Karlsruhe 2024 – scientific programme

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T: Fachverband Teilchenphysik

T 95: Gravitational waves 1

T 95.1: Talk

Thursday, March 7, 2024, 16:00–16:15, Geb. 30.23: 6/1

A superconducting cavity for the SUPAX experiment — •Tim Schneemann, Kristof Schmieden, and Matthias Schott — Johannes Gutenberg-Universität Mainz

The SUPAX experiment is one of the first RF cavity based haloscope experiments in Germany to search for axions and dark photons as well as high frequency gravitational waves. A proof-of-concept analysis was presented in summer 2023. Our ongoing effort, within the RADES collaboration, is now focused on developing a tuning mechanism of the RF cavity’s resonance frequency without the need of tuning rods as well as improving the quality factor Q₀ within a magnetic field of up to 14 T. The quality factor of a resonant system like an RF cavity is a measure of the energy losses, determining the resonance amplification of a signal. Since it mainly depends on the surface resistance of the cavity material superconducting surfaces should yield a boost in Q₀, directly resulting in an increased sensitivity.

Currently superconducting REBCO or YBCO tapes yield the best results. These layered tapes have a very high critical magnetic field, making them suitable for axion searches where the cavity is inside a strong magnetic field. However, they are very sensitive to any kind of curvature in the surface they are applied to. We are presenting a different approach, using a cavity coated with NbN, a superconductor with a high critical magnetic field of O(10 T) which does not have any constraints on surface curvature. In this talk the production and coating process, characterization of the coated cavity and expected improvement on sensitivity will be presented.

Keywords: Superconducting; Cavity; Axion; Dark Photon; Dark Matter