First laser spectroscopy of Mg⁺ at CRYRING@ESR and He-Like Boron at HITRAP

At the storage ring CRYRING@ESR, which was installed at GSI in 2014, the infrastructure requirements for laser spectroscopy were established within the scope of this work. This includes the installation of the laser systems, the laser beam transport as well as the coupling units to the storage ring and the infrastructure for the superposition of ion and laser beam. Moreover, a Labview-based interface for laser frequency control was developed, which uses a Fizeau interferometer of type WSU10 (HighFinesse) as a frequency standard. In the first part of this work, the experimental conditions at CRYRING@ESR were investigated with respect to laser spectroscopic studies on singly charged Mg+-ions. Particularly, the properties of the electron cooler and possible applications of the laser Doppler-velocimetry are discussed. One very interesting aspect was the laser-based observation of the excitation of synchrotron oscillations due to a slight misalignment of electron and ion beam in the electron cooler section. The main objective of the laser spectroscopic studies on Mg+ was to investigate a possible polarization build-up and preservation by optical pumping. This technique is already well established at linear accelerator facilities around the world, but has not yet been demonstrated unambiguously in storage rings. While an efficient resonant population transfer of the complete ion ensemble between different hyperfine structure states in 25Mg+ was clearly proven, an enduring polarization of the ion beam was not obtained under the current experimental conditions. From the first analysis of the recorded data, novel approaches for further systematic studies of this aspect are discussed. In the second part of the thesis, collinear laser spectroscopy was performed at the HITRAP facility. In a proof-of-principle experiment it was demonstrated that the meta-stable triplet state 2 3S1 in helium-like 11B3+ ions is sufficiently populated for laser spectroscopic studies when produced by an electron beam ion source (EBIS) of the DREEBIT type. To analyze the data, a fit-model including relativistic configuration mixing in He-like systems was applied and the so far most accurate experimental values for the rest-frame transition frequencies of the fine-structure transitions 2s 3S1 2p 3P0 and 2s 3S1 2p 3P2 were reproduced with similar accuracy. Based on these results, more accurate measurements of He-like ions are ongoing at the Collinear Apparatus for Laser Spectroscopy and Applied Sciences (COALA) at TU Darmstadt