CPT

Calendar of Physics Talks Vienna

Maximally symmetric spacetimes reconsidered
Speaker:Stefan Prohazka (ULB)
Abstract:Spacetimes, like Minkowski space, are omnipresent in physics. I will introduce a recent classification of spacetimes that generalizes the classification of maximally symmetric lorentzian geometries and includes further physically interesting ones. Among them are galilean, carrollian and aristotelian geometries for which there is renewed interest due to applications in holography. These spacetimes posses infinite dimensional (BMS-like) symmetries which we will also discuss. Mainly based on: arXiv:1809.01224, arXiv:1903.09165
Date: Tue, 05.11.2019
Time: 13:45
Duration: 60 min
Location:TU Wien - Wiedner Hauptstraße 8 - Red Area, 7th floor, Seminar Room (DC 07 A15)
Contact:D. Grumiller, S. Fredenhagen

Erosion investigations of fusion relevant plasma facing materials
Speaker:Reinhard Stadlmayr (TU Wien, Institut für Angewandte Physik)
Abstract:Nuclear fusion could be a clean and climate protecting energy source of the future, but still a lot of physical and technical issues need to be solved. In order to operate a future fusion power plant economically the first wall in the reactor must withstand the tremendous heat load and the continuous particle bombardment long enough. To investigate the erosion of such plasma facing materials (PFM) of a fusion device under well-defined laboratory conditions, the TU Wien quartz crystal microbalance technique (QCM) is ideally suited. In-situ studies with the QCM allow a unique insight into the dynamics of material mixing, erosion phenomena and particle retention processes. In addition, experimental results can be used to benchmark new surface morphology sensitive BCA (binary-collision-approximation) codes, like TRI3DYN and SDTrimSP-3D. We can show that by taking surface morphology informati
Date: Tue, 05.11.2019
Time: 16:00
Duration: 20 min
Location:TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner Hauptstraße 8-10 Yellow Tower „B“, 5th floor, SEM.R. DB gelb 05 B
Contact:Univ.Prof. Dr. Friedrich Aumayr

Small ELMs – A promising reactor scenario
Speaker:Georg F. Harrer (TU Wien, Institut für Angewandte Physik)
Abstract:The foreseen operational scenario for future fusion devices is the high confinement mode, which is characterized by a strong increase in confinement due to the formation of a transport barrier at the plasma edge. The periodic crash of this so-called pedestal is caused by large edge localized modes (type-I ELMs) which lead to possibly intolerable heat and particle loads if not controlled. In ASDEX Upgrade, discharges with plasma edge conditions comparable to ITER, exhibit small ELMs at good confinement, if these high density plasmas are strongly shaped. In the experiment, type-I ELMs and small ELMs can coexist. In this contribution a model is proposed that explains how the small ELMs modify the shape of density profile in such a way that it is stable against large type-I ELMs. The manifestation of small ELMs at reactor-like conditions as filamentary transport rather than large bursts offe
Date: Tue, 05.11.2019
Time: 16:00
Duration: 20 min
Location:TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner Hauptstraße 8-10 Yellow Tower „B“, 5th floor, SEM.R. DB gelb 05 B
Contact:Univ.Prof. Dr. Friedrich Aumayr

Variants and parametrization of self-interacting dark matter
Speaker:Xiaoyong Chu (HEPHY, Wien)
Abstract:Im Rahmen des Teilchenphysikseminars: Cosmological simulations suggest that there exists an unexpected mass deficit in dark matter inner halos. This has inspired the study of self-scattering dark matter. In this talk, I will first discuss various dark matter models that can address such mass deficit while satisfying other observational bounds, such as self-interactions enhanced by light mediators, or by a s-wave resonance, at low velocities. The second half of my talk will introduce the so-called effective-range approach, which describes the velocity dependence of the self-interaction cross section in a model-independent way, with only two parameters.
Date: Tue, 05.11.2019
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:A. Hoang, S. Plätzer

Sculpted light in nano- and microsystems
Speaker:Prof. Halina Rubinsztein-Dunlop (University of Queensland, Australia)
Date: Tue, 05.11.2019
Time: 17:00
Location:Technische Universität Wien, Hauptgebäude, Festsaal, 1040 Wien, Karlsplatz 13
Contact:Univ.Prof. Dr. Ulrike Diebold

CLIC - From the machine to the science
Speaker:Erica Brondolin (CERN)
Abstract:The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear electron- positron collider under study at CERN. For an optimal exploitation of its physics potential, CLIC is foreseen to be built and operated in three stages, at centre-of- mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, and searches for new phenomena through direct and indirect measurements. The construction of the first CLIC energy stage could start by 2026 and first beams would be available by 2035. An overview of the CLIC project, its physics potential and the design, technology, and implementation aspects of the accelerator and the detector will be presented.
Date: Thu, 07.11.2019
Time: 09:30
Duration: 60 min
Location:HEPHY Library
Contact:Josef Pradler

Linear stability of slowly rotating Kerr spacetimes
Speaker:Dietrich Haefner (Grenoble, Frankreich)
Abstract:In joint work with Peter Hintz and András Vasy, we study the asymptotic behavior of linearized gravitational perturbations of Schwarzschild and slowly rotating Kerr black hole spacetimes. We show that solutions of the linearized Einstein equation decay at an inverse polynomial rate to a stationary solution (given by an infinitesimal variation of the mass and angular momentum of the black hole), plus a pure gauge term. In this talk, I will describe the geometric background and the analytic setup of our result, including a discussion of gauge fixing. Our proof is based on a precise description of the resolvent of an associated wave equation on symmetric 2-tensors near zero energy.
Date: Thu, 07.11.2019
Time: 14:00
Duration: 60 min
Location:Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien
Contact:P.T. Chrusciel, D. Fajman