A tunable dielectric resonator for axion searches at 11 GHz

TL;DR

This paper presents a tunable dielectric resonator designed for axion searches at 11 GHz, featuring a high quality factor and a broad tuning range, advancing the capabilities of haloscope experiments.

Contribution

It introduces a novel, cryogenically tested, tunable dielectric resonator with a clamshell tuning mechanism suitable for high-frequency axion detection.

Findings

Achieved about 2% frequency tuning range

Maintained a quality factor of approximately 175,000

Confirmed the resonator's applicability for axion searches at 11 GHz

Abstract

In the context of axion search with haloscopes, tunable cavity resonators with high quality factor and high effective volume at frequencies above about 8 GHz are central for probing the axion-photon coupling with the required sensitivity to reach the QCD axion models. Higher order modes in dielectrically-loaded cavities allow for higher effective volumes and larger quality factors compared to basic cylindrical cavities, but a proper cavity frequency tuning mechanism to probe broad axion mass ranges is yet not available. In this work, we report about the design and construction of a tunable prototype of a single-shell dielectric resonator with its axion-sensitive pseudo-TM$_{030}$ high-order mode at about 11 GHz frequency. A clamshell tuning method previously tested for empty cylindrical resonators has been perfected for this geometry through simulations and in situ tests conducted at cryogenic temperature. Tuning is accomplished in a range of about 2 $\%$ the central frequency, without significantly impacting the quality factor of about 175000. The experimental results presented in this work demonstrate the tunability of this type of resonator, definitely confirming its applicability to high frequency axion searches.