Compact beam position monitor using a segmented toroidal coil

An inductive compact beam position monitor based on a segmented toroidal coil surrounding the charged particle beam has been investigated. It makes use of the induced voltages in the windings instead of the induced charge imbalance on capacitor plates in the popular beam position monitors. We theoretically investigate the response of the coils to the bunched particle beam based on a lumped-element model and compare it to the measurements in the laboratory and in the storage ring COSY in terms of beam displacement. As to the frequency response of the coils, we find a resonant behavior, which may be exploited to further increase the sensitivity of the device. The resolution presently achieved is about 5 μm in a 1 s time interval for a beam current of 0.5 mA.