Unusual and multicore extensive air showers

2019 ◽  
Vol 28 (11) ◽  
pp. 1950145
Author(s):  
Saeed Doostmohammadi ◽  
Seyed Jaliledin Fatemi ◽  
Maryam Nikpour

Unusual and multicore extensive air showers are detected in some experiments. Study of these kinds of showers is an important issue in nuclear collisions at high energies and need to be interpreted by hadronic interaction models. In the work, taking into account results Sleptsova et al. of which emphasized shower size variations at energies above [Formula: see text][Formula: see text]eV, and also by using of the auger experimental data, some characteristics of multicore events are investigated. Intense nuclear variations are seen in energy range of [Formula: see text]–[Formula: see text][Formula: see text]eV, and nuclear distinctive properties of multicore showers relative to normal showers are shown.

2019 ◽  
Vol 210 ◽  
pp. 02004 ◽  
Author(s):  
H.P. Dembinski ◽  
J.C. Arteaga-Velázquez ◽  
L. Cazon ◽  
R. Conceição ◽  
J. Gonzalez ◽  
...  

We present a summary of recent tests and measurements of hadronic interaction properties with air showers. This report has a special focus on muon density measurements. Several experiments reported deviations between simulated and recorded muon densities in extensive air showers, while others reported no discrepancies. We combine data from eight leading air shower experiments to cover shower energies from PeV to tens of EeV. Data are combined using the z-scale, a unified reference scale based on simulated air showers. Energy-scales of experiments are cross-calibrated. Above 10 PeV, we find a muon deficit in simulated air showers for each of the six considered hadronic interaction models. The deficit is increasing with shower energy. For the models EPOS-LHC and QGSJet-II.04, the slope is found significant at 8 sigma.


2019 ◽  
Vol 210 ◽  
pp. 02003
Author(s):  
Takashi Sako

Two studies by the Telescope Array group related to the hadronic interaction observed with Extensive Air Showers are reviewed. (1) Inelastic p-air cross section $ \sigma _{p - air}^{inel} = 567.0 \pm 70.5\,[{\rm{stat]}}_{ - 25}^{ + 29} [{\rm{sys}}]\,{\rm{mb}} $ and total p-p cross section $ \sigma _{p - p}^{tot} = 170_{ - 44}^{ + 48} [{\rm{stat}}]_{ - 17}^{ + 19} [{\rm{sys}}]\,{\rm{mb}} $ were determined using the 5 years of TA hybrid data with one of the 3 FD stations. These results at the highest energy $ \sqrt {S_{NN} } = 95\,{\rm{TeV}} $ showed good agreements with the extrapolation from the previous measurements and model predictions. (2) The signal sizes of SD were compared between data and MC using 7 years of TA SD data in the energy range from 1018.8 eV to 1019.2 eV. It was found that the data/MC ratios exceed unity and the deviation becomes larger when the expected fraction of muon signal, defined as muon purity P, is higher. The results support the muon excess (with respect to MC) problem reported by the previous observations.


1968 ◽  
Vol 46 (10) ◽  
pp. S92-S94 ◽  
Author(s):  
N. M. Nesterova

The experimental data concerning the fluctuations of Cerenkov flashes in the atmosphere are analyzed to investigate the composition of primary particles for the energy range 1014–1016 eV.


2019 ◽  
Vol 208 ◽  
pp. 08004
Author(s):  
R. Takeishi

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.


2013 ◽  
Vol 53 (A) ◽  
pp. 728-731
Author(s):  
A. Chiavassa ◽  
W. D. Apel ◽  
J. C. Arteaga-Velázquez ◽  
K. Bekk ◽  
M. Bertaina ◽  
...  

KASCADE-Grande is an extensive air shower experiment devoted to the study of cosmic rays in the 1016 ÷ 1018 eV energy range. The array is composed by different detectors allowing independent measurements of the number of muons (Nμ) and charged particles (Nch) of extensive air showers (EAS). These two observables are then used to study the primary energy spectrum, separating the events in two samples, on the basis of the shower size ratio, corrected for attenuation in the atmosphere, lnNμ/ lnNch. The two samples represent the light and heavy mass groups of the primaries. In the studied energy range only the spectrum of heavy primaries shows a significant change of slope, the energy (estimated using the QGSJET II hadronic interaction model) of this feature is in agreeement with the expectations of a rigidity dependent knee feature.


2019 ◽  
Vol 208 ◽  
pp. 08013
Author(s):  
M. Amenomori ◽  
X. J. Bi ◽  
D. Chen ◽  
T. L. Chen ◽  
W. Y. Chen ◽  
...  

A hybrid experiment has been started by the ASγ experiment at Yangbajing (4300m a.s.l.) in Tibet since May 2009, that consists of a high-energy air-shower-core array (YAC-I) and a high-density air-shower array (Tibet-III). In this paper, we report our results to check the hadronic interaction models SIBYLL2.3, SIBYLL2.1, EPOS-LHC and QGSJETII-04 in the multi-tens TeV energy region using YAC-I+Tibet-III experimental data from May 2009 through January 2010. The effective live time is calculated as 106.05 days. The results show that the description of transverse momentum, inelastic cross-section and inelasticity for the 4 hadronic interaction models is consistent with YAC-I experimental data within 15% systematic errors range in the forward region below 100 TeV. Among them, the EPOS-LHC model is the best hadronic interaction model. Furthermore, we find that the H4a composition model is the best one below the 100 TeV energy region.


2019 ◽  
Vol 210 ◽  
pp. 02012
Author(s):  
R. Takeishi

One of the uncertainties in ultrahigh energy cosmic ray (UHECR) observation derives from the hadronic interaction model used for air shower Monte-Carlo (MC) simulations. One may test the hadronic interaction models by comparing the measured number of muons observed at the ground from UHECR induced air showers 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 UHECRs 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. 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 proton-induced showers. The same feature was also obtained for other hadronic interaction models, such as QGSJET II-04.


2019 ◽  
Vol 28 (08) ◽  
pp. 1950097
Author(s):  
Maciej Rybczyński ◽  
Zbigniew Włodarczyk

In order to examine a muon excess observed by the Pierre Auger Observatory, detailed Monte Carlo simulations were carried out for primary protons, iron nuclei and strangelets (hypothetical stable lumps of strange quark matter). We obtained a rough agreement between the simulations and the data for ordinary nuclei without any contribution of strangelets in primary flux of cosmic rays. Our simulations suggest that the shower observables are dominated by details of hadronic interaction models.


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