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 Q(300K) = (150,000 +/- 2,000) and Q(4K) = (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 C-030 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.