Calendar of Physics Talks Vienna

Measurement of Cosmic Rays with Primary Energies up to 10**20 eV
Speaker:Prof. Danilo Zavrtanik (Nova Gorica Technical University)
Abstract:Measurement of Cosmic Rays with Primary Energies up to 10**20 eV- Recent results from the Pierre Auger Experiment
Date: Tue, 25.05.2010
Time: 16:30
Duration: 60 min
Location:Inst. f. Hochenergiephysik, OeAW, Nikolsdorfergasse 18, 1050 Wien, Bibliothek
Contact:Dietrich Liko

The Level-1 Trigger of the CMS experiment at the LHC
Speaker:Manfred Jeitler (HEPHY)
Abstract:The two-stage trigger system of the CMS experiment consists of a hardware-based trigger, which has to reduce the rate from the 40-MHz bunch-crossing rate in the LHC down to 100 kHz, and a software-based "High-Level Trigger", which runs on a computer farm and achieves the further reduction from 100 kHz to 100 Hz, which will be written to tape. HEPHY has developed and is operating several vital parts of the complex Level-1 architecture: the Drift-Tube Track Finder (DTTF), the Global Muon Trigger (GMT) and the Global Trigger (GT).The DTTF reconstructs muon tracks in the CMS barrel region in real time. The GMT combines this information with trigger data from the muon endcaps (cathode-strip chambers) and from RPCs (which cover the whole detector) and forwards it to the GT, which combines the muon information with calorimeter data and trigger information from several additional systems ("technical triggers" and "external conditions"), calculates the trigger verdict based on 128 "algorithms" implemented in firmware, issues physics triggers as well as random and calibration triggers when the detectoris able to accept triggers, and monitors trigger rates and deadtimes. The setup of the trigger electronics and the performance within the framework of CMS data taking operations will be presented.
Date: Wed, 26.05.2010
Time: 16:00
Duration: 45 min
Location:SMI, Seminar room, Boltzmanngasse 3, 1090 Wien, Room 2.08
Contact:Roland Gsell

Testing the CPT symmetry with antimatter: ASACUSA collaboration at CERN
Speaker:Bertalan Juhasz (SMI)
Abstract:Even though the Charge-Parity-Time (CPT) symmetry is assumed to be valid in all mainstream quantum field theories like QED or QCD, the apparent dominance of matter in our Universe hints that the CPT symmetry might be violated in certain physical processes or systems. Such a violation would result in a non-equality of the properties of a particle and its antiparticle. The goal of the ASACUSA collaboration at CERN is to study the properties (mass, charge, magnetic moment) of the antiproton, and thus search for a violation of the CPT symmetry. At CERN's Antiproton Decelerator (AD), ASACUSA has been measuring these properties using antiprotonic helium. By comparing the measured transition frequencies between the various energy levels of antiprotonic helium with theoretical three-body calculations, the mass and charge of antiproton have been obtained with a precision of 2 parts per billion. Besides, each energy level is split due to the interaction between the spins of its constituents, and again by comparing the measured hyperfine splitting values with theoretical calculations, the magnetic moment of the antiproton has been obtained with a precision of 0.29%. ASACUSA also plans to measure the ground-state hyperfine splitting (GS-HFS) of antihydrogen, the antimatter counterpart of hydrogen. According to a theoretical model, the antihydrogen GS-HFS is particularly sensitive to CPT violation effects. Thus by measuring it with a precision of only 0.1 ppm can already surpass the existing best CPT limit (neutral kaon-antikaon mass comparison) on the absolute scale.
Date: Wed, 26.05.2010
Time: 16:45
Duration: 45 min
Location:SMI, Seminar room, Boltzmanngasse 3, 1090 Wien, Room 2.08
Contact:Roland Gsell

Black holes and their topology in higher dimensions
Speaker:Stefan Hollands (University of Cardiff and ESI) (Fakultät für Physik)
Date: Fri, 28.05.2010
Time: 13:30
Duration: 60 min
Location:Währinger Strasse 17, Seminarraum A, 2. Stock
Contact:R. Beig