Comparison of SNS superconducting cavity calibration methods

Three different methods have been used to calibrate the SNS superconducting cavity RF field amplitude. Two are beam based and the other is strictly RF based. One beam based method uses time-of-flight signature matching (phase scan method), and the other uses the beam-cavity interaction itself (drifting beam method). Both of these methods can be used to precisely calibrate the pickup probe of a SC cavity and determine the synchronous phase. The initial comparisons of the beam based techniques at SNS did not achieve the desired precision of 1% due to the influence of calibration errors, noise and coherent interfaces in the system. To date the beam-based SC cavity pickup probe calibrations agree within approximately 4%, comparable to the conventional RF calibrations.