An increase in the quality factor of superconducting radiofrequency cavitiesis achieved by minimizing the surface resistance during processing steps. Thesurface resistance is the sum of temperature independent residual resistanceand temperature/material dependent Bardeen-Cooper-Schrieffer (BCS) resistance.High temperature heat treatment usually reduces the impurities concentrationfrom the bulk niobium, lowering the residual resistance. The BCS part can bereduced by selectively doping non-magnetic impurities. The increase in qualityfactor, termed as Q-rise, was observed in cavities when titanium or nitrogenthermally diffused in the inner cavity surface.
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