  For many years, various experiments have attempted to shed light on the
nature of dark matter (DM). This work investigates the possibility of using
CaWO4 crystals for the direct search of spin-dependent DM interactions using
the isotope 17O with a nuclear spin of 5/2. Due to the low natural abundance of
0.038%, an enrichment of the CaWO4 crystals with 17O is developed during the
crystal production process at the Technical University of Munich. Three CaWO4
crystals were enriched, and their 17O content was measured by nuclear magnetic
resonance spectroscopy at the University of Leipzig. This paper presents the
concept and first results of the 17O enrichment and discusses the possibility
of using enriched crystals to increase the sensitivity for the spin-dependent
DM search with CRESST.
