High-Q, 15% Tunable Bragg Fiber Cavity with Dielectric Tuning Rod for Axion Haloscope Experiments at 11GHz

The QCD Axion is one of the leading candidates to explain what constitutes dark matter. Searches for these axions involve a resonant microwave cavity, called a haloscope, where the axion scatters with the cavity walls in the presence of a magnetic field and deposits a photon in the cavity only if the resonant frequency of the cavity matches that of the axion. We will present a new cavity design featuring concentric sapphire shells and a sapphire tuning rod. The cavity TM030 mode is tunable across the 10GHz-11.7GHz frequency range with an internal quality factor of Q~ 2.5*10^5 at 15mK. Tuning challenges and design improvements will be discussed.