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51.
Studies of the UHECR Mass Composition and Hadronic Interactions with the FD and SD of the Pierre Auger Observatory
J.M. Carceller, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution

Abstract: With data on the depth of maximum Xmax collected during more than a decade of operation of the Pierre Auger Observatory, we report on the inferences on the mass composition of UHECRs in the energy range E = 10[sup]17.2 − 10[sup]19.6 eV and on the measurements of the proton-air cross section for energies up to 10[sup]18.5 eV. We also present the results on Xmax obtained using the information on the particle arrival times recorded by the SD stations allowing us to extend the Xmax measurements up to 10[sup]20 eV. The inferences on mass composition, in particular using the data of the SD, are subject to systematic uncertainties due to uncertainties in the description of hadronic interactions at ultra-high energies. We discuss this problem with respect to the properties of the muonic component of extensive air-showers as derived from the SD data.
Keywords: ultra-high-energy cosmic rays (UHECRs), extensive air showers (EAS), EAS muonic component, EAS electromagnetic component, Pierre Auger Observatory, UHECR mass composition, UHECR hadronic interactions
Published in RUNG: 11.10.2023; Views: 565; Downloads: 8
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52.
Measurement of the cosmic ray spectrum with the Pierre Auger Observatory
Daniela Mockler, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution

Abstract: The flux of ultra-high energy cosmic rays above 3×10[sup]17 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 combining 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.
Keywords: ultra-high-energy cosmic rays (UHECRs), Pierre Auger Observatory, UHECR energy spectrum
Published in RUNG: 11.10.2023; Views: 586; Downloads: 6
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53.
Status of the AugerPrime upgrade of the Pierre Auger Observatory
Niraj Dhital, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution

Abstract: The Pierre Auger Observatory has been very successful in determining many aspects of the highest-energy cosmic rays including, among others, the flux suppression at energies above 4 × 10[sup]19 eV, stringent upper limits on photon and neutrino fluxes at ultra-high energies and an unexpected evolution of the mass composition with energy. We expect an extension of the frontiers of our knowledge on these aspects from a major upgrade of the Observatory. The upgrade, known as AugerPrime, will include an addition of a 4 sq. m Surface Scintillator Detector atop each water-Cherenkov station of the Surface array. The new detectors will provide us with an unprecedented opportunity to perform a complementary measurement of the shower particles and thus determine the primary mass composition with good accuracy on an event-by-event basis. AugerPrime will also include an upgrade of electronics, installation of the AMIGA Underground Muon Detector and a change of observation mode of the Fluorescence Detector, which will increase its current duty cycle by about 50%. Current status of the upgrade with the main focus on the Surface Scintillator Detectors will be presented, following a brief description of the physics motivation for the upgrade.
Keywords: ultra-high-energy cosmic rays (UHECRs), Pierre Auger Observatory, AugerPrime upgrade
Published in RUNG: 11.10.2023; Views: 738; Downloads: 5
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54.
Results from the Pierre Auger Observatory
Esteban Roulet, Andrej Filipčič, Gašper Kukec Mezek, Ahmed Saleh, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution

Abstract: Some of the results on ultrahigh-energy cosmic rays that have been obtained with the Pierre Auger Observatory are presented. These include measurements of the spectrum, composition and anisotropies. Possible astrophysical scenarios that account for these results are discussed.
Keywords: ultra-high-energy cosmic rays (UHECRs), Pierre Auger Observatory, UHECR energy spectrum, UHECR anisotropies, UHECR mass composition
Published in RUNG: 11.10.2023; Views: 606; Downloads: 5
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55.
Highlights from the Telescope Array Experiment
J. Kim, Jon Paul Lundquist, 2023, published scientific conference contribution (invited lecture)

Abstract: The Telescope Array (TA) is the largest ultra-high energy cosmic ray (UHECR) observatory in the Northern Hemisphere. Together with the TA Low Energy Extension (TALE), TA×4, and TALE infill detector, the TA measures the properties of UHECR-induced extensive air showers (EAS) in the energy region from 10^15 eV to over 10^20 eV. Each of these uses a hybrid system with an array of scintillators to sample the footprint of the EAS at the Earth’s surface along with telescopes that measure the fluorescence and Cherenkov light from the EAS. The statistics at the highest energies are being enhanced with the TA×4 detector, half completed but still under construction, which will quadruple the surface detector area with telescopes. The TALE infill surface detectors were recently deployed to further lower the hybrid energy threshold of TALE. We present the status of the experiment and recent results on the energy spectrum, mass composition, and anisotropy, including new features in the energy spectrum at about 10^19.2 eV and in the UHECR arrival direction anisotropy.
Keywords: Telescope Array, TALE, low energy extension, TAx4, indirect detection, hybrid detection, ground array, surface detection, fluorescence detection, cerenkov light, ultra-high energy, cosmic rays, energy spectrum, composition, anisotropy
Published in RUNG: 10.10.2023; Views: 512; Downloads: 6
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56.
Effect of optical properties of FDs on reconstruction analysis
Daiki Sato, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: The TA experiment uses fluorescence telescopes to observe cosmic ray air showers. The telescope camera uses PMTs as Pixels. The telescope’s PMT pointing direction has an uncertainty of 0.1°, and more precise measurements of the telescope's optical properties are needed to more accurately reconstruct the cosmic ray air showers. We have developed the Opt-copter which is a light source mounted on a drone that can be flown within the telescope's field of view. Observational experiments with the Opt-copter have provided a more accurate analysis of the telescope viewing direction. In this study, we estimate the effect of this measurement of accurate telescope viewing direction on the reconstruction of cosmic ray air showers.
Keywords: Telescope Array, indirect detection, fluorescence detection, ultra-high energy, cosmic rays, composition, calibration, Xmax
Published in RUNG: 10.10.2023; Views: 543; Downloads: 6
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57.
TA SD analysis for inclined air showers
K. Takahashi, Jon Paul Lundquist, 2023, published scientific conference contribution

Abstract: The origin of UHECRs is an open question which is complicated due to not very well-known deflections of the charged particles in Galactic and intergalactic magnetic fields. Finding the EeV neutrinos from astronomical sources will be a key to solve the problem of the origin. EeV neutrinos are expected to produce extensive air showers which are observable by the current operational air shower arrays. To search for neutrino-induced showers, it is important to increase both the interaction probability and background rejection power in the analysis of the inclined showers. We study a reconstruction method of the Telescope Array surface detector (TA SD) data for the neutrino-induced inclined air showers. The prime target is to improve the angular resolution for the astronomical objects. In this contribution, we present the detail of analysis method, angular resolution and total exposure of TA SD for neutrinos from the astronomical objects as a function of the declination.
Keywords: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, inclined showers, neutrinos
Published in RUNG: 09.10.2023; Views: 489; Downloads: 5
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58.
Measurement of the cosmic ray energy spectrum with the TA×4 SD array
Kozo Fujisue, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: The TA×4 experiment aims to better understand the origin and nature of ultra-high energy cosmic rays (UHECRs) by expanding the observation area of the Telescope Array (TA) experiment by a factor of 4. This expansion will increase the statistics of UHECR events with energies greater than 10^19.5 eV. The SD, which means the additionally deployed surface detectors (SD) for the TA×4 experiment, has been collecting data since 2019, and the analysis of this data is currently underway. In this presentation, we will report comparisons between the Monte Carlo simulation and the data obtained by the TA×4 SD array and highlight the agreement between the two. We will also report on the UHECR energy spectrum observed by the TA×4 SD array from October 2019 to September 2022.
Keywords: Telescope Array, TAx4, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, energy spectrum
Published in RUNG: 09.10.2023; Views: 488; Downloads: 7
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59.
Search for EeV photon-induced events at the Telescope Array
I. Kharuk, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: We report on the updated results on the search for photon-like-induced events in the data, collected by Telescope Array's Surface Detectors during the last 14 years. In order to search for photon-like-induced events, we trained a neural network on Monte-Carlo simulated data to distinguish between the proton-induced and photon-induced air showers. Both reconstructed composition-sensitive parameters and raw signals registered by the Surface Detectors are used as input data for the neural network. The classification threshold was optimized to provide the strongest possible constraint on the photons' flux.
Keywords: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, photons, neural network, machine learning
Published in RUNG: 09.10.2023; Views: 598; Downloads: 6
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60.
Systematic uncertainty in the analysis of the TA fluorescence detector from fluorescence yield models
Kohei Komori, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: Ultra-high energy cosmic rays have been observed by various experiments such as Telescope Array (TA) and the Pierre Auger Observatory (Auger). There are differences in the energy spectra measured by TA and Auger. One reason for this difference is systematic uncertainty in the energy determination. The fluorescence yield model, which consists of fluorescence emission efficiencies and spectra, is one of the most significant components of this systematic uncertainty. Fluorescence emission efficiencies and spectra have been measured in various experiments, and different measurements are currently used to determine the energy of the TA and Auger experiments. In this study, we estimate the influence of the fluorescence yield model on the systematic uncertainty in the energy determination of the TA fluorescence detector.
Keywords: Telescope Array, TAx4, indirect detection, fluorescence detection, fluorescence yield, ultra-high energy, cosmic rays, energy uncertainty
Published in RUNG: 09.10.2023; Views: 543; Downloads: 5
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