Conceptual Design Report of the SUPAX Experiment

TL;DR

The Supax experiment is a novel haloscope designed to detect axion-like particles and dark photons using a 12 T magnetic field and tunable superconducting cavities, achieving new constraints on dark photon parameter space.

Contribution

This paper introduces the technical design and preliminary results of the Supax experiment, including innovative tuning mechanisms and new exclusion limits for dark photons.

Findings

Excluded dark photons around 35 μeV with kinetic mixing χ > 5×10⁻¹⁴

Demonstrated effective tuning of cavities from 2 to 7.2 GHz

Achieved preliminary sensitivity in axion mass range 8-30 μeV

Abstract

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\,$\mu$eV and 30\,$\mu$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, preliminary R\&D efforts, and results from prototype experiments. In particular, we exclude dark photons with masses around $35\,\mu$eV with a kinetic mixing parameter $\chi > 5\cdot 10^{-14}$, i.e. a region of parameter space which has not been previously explored.