31. Telescope Array Surface Detector Energy and Arrival Direction Estimation Using Deep LearningO. Kalashev, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: A novel ultra-high-energy cosmic rays energy and arrival direction reconstruction method for Telescope Array surface detector is presented. The analysis is based on a deep convolutional neural network using detector signal time series as the input and the network is trained on a large Monte-Carlo dataset. This method is compared in terms of statistical and systematic energy and arrival direction determination errors with the standard Telescope Array surface detector event reconstruction procedure. Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, energy, arrival directions, reconstruction, machine learning, neural network Objavljeno v RUNG: 04.10.2023; Ogledov: 1592; Prenosov: 8 Celotno besedilo (1,10 MB) Gradivo ima več datotek! Več... |
32. The status of the TALE surface detector array and TALE infill projectA. Iwasakia, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Routine hybrid observations of the surface detectors (SD) in conjunction with the fluorescence detectors (FD) of the Telescope Array Low-energy Extension (TALE) began in November 2018. In this presentation, we will describe the simulation studies of detector aperture and resolution of the TALE SD, and report on the latest observation results other than the energy spectrum. We are also in the process of expanding the experiment by 50 SDs, with even smaller nearest-neighbor spacing, in order lower the energy threshold to match that of the Cherenkov-dominated events seen by the FD. Details of the upgrade and expected performance of this new extension will be discussed. Ključne besede: Telescope Array, TALE, low energy extension, indirect detection, surface detection, hybrid detection, ground array, fluorescence detection, ultra-high energy, cosmic rays Objavljeno v RUNG: 04.10.2023; Ogledov: 1749; Prenosov: 83 Celotno besedilo (1011,84 KB) Gradivo ima več datotek! Več... |
33. First results from the AugerPrime Radio DetectorT. Fodran, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: The Pierre Auger Observatory investigates the properties of the highest-energy cosmic rays with unprecedented precision. The aim of the AugerPrime upgrade is to improve the sensitivity to the primary particle type. The improved mass sensitivity is the key to exploring the origin of the highest-energy particles in the Universe. The purpose of the Radio Detector (as part of AugerPrime) is to extend the sensitivity of the mass measurements to zenith angles in the range from 65° to 85°. A radio antenna, sensitive in two polarization directions and covering a bandwidth from 30 to 80 MHz, will be added to each of the 1661 surface detector stations over the full 3000 km^2 area, forming the world’s largest radio array for the detection of cosmic particles. Since November 2019, an engineering array comprised of ten stations has been installed in the field. The radio antennas are calibrated using the Galactic (diffuse) emission. The sidereal
modulation of this signal is monitored continuously and is used to obtain an end-to-end calibration from the receiving antenna to the ADC in the read-out electronics. The calibration method and first results will be presented. The engineering array is also fully integrated in the data acquisition of the Observatory and records air showers regularly. The first air showers detected simultaneously with the water-Cherenkov detectors and the Radio Detectors will be presented. Simulations of the detected showers, based on the reconstructed quantities, have been conducted with CORSIKA/CoREAS. A comparison of the measured radio signals with those predicted by simulations exhibits satisfying agreement. Ključne besede: Pierre Auger Observatory, AugerPrime, indirect detection, radio detection, radio antenna array, surface detection, ground array, ultra-high energy, cosmic rays, galactic radio emission Objavljeno v RUNG: 04.10.2023; Ogledov: 1565; Prenosov: 7 Celotno besedilo (1,62 MB) Gradivo ima več datotek! Več... |
34. Update on the large-scale cosmic-ray anisotropy search at the highest energies by the Telescope Array ExperimentT. Fujii, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: The study of large-scale anisotropy at the highest energies is essential for understanding the transition from cosmic rays of galactic origin to those of extra-galactic origin, along with the magnetic fields in the galaxy and those beyond. Motivated by a significant detection of the large-scale anisotropy above 8 EeV by the Pierre Auger Observatory (Auger), we had previously reported, using 11 years of Telescope Array (TA) surface array data, a result compatible both with that of Auger, and with an isotropic source distribution [R. U. Abbasi et al., Astrophys. J. Lett. 898, L28 (2020)]. In this contribution, we will show the preliminary updated results using 12 years TA SD data to search for the large-scale anisotropy at the highest energies. Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, anisotropy, large-scale, dipole Objavljeno v RUNG: 04.10.2023; Ogledov: 1694; Prenosov: 5 Celotno besedilo (1,95 MB) Gradivo ima več datotek! Več... |
35. UHECR mass composition from anisotropy of their arrival directions with the Telescope Array SDM. Kuznetsov, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: We propose a new method for the estimation of ultra-high energy cosmic ray (UHECR) mass composition from a distribution of their arrival directions. The method employs a test statistic (TS) based on a characteristic deflection of UHECR events with respect to the distribution of luminous matter in the local Universe modeled with a flux-weighed 2MRS catalog. Making realistic simulations of the mock UHECR sets, we show that this TS is robust to the presence of galactic and non-extreme extra-galactic magnetic fields and sensitive to the mass composition of events in a set.
We apply the method to Telescope Array surface detector data for 11 years and derive new independent constraints on fraction of protons and iron in p-Fe mix at E>10 EeV. At 10100 EeV --- pure iron or even more massive composition. This result is in tension with Auger composition model inferred from spectrum-Xmax fit at 2.7σ (2.0σ) for PT'11 (JF'12) regular GMF model. Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, composition, anisotropy, magnetic fields, 2MRS Objavljeno v RUNG: 04.10.2023; Ogledov: 1961; Prenosov: 6 Celotno besedilo (3,02 MB) Gradivo ima več datotek! Več... |
36. Observation of Variations in Cosmic Ray Shower Rates During Thunderstorms and Implications for Large-Scale Electric Field ChangesR. Abbasi, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: This work presents the first observation by the Telescope Array Surface Detector (TASD) of the effect of thunderstorms on the development of the cosmic ray showers. Observations of variations in the cosmic ray showers, using the TASD, allows us to study the electric field inside thunderstorms on a large scale without dealing with all the limitation of narrow exposure in time and space using balloons and aircraft detectors. In this work, observations of variations in the cosmic ray shower intensity (ΔN/N) using the TASD, was studied and found to be on average at the (1−2)% level. These observations where found to be both negative and positive in polarity. They were found to be correlated with lightning but also with thunderstorms. The size of the footprint of these variations on the ground ranged from (4-24) km in diameter and lasted for 10s of minutes. Dependence of (ΔN/N) on the electric field inside thunderstorms, in this work, is derived from CORSIKA simulations. Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, shower profile, lightning, atmospheric electric fields Objavljeno v RUNG: 04.10.2023; Ogledov: 1422; Prenosov: 6 Celotno besedilo (4,65 MB) Gradivo ima več datotek! Več... |
37. Mass composition anisotropy with the Telescope Array Surface Detector dataY. Zhezher, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Mass composition anisotropy is predicted by a number of theories describing sources of ultra-high-energy cosmic rays. Event-by-event determination of a type of a primary cosmic-ray particle is impossible due to large shower-to-shower fluctuations, and the mass composition usually is obtained by averaging over some composition-sensitive observable determined independently for each extensive air shower (EAS) over a large number of events. In the present study we propose to employ the observable ξ used in the TA mass composition analysis for the mass composition anisotropy analysis. The ξ variable is determined with the use of Boosted Decision Trees (BDT) technique trained with the Monte-Carlo sets, and the ξ value is assigned for each event, where ξ=1 corresponds to an event initiated by the primary iron nuclei and ξ=−1 corresponds to a proton event.
Use of ξ distributions obtained for the Monte-Carlo sets allows us to separate proton and iron candidate events from a data set with some given accuracy and study its distributions over the observed part of the sky. Results for the TA SD 11-year data set mass composition anisotropy will be presented. Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, composition, anisotropy, machine learning, boosted decision tree Objavljeno v RUNG: 04.10.2023; Ogledov: 1474; Prenosov: 7 Celotno besedilo (1,14 MB) Gradivo ima več datotek! Več... |
38. Cosmic-ray mass composition with the TA SD 12-year dataY. Zhezher, Jon Paul Lundquist, 2022, objavljeni znanstveni prispevek na konferenci Opis: Telescope Array (TA) is the largest ultra-high-energy cosmic-ray (UHECR) observatory in the Northern Hemisphere. It is dedicated to detect extensive air showers (EAS) in hybrid mode, both by measuring the shower’s longitudinal profile with fluorescence telescopes and their particle footprint on the ground from the surface detector (SD) array. While fluorescence telescopes can measure the most composition-sensitive characteristic of EAS, the depth of the shower maximum (\xmax), they also have the drawback of small duty cycle. This work aims to study the UHECR composition based solely on the surface detector data. For this task, a set of composition-sensitive observables obtained from the SD data is used in a machine-learning method -- the Boosted Decision Trees. We will present the results of the UHECR mass composition based on the 12-year data from the TA SD using this technique, and we will discuss of the possible systematics imposed by the hadronic interaction models. Ključne besede: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, composition, machine learning, boosted decision tree Objavljeno v RUNG: 04.10.2023; Ogledov: 1433; Prenosov: 8 Celotno besedilo (763,42 KB) Gradivo ima več datotek! Več... |
39. The ultra-high-energy cosmic-ray sky above 32 EeV viewed from the Pierre Auger ObservatoryJ. Biteau, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: The region of the toe in the cosmic-ray spectrum, located at about 45 EeV by the Pierre Auger Collaboration, is of primary interest in the search for the origin of ultra-high energy cosmic rays (UHECRs). The suppression of the flux with increasing energy can be explained by the interaction of UHECRs with intergalactic photons, resulting in a shrinking of the observable universe, and/or by cut-offs in acceleration potential at the astrophysical sources, yielding a high-rigidity sample of single (or few) UHECR species around the toe. The predominance of foreground sources combined with reduced deflections could thus offer a path towards localizing ultra-high energy accelerators, through the study of UHECR arrival directions.
In this contribution, we present the results of blind and astrophysically-motivated searches for anisotropies with data collected above 32 EeV during the first phase of the Pierre Auger Observatory, i.e. prior to the AugerPrime upgrade, for an exposure of over 120,000 km^2 yr sr. We have conducted model-independent searches for overdensities at small and intermediate angular scales, correlation studies with several astrophysical structures, and cross-correlation analyses with catalogs of candidate extragalactic sources. These analyses provide the most important evidence to date for anisotropy in UHECR arrival directions around the toe as measured from a single observatory. Ključne besede: Pierre Auger Observatory, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, anisotropy, overdensities, hotspot, source correlation, cross-correlation Objavljeno v RUNG: 04.10.2023; Ogledov: 1497; Prenosov: 7 Celotno besedilo (2,15 MB) Gradivo ima več datotek! Več... |
40. UHECR arrival directions in the latest data from the original Auger and TA surface detectors and nearby galaxiesA. di Matteo, Andrej Filipčič, Jon Paul Lundquist, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2022, objavljeni znanstveni prispevek na konferenci Opis: The distribution of ultra-high-energy cosmic-ray arrival directions appears to be nearly isotropic except for a dipole moment of order 6×(E/10 EeV) per cent. Nonetheless, at the highest energies, as the number of possible candidate sources within the propagation horizon and the magnetic deflections both shrink, smaller-scale anisotropies might be expected to emerge. On the other hand, the flux suppression reduces the statistics available for searching for such anisotropies. In this work, we consider two different lists of candidate sources: a sample of nearby starburst galaxies and the 2MRS catalog tracing stellar mass within 250 Mpc.
We combine surface-detector data collected at the Pierre Auger Observatory until 2020 and the Telescope Array until 2019, and use them to test models in which UHECRs comprise an isotropic background and a foreground originating from the candidate sources and randomly deflected by magnetic fields. The free parameters of these models are the energy threshold, the signal fraction, and the search angular scale.
We find a correlation between the arrival directions of 11.8%+5.0%−3.1% of cosmic rays detected with E≥38 EeV by Auger or with E≳49 EeV by TA and the position of nearby starburst galaxies on a 15.5∘+5.3∘−3.2∘ angular scale, with a 4.2σ post-trial significance, as well as a weaker correlation with the overall galaxy distribution. Ključne besede: Pierre Auger Observatory, Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, anisotropy, full-sky, starburst galaxies, source correlations, dipole Objavljeno v RUNG: 04.10.2023; Ogledov: 1800; Prenosov: 5 Celotno besedilo (2,53 MB) Gradivo ima več datotek! Več... |