Li, W; Hao, H; Xu, W; Li, W; Wu, YK, *Direct and high resolution beta-function measurements for storage ring lattice characterization*,
IPAC 2016 - Proceedings of the 7th International Particle Accelerator Conference
(January, 2016),
pp. 3272-3274 .
**Abstract:**

*Copyright © 2016 CC-BY-3.0 and by the respective authors. Betatron functions are a set of commonly used merits to characterize the lattice performance of a circular accelerator. The betatron functions in many accelerators can be computed using a lattice model trained or calibrated using a set of closed orbit responses, which is exemplified by the widely used Linear Optics from Closed Orbit (LOCO) technique. However, for some accelerators, like Duke storage ring with quad-sextupole combined function magnets, LOCO cannot be employed in any straight forward manner. In this case, direct measurements for betatron function are required. One way to determine betatron functions at the location of quadrupoles for a circular accelerator is to use the relationship between the quadrupole strength variations and the corresponding betatron tune change. In this paper, we present a set of carefully developed techniques to measure the betatron functions at the location of quadrupoles, which allow us to achieve extremely high resolution. Measurement errors will be discussed, and the detailed measurement technique will be present. Finally, the experimental results of betatron function measurements in the Duke storage ring with statistical error on the order of 1% will be presented.*