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Abstract:
Highly charged ions (HCIs) are promising candidates to search for physics beyond
the Standard Model, as they feature narrow transitions with an enhanced sensitivity
to a possible variation of the fine-structure constant alpha. For high-precision
laser spectroscopy with a relative uncertainty of < 10−19, HCIs have to be trapped
and cooled to the motional ground state. As HCIs lack suitable optical transitions
for laser cooling, at the Cryogenic Paul Trap Experiment CryPTEx they are
sympathetically cooled down to the mK-range using directly laser-cooled 9Be+
ions. The 9Be atoms are ionized by resonance-enhanced two-photon ionization
using 235nm laser light and Doppler-cooled with a laser at 313nm.
The present Master’s thesis is dedicated to provide the laser systems for the successor
experiment CryPTEx II, and focuses on their stabilization. Employing the
wavelength stabilization for the photoionization laser, which was set up during
this thesis, its wavelength is stable within a 0.02pm-interval, which is a factor
of five smaller than required for an efficient beryllium-ionization process. Sympathetic
cooling of HCIs requires a stable power of the cooling laser. Therefore,
the already existing stabilization of slow power fluctuations, which was modified
during this thesis, as well as the newly built stabilization of the fast power fluctuations
were characterized. Additionally, an apparatus for aligning the lasers
to the trap center was designed. In addition, an active spatial stabilization was
implemented and tested to keep the laser beams stable in the center of the Paul
trap despite external perturbations.
