• W. Wittmer, W. S. Colocho, G. R. White
  SLAC, Menlo Park, California

The controls software in use at PEP II had originally been developed in the eighties. The functionality and maturity of the applications in that system have made it very successful in routine operation, but this same longevity and orientation toward fixed requirements, make it largely unsuitable for rapid machine development and ad-hoc online experimentation. A successful recent trend at light sources has been to use the so called MATLAB Middle Layer (MML). This package abstracts each underlying control system framework to which it is connected, such as Channel Access. We describe the middle layer implementation for PEP II and LCLS based on AIDA (described elsewhere in these proceedings), which is unusual in that it provides access to the high level functionality of the legacy control system, as well as to a very large assortment of useful data in addition to channel access read and control. The MML had to be adapted for the implementation at PEP II since colliders differ significantly from light sources by scale and symmetry of the lattice, and PEP II is the first collider at which such an implementation is being done.

• U. Wienands, W. S. Colocho, S. DeBarger, F.-J. Decker, S. Ecklund, A. S. Fisher, J. D. Fox, A. Kulikov, A. Novokhatski, M. Stanek, M. K. Sullivan, W. Wittmer, D. Wright, G. Yocky
  SLAC, Menlo Park, California

During Run 5, PEP-II has been plagued by beam instabilities causing beam aborts due to radiation in the BaBar detector or due to fast beam loss triggering the dI/dt interlock. The latest of such instabilities occurred in the High Energy Ring (HER), severely curtailing the maximum beam current achievable during physics running. Techniques used in tracking down this instability included fast monitoring of background radiation, temperatures and vacuum pressure. In this way, the origin of the instability was localized and inspection of the vacuum system revealed several damaged bellows shields. Replacing these units significantly reduced the incident rate but did not eliminate it fully. After the end of the run, a number of damaged rf seals were found, possibly having caused the remaining incidents of instability. In this paper we will outline the steps taken to diagnose and remedy the issue and also compare the different signatures of vacuum-induced instabilities we have seen in both rings of PEP-II during the run.

• Y. T. Yan, Y. Cai, W. S. Colocho, F.-J. Decker
  SLAC, Menlo Park, California

For optics measurement and modeling of the PEP-II electron (HER) and position (LER) storage rings, we have been doing well with MIA* which requires analyzing turn-by-turn Beam Position Monitor (BPM) data that are resonantly excited at the horizontal, vertical, and longitudinal tunes respectively. However, in anticipating that certain BPM buttons or even pins in the PEP-II IR region will be missing for the next run starting in January 2007, we have been developing a data validation process, hoping to reduce the effect due to the reduced BPM data accuracy on PEP-II optics measurement and modeling. Besides the routine process for ranking BPM noise level through data correlation among BPMs, allowing BPMs to have linear gains and linear cross couplings, we can also check BPM data symplecticity by comparing the invariant ratios. We may also work out nonlinear BPM data correction if needed. Results on PEP-II measurement will be presented.

* Y. T. Yan, et. al. EPAC06 Proceedings, WEPCH062, (2006)