scholarly journals Hadronic Interactions and Air Showers: Where Do We Stand?

2019 ◽  
Vol 208 ◽  
pp. 02002
Author(s):  
Tanguy Pierog

The interpretation of EAS measurements strongly depends on detailed air shower simulations. CORSIKA is one of the most commonly used air shower Monte Carlo programs. The main source of uncertainty in the prediction of shower observables for different primary particles and energies is currently dominated by differences between hadronic interaction models even after recent updates taking into account the first LHC data. As a matter of fact the model predictions converged but at the same time more precise air shower and LHC measurements introduced new constraints. Last year a new generation of hadronic interaction models was released in CORSIKA. Sibyll 2.3c and DPMJETIII.17-1 are now available with improved descriptions of particle production and in particular the production of charmed particles. The impact of these hadronic interaction models on air shower predictions are presented here and compared to the first generation of post-LHC models, EPOS LHC and QGSJETII-04. The performance of the new models on standard air shower observables is derived. Due to the various approaches in the physics treatment, there are still large differences in the model predictions but this can already be partially resolved by comparison with the latest LHC data.

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Á. Pastor-Gutiérrez ◽  
H. Schoorlemmer ◽  
R. D. Parsons ◽  
M. Schmelling

AbstractIn the sub-TeV regime, the most widely used hadronic interaction models disagree significantly in their predictions for post-first interaction and ground-level particle spectra from cosmic ray induced air showers. These differences generate an important source of systematic uncertainty in their experimental use. We investigate the nature and impact of model uncertainties through a simultaneous analysis of ground level particles and first interaction scenarios. We focus on air shower primaries with energies close to the transition between high and low energy hadronic interaction models, where the dissimilarities have been shown to be the largest and well within the range of accelerator measurements. Interaction models are shown to diverge as several shower scenarios are compared, reflecting intrinsic differences in the model theoretical frameworks. Finally, we discuss the importance of interactions in the energy regime where the switching between models occurs ($$<1$$ < 1  TeV) and the effect of the choice of model on the number of hadronic interactions within cosmic ray induced air showers of higher energies.


2019 ◽  
Vol 208 ◽  
pp. 08003 ◽  
Author(s):  
Raul R. Prado

The hybrid design of the Pierre Auger Observatory allows for the measurement of a number of properties of extensive air showers initiated by ultra-high energy cosmic rays. By comparing these measurements to predictions from air shower simulations, it is possible to both infer the cosmic ray mass composition and test hadronic interactions beyond the energies reached by accelerators. In this paper, we will present a compilation of results of air shower measurements by the Pierre Auger Observatory which are sensitive to the properties of hadronic interactions and can be used to constrain the hadronic interaction models. The inconsistencies found between the interpretation of different observables with regard to primary composition and between their measurements and simulations show that none of the currently used hadronic interaction models can provide a proper description of air showers and, in particular, of the muon production.


2018 ◽  
Vol 33 (26) ◽  
pp. 1850153 ◽  
Author(s):  
L. B. Arbeletche ◽  
V. P. Gonçalves ◽  
M. A. Müller

The understanding of the basic properties of the ultrahigh-energy extensive air showers is dependent on the description of hadronic interactions in an energy range beyond that probed by the LHC. One of the uncertainties present in the modeling of air showers is the treatment of diffractive interactions, which are dominated by nonperturbative physics and usually described by phenomenological models. These interactions are expected to affect the development of the air showers, since they provide a way of transporting substantial amounts of energy deep in the atmosphere, modifying the global characteristics of the shower profile. In this paper, we investigate the impact of diffractive interactions in the observables that can be measured in hadronic collisions at high energies and ultrahigh-energy cosmic ray interactions. We consider three distinct phenomenological models for the treatment of diffractive physics and estimate the influence of these interactions on the elasticity, number of secondaries, longitudinal air shower profiles and muon densities for proton-air and iron-air collisions at different primary energies. Our results demonstrate that even for the most recent models, diffractive events have a non-negligible effect on the observables and that the distinct approaches for these interactions, present in the phenomenological models, still are an important source of theoretical uncertainty for the description of the extensive air showers.


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 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 208 ◽  
pp. 05006 ◽  
Author(s):  
Raul R. Prado

NA61/SHINE is a fixed target experiment designed to study hadron-proton, hadron-nucleus and nucleus-nucleus interactions at the CERN Super-Proton-Synchrotron. In this paper we summarize the results from pion-carbon collisions recorded at beam momenta of 158 and 350 GeV=c. Hadron production measurements in these types of interactions is of fundamental importance for the understanding of the muon production in extensive air showers. In particular, production of (anti)baryons and ρ0 are mechanisms responsible for increasing the number of muons which reach the ground. The underestimation of the (anti)baryons or ρ0 production rates in current hadronic interaction models could be one of the sources of the excess of muons observed by cosmic ray experiments. The results on the production spectra of π±, K±, p, ¯p, Λ , ¯Λ, K0S, ρ0, ω and K*0 are presented, as well as their comparison to predictions of hadronic interaction models currently used in air shower simulations.


2019 ◽  
Vol 210 ◽  
pp. 02008 ◽  
Author(s):  
Tanguy Pierog ◽  
Benjamin Guiot ◽  
Iurii Karpenko ◽  
Gabriel Sophys ◽  
Maria Stefaniak ◽  
...  

With the recent results of large hybrid air-shower experiments, it is clear that the simulations of the hadronic interactions are not reliable enough to obtain a consistent description of the observations. Even the mostrecentmodelstunedafterthefirstrunoftheLHCshowsignificantdiscrepancywithair-showerdata. Since then many more data have been collected at the LHC and at lower energies at the SPS which are not necessarily well described by these models. So before claiming any explanation involving new physics, it is necessary to have a model which can actually describe accelerator data in a very detailed way. That is the goal of EPOS 3, to understand both soft and hard particle production not only in light systems like proton-proton interactions but in heavy ions too. The latest results of the model will be presented and in particular the correlations between various observables which are very important to understand the real physical processes.


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. 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.


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