Dresden 2011 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 4: Precision spectroscopy of atoms and ions I
A 4.1: Vortrag
Montag, 14. März 2011, 14:00–14:15, BAR 205
Absolute determination of X-ray transition energies in H-like and He-like ions — •Katharina Kubicek, Hjalmar Bruhns, Johannes Braun, José R. Crespo López-Urrutia, and Joachim Ullrich — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
We present high-precision wavelength measurements for H- and He-like ions performed with the FLASH-EBIT using a flat crystal x-ray spectrometer applying a collimation-free technique [Braun et al., Rev. Sci. Instrum. 76 (2005), p. 073105] which allows to determine absolute Bragg angles without the need of reference lines. We have reduced further the already small leading experimental uncertainty [Bruhns et al., Phys. Rev. Lett. 99 (2007), p. 113001] by installing the spectrometer coaxially to the electron beam, thus viewing the ion cloud as a point source. This setup reveals a minute curvature of the x-ray lines on the detector plane which hitherto had to be estimated. Results for the Lyman-α1 and “w” (1s2p 1P1→1s2 1S0) transition wavelengths in H-like and He-like argon, sulfur and iron ions with experimental uncertainties of esimated Δ E < 4 meV are sensitive to the far larger QED contributions of 1 eV.