| Paper |
Title |
Page |
| WEPCH102 |
Studies of the Nonlinear Dynamics Effects of APPLE-II Type EPUs at the ALS
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2152 |
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- C. Steier, S. Marks, S. Prestemon, D. Robin, D. Schlueter, W. Wan, W. Wittmer
LBNL, Berkeley, California
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Elliptically Polarizing Undulators (EPUs) have become more and more popular at synchrotron radiation sources, providing full polarization control of the photon beam. The fields of the most commonly used APPLE-II type EPUs have a very fast, intrinsic field roll-off, creating significant non-linearities of the beam motion with in some cases large impact on the dynamic (momentum) aperture. In general, the nonlinear effects get stronger with longer periods and higher undulator magnetic fields. One of the planned future beamlines at the ALS (MERLIN) will use a quasiperiodic EPU with 9 cm period and maximum B fields of about 1.3 T. We will present simulation studies for the proposed shimming schemes for this future device to reduce the nonlinear effects to acceptable values, as well as experimental studies for the existing 5 cm period EPUs already installed in the ALS.
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| MOPLS045 |
Achieving a Luminosity of 1034/cm2/s in the PEP-II B-factory
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643 |
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- J. Seeman, J. Browne, Y. Cai, W.S. Colocho, F.-J. Decker, M.H. Donald, S. Ecklund, R.A. Erickson, A.S. Fisher, J.D. Fox, S.A. Heifets, R.H. Iverson, A. Kulikov, A. Novokhatski, V. Pacak, M.T.F. Pivi, C.H. Rivetta, M.C. Ross, P. Schuh, K.G. Sonnad, M. Stanek, M.K. Sullivan, P. Tenenbaum, D. Teytelman, J.L. Turner, D. Van Winkle, M. Weaver, U. Wienands, W. Wittmer, M. Woodley, Y.T. Yan, G. Yocky
SLAC, Menlo Park, California
- M.E. Biagini
INFN/LNF, Frascati (Roma)
- W. Kozanecki
CEA, Gif-sur-Yvette
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For the PEP-II Operation Staff: PEP-II is an asymmetric e+e- collider operating at the Upsilon 4S and has recently set several performance records. The luminosity has exceeded 1x1034/cm2/s and has delivered an integrated luminosity of 728/pb in one day. PEP-II operates in continuous injection mode for both beams, boosting the integrated luminosity. The peak positron current has reached 2.94 A and 1.74 A of electrons in 1732 bunches. The total integrated luminosity since turn on in 1999 has reached over 333/fb. This paper reviews the present performance issues of PEP-II and also the planned increase of luminosity in the near future to over 2 x 1034/cm2/s. Upgrade details and plans are discussed.
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| MOPLS052 |
Luminosity Improvement at PEP-II Based on Optics Model and Beam-beam Simulation
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661 |
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- Y. Cai, W.S. Colocho, F.-J. Decker, Y. Nosochkov, P. Raimondi, J. Seeman, K.G. Sonnad, M.K. Sullivan, J.L. Turner, M. Weaver, U. Wienands, W. Wittmer, M. Woodley, Y.T. Yan, G. Yocky
SLAC, Menlo Park, California
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The model independent analysis (MIA) has been successfully used at PEP-II to understand machine optics and improve the luminosity. However, the rate of success was limited because the improvement of optics does not necessarily lead to increase of luminosity. Recently, we were able to reconstruct MIA model in a full optics code, LEGO, and used it to calculate complete lattice and beam parameters. These parameters were fed to the beam-beam code, BBI, to understand the luminosity histories at PEP-II over the past year. Using these tools, we optimized the luminosity by varying the beam parameters such as emittance. Finally, we implemented an optimized solution with a set of asymmetric horizontal orbit bumps into the machines during a delivery shift with a few percentage gain in luminosity. The solution was retained at PEP-II machines along with the luminosity. Later, these asymmetric bumps also played a vital role in reaching 1x1034cm-2s-1 as the beam currents increased.
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