arXiv subjects

Thomas Braine

Publications and source records attributed to Thomas Braine.

3 recordsLinked to original sources

arXiv2026

Characterization of a hybrid superconducting RF cavity for use in axion searches

We report on the development of a hybrid superconducting radio-frequency (SRF) cavity for axion haloscopes. The Axion Dark Matter eXperiment (ADMX) Sidecar has been a program of ADMX for testing technologies with the potential for improving high frequency cavity haloscopes in the 4-6 GHz range. A replica of the Sidecar cavity, an aluminum clamshell microwave resonator loaded with a niobium tuning rod coated with Nb3Sn, was characterized in a dilution fridge through its critical temperature transitions down to 25 mK and through magnetic fields up to 6 T. The quality factor of five resonant modes of the cavity system were monitored throughout the process, including the TM010 mode used in axion searches. Distinct superconducting transitions were observed near the expected critical temperatures of Nb3Sn, pure niobium, and aluminum. The TM010 mode exhibited a factors of improvement in quality factor of 1.86 and 2.87 through the two niobium transitions, which implied the rod had a zero-field surface resistance of roughly 79% that of copper at cryogenic temperatures. Magnet tests showed a distinct superconducting transition for aluminum, and gradual degradation of quality factor expected for Nb3Sn in a mixed superconducting state. This hybrid resonator design has been integrated in the ADMX insert for performing an axion-like particle search.

physics.ins-det↗

arXiv2025

Identifying environmentally induced calibration changes in cryogenic RF axion detector systems using Deep Neural Networks

The axion is a compelling hypothetical particle that could account for the dark matter in our universe, while simultaneously explaining why quark interactions within the neutron do not appear to give rise to an electric dipole moment. The most sensitive axion detection technique in the 1 to 10 GHz frequency range makes use of the axion-photon coupling and is called the axion haloscope. Within a high Q cavity immersed in a strong magnetic field, axions are converted to microwave photons. As searches scan up in axion mass, towards the parameter space favored by theoretical predictions, individual cavity sizes decrease in order to achieve higher frequencies. This shrinking cavity volume translates directly to a loss in signal-to-noise, motivating the plan to replace individual cavity detectors with arrays of cavities. When the transition from one to (N) multiple cavities occurs, haloscope searches are anticipated to become much more complicated to operate: requiring N times as many measurements but also the new requirement that N detectors function in lock step. To offset this anticipated increase in detector complexity, we aim to develop new tools for diagnosing low temperature RF experiments using neural networks for pattern recognition. Current haloscope experiments monitor the scattering parameters of their RF receiver for periodically measuring cavity quality factor and coupling. However off-resonant data remains relatively useless. In this paper, we ask whether the off resonant information contained in these VNA scans could be used to diagnose equipment failures/anomalies and measure physical conditions (e.g., temperatures and ambient magnetic field strengths). We demonstrate a proof-of-concept that AI techniques can help manage the overall complexity of an axion haloscope search for operators.

hep-ex↗

arXiv2024

Superconducting Resonator Development for the Axion Dark Matter eXperiment

The Axion Dark Matter eXperiment (ADMX) is the first axion haloscope search to reach DFSZ sensitivity in any mass range for the QCD axion. The QCD axion is a well-motivated dark matter candidate that additionally solves the strong CP problem in nuclear physics. A haloscope has three necessary components; a very strong external magnet, a high Q cavity resonator embedded in this field, and an ultra-sensitive RF read-out system. This dissertation mainly reports on the future development of the resonators for ADMX, specifically superconducting RF (SRF) cavities. It starts with an overview of axions, haloscopes, and the current ADMX experiment, followed by the work done at Lawrence Livermore National Laboratory (LLNL) on SRF cavities, and finally the preliminary results of the ADMX "hybrid" superconducting-copper Sidecar cavity in run 1D.

hep-ex↗