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

Abstract

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 is discussed. The quality factor was measured at the temperatures 300 K and 4 K obtaining $\text{mbox}{Q}_{300\text{mbox}K}=(150,000\pm 2,000)$ and $\text{mbox}{Q}_{4\text{mbox}K}=(720,000\pm 10,000)$respectively, the latter corresponding to a gain of one order of magnitude with respect to a traditional copper cylindrical-cavity with the corresponding TM${}_{010}$ 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.