Beam position measurement during fast ejection

A series of electrostatic pick-up electrodes is used to measure the horizontal position of a single bunch during fast ejection in the Serpukhov proton synchrotron. Any one of the 30 circulating bunches can be followed, whether it is being ejected or stays in the accelerator. The electrode signals go directly into long coaxial cables and no active components are present in the radioactive zone. The signals are digitized and go to a minicomputer. The response of the system is linear over the whole width of the electrodes (200 mm). (2 refs).