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Found in: ključnih besedah
Keywords: cosmic rays (CR), extensive air showers, EAS radio emission, Pierre Auger Observatory, Auger Engineering Radio Array, multi-hybrid CR detection
Published: 09.11.2016; Views: 3647; Downloads: 255
Fulltext (1,98 MB)

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.
Found in: ključnih besedah
Keywords: Pierre Auger Observatory, multi-messenger, neutrino, gravitational wave
Published: 17.01.2018; Views: 3210; Downloads: 0
Fulltext (9,04 MB)

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.
Found in: ključnih besedah
Keywords: thermal lens spectrometry, Fe(II) determination, photothermal technique, multi-wavelength excitation
Published: 21.02.2018; Views: 3211; Downloads: 0
Fulltext (889,82 KB)

Found in: ključnih besedah
Keywords: Pierre Auger Observatory, ultra-high energy cosmic rays, photons, neutrinos, protons, multi-messenger physics and astrophysics
Published: 06.05.2019; Views: 2463; Downloads: 99
Fulltext (2,46 MB)

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.
Found in: ključnih besedah
Keywords: Brown carbon, Multi sites, Residential wood burning, Mass absorption efficiency, France
Published: 20.07.2020; Views: 2091; Downloads: 0
Fulltext (2,94 MB)