The superconducting RF-system performed very reliably, providing the longitudinal dynamic aperture necessary for operation at this energy. In initial tests at the end of 1997, the luminosity performance of the new optics already approached that of the optics. Still, there had been some concern about dynamic aperture and non-gaussian tails developing when the emittance was made large. The optics used in 1998 profited from a specially designed sextupole configuration that reduced the detuning with horizontal amplitude whilst allowing a good correction of the non-linear chromaticity. The predicted dynamic aperture was substantially larger.
Time runs from right to left as the beam current decays.
The values represent an average sustained over 15 minutes of luminosity production. For luminosity production, the horizontal damping partition was increased to to further reduce the emittance. In addition, this change allows an almost symmetrical layout about the interaction points, thereby increasing the similarity between Ring1 and Ring2 and simplifying the simultaneous -squeeze. The beam distribution can then be cut at without a significant cut in the betatron distribution. The nominal tune split between the integer parts of the tunes will be increased from 4 to 5, reducing the probability of constructive excitations.