A new Limit for Axion Dark Matter with SPACE

The axion, which has yet to be discovered, is a promising candidate for dark matter that emerges from Peccei-Quinn theory. This article presents the search for axion dark matter with the “Student Project for an Axion Cavity Experiment” (SPACE), which is also the first one in Germany. The hypothetical particle was looked for in the mass range from $16.626\mu \mathrm{e}\mathrm{V}$ to $16.653\mu \mathrm{e}\mathrm{V}$, corresponding to a frequency range of 4.020 GHz to 4.027 GHz, using a resonant cavity in a peak magnetic field of 14 T. No significant signal was found, allowing us to exclude an axion-photon coupling $g_{a\gamma \gamma }=14.6\cdot {10}^{-13}{\mathrm{G}\mathrm{e}\mathrm{V}}^{-1}$ for the full mass range and $g_{a\gamma \gamma }=2.811\cdot {10}^{-13}{\mathrm{G}\mathrm{e}\mathrm{V}}^{-1}$ at peak sensitivity with a 95% confidence level. This limit surpasses previous constraints by more than two orders of magnitude.