Reduction of open-loop low frequency beam motion at the APS

The Advanced Photon Source (APS) 7-GeV positron storage ring at Argonne National Laboratory (ANL) produces high brilliance bending magnet and insertion device X-rays for up to 70 X-ray beamlines. To efficiently make use of the storage ring's high brilliance, an extremely tight tolerance has been placed on positron beam stability, namely that the beam be stable to a level which is less than 5% of its rms size. This requirement amounts to /spl plusmn/4.4 microns rms in the vertical plane and /spl plusmn/17 microns horizontally, assuming 10% coupling. While real-time closed orbit feedback (discussed elsewhere in these proceedings) will be employed to exceed the required stability requirement, efforts are underway to identify and reduce sources of beam motion in the absence of feedback. These sources include ground- and water-system-induced vibrations in addition to power supply jitter and drift. Results to date of this effort will be presented.