Signatures of Enhanced Superconducting Properties in Niobium Cavities

Fuente: arXiv
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Hauptverfasser: Bafia, D., Grassellino, A., Checchin, M., Zasadzinski, J. F., Romanenko, A.
Format: Preprint
Veröffentlicht: 2021
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author Bafia, D.
Grassellino, A.
Checchin, M.
Zasadzinski, J. F.
Romanenko, A.
author_facet Bafia, D.
Grassellino, A.
Checchin, M.
Zasadzinski, J. F.
Romanenko, A.
contents Superconducting radio-frequency (SRF) niobium cavities are critical for modern particle accelerators, as well as for advancing superconducting quantum systems and enabling ultra-sensitive searches for new physics. In this work, we report a systematic observation of an anomalous frequency dip in Nb cavities, which occurs at temperatures just below the critical temperature ($T_\mathrm{c}$), indicative of enhanced superconducting properties at $T \ll T_c$. The magnitude of this dip is strongly correlated with the RF surface resistance, impurity distribution near the surface, and $T_\mathrm{c}$. Additionally, we report measurements of the coherence peak in the AC conductivity of two Nb SRF cavities processed using distinct methods. By comparing recent theories developed to model this experimental data, we show that the frequency dip feature, larger coherence peak height, and reduction in the temperature-dependent surface resistance with RF current occur at minimal but finite levels of disorder.
format Preprint
id arxiv_https___arxiv_org_abs_2103_10601
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Signatures of Enhanced Superconducting Properties in Niobium Cavities
Bafia, D.
Grassellino, A.
Checchin, M.
Zasadzinski, J. F.
Romanenko, A.
Accelerator Physics
Superconductivity
Quantum Physics
Superconducting radio-frequency (SRF) niobium cavities are critical for modern particle accelerators, as well as for advancing superconducting quantum systems and enabling ultra-sensitive searches for new physics. In this work, we report a systematic observation of an anomalous frequency dip in Nb cavities, which occurs at temperatures just below the critical temperature ($T_\mathrm{c}$), indicative of enhanced superconducting properties at $T \ll T_c$. The magnitude of this dip is strongly correlated with the RF surface resistance, impurity distribution near the surface, and $T_\mathrm{c}$. Additionally, we report measurements of the coherence peak in the AC conductivity of two Nb SRF cavities processed using distinct methods. By comparing recent theories developed to model this experimental data, we show that the frequency dip feature, larger coherence peak height, and reduction in the temperature-dependent surface resistance with RF current occur at minimal but finite levels of disorder.
title Signatures of Enhanced Superconducting Properties in Niobium Cavities
topic Accelerator Physics
Superconductivity
Quantum Physics
url https://arxiv.org/abs/2103.10601