Spektroskopie von Lyman-alpha Übergängen schwerster wasserstoffähnlicher Ionen mittels Kristallspektroskopie und Absorptionskanten-Technik

The theory of Quantumelectrodynamics in the case of strong electric fields still remains untested. An experimental verification with an accuracy comparable to modern calculations can be realized by the spectroscopy of Lyman-α transitions of heavy, highly-charged atomic systems. However, new kinds of experimental approaches have become indispensable. Therefore, a special crystal spectrometer has been set up. An energy resolution of 60 eV for photons of 50 keV energy has been verified. The detection system used is based on the principle of a drift chamber. It exhibits a linearity in position resolution of 200 µm. Investigations show an increased darkrate when Xenon is used as the detector gas. In addition, the electronic read-out system has been adjusted to the conditions at the gasjet-target of the ESR storage ring at the GSI Darmstadt. Moreover, an experiment at the ESR storage ring was performed with this spectrometer for the very first time. Due to the low efficiency of the spectrometer, no quantitative results could be obtained. Making use of these detectors, an experiment exploring the hydrogen-like system Au 78+ was performed at the ESR, based on the absorption-edge technique. As a result of the stringent geometrical control applied, deviations of the ion-beam from its expected position have been found. These imply a change in photonic energy of about 200 eV as induced by the Doppler shift. Nevertheless, the 1s-Lambshift of Au 78+ could be determined to (210.5 ± 8.8) eV. The relative accuracy in the determination of photonic energies of 1.27 à 10 -4 represents the most precise one reached with the absorption-edge technique. Moreover, the experimental results show that an absolute energy resolution of 1 eV is attainable.