Conceptual design report of the SUPAX experiment

The SUPerconduction AXion search experiment ( Supax ) is a haloscope designed to probe axion-like particles (ALPs) as candidates for dark matter and solutions to the strong CP problem. ALPs are predicted to couple to photons, allowing their detection through resonant conversion in electromagnetic cavities placed within strong magnetic fields. Supax employs a 12 T magnetic field and tunable superconducting cavities with resonance frequencies ranging from 2 GHz to 7.2 GHz, enabling the exploration of axion masses between 8 μ eV and 34 μ eV. The tuning mechanism, based on piezo motors and gas-pressure regulation, allows for simultaneous scanning of up to three frequencies, significantly improving search efficiency. This paper presents the technical design of the Supax experiment and preliminary R&D efforts including results from a prototype experiments operating at larger frequencies corresponding to masses around 35 μ eV at which we exclude dark photons with a kinetic mixing parameter χ > 3 ⋅ 1 0 − 14 , i.e. a region of parameter space which has not been previously explored.