Vibrational modes of the pedestal support system for the SLC Arc magnets

The magnet support system for the SLC Arcs will be a long series of pedestals with each pedestal supporting the ends of two adjacent magnets. It has been pointed out by several authors that random magnet vibrations in the Arc with amplitudes larger than 0.1 ..mu..m rms are potentially harmful for the SLC operation. In order to assess the vibrational behavior of the Arc magnet system, we need to understand: (1) the sources and characteristics of the ground disturbances, (2) the coupled vibrational modes of the composite pedestal-magnet system and, (3) the response of the system to ground disturbance.