Least-squares fitting procedure for setting RF phase and amplitude in drift-tube-linac tanks

A method involving the use of least-squares analysis of relative phase measurements is presented. In this method bunch phases relative to RF power are measured at the input and output of the tank and at a reasonable drive distance downstream (or after the next tank with its RF off). The RF phase and amplitude are varied in a predetermined way; the resulting measured phase shifts are compared by least-squares fitting with their corresponding values from a beam-dynamics code simulation. The absolute calibration errors (assumed constant) of the phase sensors are the quantities which are varied to obtain the best fit. If these calibration errors are known, absolute values of RF phase and amplitude can be determined and the correct values set in the tank.<>