Koufalis, P.N. Furuta, F. Kaufman, J.J. Liepe, M. JACoW Geneva, Switzerland 978-3-95450-191-5 10.18429/JACoW-SRF2017-THPB004 English 750-753 THPB004 cavity ion niobium vacuum superconducting-cavity Contribution to a conference proceedings 2018 2018-01 https://doi.org/10.18429/JACoW-SRF2017-THPB004 http://jacow.org/srf2017/papers/thpb004.pdf Low temperature treatments of superconducting cavities in a low pressure ambient atmosphere have been shown to introduce a 'Q-rise' up to moderate surface fields and an overall increase in quality factor. However, the effect of varying the doping time at a fixed temperature on cavity performance has not been systematically examined. We present results of such an investigation for cavities prepared at 120 and 160 C in a continuously flowing low pressure atmosphere for various amounts of time. We show that the introduction of impurities to the RF penetration layer can improve cavity performance and investigate the relationship between electron mean free path and the temperature-dependent component of the surface resistance.