(N.Yamamoto, S.Matsumoto) Ground motion can be corrected at the frequency of less than 10Hz with BPMs by using beam-beam deflection, that is slow feedback of SLC type. The ground motion, whose amplitude is at the order of nm at > 10Hz, causes 5% loss of luminosity. BPMs with 10nm resolution is necessary for a beam based alignment (orbit correction).
For NLC, in addition, a fast feedback system is considered within 2.8nsec at <200 Hz by BPMs with pilot beam and also by beam-beam deflection. Feedback systems of SLC and B-factories can be again the prototype. The feedback simulation is necessary with 10-100nm resolution BPMs.