Speaker
Description
Cavity-based searches for wave-like dark matter require microwave resonators combining high quality factors to enhance sensitivity with wide frequency tunability to probe the largest possible range of candidate particle masses. This is particularly important at high frequencies, where the parameter space is largely unexplored due to the poor scaling of the expected signal with the cavity volume, making high-$Q$ resonators essential for preserving experimental sensitivity.
Although superconducting cavities with quality factors as high as $10^{11}$ have been demonstrated for wave-like dark matter searches, achieving such performance together with wide frequency tunability remains a major challenge. In this contribution we present the tuning-by-opening technique that we demonstrated with a superconducting Nb$_3$Sn-coated cavity resonating around $9\,\mathrm{GHz}$ [1]. We accomplished frequency tuning by varying the gap between two cavity halves, enabling a tuning range exceeding $1\,$GHz while maintaining an unloaded quality factor above $10^6$, with no observed mode crossing throughout the explored range.
Building on these results, we set new limits on the dark photon parameter space, excluding kinetic mixing values $|\varepsilon| \gtrsim 5\times10^{-13}$ over the $7.7 -8.9\,\mathrm{GHz}$ frequency range using six week of data taking [2]. We also introduce a novel haloscope operation strategy in which the cavity resonance is continuously tuned at a constant rate while being tracked through the injection of a weak thermal noise signal. This approach results only in a negligible loss of experimental sensitivity, while providing a practical scanning protocol for next-generation superconducting haloscopes.
[1] https://arxiv.org/abs/2603.08175v1.
[2] \textit{A 1-GHz dark photon search with a widely tunable superconducting haloscope}, in preparation.
| Primary Abstract Topic | Experiment: Axions and Wave-Like-DM |
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