Lattice Diagnostics Using Single Kick Closed Orbit at Kekb
نویسندگان
چکیده
We have measured beta functions using single kick closed orbit at KEKB. The measured beta functions were compared with the model lattice and gradient errors were extracted from the result in a beta beat. The gradient errors were also obtained by changing strength of steering magnets and measuring beam positions as the second method. The methods of the error estimation and preliminary results will be reported. KEKB[1] is an asymmetric-energy, double-ring, electronpositron collider. The beam energy is 3.5 GeV for positron(LER) and 8.0 GeV for electron(HER), respectively. The requirement of the peak luminosity is 1034cm−2s−1 for study of CP violation. In order to achieve such high luminosity operations, large beam current and small β∗ y which is the beta function at I.P. in the vertical plane are needed. The β∗ y = 1cm optics has been done successfully for both rings. The final focusing of two beams is provided by a pair of super conducting quadrupole magnets which are called QCS. The small β∗ y produces a large amount of chromaticity which makes the field of sextupole magnets strong. The nonlinear of sextupole magnets reduces the transverse dynamic aperture. It is, therefore, considered to use a pair of identical sextupole magnets which are connected with a -I' transformer in both the horizontal and vertical planes. The nonlinear effect due to the sextupole magnets should be compensated by the -I' transformer up to the third order in Hamiltonian. Diagnostics of the lattice has been studied since the commissioning of KEKB started in December 1998. Measurements of the closed orbit distortion(COD) give us a large amount of information for a lattice. The formula for the closed orbit distortion, ∆x, induced by a single steering magnet is
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تاریخ انتشار 1999