A new measurement method of the delay line length in the X-band Delay Line Distribution System (DLDS)

In order to control the driving RF phase at the input of the accelerating structure of X-band linear collider main linacs, it is necessary to measure the length of the long TE01 mode delay lines of 40-80m. A new measurement scheme by using the low frequency resonant mode of the TE01mode delay line was proposed. The delay lines have the tapered guide on its both ends, thus the low frequency resonant mode around 2GHz can be the measure of the delay line dimensions. The operational principle and the elementary characteristics of this measurement method such as, sensitivity, and other basic design parameters are presented.