Pulse to pulse stability issues in the SLC

Although the SLC achieved record luminosity in 1994, a major hindrance to further increases is pulse-to-pulse stability of the machine, often referred to as jitter. Raising the intensity of the SLC beams has gained luminosity but the intensity-normalized luminosity has decreased due to additional emittance dilution and to increasing jitter at higher intensities. Precision tuning of the final focus using beam-beam deflection scans is hampered by the pulse-to-pulse variations in both beam position and beam size. These were traced to position, intensity and energy jitter in various subsystems of the collider. Contributions to both the origin and amplification of the jitter have been identified as coming from wakefields in the linac, instabilities in the damping rings, acceptance limitations and feedback performance. The intensity fluctuations from the source can easily be amplified as a result of the SLC configuration of accelerating the two electron and positron bunches in the same linac