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1.
Performance analysis of high-spectral-resolution lidar with/without laser seeding technique for measuring aerosol optical properties
Fengjia Gao, Fei Gao, Gaipan Li, Fan Yang, Li Wang, Song Yuehui, Dengxin Hua, Samo Stanič, 2024, izvirni znanstveni članek

Opis: High-spectral-resolution lidar (HSRL) is a powerful tool for aerosol measurements. With/without laser seeding technique in the transmitted laser, the HSRL can be distinguished as the single-longitudinal-mode (SLM) HSRL or the multi-longitudinal-mode (MLM) HSRL, and the Mach-Zehnder interferometer (MZI) with periodic transmittance function can be used as the spectral discriminator in both the SLM HSRL and MLM HSRL. To in-depth knowledge of the respective advantages of the SLM HSRL and MLM HSRL for measuring aerosol optical properties, the working principle, optimal parameter setting, and detection performance of the SLM HSRL and MLM HSRL are analyzed and discussed in detail, respectively. The working principle of the SLM HSRL and MLM HSRL indicate that the effective transmittance of MZI is the important parameter of data retrieval, the main source of retrieval uncertainties, and the key factor of MZI optical path difference (OPD) settings. To ensure that the MZI can achieve the preferable separation for aerosol Mie scattering signals and molecular Rayleigh scattering signals, the optimal OPDs of MZI are set at 165 mm and 1000 mm in the SLM HSRL and MLM HSRL from the aspects of the effective transmittance of MZI and the spectral discrimination ratio (SDR). Besides, to analyze the influence of frequency difference and divergence angle for the detection performance of HSRL, the effective transmittance of MZI and SDR are simulated and the results show that the MLM HSRL has higher requirements for the environmental parameters and the echo beam collimation than the SLM HSRL. Moreover, the HSRLs with SLM and MLM transmitted lasers are constructed in Xi'an for measuring aerosol optical properties. The preliminary measurement results show that the range square corrected signal (RSCS) of Rayleigh channel is smaller than that of Mie channel in both the SLM HSRL and MLM HSRL, while the difference between RSCS of Rayleigh channel and RSCS of Mie channel in the SLM HSRL is larger than that in the MLM HSRL, and the detection range of the SLM HSRL is lower than that of the MLM HSRL.
Ključne besede: aerosol optical properties, high-spectral-resolution lidar, single-longitudinal-mode, multi-longitudinal-mode, spectral discrimination ratio
Objavljeno v RUNG: 28.02.2024; Ogledov: 86; Prenosov: 0
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Anisotropy studies of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory
Josina Schulte, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: Measurements of anisotropic arrival directions of ultra-high-energy cosmic rays provide important information for identifying their sources. On large scales, cosmic rays with energies above 8 EeV reveal a dipolar flux modulation in right ascension with a significance of 6.9 deg., with the dipole direction pointing 113◦ away from the Galactic center. This observation is explained by extragalactic origins. Also, model-independent searches for small- and intermediate-scale overdensities have been performed in order to unveil astrophysically interesting regions. On these scales, no statistically significant features could be detected. However, intermediate-scale analyses comparing the measured arrival directions with potential source catalogs show indications for a coincidence of the measured arrival directions with catalogs of starburst galaxies and the Centaurus A region. In this contribution, an overview of the studies regarding anisotropies of the arrival directions of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory on different angular scales is presented and the current results are discussed.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, UHECR anisotropy studies, UHECR sources
Objavljeno v RUNG: 24.01.2024; Ogledov: 249; Prenosov: 5
.pdf Celotno besedilo (5,01 MB)
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With AugerPrime to the phase II of the Pierre Auger Observatory
Daniele Martello, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: AugerPrime, the upgrade of the Pierre Auger Observatory, is nearing completion and the Observatory is now prepared to collect physics data after the commissioning of the new components. The Pierre Auger Observatory has demonstrated, based on the data collected thus far, the existence of the cutoff in the spectrum with high accuracy. However, the origin of this cutoff remains incompletely understood. The upgraded Observatory is designed to address the unresolved questions regarding the nature of the cosmic ray flux cutoff thanks to its capability to disentangle the muon and electromagnetic components of extensive air showers. Furthermore, the measurement of the muon component at ground level can verify the accuracy of hadronic interaction models currently used. This presentation will provide an overview of the status of the Observatory and the accurate commissioning done before the start of the physics run. Furthermore, we will present the initial data from Phase II data mainly dedicated to proving the continuity of operation of the Observatory from Phase I to Phase II.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, AugerPrime detector upgrade, Pierre Auger data
Objavljeno v RUNG: 24.01.2024; Ogledov: 272; Prenosov: 6
.pdf Celotno besedilo (4,23 MB)
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Advances on the Pierre Auger outreach and education program
Gabriella Cataldi, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The Pierre Auger Observatory has implemented a novel method of astroparticle detection that combines various techniques and has an open data policy. The dissemination of information about the different astroparticle detection methods, ranging from surface water-Cherenkov detectors to underground scintillator detectors, is now possible due to access to specialized tools for data analysis. This allows for the introduction of the topic of astroparticles to teachers and students at different educational levels. This marks a significant moment for the Observatory. In this work, we will discuss the diverse outreach initiatives undertaken by the Observatory, which have facilitated interaction among members of the international collaboration and enabled collaborative actions between the permanent staff of the Observatory in Malargüe and other institutions worldwide through synchronous meetings. These programs provide visitors with the opportunity to explore the environment of secondary particle cascades produced by cosmic rays, leading to a record number of monthly visitors since the opening of the Observatory 25 years ago.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, Pierre Auger Outreach and Education program
Objavljeno v RUNG: 24.01.2024; Ogledov: 253; Prenosov: 7
.pdf Celotno besedilo (719,11 KB)
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Astrophysical interpretation of energy spectrum and mass composition of cosmic rays as measured at the Pierre Auger Observatory
Eleonora Guido, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The combined interpretation of the spectrum and composition measurements plays a key role in the quest for the origin of ultra-high-energy cosmic rays (UHECRs). The Pierre Auger Observatory, thanks to its huge exposure, provides the most precise measurement of the energy spectrum of UHECRs and the most reliable information on their composition, exploiting the distributions of the depth of maximum of the showers in the atmosphere. A combined fit of a simple astrophysical model of UHECR sources to the spectrum and mass composition measurements is used to evaluate the constraining power of the data measured by the Pierre Auger Observatory on the source properties. We find that our data across the “ankle” feature are well reproduced if two extragalactic populations of sources are considered, one emitting a very soft spectrum which dominates the region below the ankle, and the other taking over at energies above the ankle, with an intermediate mixed composition, a hard spectrum and a low rigidity cutoff. Interestingly, similar results can also be obtained if the medium-mass contribution at lower energy is provided by an additional galactic component.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, UHECR energy spectrum, UHECR mass composition
Objavljeno v RUNG: 24.01.2024; Ogledov: 228; Prenosov: 7
.pdf Celotno besedilo (381,66 KB)
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Latest results from the searches for ultra-high-energy photons and neutrinos at the Pierre Auger Observatory
Marcus Niechciol, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The Pierre Auger Observatory is the largest air-shower experiment in the world, offering an unprecedented exposure not only to ultra-high-energy (UHE, �>10^17 eV) cosmic rays, but also to UHE neutral particles, specifically photons and neutrinos. Since the beginning of data taking almost 20 years ago, a number of searches for UHE photons and neutrinos using the different detector systems of the Observatory have been carried out. These searches led to some of the most stringent upper limits on the diffuse—i.e., direction-independent, unresolved—fluxes of photons and neutrinos in the UHE regime. These limits severely constrain current models for the origin of UHE cosmic rays and underline the capabilities of the Pierre Auger Observatory and its leading role in the context of multimessenger astronomy at the highest energies. In this contribution, we give an overview of the current activities concerning searches for UHE photons and neutrinos in the data from the Pierre Auger Observatory. The latest results of the searches for diffuse fluxes of photons and neutrinos will be shown. Furthermore, the follow- up searches for UHE photons and neutrinos in association with transient events, such as gravitational wave events, will be summarized. In addition, future perspectives in view of the ongoing AugerPrime detector upgrade will be discussed, which will further improve the sensitivity of the Pierre Auger Observatory to neutral particles at the highest energies.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, AugerPrime, multimessenger astronomy
Objavljeno v RUNG: 24.01.2024; Ogledov: 253; Prenosov: 6
.pdf Celotno besedilo (712,17 KB)
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Investigating the UHECR characteristics from cosmogenic neutrino limits with the measurements of the Pierre Auger Observatory
Camilla Petrucci, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: Cosmogenic neutrinos are expected to originate in the extragalactic propagation of ultra-highenergy cosmic rays (UHECRs), as a result of their interactions with background photons. Due to these reactions, the visible Universe in UHECRs is more limited than in neutrinos, which instead could reach us without interacting after traveling cosmological distances. In this contribution, we exploit a multimessenger approach by computing the expected energy spectrum and mass composition of UHECRs at Earth corresponding to combinations of spectral parameters and mass composition at their sources, as well as parameters related to the UHECR source distribution, and by determining, at the same time, the associated cosmogenic neutrino fluxes. By comparing the expected UHECR observables to the energy spectrum and mass composition measured at the Pierre Auger Observatory above 10^17.8 eV and the expected neutrino fluxes to the most updated neutrino limits, we show the dependence of the neutrino fluxes on the characteristics of the the properties of the potential sources of UHECRs, such as their cosmological evolution and maximum redshift. In addition, the fraction of protons compatible with the data is also investigated in terms of expected neutrino fluxes.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays
Objavljeno v RUNG: 24.01.2024; Ogledov: 234; Prenosov: 4
.pdf Celotno besedilo (647,90 KB)
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International Masterclasses as part of the Pierre Auger Observatory program of Outreach and Education
R. Sarmento, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, objavljeni znanstveni prispevek na konferenci

Opis: The Pierre Auger Observatory is committed to bringing education and knowledge of cosmic rays to the public, with a strong focus on schools and students. Over the last few years, initiatives have been developed, such as the Science Fair, virtual visits, and participation in international activities on the subject of cosmic rays, including collaborations with external groups. Modern digital tools bringing novel ways of interacting with the public have been explored at these initiatives and also locally at a renewed Visitor Center in Malargüe. The development of tools for the public release of the Auger data, including standardized data formats, analysis notebooks, and a 3D interactive event display, led to the creation of a new activity directed to high-school students called Masterclasses. The participants are challenged to perform the reconstruction and selection of events using a graphical interface with 3D effects, then combined into a smoothed, exposure-corrected sky map of arrival directions. A final discussion takes place in which the students engage with peers and scientists, looking for answers about the origin of ultra-high-energy cosmic rays. The concept had a successful debut in 2022 and was included in the 2023 edition of the International Masterclasses on Particle Physics, reaching students worldwide.
Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays
Objavljeno v RUNG: 24.01.2024; Ogledov: 253; Prenosov: 5
.pdf Celotno besedilo (12,06 MB)
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