X{sub max}{sup μ} vs. N{sup μ} from extensive air showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory
Abstract
We study the possibility of primary mass estimation for Ultra High Energy Cosmic Rays (UHECR's) using the X{sub max}{sup μ} (the height where the number of muons produced on the core of Extensive Air Showers (EAS) is maximum) and the number N{sup μ} of muons detected on ground. We use the 2D distribution  X{sub max}{sup μ} against N{sup μ} in order to find its sensitivity to the mass of the primary particle. For that, we construct a 2D Probability Function Prob(p,Fe  X{sub max}{sup μ}, N{sup μ}) which estimates the probability that a certain point from the plane (X{sub max}{sup μ}, N{sup μ}) corresponds to a shower induced by a proton, respectively an iron nucleus. To test the procedure, we analyze a set of simulated EAS induced by protons and iron nuclei at energies of 10{sup 19}eV and 20° zenith angle with CORSIKA. Using the Bayesian approach and taking into account the geometry of the infill detectors from the Pierre Auger Observatory, we observe an improvement in the accuracy of the primary mass reconstruction in comparison with the results obtained using only the X{sub max}{sup μ} distributions.
 Authors:
 Institute of Space Science, P.O.Box MG23, Ro 077125 BucharestMagurele, Romania and Physics Department, University of Bucharest, BucharestMagurele (Romania)
 Physics Department, University of Bucharest, BucharestMagurele (Romania)
 Publication Date:
 OSTI Identifier:
 22390983
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: AIP Conference Proceedings; Journal Volume: 1645; Journal Issue: 1; Conference: Carpathian Summer School of Physics 2014, Sinaia (Romania), 1326 Jul 2014; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COSMIC MUONS; COSMIC NUCLEI; COSMIC PROTONS; EEV RANGE; EXTENSIVE AIR SHOWERS; IRON; MUON DETECTION; SENSITIVITY
Citation Formats
Arsene, Nicusor, and Sima, Octavian. X{sub max}{sup μ} vs. N{sup μ} from extensive air showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory. United States: N. p., 2015.
Web. doi:10.1063/1.4909587.
Arsene, Nicusor, & Sima, Octavian. X{sub max}{sup μ} vs. N{sup μ} from extensive air showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory. United States. doi:10.1063/1.4909587.
Arsene, Nicusor, and Sima, Octavian. 2015.
"X{sub max}{sup μ} vs. N{sup μ} from extensive air showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory". United States.
doi:10.1063/1.4909587.
@article{osti_22390983,
title = {X{sub max}{sup μ} vs. N{sup μ} from extensive air showers as estimator for the mass of primary UHECR's. Application for the Pierre Auger Observatory},
author = {Arsene, Nicusor and Sima, Octavian},
abstractNote = {We study the possibility of primary mass estimation for Ultra High Energy Cosmic Rays (UHECR's) using the X{sub max}{sup μ} (the height where the number of muons produced on the core of Extensive Air Showers (EAS) is maximum) and the number N{sup μ} of muons detected on ground. We use the 2D distribution  X{sub max}{sup μ} against N{sup μ} in order to find its sensitivity to the mass of the primary particle. For that, we construct a 2D Probability Function Prob(p,Fe  X{sub max}{sup μ}, N{sup μ}) which estimates the probability that a certain point from the plane (X{sub max}{sup μ}, N{sup μ}) corresponds to a shower induced by a proton, respectively an iron nucleus. To test the procedure, we analyze a set of simulated EAS induced by protons and iron nuclei at energies of 10{sup 19}eV and 20° zenith angle with CORSIKA. Using the Bayesian approach and taking into account the geometry of the infill detectors from the Pierre Auger Observatory, we observe an improvement in the accuracy of the primary mass reconstruction in comparison with the results obtained using only the X{sub max}{sup μ} distributions.},
doi = {10.1063/1.4909587},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1645,
place = {United States},
year = 2015,
month = 2
}

In this paper we study the possibility to discriminate the mass of the primary cosmic ray by observing the muon arrival times in ground detectors. We analyzed extensive air showers (EAS) induced by proton and iron nuclei with the same energy 8 MultiplicationSign 10{sup 17} eV simulated with CORSIKA, and analyzed the muon arrival times at ground measured by the infill array detectors of the Pierre Auger Observatory (PAO). From the arrival times of the core and of the muons the atmospheric depth of muon generation locus is evaluated. The results suggest a potential mass discrimination on the basis ofmore »

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Interpretation of the depths of maximum of extensive air showers measured by the Pierre Auger Observatory
To interpret the mean depth of cosmic ray air shower maximum and its dispersion, we parametrize those two observables as functions of the first two moments of the ln A distribution. We examine the goodness of this simple method through simulations of test mass distributions. The application of the parameterization to Pierre Auger Observatory data allows one to study the energy dependence of the mean ln A and of its variance under the assumption of selected hadronic interaction models. We discuss possible implications of these dependences in term of interaction models and astrophysical cosmic ray sources. 
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