scholarly journals Mass Composition of UHECRs from Xmax Distributions Recorded by the Pierre Auger and Telescope Array Observatories

Universe ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 321
Author(s):  
Nicusor Arsene
Keyword(s):  
Statistical Tests ◽  
High Energy ◽  
Mass Composition ◽  
Large Set ◽  
Ultra High Energy ◽  
Telescope Array ◽  
High Energy Cosmic Rays ◽  
Low Energies ◽  
The Individual ◽  
Indirect Comparisons

In this paper we infer the mass composition of the ultra high energy cosmic rays (UHECRs) from measurements of Xmax distributions recorded at the Pierre Auger (2014) and Telescope Array (TA) (2016) Observatories, by fitting them with all possible combinations of Monte Carlo (MC) templates from a large set of primary species (p, He, C, N, O, Ne, Si and Fe), as predicted by EPOS-LHC, QGSJETII-04 and Sibyll 2.1 hadronic interaction models. We use the individual fractions of nuclei reconstructed from one experiment in each energy interval to build equivalent MC Xmax distributions, which we compare with the experimental Xmax distributions of the other experiment, applying different statistical tests of compatibility. The results obtained from both experiments confirm that the mass composition of the UHECRs is dominated (≳70%) by protons and He nuclei in the energy range investigated lgE(eV) = [17.8–19.3] (Auger) and lgE(eV) = [18.2–19.0] (TA). The indirect comparisons between the Xmax distributions recorded by the two experiments show that the degree of compatibility of the two datasets is good, even excellent in some high energy intervals, especially above the ankle (lgE(eV)∼18.7). However, our study reveals that, at low energies, further effort in data analysis is required in order to harmonize the results of the two experiments.

RESULTS FROM THE TELESCOPE ARRAY EXPERIMENT

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1275-1283
Author(s):  
◽  
H. SAGAWA
Keyword(s):  
Cosmic Rays ◽  
High Energy ◽  
Mass Composition ◽  
Ultra High Energy ◽  
Arrival Direction ◽  
Data Set ◽  
Telescope Array ◽  
High Energy Cosmic Rays ◽  
The Status ◽  
Hybrid Detector

The Telescope Array (TA) is the largest hybrid detector in the northern hemisphere, which consists of an array of surface detectors (SD) and fluorescence detectors (FD), to explore the origin of ultra-high energy cosmic rays (UHECR) by measuring energy, arrival direction, mass composition, and other characteristics of UHECRs. Here we present the status and preliminary results based on the first data set of the experiment.

scholarly journals Ultra-high-energy cosmic rays mass composition studies with the Telescope Array Surface Detector data

2018 ◽  
Vol 191 ◽  
pp. 08007
Author(s):  
Yana Zhezher
Keyword(s):  
Monte Carlo ◽  
Cosmic Rays ◽  
High Energy ◽  
Atomic Mass ◽  
Mass Composition ◽  
Ultra High Energy ◽  
Telescope Array ◽  
High Energy Cosmic Rays ◽  
Comparison Results ◽  
Surface Detector

The results on ultra-high energy cosmic rays’ chemical composition based on the data from the Telescope Array surface detector are reported. The analysis is based the boosted decision tree (BDT) multivariate analysis built upon 14 observables related to both the properties of the shower front and the lateral distribution function. The multivariate classifier is trained with Monte-Carlo sets: proton-induced, which is considered as background events, and ironinduced, considered as signal events. The classifier results in a single variable ξ for data and Monte-Carlo sets, available for one-dimensional analysis. The data to Monte-Carlo comparison results in an average atomic mass of UHECR for energy range 1018:0 - 1020:0 eV. The average atomic mass of primary particles corresponds to 〈ln A〉 = 1:52± 0:08(stat.)± 0:1(syst.). The comparison with TA hybrid composition results and the other experiments is presented.

scholarly journals Observation of ultra-high energy cosmic rays with the Telescope Array experiment

2018 ◽  
Vol 182 ◽  
pp. 02122
Author(s):  
Ryuji Takeishi
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Mass Composition ◽  
Ultra High Energy ◽  
Air Showers ◽  
Telescope Array ◽  
High Energy Cosmic Rays ◽  
Fluorescence Light ◽  
Hybrid Detector

The origin of ultra-high energy cosmic rays (UHECRs) has been a longstanding mystery. 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. TA is a hybrid detector comprised of three air fluorescence stations which measure the fluorescence light induced from cosmic ray extensive air showers, and 507 surface scintillator counters which sample charged particles from air showers on the ground. We present the cosmic ray spectrum observed with the TA experiment. We also discuss our results from measurement of the mass composition. In addition, we present the results from the analysis of anisotropy, including the excess of observed events in a region of the northern sky at the highest energy. Finally, we introduce the TAx4 experiment which quadruples TA, and the TA low energy extension (TALE) experiment.

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

2019 ◽  
Vol 208 ◽  
pp. 08004
Author(s):  
R. Takeishi
Keyword(s):  
Cosmic Rays ◽  
High Energy ◽  
Extensive Air Showers ◽  
Mass Composition ◽  
Ultra High Energy ◽  
Air Showers ◽  
Hadronic Interaction ◽  
Telescope Array ◽  
Interaction Models ◽  
High Energy Cosmic Rays

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.

ULTRA HIGH ENERGY COSMIC RAYS WITH THE PIERRE AUGER OBSERVATORY

2012 ◽  
Vol 18 ◽  
pp. 221-229
Author(s):  
◽  
J. R. T. DE MELLO NETO
Keyword(s):  
Energy Spectrum ◽  
Cosmic Rays ◽  
Cross Section ◽  
High Energy ◽  
Pierre Auger Observatory ◽  
Mass Composition ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
The Status ◽  
Shower Maximum

We present the status and the recent measurements from the Pierre Auger Observatory. The energy spectrum is described and its features discussed. We report searches for anisotropy of cosmic rays arrival directions in large scales and through correlation with catalogues of celestial objects. The measurement of the cross section proton-air is discussed. Finally, the mass composition is addressed with the measurements of the variation of the depth of shower maximum with energy and with the muon density at ground.

scholarly journals Supergalactic Structure of Multiplets with the Telescope Array Surface Detector

2019 ◽  
Vol 210 ◽  
pp. 01006 ◽  
Author(s):  
Jon Paul Lundquist ◽  
Pierre V. Sokolsky
Keyword(s):  
Magnetic Fields ◽  
Spherical Surface ◽  
High Energy ◽  
Ultra High Energy ◽  
Telescope Array ◽  
High Energy Cosmic Rays ◽  
Surface Detector ◽  
Trial Probability ◽  
Post Trial ◽  
Event Energy

Evidence of supergalactic structure of multiplets has been found for ultra-high energy cosmic rays (UHECR) with energies above 1019 eV using 7 years of data from the Telescope Array (TA) surface detector. The tested hypothesis is that UHECR sources, and intervening magnetic fields, may be correlated with the supergalactic plane, as it is a fit to the average matter density within the GZK horizon. This structure is measured by the average behavior of the strength of intermediate-scale correlations between event energy and position (multiplets). These multiplets are measured in wedge-like shapes on the spherical surface of the fieldof-view to account for uniform and random magnetic fields. The evident structure found is consistent with toy-model simulations of a supergalactic magnetic sheet and the previously published Hot/Coldspot results of TA. The post-trial probability of this feature appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be ~4.5σ.

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