density data. A modified LDF is proposed, based on these features of the simulated densities for the purpose of shower reconstruction in EAS experiments. The GL arises from attenuation effect is found to increase with the mass of the shower initiating particle. A different radial dependence of the local age parameter (LAP) is seen, if the modified LDF is applied to simulated electron densities. Primary cosmic-ray mass sensitivity of the LAP is also re-examined.

Evidence for the charge-excess contribution in air shower radio emission observed by the CODALEMA experiment

CODALEMA is one of the pioneer experiments dedicated to the radio detection of ultra high energy cosmic rays (UHECR), located at the radio observatory of Nançay (France). The CODALEMA experiment uses both a particle detector array and a radio antenna array. Data from both detection systems have been used to determine the ground coordinates of the core of extensive air showers (EAS). We discuss the observed systematic shift of the core positions determined with these two detection techniques. We show that this shift is due to the charge-excess contribution to the total radio emission of air showers, using the simulation code SELFAS. The dependences of the radio core shift to the primary cosmic ray characteristics are studied in details. The observation of this systematic shift can be considered as an experimental signature of the charge excess contribution.

Muon and neutrino collimation in extensive air shower cores

Detailed simulations of extensive air showers have been carried out with the CORSIKA program in order to evaluate the energy brought by the different shower components at ground level and transmitted underground. A special attention is given to the angular distributions and to the collimation of beams penetrating deep underground or underwater. The natural collimation of high energy particles in extensive air shower cores results mainly from the ratio between the transverse and the longitudinal momenta of secondary particles generated in the earliest interactions. This collimation is partly conserved by the high energy muons and neutrinos. It is comparable to the magnetic focusing of charged pions and kaons decaying in tunnels of suitable length after production in accelerators. Such is the case for neutrino beams of KEK J-PARC/T2K (300km to Kamiokande), OPERA (730km to Gran Sasso) and MINOS (735km to Irvine Mine).

Partial reanimation of experimental complex ANI at Mt. Aragats (proposal)

The proposal is presented for reanimation of the half-built experimental complex ANI at Mt. Aragats (Armenia, 3200 m a.s.l.). It is proposed as a first stage to complete the functioning GAMMA installation by big X-ray emulsion chamber for detailed study of extensive air shower cores at energies 1–100 PeV. Preliminary data obtained in this field by the Tien-Shan HADRON installation are presented. This proposal is an EFT and requests creation of an international cooperation.

Study of extensive air showers and primary energy spectra by MAKET-ANI detector on mountain Aragats

Small and middle size surface detectors measuring extensive air showers (EAS) initiated by primary cosmic rays (PCR) incident on terrestrial atmosphere have been in operation for the last 50 years. Their main goal is to explore the “knee” in all particle spectrum to solve the problem of cosmic ray (CR) origin and acceleration. The recent achievements of atmospheric Cherenkov telescopes and X-ray space laboratories, establishing the supernova remnants (SNRs) as a source of hadronic cosmic rays, pose stringent conditions on the quality of EAS evidence. After establishing the existence of the “knee” itself, the most pronounced result from EAS studies is the rigidity dependent shift of the knee position to the highest energies. This feature was first observed by separation of the primary flux in different mass groups in MAKET-ANI, EAS-TOP and KASCADE experiments. The MAKET-ANI detector is placed on Mt. Aragats (Armenia) at 3200 m above the sea level (40°25′N, 44°15′E). More than 1.3 × 10 6 showers with size greater than 10 5 particles were registered in 1997–2004. The detector effectively collected the cores of EAS, initiated by primaries with energies of 10 14–10 17 eV. After proving that the quality of the EAS size and shape reconstruction was reasonably high, we present the lateral distribution function (LDF) for distances from 10 to 120 m from EAS core and EAS size spectra in 5 zenith angle intervals. We use CORSIKA simulations to present the energy spectra. The results from the MAKET-ANI experiment on the energy spectra of the “light”(p + He) and “heavy” (O + Si + Fe) nuclear groups are compared to the spectra obtained by balloon experiments and to other available spectra.

HYDRA hydroacoustic antenna in the NEVOD experimental complex

The main characteristics of the HYDRA hydroacoustic antenna intended for the detection of signals generated by cores of extensive air showers in a water Cherenkov detector involved in the NEVOD experimental complex are considered. Primary attention is focused on the calibration of antenna sensors and on the selection of an optimum trigger that ensures an effective detection of acoustic signals generated by cores of extensive air showers in the water volume of the Cherenkov detector.

The knee in the primary-cosmic-ray spectrum, observed in the hadron component of extensive-air-shower cores at the mountain level

The spectra of the hadron component in extensive-air-shower (EAS) cores detected at the Tien Shan high-altitude scientific station of the Lebedev Institute of Physics, Russian Academy of Sciences, have been analyzed. Simulation was performed using the CORSIKA code within the QGSJET01 and QGSJET02 models under different assumptions about the primary-cosmic-ray (PCR) spectrum in the knee region. It is shown that the QGSJET01 model underestimates the energy of the hadron component of EAS cores at the mountain level. It is also shown that a pronounced knee in the experimental spectrum suggests a sharp (dγ ∼ 1.5) change in the exponent of the proton spectrum slope at an energy of about 5 PeV.

Geometric structures in hadronic cores of extensive air showers observed by KASCADE

The geometric distribution of high-energy hadrons >100 GeV in shower cores measured with the KASCADE calorimeter is analyzed. The data are checked for sensitivity to hadronic interaction features and indications of new physics as discussed in the literature. The angular correlation of the most energetic hadrons and in particular the fraction of events with hadrons being aligned are quantified by means of the commonly used parameter lambda_4. The analysis shows that the observed lambda_4 distribution is compatible with that predicted by simulations and is not linked to an angular correlation from hadronic jet production at high energy. Another parameter, d_4^max, describing distances between hadrons measured in the detector, is found to be sensitive both to the transverse momenta in secondary hadron production and the primary particle type. Transverse momenta in high-energy hadron interactions differing by a factor two or more from what is assumed in the standard simulations are disfavoured by the measured d_4^max distribution.

Distortions of experimental muon arrival time distributions of extensive air showers by the observation conditions

Event-by-event measured arrival time distributions of extensive air shower (EAS) muons are affected and distorted by various interrelated effects which originate from the time resolution of the timing detectors, from fluctuations of the reference time and the number (multiplicity) of detected muons spanning the arrival time distribution of the individual EAS events. The origin of these effects is discussed, and different correction procedures, which involve detailed simulations, are proposed and illustrated. The discussed distortions are relevant for relatively small observation distances ( R μ<200 m) from the EAS core. Their significance decreases with increasing observation distance and increasing primary energies. Local arrival time distributions which refer to the observed arrival time of the first local muon prove to be less sensitive to the mass of the primary. This feature points to the necessity of arrival time measurements with additional information on the curvature of the EAS disk.

Hadronic structures of extensive air shower cores

The experimental results obtained from the Kiel EAS device have been made to study the properties of the core of the electromagnetic component as well as the hadron and muon components are measured by the underground neon hodoscope. Most energetic hadrons and hadron patterns at small distances from the core have been analysed for proton-like and iron-like showers.

Test of high-energy interaction models using the hadronic core of EAS

Using the large hadron calorimeter of the KASCADE experiment, hadronic cores of extensive air showers have been studied. The hadron lateral and energy distributions have been investigated in order to study the reliability of the shower simulation program CORSIKA with respect to particle transport, decays, treatment of low-energy particles, etc. A good description of the data has been found at large distances from the shower core for several interaction models. The inner part of the hadron distribution, on the other hand, reveals pronounced differences among interaction models. Several hadronic observables are compared with CORSIKA simulations using the QGSJET, VENUS and SIBYLL models. QGSJET reproduces the hadronic distributions best. At the highest energy, in the 10 PeV region, however, none of these models can describe the experimental data satisfactorily. The expected number of hadrons in a shower is too large compared with the observed number, when the data are classified according to the muonic shower size.