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1.
Advantages and disadvantages of experiments with ultrashort two-color pulses
Matija Stupar, 2020, doctoral dissertation

Abstract: Advances in the development of lasers have led to a new class of radiation sources generating coherent, tunable, ultrashort light pulses in the spectral region ranging from infrared to soft X-rays. This includes high-order harmonics generation in gas (HHG), on which relies the CITIUS facility at University of Nova Gorica (Slovenia), and free-electron lasers (FELs), such as the facility FERMI at Elettra-Sincrotrone Trieste (Italy). The distinctive structure of HHG and FEL radiation paved the way to time-resolved experiments, which are performed to investigate events occurring on a short, or very short, temporal scale, from picoseconds to femtoseconds. This work focuses on the advantages and disadvantages of some experimental techniques based on using these novel light sources to investigate the microscopic and/or ultrafast dynamics of matter samples, which have been previously driven out of equilibrium. Advantages rely on the implementation of various applications based on two-color schemes and, more specifically, include the possibility of acquiring two-dimensional frequency maps, measuring electrons’ effective masses, or investigating electronic properties decoupled from the influence of the lattice. Particular focus will be put on experimental methods relying on photoelectric effect and photoelectron spectroscopy. In all experiments, we took advantage of one or more specific properties of HHG and FEL sources, such as controllable chirp, to study laser dressed states in helium, variable polarization, to study electronic properties of iron-based pnictides and ultrashort pulses (< 10 fs) to study the purely electronic dynamics in transition metal dichalcogenides. On the other hand, the study of the interface between a molecule and a topological insulator revealed some intrinsic limitations and physical drawbacks of the technique, such as spurious effects originating from the high power pulses, like multiphoton absorption and the space charge effect, or the reduction of experimental resolution when pushing for shorter and shorter pulse durations. Some disadvantages are also connected to the current state-of-the-art in the field of ultrashort laser systems, where a trade-off needs to be found between repetition rate and laser power. Finally, state-of-the-art experiments based on the ability to generate ultrashort pulses carrying orbital angular momentum in visible, near-infrared as well as extreme UV range will be presented. The use of these pulses opens the door to the investigation of new physical phenomena, such as probing magnetic vortices using extreme ultraviolet light from a free-electron laser or imprinting the spatial distribution of an ultrashort infrared pulse carrying orbital angular momentum onto a photoelectron wave packet.
Found in: ključnih besedah
Keywords: ultrafast lasers, two-color experiments, photoemission, high-order harmonic generation, free-electron lasers, hot-electrons dynamics, surface science, pump-probe photoemission, ultraviolet photoemission, orbital angular momentum
Published: 02.12.2020; Views: 545; Downloads: 15
.pdf Fulltext (19,78 MB)

2.
AugerNext: R&D studies at the Pierre Auger Observatory for a next generation ground-based ultra-high energy cosmic-ray experiment
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, Andreas Haungs, 2015, published scientific conference contribution

Abstract: The findings so far of the Pierre Auger Observatory and those of the Telescope Array define some requirements for a possible next generation global cosmic ray observatory: it needs to be considerably increased in size, it needs enhanced sensitivity to composition, and it has to cover the full sky. At the Pierre Auger Observatory, AugerNext aims to conduct some innovative initial research studies on a design of a sophisticated hybrid detector fulfilling these demands. Within a European supported ASPERA/APPEC (Astroparticle Physics European Consortium) project for the years 2011-2014, such R&D studies primarily focused on the following areas: i) consolidation of the detection of cosmic rays using MHz radio antennas; ii) proof- of-principle of cosmic ray microwave detection; iii) test of the large-scale application of new generation photo sensors; iv) generalization of data communication techniques; and v) development of new schemes for muon detection with surface arrays. The AugerNext Consortium consists of 14 principal investigators from 9 countries. This contribution summarizes some achievements of the R&D studies within the AugerNext project.
Found in: ključnih besedah
Summary of found: ...ultra-high energy cosmic-ray experiments, Pierre Auger Observatory, Telescope Array, AugerNext research and development...
Keywords: ultra-high energy cosmic-ray experiments, Pierre Auger Observatory, Telescope Array, AugerNext research and development study
Published: 03.03.2016; Views: 2278; Downloads: 137
.pdf Fulltext (594,23 KB)

3.
Complementarity of Galactic radio and collider data in constraining WIMP dark matter models
Yann Mambrini, Michel H.G. Tytgat, Gabrijela Zaharijas, Brzan Zaldívar, 2012, original scientific article

Found in: ključnih besedah
Summary of found: ...dark matter theory, dark matter experiments, absorption, radiation, ...
Keywords: dark matter theory, dark matter experiments, absorption, radiation
Published: 09.05.2017; Views: 1704; Downloads: 11
URL Fulltext (0,00 KB)

4.
High Energy Astrophysics
Lili Yang, unpublished conference contribution

Abstract: I was invited as a lecturer at the Sumer School on Astrophysics and Astroparticles in Petnica Serbia. I gave talks on "High Energy Astrophysics", where I mainly focused on the production, propagation and detection of high energy astroparticles. Especially, I introduced the current experiments and technique and facilities.
Found in: ključnih besedah
Summary of found: ...energy astroparticles. Especially, I introduced the current experiments and technique and facilities....
Keywords: High-energy astroparticles, experiments, detection, production
Published: 06.12.2016; Views: 2343; Downloads: 0
.pdf Fulltext (16,77 MB)
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5.
Search for photons with energies above 10^18 eV using the hybrid detector of the Pierre Auger Observatory
Marko Zavrtanik, Danilo Zavrtanik, Lili Yang, Serguei Vorobiov, Darko Veberič, Marta Trini, Samo Stanič, Ahmed Saleh, Gašper Kukec Mezek, Andrej Filipčič, A. Aab, 2017, original scientific article

Found in: ključnih besedah
Summary of found: ...high energy (UHE) cosmic rays, cosmic ray experiments, Pierre Auger Observatory, UHE photon search...
Keywords: ultra high energy (UHE) cosmic rays, cosmic ray experiments, Pierre Auger Observatory, UHE photon search
Published: 13.04.2017; Views: 1880; Downloads: 0
.pdf Fulltext (775,01 KB)

6.
7.
FYSIKSHOW: TOWARDS AN EVEN BRIGHTER FUTURE
Tanja Petrushevska, S. Papadogiannakis, Tor Kjellsson, other performed works

Abstract: Report of the Fysikshow activities of 2015-2016
Found in: ključnih besedah
Keywords: physics outreach with experiments
Published: 06.02.2018; Views: 1160; Downloads: 0 
(1 vote)
.pdf Fulltext (213,03 KB)

8.
Search for dark matter gamma-ray emission from the Andromeda Galaxy with the High-Altitude Water Cherenkov Observatory
Gabrijela Zaharijas, Christopher Eckner, 2018, original scientific article

Found in: ključnih besedah
Summary of found: ...dark matter experiments, semi-analytic modeling...
Keywords: dark matter experiments, semi-analytic modeling
Published: 24.08.2018; Views: 1497; Downloads: 0
.pdf Fulltext (21,60 MB)

9.
Dispersion experiments in central London: The 2007 DAPPLE project
Curtis R Wood, Samantha J Arnold, Ahmed A Balogun, Janet F Barlow, Stephen E Belcher, Rex E Britter, Hong Cheng, Adrian Dobre, Justin J N Lingard, Damien Martin, Marina K Neophytou, Fredrik K Petersson, Alan G Robins, Dudley E. Shallcross, Robert J Smalley, James E Tate, Alison S Tomlin, Iain R White, 2009, original scientific article

Abstract: In the event of a release of toxic gas in the center of London, emergency services personnel would need to determine quickly the extent of the area contaminated. The transport of pollutants by turbulent flow within the complex streets and building architecture of London, United Kingdom, is not straightforward, and we might wonder whether it is at all possible to make a scientifically reasoned decision. Here, we describe recent progress from a major U.K. project, Dispersion of Air Pollution and its Penetration into the Local Environment (DAPPLE; information online at www.dapple.org.uk). In DAPPLE, we focus on the movement of airborne pollutants in cities by developing a greater understanding of atmospheric flow and dispersion within urban street networks. In particular, we carried out full-scale dispersion experiments in central London from 2003 through 2008 to address the extent of the dispersion of tracers following their release at street level. These measurements complemented previous studies because 1) our focus was on dispersion within the first kilometer from the source, when most of the material was expected to remain within the street network rather than being mixed into the boundary layer aloft; 2) measurements were made under a wide variety of meteorological conditions; and 3) central London represents a European, rather than North American, city geometry. Interpretation of the results from the full-scale experiments was supported by extensive numerical and wind tunnel modeling, which allowed more detailed analysis under idealized and controlled conditions. In this article, we review the full-scale DAPPLE methodologies and show early results from the analysis of the 2007 field campaign data.
Found in: ključnih besedah
Keywords: Air quality, Atmospheric thermodynamics, Dispersions, Experiments
Published: 18.07.2019; Views: 981; Downloads: 0
.pdf Fulltext (17,86 MB)

10.
Sensitivity of the Cherenkov Telescope Array for probing cosmology and fundamental physics with gamma-ray propagation
Serguei Vorobiov, Samo Stanič, Christopher Eckner, R. Adam, A. Acharyya, F. Acero, H. Abe, H. Abdalla, Gabrijela Zaharijas, Marko Zavrtanik, Danilo Zavrtanik, Miha Živec, 2021, original scientific article

Abstract: The Cherenkov Telescope Array (CTA), the new-generation ground-based observatory for γ astronomy, provides unique capabilities to address significant open questions in astrophysics, cosmology, and fundamental physics. We study some of the salient areas of γ cosmology that can be explored as part of the Key Science Projects of CTA, through simulated observations of active galactic nuclei (AGN) and of their relativistic jets. Observations of AGN with CTA will enable a measurement of γ absorption on the extragalactic background light with a statistical uncertainty below 15% up to a redshift z=2 and to constrain or detect γ halos up to intergalactic-magnetic-field strengths of at least 0.3 pG . Extragalactic observations with CTA also show promising potential to probe physics beyond the Standard Model. The best limits on Lorentz invariance violation from γ astronomy will be improved by a factor of at least two to three. CTA will also probe the parameter space in which axion-like particles could constitute a significant fraction, if not all, of dark matter. We conclude on the synergies between CTA and other upcoming facilities that will foster the growth of γ cosmology.
Found in: ključnih besedah
Summary of found: ...Cherenkov Telescope Array, active galactic nuclei, gamma-ray experiments, axions, extragalactic magnetic fields...
Keywords: Cherenkov Telescope Array, active galactic nuclei, gamma-ray experiments, axions, extragalactic magnetic fields
Published: 02.03.2021; Views: 156; Downloads: 5
URL Fulltext (0,00 KB)
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