Observations of the effects of the beam-beam interaction on the orbits of stored beams in CESR

Luminosity in the Cornell Electron Storage Ring (CESR) depends critically on the degree of overlap of the counter-rotating beams at the interaction point (IP). However, due to the pretzel, this overlap is sensitive to changes in quadrupole and sextupole strengths. The beam-beam interaction (BBI) perturbs the closed orbits and depends on the transverse distance between the opposing beams as they pass each other. If a real time measurement of this small orbit change were possible, then this effect could be used to determine whether the bunches remain in collision while tuning CESR for high luminosity. Our purpose was to determine whether this would be possible with the present beam position detector system.