GENERAL PHYSICS COLLOQUIUM _____ Title: Testing CPT with antiprotonic helium and antihydrogen Speaker: Eberhard Widmann, Austrian Academy of Science, Vienna Time: Wednesday, 16 March, 2011 at 3:15 p.m. Place: Physics Auditorium, 3rd floor, Department of Physics Abstract Experiments with low-energy antiprotons are currently performed at the antiproton De-celerator (AD) of CERN. The main focus of the experimental collaborations is the study of fundamental symmetries, especially CPT invariance, using antiprotonic atoms and antihydrogen. The ASACUSA collaboration focuses on precision spectroscopy of antiprotonic helium, an exotic three-body system consisting of a helium nucleus, an electron and an antiproton. The antiproton occupies metastable states, which allows precision determination of its mass and magnetic moment by comparison to three-body QED calculations. Anthydrogen, the simplest neutral antimatter atom, promises CPT tests of highest precision by comparison to hydrogen, which is one of the best studied atoms. ASACUSA is preparing an experiment to measure the ground-state hyperfine structure of antihydrogen, the corresponding quantity for hydrogen being measured to relative precision of ∼ 10−12 in the hydrogen maser. A major breakthrough occurred in 2010 when ASACUSA for the first time demonstrated antihydrogen formation in a so-called “cusp trap” suitable for the production of an antihydrogen beam, which is essential for our proposed experiment. _____ Coffee/tea and cake will be served at 3 p.m. David Field ******************************* Trine Binderup Department of Physics and Astronomy Aarhus University Ny Munkegade 120, building 1525 DK-8000 Aarhus C e-mail: trinebm@phys.au.dk Phone: +45 8942 3603 Office: 1525-324