Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Opis: The Pierre Auger Observatory is the most sensitive instrument to detect photons with energies above 1⁢0[sup]17  eV. It measures extensive air showers generated by ultrahigh energy cosmic rays using a hybrid technique that exploits the combination of a fluorescence detector with a ground array of particle detectors. The signatures of a photon-induced air shower are a larger atmospheric depth of the shower maximum (�max) and a steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced cascades. In this work, a new analysis technique in the energy interval between 1 and 30 EeV (1  EeV=1⁢0[sup]18  eV) has been developed by combining the fluorescence detector-based measurement of �max with the specific features of the surface detector signal through a parameter related to the air shower muon content, derived from the universality of the air shower development. No evidence of a statistically significant signal due to photon primaries was found using data collected in about 12 years of operation. Thus, upper bounds to the integral photon flux have been set using a detailed calculation of the detector exposure, in combination with a data-driven background estimation. The derived 95% confidence level upper limits are 0.0403, 0.01113, 0.0035, 0.0023, and 0.0021  km[sup]−2 sr[sup]−1 yr[sup]−1 above 1, 2, 3, 5, and 10 EeV, respectively, leading to the most stringent upper limits on the photon flux in the EeV range. Compared with past results, the upper limits were improved by about 40% for the lowest energy threshold and by a factor 3 above 3 EeV, where no candidates were found and the expected background is negligible. The presented limits can be used to probe the assumptions on chemical composition of ultrahigh energy cosmic rays and allow for the constraint of the mass and lifetime phase space of super-heavy dark matter particles.
Ključne besede: ultra-high-energy photons, ultra-high-energy cosmic rays, Pierre Auger Observatory, extensive air showers
Objavljeno v RUNG: 30.09.2024; Ogledov: 721; Prenosov: 2
Celotno besedilo (4,39 MB)
Gradivo ima več datotek! Več...

Ključne besede: hadronske interakcije, detektorji fluorescence, talni detektorji, Observatorij Pierre Auger
Objavljeno v RUNG: 16.05.2024; Ogledov: 1215; Prenosov: 6
Celotno besedilo (2,47 MB)

Ključne besede: radio meritve, pljuski delcev, kozmični žarki ekstremnih energij, Observatorij Pierre Auger
Objavljeno v RUNG: 31.01.2024; Ogledov: 1588; Prenosov: 10
Celotno besedilo (4,03 MB)

Opis: The Pierre Auger Observatory (Auger) and the Telescope Array (TA), located, respectively, in the Southern and Northern hemispheres, are the largest ultra-high-energy cosmic ray (UHECR) observatories. The Auger and TA Collaborations have collected unprecedented statistics providing us with a unique opportunity to search for the differences between the UHECR energy spectra and mass compositions in the complementary sky regions. To correctly attribute such differences to the properties of the UHECR sources or propagation, the systematic effects in the measurements of each observatory should be considered properly. In this context, the task of the Auger – TA mass composition working group is to identify possible differences of astrophysical origin in the measurements of the depth of the maximum of air-shower profiles, X_max, performed at both observatories using the fluorescence technique. Due to distinct approaches to event selection and analysis atAuger and TA, theworking group uses a specially designed method to transfer the Auger X_max distributions into the TA detector. To this end, dedicated air-shower and detector simulations for the TA Black Rock Mesa and Long Ridge fluorescence detector stations were performed with the Sibyll 2.3d hadronic interaction model. From the comparison of the first two moments and the shapes of X_max distributions for energies above 10^18.2 eV, no significant differences between the Auger and TA measurements were found.
Ključne besede: Pierre Auger Observatory, Telescope Array, ultra-high energy cosmic rays, fluorescence detectors
Objavljeno v RUNG: 22.01.2024; Ogledov: 1670; Prenosov: 6
Celotno besedilo (1,19 MB)
Gradivo ima več datotek! Več...

Opis: Operating since 2004, the Pierre Auger Observatory has led to major advances in our understanding of the ultra-high-energy cosmic rays. The latest findings have revealed new insights that led to the upgrade of the Observatory, with the primary goal of obtaining information on the primary mass of the most energetic cosmic rays on a shower-by-shower basis. In the framework of the upgrade, called AugerPrime, the 1660 water-Cherenkov detectors of the surface array are equipped with plastic scintillators and radio antennas, allowing us to enhance the composition sensitivity. To accommodate new detectors and to increase experimental capabilities, the electronics is also upgraded. This includes better timing with up-to-date GPS receivers, higher sampling frequency, increased dynamic range, and more powerful local processing of the data. In this paper, the design characteristics of the new electronics and the enhanced dynamic range will be described. The manufacturing and test processes will be outlined and the test results will be discussed. The calibration of the SD detector and various performance parameters obtained from the analysis of the first commissioning data will also be presented.
Ključne besede: ultra-high-energy cosmic rays, Pierre Auger Observatory, AugerPrime detector upgrade, surface detector array, surface detector electronics
Objavljeno v RUNG: 18.10.2023; Ogledov: 2386; Prenosov: 6
Celotno besedilo (2,07 MB)
Gradivo ima več datotek! Več...