Realization of a high quality factor resonator with hollow dielectric cylinders for axion searches.

We discuss the realization and characterization of a high quality factor resonator composed of two hollow-dielectric cylinders with its pseudo-TM$_{030}$ mode resonating at 10.9 GHz frequency. We measured the quality factor at the temperatures 300~K and 4~K obtaining Q$_{300K}$=150,000 and Q$_{4K}$=720,000 respectively, the latter corresponding to a gain of one order of magnitude with respect to a traditional copper cylindrical-cavity with the corresponding TM$_{010}$ mode resonating at the same frequency. We discuss the implications to dark-matter axion-searches with cavity experiments and show that the gain in quality factor is not spoiled by a reduced coupling to the axion field, estimating a reduction effect at most of 20\%. We show with numerical simulations that frequency tuning of several hundreds MHz is feasible.