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1.
Mass composition from 3 EeV to 100 EeV using the depth of the maximum of air-shower profiles estimated with deep learning using surface detector data of the Pierre Auger Observatory
Jonas Glombitza, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2023, published scientific conference contribution

Abstract: We present a new analysis for estimating the depth of the maximum of air-shower profiles, �max, to investigate the evolution of the ultra-high-energy cosmic ray mass composition from 3 to 100 EeV. We use a recently developed deep-learning-based technique for the reconstruction of �max from the data of the surface detector of the Pierre Auger Observatory. To avoid systematic uncertainties arising from hadronic interaction models in the simulation of surface detector data, we calibrate the new reconstruction technique with observations of the fluorescence detector. Using the novel analysis, we have a 10-fold increase of statistics at � > 5 EeV with respect to fluorescence detector data. We are able, for the first time, to study the evolution of the mean and standard deviation of the �max distributions up to 100 EeV. We find an excellent agreement with fluorescence observations and confirm the increase of the mean logarithmic mass ⟨ln(�)⟩ and a decrease of the �max fluctuations with energy. The �max measurement at the highest — so far inaccessible — energies is consistent with a pure mass composition and a mean logarithmic mass of around ∼ 3 (estimated using the Sibyll 2.3d and the EPOS-LHC hadronic interaction models). Furthermore, with the increase in statistics, we find indications for a structure beyond a constant elongation rate in the evolution of �max.
Keywords: ultra-high energy cosmic rays, Pierre Auger Observatory, surface detector, flourescence detector
Published in RUNG: 22.01.2024; Views: 302; Downloads: 6
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Orographic gravity waves in OH-airglow imaging systems
Sabine Wuest, Jonas Till, René Sedlak, Patrick Hannawald, Carsten Schmidt, Samo Stanič, Michael Bittner, 2020, published scientific conference contribution abstract

Abstract: Atmospheric dynamics is strongly influenced by waves on different scales. Airflow over mountains can lead to all kinds of atmospheric waves, planetary and gravity waves as well as infrasound. Under certain circumstances these waves can propagate through the atmosphere and lead to a re- distribution of energy. In the case of gravity waves, a stably stratified atmosphere is a mandatory requirement for their generation and vertical propagation. Additionally, the vertical propagation depends on the horizontal wind field. In the Alpine and pre-Alpine region, we currently operate five OH-airglow imaging systems, which allow the investigation of orographic gravity waves. Depending on tropo-, strato- and mesospheric wind and temperature, it is checked which wavelengths can propagate into the fields of view of our instruments. This is done for a whole year in order to take into account annual and semi- annual cycles in wind and temperature. Concerning the generation of gravity waves, we put our focus on our OH-airglow imager (FAIM) deployed at Otlica (45.9°N, 13.9°E), Slovenia. Here, we also have additional measurements of an OH-airglow spectrometer (GRIPS). In case studies, we investigate whether strong wind events (Bora) lead to strong gravity waves activity or enhanced potential energy density.
Keywords: Orographic gravity waves, Bora, Otlica, Slovenia, OH-airglow imaging
Published in RUNG: 08.10.2020; Views: 2375; Downloads: 0
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Photoelectric effect with a twist
Giovanni De Ninno, Jonas Wätzel, Primož Rebernik Ribič, Enrico Allaria, Marcello Coreno, Miltcho B. Danailov, Christian David, Alexander Demidovich, Michele Di Fraia, Luca Giannessi, Klaus Hansen, Špela Krušič, Michele Manfredda, Micheal Meyer, Andrej Mihelič, Najmeh Mirian, Oksana Plekan, Barbara Ressel, Benedikt Rösner, Alberto Simoncig, Simone Spampinati, Janez Štupar, Matjaž Žitnik, Marco Zangrando, Carlo Callegari, Jamal Berakdar, 2020, original scientific article

Abstract: Photons have fixed spin and unbounded orbital angular momentum (OAM). While the former is manifested in the polarization of light, the latter corresponds to the spatial phase distribution of its wavefront1. The distinctive way in which the photon spin dictates the electron motion upon light– matter interaction is the basis for numerous well-established spectroscopies. By contrast, imprinting OAM on a mat- ter wave, specifically on a propagating electron, is gener- ally considered very challenging and the anticipated effect undetectable2. In refs. 3,4, the authors provided evidence of OAM-dependent absorption of light by a bound electron. Here, we seek to observe an OAM-dependent dichroic photo- electric effect, using a sample of He atoms. Surprisingly, we find that the OAM of an optical field can be imprinted coher- ently onto a propagating electron wave. Our results reveal new aspects of light–matter interaction and point to a new kind of single-photon electron spectroscopy.
Keywords: FEL, OAM, Photoelectric effect
Published in RUNG: 09.09.2020; Views: 2822; Downloads: 0
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