IBCM: Internal bunch coordinate monitor

The outputs of AGS pick-up electrodes have been digitized with 100 MHz transient recorders in order to study the motion of individual rf bunches during the AGS acceleration cycle. Pick-Up Electrodes (PUEs) have been used at the AGS for many years in order to locate the beam. As an RF bunch passes a pair of electrodes, a signal is induced in each electrode proportional to the bunch-electrode separation. Thus, the /inner-outer/ or /upper-lower/ difference signals are proportional to the bunch coordinate. For normalization, these differences are divided by the corresponding sum. The present system provides dc signals proportional to both horizontal and vertical positions at many locations around the ring averaged over several milliseconds. However, with faster electronics, waveforms can be studied on a much shorter time scale, making possible the tracking of each of the twelve rf bunches within the AGS