Development of beam-position monitor for the SuperKEKB positron beam line at the KEKB injector linac

New stripline-type beam position monitors (BPMs) are under development at the KEKB injector linac in order to measure transverse beam positions with a high precision less than 10 μm towards the Super B-factory at KEK. The high-precision BPM system is strongly required to stably accelerate single-bunch electron and positron beams with bunch charges of ∼5 nC, and also to keep the beam stability with higher brightness. In this report, new theoretical analysis and experimental investigations on the signal propagation characteristics and performance with stripline electrodes are described in detail on the base of a coupled-mode analysis in uniform coupled transmission lines. (author)