PEP-II Beta Beat Fixes with MIA

Technical Report · Tue Mar 02 04:00:00 EST 2004

DOI:https://doi.org/10.2172/826797· OSTI ID:826797

Yan, Y ^[1]

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1. SLAC

We first find a virtual accelerator for the HER or the LER through determination of all quadrupole strengths and sextupole feed-downs as well as all BPM gains and BPM cross-plane couplings by an SVD-enhanced Least-squares fitting of the quantities derivable from a complete set of orbits. These quantities are the phase advances, the Green's functions, and the tilt angles and axis ratios of the coupling eigen ellipses. They are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a high-resolution model-independent analysis (MIA). Once the virtual accelerator is found, we select a limited number of key quadrupoles, for example, the linear trombone quadrupoles and the global skews, for Least-square fitting of their strengths to minimize the beta beat while keeping other optics characters unchanged if not improved. We then dial in these limited number of quadrupole strength changes to the real accelerator (HER or LER) to achieve a better-performance PEP-II. Noticeable achievement by this MIA technique has been that MIA has helped PEP-II achieve its breaking record peak luminosity of 6.5 x 10{sup 33}cm{sup -2}s{sup -1} in 2003 by bringing the LER working tune to near half integer and simultaneously fixing the beta beat, which would, otherwise, be difficult without MIA because of the strong LER coupling effect.

• Research Organization: Stanford Linear Accelerator Center, Menlo Park, CA (US)
• Sponsoring Organization: USDOE Office of Science (US)
• DOE Contract Number: AC03-76SF00515
• OSTI ID: 826797
• Report Number(s): SLAC-PUB-10369
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
ACCELERATORS
BEAM POSITION
LUMINOSITY
MONITORS
OPTICS
QUADRUPOLES