The tevatron global radius and Øs system

It has been found to be practical to extract a turn-average measurement of bunch beam phase relative to cavity gap voltage. This Øs signal shows the bunch position on the R.F. wave throughout injection, acceleration and extraction, including coherent synchrotron oscillations when present. In turn, the time derivative of Øs is a direct measure of global radial position error. We use the Os signal, driving a phase shifter in the R.F. low-level system, to damp coherent synchrotron oscillations. Design and operation will be discussed including single beam bunch operation if available.