21. 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, original scientific article Keywords: multi-messenger astrophysics, Gamma-ray bursts, X-ray sources, gravitation wave sources
Published in RUNG: 02.11.2021; Views: 3023; Downloads: 0
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22. 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, doctoral dissertation Abstract: 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.
Keywords: 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
Published in RUNG: 27.10.2021; Views: 4480; Downloads: 221
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23. New Data Policy in South-East Europe : (related to the SEE-MHEWS-A project)Klemen Bergant, unpublished conference contribution Abstract: 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.
Keywords: Multi-Hazard Early Warning System, Meteorological and Hydorlogical Warnings, Data Exchnage, Data Policy
Published in RUNG: 06.01.2021; Views: 3507; Downloads: 0
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24. 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, original scientific article Abstract: 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.
Keywords: Brown carbon, Multi sites, Residential wood burning, Mass absorption efficiency, France
Published in RUNG: 20.07.2020; Views: 4654; Downloads: 0
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25. 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, original scientific article Abstract: 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.
Keywords: UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy
Published in RUNG: 30.04.2020; Views: 3676; Downloads: 0
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26. 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, original scientific article Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays, photons, neutrinos, protons, multi-messenger physics and astrophysics
Published in RUNG: 06.05.2019; Views: 4673; Downloads: 111
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29. Trace Detection and Photothermal Spectral Characterization by a Tuneable Thermal Lens Spectrometer with White-Light ExcitationHumberto Cabrera, Dorota Korte, Mladen Franko, 2018, original scientific article Abstract: In the thermal lens experimental set-up we replaced the commonly employed pump laser by a halogen lamp, combined with an interference lter, providing a tuneable, nearly monochromatic pump source over the range of wavelengths 430–710 nm. Counter-propagating pump and probe beams are used and a 1 mm path-length sam- ple cell together with the interference lter makes an optical cavity, providing ampli cation of the thermal lens signal, which leads to enhancement of the measurement sensitivity, and enables detection of absorbances on the order of 5×10− 6. Ampli ed thermal lens signal allows us to replace the typical lock-in ampli er and digital os- cilloscope with a silicon photodetector, Arduino board, and a personal computer, offering the possibility for a compact, robust and portable device, useful for in- eld absorption measurements in low concentration or weakly absorbing species. The use of a white light source for optical pumping, an interference lter for wavelength selection and direct diagnostic of the thermal lens signal increase the versatility of the instrument and simpli- es substantially the experimental setup. Determination of Fe(II) concentrations at parts per billion levels was performed by the described white-light thermal lens spectrophotometer and the absorption spectrum for 50μg/ L Fe(II)-1,10-phenanthroline was well reproduced with an average measurement precision of 4%. The obtained limits of detection and quantitation of Fe(II) determination at 510nm are 3μgL− 1 and 11μgL− 1, respectively. The calibration curve was linear in the concentration range of LOQ-500μgL− 1 with reproducibility between 2% and 6%, con rming that this instrument provides good spectrometric capabilities such as high sensitivity, tune- ability and good reproducibility. In addition, the versatility of the instrument was demonstrated by recording the photothermal spectrum of gold nanostructured material and determination of excitation wavelength with most ef cient optical to thermal energy conversion, which differs considerably (cca 100 nm) from the absorption maximum of the investigated sample.
Keywords: thermal lens spectrometry, Fe(II) determination, photothermal technique, multi-wavelength excitation
Published in RUNG: 21.02.2018; Views: 6307; Downloads: 0
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30. Multi-messenger study with the Pierre Auger ObservatoryLili Yang, unpublished invited conference lecture Abstract: The Pierre Auger Observatory is the largest cosmic ray detector in the world, studying particles with energy above 10^17 eV. Even though Auger is dedicated to charged cosmic rays, it’s also sensitive to ultra-high energy neutral particles, such as photons, neutrinos and neutrons, which are undeflected by magnetic field and pointing back to the source site. More exciting, with the breakthrough observations of gravitational-wave signal, the new era of multi-messenger analysis has come. I will present the recent results and prospects of multi-messenger study with Auger and also the first joint detection of gravitational and electromagnetic radiation from the source, with a focus on the UHE neutrino search.
Keywords: Pierre Auger Observatory, multi-messenger, neutrino, gravitational wave
Published in RUNG: 17.01.2018; Views: 5191; Downloads: 0
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