Title: X-ray laser spectroscopy with an electron beam ion trap at the free electron laser LCLS Speaker: Prof. José Crespo López-Urrutia, Max-Planck-Institut für Kernphysik, Heidelberg Time: Thursday, September 22, 15.15 to 16.00 Place: Fysisk Auditorium Abstract: Highly charged ions (HCI) are a main component of many astrophysical plasmas: stars and their coronae, active galactic nuclei, or accretion disks surrounding black holes. Until now, resonant photon scattering of x rays interacting with HCI could not be investigated in the laboratory. The new X-ray free electron laser LCLS opens the door for a complete new way of studying photoionized plasmas under well controlled conditions, as laser spectroscopy did in the visible range. For the first time, HCI targets produced and trapped with an electron beam ion trap (EBIT) are brought to interact with an x-ray laser to excite their electrons. By observing photon absorption and reemission, direct access is gained to both x-ray transition energies and oscillator strengths without theoretical and experimental uncertainties occurring under thermal excitation. The EBIT experiment at LCLS has measured the line ratios of Fe16+ and Fe15+, basic for plasma diagnostics, and compared them to lines in F8+, an hydrogenic ion, the only HCI type which can be calculated with extreme accuracy. Jacob Sherson and Aurélien Dantan Coffee, tea and cake will be served at 15.05 ----------------------------------- Aurelien Dantan Ion Trap Group Department of Physics and Astronomy University of Aarhus Ny Munkegade, bygn. 1520 8000 Aarhus Denmark +4589423602