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TY - CPAPER AU - Eremeev, G.V. AU - Hannon, F.E. TI - Observation of High Field Q-Slope in 3 GHz Nb Cavities J2 - Proc. of International Conference on RF Superconductivity (SRF2015), Whistler, BC, Canada, Sept. 13-18, 2015 AB - A degradation of the unloaded quality factor is commonly observed above about 100 mT in elliptical niobium cavities. The cause of this degradation has not been fully understood yet, but the empirically found solution of heating to about 100-120 C for 24-48 hrs. eliminates the degradation in electropolished fine grain or large grain niobium cavities. While numerous experiments related to this phenomenon have been done at 1.3 GHz and 1.5 GHz, little data exists at other frequencies, and the frequency dependence of this degradation is not clear. We have measured the unloaded quality factor of 3 GHz fine grain niobium cavities, which were chemically polished as the final treatment before RF tests in a vertical Dewar and observed the characteristic degradation in two cavities. The measurement of the quality factor degradation at different bath temperatures points to a field-dependent rather than a temperature-related effect. PB - JACoW CY - Geneva, Switzerland SP - 66 EP - 69 KW - cavity KW - niobium KW - SRF KW - radiation KW - feedback DA - 2015/12 PY - 2015 SN - 978-3-95450-178-6 DO - 10.18429/JACoW-SRF2015-MOPB002 UR - http://srf2015.vrws.de/papers/mopb002.pdf ER -