Axion dark matter detection by laser spectroscopy of ultracold molecular oxygen: a proposal

Generalizing Sikivie's approach (Sikivie 2014 Phys. Rev. Lett. 113 201301), according to which dark matter axions may induce transitions between Zeeman states in an atomic system, an experiment based on a molecular gas is proposed for a search in the axion mass range between 1.4 and 1.9 meV. In particular, a O-16(2) sample is brought to the temperature of 280 mK via buffer-gas cooling and then subjected to an external magnetic field; axion-driven transitions are eventually detected by resonance-enhanced multi-photon ionization spectroscopy.