A turn-by-turn vertical profile monitor

A turn-by-turn vertical beam profile monitor has been developed at the Cornell Electron Storage Ring (CESR). The instrument optically images the vertical beam distribution with an array of optical fibers that transport visible synchrotron radiation to an array of photo-multiplier tubes. Each PMT signal is recorded by a turn-by-turn data acquisition system. With this instrument, we compare profiles of colliding and non-colliding electron bunches, from which we calculate an upper limit on the coherent beam-beam effect.