Asymmetrical cavity design that bypasses mode mixings in axion haloscope experiments

Journal Article · Fri Aug 01 00:00:00 EDT 2025 · Journal of the Korean Physical Society

DOI:https://doi.org/10.1007/s40042-025-01445-z· OSTI ID:3024159

Ko, Byeong Rok; Yi, Andrew K.

Microwave cavities used in axion haloscope experiments typically employ a tun- ing rod as a means to widen the range of resonance frequencies at which it is sensitive to axion-to-photon conversion. A realistic tuning mechanism requires a gap between the cavity end caps and the tuning rod to ensure movement, and causes some modes to hybridize with the resonant mode that is being tracked for the experiment. These so-called mode mixings lead to gaps in the frequency range that practically lose sensitivity to axions. In order to solve this problem, we present a cavity design which, for two tuning rod configurations corresponding to a lower and higher frequency range, have a dielectric rod inserted at a spe- cific location that makes the cavity asymmetrical. Moving the tuning rod closer to the dielectric insert changes the location and frequency of the mode mixing compared to when it is farther away from it. This design is easily realizable in practical experiments and makes possible an axion dark matter search with min- imal loss in sensitivity due to mode mixings. We also show that the same design has the same desired effect when cavity dimensions are scaled down to be smaller and are at higher resonance frequencies.

• Research Organization: SLAC National Accelerator Laboratory (SLAC)
• Sponsoring Organization: Korea Basic Science Institute; National Research Foundation of Korea; USDOE Office of Science (SC)
• Grant/Contract Number: AC02-76SF00515
• Other Award/Contract Number: RS-2025-00556247; NFEC-2019R1A6C1010027
• OSTI ID: 3024159
• Journal Information: Journal of the Korean Physical Society, Journal Name: Journal of the Korean Physical Society Journal Issue: 8 Vol. 87; ISSN 1976-8524; ISSN 0374-4884
• Publisher: Springer Science and Business Media LLC
• Country of Publication: United States
• Language: English