11. Order fluctuation induced tunable light emission from carbon nano systemMohanachandran Nair Sindhu Swapna, Sankararaman S, 2019, izvirni znanstveni članek Opis: The paper reports the thermal-induced order fuctuations, in a carbon nanosystem with carbon nanotubes (CNTs) synthesized
by the incomplete combustion of gingelly oil. The sample annealed at diferent temperatures (30–400 °C) is subjected to
various morphological and spectroscopic characterizations. The ultraviolet–visible spectroscopic and thermogravimetric
analyses reveal the CNTs in the sample. The high-resolution transmission electron microscopy (HR-TEM) also confrms the
formation of CNTs in the sample. The Raman spectrum and X-ray difraction pattern show the signature of multi-walled
to single-walled CNT transformation and thus an order fuctuation on annealing. The quantum yield of the sample, measured by integrating sphere method, yields 46.15% at an emission wavelength of 575 nm. When the excitation wavelength
is varied from 350 to 510 nm, the CIE coordinate moves from the white region to the yellowish-green region. The varying
amount of CNTs in the soot, upon annealing is found to vary the luminescence emission from the sample. The study reveals
the thermal-induced oscillatory order in carbon nanosystem with carbon nanotubes (CNTs) leading to tunable excitation/
thermal-dependent luminescence emission and thereby suggesting the possibility of converting the futile soot for fruitful
applications in photonics and nanoelectronics. Ključne besede: Carbon nanosystem, Single-walled carbon nanotubes, Multi-walled carbon nanotubes, Raman spectroscopy, Thermogravimetric analysis, CIE plot, Quantum yield, gingelly oil Objavljeno v RUNG: 05.07.2022; Ogledov: 1262; Prenosov: 0 Gradivo ima več datotek! Več... |
12. Multi-messenger studies with the Pierre Auger ObservatoryLukas Zehrer, Andrej Filipčič, Gašper Kukec Mezek, Jon Paul Lundquist, Samo Stanič, Marta Trini, Serguei Vorobiov, Marko Zavrtanik, Danilo Zavrtanik, 2021, objavljeni znanstveni prispevek na konferenci Opis: Over the past decade the multi-messenger astrophysics has emerged as a distinct discipline,
providing unique insights into the properties of high-energy phenomena in the Universe. The
Pierre Auger Observatory, located in Malargüe, Argentina, is the world’s largest cosmic ray
detector sensitive to photons, neutrinos, and hadrons at ultra-high energies. Using its data, stringent
limits on photon and neutrino fluxes at EeV energies have been obtained. The collaboration uses
the excellent angular resolution and the neutrino identification capabilities of the Observatory
for follow-up studies of events detected in gravitational waves or other messengers, through
cooperation with global multi-messenger networks. We present a science motivation together
with an overview of the multi-messenger capabilities and results of the Pierre Auger Observatory. Ključne besede: high-energy cosmic phenomena, multi-messenger astrophysical studies, cosmic rays, gamma-rays, neutrinos, Pierre Auger Observatory Objavljeno v RUNG: 06.05.2022; Ogledov: 1511; Prenosov: 0 Gradivo ima več datotek! Več... |
13. Multi-messenger astrophysics with THESEUS in the 2030sRiccardo Ciolfi, Giulia Stratta, Marica Branchesi, Bruce Gendre, Stefan Grimm, Jan Harms, Gavin Paul Lamb, Antonio Martin-Carrillo, Ayden McCann, Andreja Gomboc, 2021, izvirni znanstveni članek Ključne besede: multi-messenger astrophysics, Gamma-ray bursts, compact binary merger, Kilonova Objavljeno v RUNG: 02.11.2021; Ogledov: 1798; Prenosov: 0 Gradivo ima več datotek! Več... |
14. Synergies of THESEUS with the large facilities of the 2030s and guest observer opportunitiesP. Rosati, S. Basa, A. W. Blain, E. Bozzo, Marica Branchesi, L. Christensen, A. Ferrara, Andreja Gomboc, P. T. O'Brien, J. P. Osborne, 2021, izvirni znanstveni članek Ključne besede: multi-messenger astrophysics, Gamma-ray bursts, X-ray sources, gravitation wave sources Objavljeno v RUNG: 02.11.2021; Ogledov: 1679; Prenosov: 0 Gradivo ima več datotek! Več... |
15. Application of machine learning techniques for cosmic ray event classification and implementation of a real-time ultra-high energy photon search with the surface detector of the Pierre Auger Observatory : dissertationLukas Zehrer, 2021, doktorska disertacija Opis: Despite their discovery already more than a century ago, Cosmic Rays (CRs) still did not divulge all their properties yet. Theories about the origin of ultra-high energy (UHE, > 10^18 eV) CRs predict accompanying primary photons. The existence of UHE photons can be investigated with the world’s largest ground-based experiment for detection of CR-induced extensive air showers (EAS), the Pierre Auger Observatory, which offers an unprecedented exposure to rare UHE cosmic particles.
The discovery of photons in the UHE regime would open a new observational window to the Universe, improve our understanding of the origin of CRs, and potentially uncloak new physics beyond the standard model.
The novelty of the presented work is the development of a "real-time" photon candidate event stream to a global network of observatories, the Astrophysical Multimessenger Observatory Network (AMON). The stream classifies CR events observed by the Auger surface detector (SD) array as regards their probability to be photon nominees, by feeding to advanced machine learning (ML) methods observational air shower parameters of individual CR events combined in a multivariate analysis (MVA).
The described straightforward classification procedure further increases the Pierre Auger Observatory’s endeavour to contribute to the global effort of multi-messenger (MM) studies of the highest energy astrophysical phenomena, by supplying AMON partner observatories the possibility to follow-up detected UHE events, live or in their archival data. Ključne besede: astroparticle physics, ultra-high energy cosmic rays, ultra-high energy photons, extensive air showers, Pierre Auger Observatory, multi-messenger, AMON, machine learning, multivariate analysis, dissertations Objavljeno v RUNG: 27.10.2021; Ogledov: 2848; Prenosov: 150 Povezava na celotno besedilo Gradivo ima več datotek! Več... |
16. New Data Policy in South-East Europe : (related to the SEE-MHEWS-A project)Klemen Bergant, prispevek na konferenci brez natisa Opis: Conference contribution presents the process of development of a new data policy for the South-East European Multi-Hazard Early Warning Advisory System project (SEE-MHEWS-A Project). The project, led by the World Meteorological Organization, is currently in a demonstration phase. National meteorological and hydrological services (NMHSs) from 17 countries in the South-East Europe are involved in the project. With common SEE-MHEWS Data Policy Agreement the involved NMHSs express their willingness and provide legal framework for the exchange of all available meteorological and hydrological data with a main purpose to improve their meteorological and hydrological forecasts and warnings. The project data policy could be seen as a first step towards the open data policy in the region. Ključne besede: Multi-Hazard Early Warning System, Meteorological and Hydorlogical Warnings, Data Exchnage, Data Policy Objavljeno v RUNG: 06.01.2021; Ogledov: 2301; Prenosov: 0 Gradivo ima več datotek! Več... |
17. Substantial brown carbon emissions from wintertime residential wood burning over FranceYunjiang Zhang, Alexandre Albinet, Jean-Eudes Petit, Véronique Jacob, Florie Chevrier, Gregory Gille, Sabrina Pontet, Eve Chrétien, Marta Dominik-Sègue, Gilles Levigoureux, Griša Močnik, Valérie Gros, Jean-Luc Jaffrezo, Olivier Favez, 2020, izvirni znanstveni članek Opis: Brown carbon (BrC) is known to absorb light at subvisible wavelengths but its optical properties and sources are still poorly documented, leading to large uncertainties in climate studies. Here, we show its major wintertime contribution to total aerosol absorption at 370 nm (18–42%) at 9 different French sites. Moreover, an excellent correlation with levoglucosan (r2 = 0.9 and slope = 22.2 at 370 nm), suggesting important contribution of wood burning emissions to ambient BrC aerosols in France. At all sites, BrC peaks were mainly observed during late evening, linking to local intense residential wood burning during this time period. Furthermore, the geographic origin analysis also highlighted the high potential contribution of local and/or small-regional emissions to BrC. Focusing on the Paris region, twice higher BrC mass absorption efficiency value was obtained for less oxidized biomass burning organic aerosols (BBOA) compared to more oxidized BBOA (e.g., about 4.9 ± 0.2 vs. 2.0 ± 0.1 m2 g−1, respectively, at 370 nm). Finally, the BBOA direct radiative effect was found to be 40% higher when these two BBOA fractions are treated as light-absorbing species, compared to the non-absorbing BBOA scenario. Ključne besede: Brown carbon, Multi sites, Residential wood burning, Mass absorption efficiency, France Objavljeno v RUNG: 20.07.2020; Ogledov: 3075; Prenosov: 0 Gradivo ima več datotek! Več... |
18. Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope ArrayM. G. Aartsen, Jon Paul Lundquist, 2016, izvirni znanstveni članek Opis: This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored. Ključne besede: UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy Objavljeno v RUNG: 30.04.2020; Ogledov: 2557; Prenosov: 0 Gradivo ima več datotek! Več... |
19. Multi-Messenger Physics With the Pierre Auger ObservatoryKarl-Heinz Kampert, Andrej Filipčič, Gašper Kukec Mezek, Samo Stanič, Marta Trini, Serguei Vorobiov, Lili Yang, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, izvirni znanstveni članek Ključne besede: Pierre Auger Observatory, ultra-high energy cosmic rays, photons, neutrinos, protons, multi-messenger physics and astrophysics Objavljeno v RUNG: 06.05.2019; Ogledov: 3328; Prenosov: 107 Celotno besedilo (2,46 MB) |
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