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

The realization and characterization of a high quality factor resonator composed of two hollow-dielectric cylinders with its pseudo-TM030 mode resonating at 10.9 GHz frequency is discussed. The quality factor was measured at the temperatures 300 K and 4 K obtaining Q300K=(150,000±2,000) and Q4K=(720,000±10,000)respectively, the latter corresponding to a gain of one order of magnitude with respect to a traditional copper cylindrical-cavity with the corresponding TM010 mode resonating at the same frequency. The implications to dark-matter axion-searches with cavity experiments are discussed showing that the gain in quality factor is not spoiled by a reduced geometrical coupling C030 of the cavity mode to the axion field. This reduction effect is estimated to be at most 20%. Numerical simulations show that frequency tuning of several hundreds MHz is feasible.