Electro-mechanical offset measurements of beam position monitors

Purpose The absolute beam position measurement in the booster and storage ring of the high energy photon source (HEPS) requires the offset between the electrical and mechanical centers of the beam position monitor (BPM).Method Traditionally, an RF signal is sent to an antenna or stretched wire aligned with the vacuum chamber, and the signal at each electrode is measured. Conversely, a replacement method using a vector network analyzer, which was proposed by Lambertson, does not involve mechanical alignment and can be used for electrical offset determination.Results and conclusions The electro-mechanical offsets of booster BPMs of the HEPS were measured using the Lambertson method. The result shows good agreement with the stretched wire method within a 30 μm error.