The surface detector array of the Telescope Array experiment

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.

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Supergalactic Structure of Multiplets with the Telescope Array Surface Detector

EPJ Web of Conferences ◽

10.1051/epjconf/201921001006 ◽

2019 ◽

Vol 210 ◽

pp. 01006 ◽

Cited By ~ 2

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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A next-generation ground array for the detection of ultrahigh-energy cosmic rays: the Fluorescence detector Array of Single-pixel Telescopes (FAST)

EPJ Web of Conferences ◽

10.1051/epjconf/201921006003 ◽

2019 ◽

Vol 210 ◽

pp. 06003

Author(s):

Toshihiro Fujii ◽

Max Malacari ◽

Justin Albury ◽

Jose A. Bellido ◽

Ladislav Chytka ◽

...

Keyword(s):

Cosmic Rays ◽

Full Scale ◽

Pierre Auger Observatory ◽

Detector Array ◽

Ultrahigh Energy ◽

Next Generation ◽

Fluorescence Detector ◽

Telescope Array ◽

Ultrahigh Energy Cosmic Rays ◽

Single Pixel

The origin and nature of ultrahigh-energy cosmic rays (UHECRs) is one of the most intriguing and important mysteries in astroparticle physics. The two largest observatories currently in operation, the Telescope Array Experiment in central Utah, USA, and the Pierre Auger Observatory in western Argentina, have been steadily observing UHECRs in both hemispheres for over a decade. We highlight the latest results from both of these experiments, and address the requirements for a next-generation UHECR observatory. The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a design concept for a next-generation UHECR observa-tory, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the highest energy cosmic rays with an unprecedented aperture. We have developed a full-scale prototype consisting of four 200 mm photomultiplier-tubes at the focus of a segmented mirror of 1.6 m in diameter. Over the last three years, we installed three such prototypes at the Black Rock Mesa site of the Telescope Array Experiment. These telescopes have been steadily taking data since installation. We report on preliminary results of the full-scale FAST prototypes, including measurements of distant ultraviolet lasers and UHECRs. Futhermore, we discuss our plan to install an additional identical FAST prototype at the Pierre Auger Observatory. Possible benefits to the Telescope Array and the Pierre Auger Observatory include a comparison of the transparency of the atmosphere above both experiments, a study of the systematic uncertainty associated with their existing fluorescence detectors, and a cross-calibration of their energy and Xmax scales.

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Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays E ≥ 1019.2 eV with the Telescope Array Surface Detector

The Astrophysical Journal ◽

10.3847/1538-4357/aac9c8 ◽

2018 ◽

Vol 862 (2) ◽

pp. 91 ◽

Cited By ~ 11

Author(s):

R. U. Abbasi ◽

M. Abe ◽

T. Abu-Zayyad ◽

M. Allen ◽

R. Azuma ◽

...

Keyword(s):

Energy Spectrum ◽

Cosmic Rays ◽

Telescope Array ◽

Intermediate Scale ◽

Surface Detector

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

10.1063/1.3628740 ◽

2011 ◽

Cited By ~ 1

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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Overview of the Auger@TA project and preliminary results from Phase I

EPJ Web of Conferences ◽

10.1051/epjconf/201921005002 ◽

2019 ◽

Vol 210 ◽

pp. 05002

Author(s):

Fred Sarazin ◽

Corbin Covault ◽

Toshihiro Fujii ◽

Robert Halliday ◽

Jeﬀrey Johnsen ◽

...

Keyword(s):

Phase I ◽

Pierre Auger Observatory ◽

Gear Up ◽

Air Showers ◽

Telescope Array ◽

Surface Detector ◽

First Results ◽

Micro Array ◽

Cross Calibration

We report on the first results of a unique in-situ experimental cross-calibration eﬀort of the surface detector of the Pierre Auger Observatory and of the Telescope Array experiment (Auger@TA). In the first phase of Auger@TA, we performed surface detector station-to-station comparisons for a collection of extensive air showers landing near the experimental setup and detected by Telescope Array. Beyond the deduced cross-calibration curve between the Water-Cherenkov-based Auger and Scintillator-based TA Surface Detector stations, we also investigate the consistency of their response for individual reconstructed showers. The dataset is currently too small to draw firm conclusions as-of-yet. Hence, phase I data taking will continue even as we gear up for the deployment of an Auger micro-array within Telescope Array as part of Phase II of this work.

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Measurements of UHECR Mass Composition by Telescope Array

EPJ Web of Conferences ◽

10.1051/epjconf/201921001008 ◽

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.

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