Author: Duan, Z.
Paper Title Page
THPZ012 Luminosity Enhancement and Performance in BEPCII 3708
 
  • Q. Qin, J. Cao, J. Cheng, Y.L. Chi, H. Dong, Z. Duan, D. Ji, W. Kang, S.P. Li, L. Ma, H. Qu, C.H. Wang, G.W. Wang, J.Q. Wang, X.H. Wang, Y. Wei, J. Xing, G. Xu, C.H. Yu, J. Yue, C. Zhang, Y. Zhang
    IHEP Beijing, Beijing, People's Republic of China
 
  The Beijing Electron Positron Collider (BEPC) was upgraded to a factory-like machine –- BEPCII, during last several years. From last November, the BEPCII was commissioned again for its luminosity. Efforts on optics correction including optimizing the strengths of superconducting quadrupoles near the IP, orbits correction concerning beam energy, etc, make the transvers tunes possible to move very close to half integer, bringing a big luminosity increase. The background of the detector is also reduced with beam commissioning, and finally fit the requirements of data taking. Further luminosity commissioing, including coupling optimization, beta-waist tuning, was carried on, and the luminosity reached 6.49·1032 cm-2 s-1 during routine operation. Some measures of luminosity enhancement and the luminosity related accelerator physics issues will be discussed.  
 
THPZ011 Optimization of Chromatic Sextupoles in Electron Storage Rings Using Genetic Algorithms 3705
 
  • Z. Duan
    IHEP Beijng, Beijing, People's Republic of China
  • Q. Qin
    IHEP Beijing, Beijing, People's Republic of China
 
  Funding: Work supported by National Science Foundation of China contract 10725525.
In order to suppress the head-tail instability, strong chromatic sextupoles are used in modern electron storage rings to correct large chromaticities due to small emittance or strong insertion quadrupoles to squeeze the bunch size at some places. However, the introduction of strong chromatic sextupoles also brings severe nonlinearity and might reduce dynamic aperture drastically. In the case of several sextupole families, the genetic algorithms are applied to find suitable configurations of sextupole strengths, directly maximizing dynamic aperture. A GeneRepair operator is introduced into the algorithm to correct chromaticities and optimize the dynamic aperture simultaneously in electron storage rings.