¹⁷O enrichment of CaWO₄ crystals for spin-dependent DM search

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.