First Axion Search Results of the SUPAX Prototype Experiment

Abstract

The SUPerconduction AXion search experiment (Supax) is a future haloscope-type detector designed to probe axion-like particles (ALPs) as candidates for dark matter and solutions to the strong-CP problem in the mass range between $8\,μ$eV and $30\,μ$eV. In the course of the preparation of Supax, a prototype experiment was built and operated. Using a copper cavity, cooled down to a temperature of 2 K and operated in a magnetic field of 12 T, we probe axion masses around $34\,μ$eV and exclude axion-photon couplings down to $|g_{aγγ}|> 1.6\cdot 10^{-13}$GeV$^{-1}$. The data was also used to exclude dark photons in the same mass range with a kinetic mixing parameter of $χ> 1.4\cdot 10^{-12}$. Details of the experimental setup and the analysis strategy are summarized in this paper.

Figures (8)

• Figure 1: Illustration of the basic principle of a haloscope search experiment.
• Figure 2: Scetch of the experimental setup of the prototype Experiment for Supax .
• Figure 3: Amount of collected data in seconds per frequency interval. For each shaded area the cavity is tuned to the centre frequency of the plotted resonance curve, where the width is taken from the measurement. The amplitude of each curve corresponds to the measurement time at that frequency.
• Figure 4: Grand unified spectrum of the analysed data. Left: Absolute values of the grand unified spectrum over the entire frequency range, where most sensitive range is between the vertical dashed lines. Right: Zoom into the most sensitive range showing the normalized values in units of $\sigma_k^g$. Small absolute values of GUS indicate high sensitivity.
• Figure 5: Rescaled expected [$(\sigma^s)^\dag$] and measured [$\sigma_k^g$] noise power fluctuations agree apart from an offset that is originating from the maximum likelihood weighting of the measured GUS giving an edge over the simple integration time weighting of the expected noise.