JACoW is a publisher in Geneva, Switzerland that publishes the proceedings of accelerator conferences held around the world by an international collaboration of editors.
@inproceedings{bafia:srf2021-frofdv03,
author = {D. Bafia and M. Checchin and A. Grassellino and A.S. Romanenko and J. Zasadzinski},
title = {{Investigating the Anomalous Frequency Variations Near Tc of Nb SRF Cavities}},
booktitle = {Proc. SRF'21},
% booktitle = {Proc. 20th International Conference on RF Superconductivity (SRF'21)},
pages = {885--892},
eid = {FROFDV03},
language = {english},
keywords = {cavity, niobium, SRF, ECR, scattering},
venue = {East Lansing, MI, USA},
series = {International Conference on RF Superconductivity},
number = {20},
publisher = {JACoW Publishing, Geneva, Switzerland},
month = {10},
year = {2022},
issn = {2673-5504},
isbn = {978-3-95450-233-2},
doi = {10.18429/JACoW-SRF2021-FROFDV03},
url = {https://jacow.org/srf2021/papers/frofdv03.pdf},
abstract = {{We report recent studies on the anomalous frequency variations of 1.3 GHz Nb SRF cavities near the transition temperature Tc and use them to investigate the underlying physics of state-of-the-art surface treatments. One such feature, a dip in frequency, correlates directly with the quality factor at 16 MV/m and the anti-Q slope that arise in cavities with dilute concentrations of N interstitial in the RF layer achieved via N-doping and mid temperature baking. For N interstitial, we find that the dip magnitude and Tc follow exponential relationships with the electronic mean free path. We present the first observation of the frequency dip near Tc in a cavity baked at 200 C in-situ for 11 hours, which is concurrent with the anti-Q slope, and may be driven by oxygen diffused from the native oxide, thus suggesting the possibility of ‘‘O-doping.’’ We also investigate the conductivities of two cavities that display different resonant frequency behaviors near Tc and suggest that the anti-Q slope and frequency dip phenomena may occur in the presence of interstitial N or possibly O that inhibit the formation of proximity coupled Nb nano-hydrides.}},
}