Maintaining micron-size beams in collision at the interaction point of the Stanford Linear Collider

In order to maintain collisions between two micron-sized beams at the interaction point of the SLC, the mutual electromagnetic deflection induced by one beam on the other as they cross with a nonzero relative impact parameter is utilized. The incoming and outgoing trajectory parameters of each beam are determined simultaneously on a pulse-by-pulse basis, using beam position monitors located near the IP. Comparing incoming and outgoing angles for a given beam yields the magnitude of the deflection the beam experienced during the collision from which the distance currently separating the two beams can be extracted. A simple proportional control is applied to calculate the change in upstream corrector settings to null out this distance.<>