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Multi-messenger study with the Pierre Auger Observatory
Lili Yang, vabljeno predavanje na konferenci brez natisa

Opis: 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.
Najdeno v: ključnih besedah
Ključne besede: Pierre Auger Observatory, multi-messenger, neutrino, gravitational wave
Objavljeno: 17.01.2018; Ogledov: 2537; Prenosov: 0
.pdf Polno besedilo (9,04 MB)

Trace Detection and Photothermal Spectral Characterization by a Tuneable Thermal Lens Spectrometer with White-Light Excitation
Mladen Franko, Dorota Korte, Humberto Cabrera, 2018, izvirni znanstveni članek

Opis: 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.
Najdeno v: ključnih besedah
Ključne besede: thermal lens spectrometry, Fe(II) determination, photothermal technique, multi-wavelength excitation
Objavljeno: 21.02.2018; Ogledov: 2701; Prenosov: 0
.pdf Polno besedilo (889,82 KB)

Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A
Gabrijela Zaharijas, 2018, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...neutrino astronomy, multi-messenger astronomy...
Ključne besede: neutrino astronomy, multi-messenger astronomy
Objavljeno: 04.09.2018; Ogledov: 1902; Prenosov: 0
.pdf Polno besedilo (2,67 MB)

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 Array
J. P. Lundquist, M. G. Aartsen, 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy...
Ključne besede: UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy
Objavljeno: 30.04.2020; Ogledov: 1400; Prenosov: 0
.pdf Polno besedilo (2,49 MB)

Substantial brown carbon emissions from wintertime residential wood burning over France
Jean-Luc Jaffrezo, Valérie Gros, Griša Močnik, Gilles Levigoureux, Marta Dominik-Sègue, Eve Chrétien, Sabrina Pontet, Gregory Gille, Florie Chevrier, Véronique Jacob, Jean-Eudes Petit, Alexandre Albinet, Yunjiang Zhang, 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.
Najdeno v: ključnih besedah
Ključne besede: Brown carbon, Multi sites, Residential wood burning, Mass absorption efficiency, France
Objavljeno: 20.07.2020; Ogledov: 1533; Prenosov: 0
.pdf Polno besedilo (2,94 MB)

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