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Opis: In this talk, we summarise the results of recent anisotropy studies conducted by the Telescope Array (TA) collaboration. At largest scales we test the TA data for the presence of a dipole. On smaller scales, an update on the excess of events in the direction of Ursa Major previously found in the TA data will be presented. These flux variations may trace the distribution of UHECR sources. We will examine the data for correlations with large-scale structures in the nearby Universe, and as a result, hints for the chemical composition of primaries will be provided. We also discuss a related anisotropy of the UHECR spectrum.
Ključne besede: Telescope Array, indirect detection, ground array, surface detection, ultra-high energy, cosmic rays, composition, energy spectrum, anisotropy
Objavljeno v RUNG: 29.09.2023; Ogledov: 530; Prenosov: 4
Celotno besedilo (1,83 MB)
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Opis: At the Pierre Auger Observatory, designed primarily to study ultra-high-energy cosmic rays, phenomena related to atmospheric electricity are also observed. Particularly, events have been detected with the surface detector, characterized by long-lasting signals (tens of microseconds) and event footprints much larger (up to 200 km2) than those produced by the highest energy cosmic rays. Moreover, some of them appear to be accompanied by smaller events occurring in the same area within about 1 ms and probably produced by the same phenomenon. A previously reported correlation with the World Wide Lightning Location Network, as well as the observation of very low-altitude clouds, confirm that such events are related to thunderstorms. An ad-hoc reconstruction points to high-energy particles being produced very close to the ground, suggesting that they originate from electrons accelerated to relativistic energies in strong electric fields inside low clouds, as is the case for terrestrial gamma-ray flashes above thunderstorms. A clear explanation of the observed phenomenon is hindered by two facts. One is that the rate of such events, detected serendipitously, is very small (less than 2 events/year) and decreases further after optimization of the surface detector trigger for low-energy shower-events. The second is that most events show a puzzling lack of signals in the central part of the footprint. We have studied in detail both effects and will present such studies here. We developed a strategy for a dedicated trigger to enhance the detection efficiency for these events associated with atmospheric-electricity events.
Ključne besede: Pierre Auger Observatory, surface detection, ultra-high energy, cosmic rays, photons, electrons, gamma-ray flashes, lightning
Objavljeno v RUNG: 29.09.2023; Ogledov: 615; Prenosov: 6
Celotno besedilo (2,42 MB)
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Opis: The TAx4 experiment is a project to observe highest energy cosmic rays by expanding the detectionarea of the Telescope Array (TA) experiment with newly constructed surface detectors (SDs) andfluorescence detectors (FDs). New SDs are arranged in a square grid with 2.08 km spacing atthe north east and south east of the TA SD array. We use CORSIKA simulations and implementthe calibration data of the new SDs to calculate the performance of the new SDs. We comparethe data with the simulation and validate the performance of the SDs. The comparison and theperformance will be shown in the presentation.
Ključne besede: Telescope Array, TAx4, indirect detection, ground array, surface detection, ultra-high energy, cosmic rays, CORSIKA
Objavljeno v RUNG: 29.09.2023; Ogledov: 551; Prenosov: 5
Celotno besedilo (3,16 MB)
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Opis: The Pierre Auger Observatory, sited in Malargüe, Argentina, is the largest observatory available for measuring ultra-high-energy cosmic rays (UHECR). The Auger Collaboration has measured and analysed an unprecedented number of UHECRs. Along with making important scientific discoveries, for example, the demonstration that cosmic rays above 8 EeV are of extragalactic origin and the observation of a new feature in the energy spectrum at around 13 EeV, outreach work has been carried out across the 18 participating countries and online. This program ranges from talks to a varied audience, to the creation of a local Visitor Center, which attracts 8000 visitors annually, to initiating masterclasses. Permanent and temporary exhibitions have been prepared both in reality and virtually. Science fairs for elementary- and high-school students have been organised, together with activities associated with interesting phenomena such as eclipses. In addition, we participate in international events such as the International Cosmic Day, Frontiers from H2020, and the International Day of Women and Girls in Science. Part of the Collaboration website is aimed at the general public. Here the most recent articles published are summarised. Thus the Collaboration informs people about work in our field, which may seem remote from everyday life. Furthermore, the Auger Observatory has been a seed for scientific and technological activities in and around Malargüe. Different outreach ventures that already have been implemented and others which are foreseen will be described.
Ključne besede: Pierre Auger Observatory, indirect detection, ultra-high energy, cosmic rays, outreach, open data
Objavljeno v RUNG: 26.09.2023; Ogledov: 595; Prenosov: 5
Celotno besedilo (7,94 MB)
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Opis: The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment successfully recorded the data for about 539 days from August 2017 to February 2019. In this talk, we report the measurement of the cosmic-ray proton energy spectrum from the ISS-CREAM experiment in the energy range of 2.5 TeV - 650 TeV. For the analysis, we used the silicon charge detector (SCD) placed at the top of the ISS-CREAM payload to identify the incoming cosmic-ray charge. The SCD is finely segmented to minimize charge misidentification due to backscatter effects. The four-layer SCD consists of 10,752 silicon pixels, each of which is 1.37×1.57×0.05 cm^3 in size. The calorimeter (CAL) consists of 20 layers of tungsten/scintillating fibers preceded by carbon targets. It provided cosmic-ray tracking, energy determination, and the high-energy trigger. The Top and Bottom Counting detectors (T/BCD) are above and below the CAL, respectively, and provided the low energy trigger. Each T/BCD is composed of an array of 20×20 photodiodes on plastic scintillators. The measured proton spectral index of 2.67±0.02 between 2.5 and 12.5 TeV is consistent with prior CREAM measurements. The spectrum softens above ∼10 TeV consistent with the bump-like structure as reported by CREAM-I+III, DAMPE, and NUCLEON, but ISS-CREAM extends measurements to higher energies than those prior measurement
Ključne besede: ISS-CREAM, silicon charge detector, calorimeter, direct detection, cosmic rays, protons, energy spectrum
Objavljeno v RUNG: 26.09.2023; Ogledov: 593; Prenosov: 6
Celotno besedilo (2,06 MB)
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