scholarly journals Measurements of UHECR Mass Composition by Telescope Array

2019 ◽  
Vol 210 ◽  
pp. 01008
Author(s):  
William Hanlon
Keyword(s):  
Monte Carlo ◽  
Cosmic Ray ◽  
High Energy ◽  
Mass Composition ◽  
Ultra High Energy ◽  
Fluorescence Detector ◽  
Telescope Array ◽  
Second Moments ◽  
Systematic Uncertainties ◽  
Surface Detector

Telescope Array (TA) has recently published results of nearly nine years of Xmax observations providing its highest statistics measurement of ultra high energy cosmic ray (UHECR) mass composition to date for energies exceeding 1018.2 eV. This analysis measured agreement of observed data with results expected for four different single elements. Instead of relying only on the first and second moments of Xmax distributions, we employ a morphological test of agreement between data and Monte Carlo to allow for systematic uncertainties in data and in current UHECR hadronic models. Results of this latest analysis and implications of UHECR composition observed by TA are presented. TA can utilize different analysis methods to understand composition as both a crosscheck on results and as a tool to understand systematics affecting Xmax measurements. The different analysis efforts utilizing fluorescence detector stereo, surface detector and fluorescence detector hybrid, and surface detector-only, currently underway at TA performed to understand composition are also discussed.

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 Search for point sources of ultra-high-energy photons with the Telescope Array surface detector

2020 ◽  
Vol 492 (3) ◽  
pp. 3984-3993 ◽  
Author(s):  
R U Abbasi ◽  
M Abe ◽  
T Abu-Zayyad ◽  
M Allen ◽  
R Azuma ◽  
...  
Keyword(s):  
Point Source ◽  
Cosmic Ray ◽  
High Energy ◽  
Point Sources ◽  
Ultra High Energy ◽  
Telescope Array ◽  
Air Shower ◽  
Upper Limits ◽  
Surface Detector ◽  
Blind Search

ABSTRACT The surface detector (SD) of the Telescope Array (TA) experiment allows us to detect indirectly photons with energies of the order of 1018 eV and higher, and to separate photons from the cosmic ray background. In this paper, we present the results of a blind search for point sources of ultra-high-energy (UHE) photons in the Northern sky using the TA SD data. The photon-induced extensive air showers are separated from the hadron-induced extensive air shower background by means of a multivariate classifier based upon 16 parameters that characterize the air shower events. No significant evidence for the photon point sources is found. The upper limits are set on the flux of photons from each particular direction in the sky within the TA field of view, according to the experiment’s angular resolution for photons. The average 95 per cent confidence level upper-limits for the point-source flux of photons with energies greater than 1018, 1018.5, 1019, 1019.5 and 1020 eV are 0.094, 0.029, 0.010, 0.0073 and 0.0058 km−2yr−1, respectively. For energies higher than 1018.5 eV, the photon point-source limits are set for the first time. Numerical results for each given direction in each energy range are provided as a supplement to this paper.

scholarly journals Measurement of the cosmic ray spectrum with the Pierre Auger Observatory

2019 ◽  
Vol 209 ◽  
pp. 01029
Author(s):  
Daniela Mockler
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Pierre Auger Observatory ◽  
Detector Array ◽  
Data Sets ◽  
Fluorescence Detector ◽  
High Energy Cosmic Rays ◽  
Systematic Uncertainties ◽  
Surface Detector

The flux of ultra-high energy cosmic rays above 3×1017 eV has been measured with unprecedented precision at the Pierre Auger Observatory. The flux of the cosmic rays is determined by four different measurements. The surface detector array provides three data sets, two formed by dividing the data into two zenith angle ranges, and one obtained from a nested, denser detector array. The fourth measurement is obtained with the fluorescence detector. By combing all four data sets, the all-sky flux of cosmic rays is determined. The spectral features are discussed in detail and systematic uncertainties are addressed.

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 TA Anisotropy Summary

2019 ◽  
Vol 210 ◽  
pp. 01004 ◽  
Author(s):  
K. Kawata ◽  
A. di Matteo ◽  
T. Fujii ◽  
D. Ivanov ◽  
C.C.H. Jui ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Fluorescence Detector ◽  
Telescope Array ◽  
Directional Anisotropy

The Telescope Array (TA) is the largest ultra-high-energy cosmic-ray (UHECR) detector in the northern hemisphere. It consists of an array of 507 surface detectors (SD) covering a total 700 km2 and three fluorescence detector stations overlooking the SD array. In this proceedings, we summarize recent results on the search for directional anisotropy of UHECRs using the latest dataset collected by the TA SD array. We obtained hints of the anisotropy of the UHECRs in the northern sky from the various analyses.

scholarly journals High energy cosmic ray interactions and UHECR composition problem

2019 ◽  
Vol 210 ◽  
pp. 02001
Author(s):  
Sergey Ostapchenko
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Hadronic Interactions ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Interactions ◽  
Composition Problem

The differences between contemporary Monte Carlo generators of high energy hadronic interactions are discussed and their impact on the interpretation of experimental data on ultra-high energy cosmic rays (UHECRs) is studied. Key directions for further model improvements are outlined. The prospect for a coherent interpretation of the data in terms of the UHECR composition is investigated.

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.

Search for ultra-high energy photons using Telescope Array surface detector

2011 ◽  
Author(s):  
G. I. Rubtsov ◽  
D. Ivanov ◽  
B. T. Stokes ◽  
G. B. Thomson ◽  
S. V. Troitsky ◽  
...  
Keyword(s):  
High Energy ◽  
Ultra High Energy ◽  
Telescope Array ◽  
Surface Detector
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