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" By comparing the zero-horizontal-emittance beam's normal mode and projected emittances, the dispersion and chromaticity contributions can be deduced. Table 2 shows the breakdown of the emittance growth into these sources (dispersion, coupling, chromaticity) after KM and knobs for the various simulations. Table 2: Errors All Aberrations Chromaticity Dispersion Coupling X/Y Offsets 0.37 nm 0.37 nm 0.00 nm 0.00 nm Add Quad Strength 3.20 nm 0.82 nm 0.01 nm 2.39 nm Add Bend Strength 3.25 nm 0.82 nm 0.06 nm 2.39 nm Add Quad Rolls 7.60 nm 1.49 nm 0.00 nm 6.08 nm Add Bend Rolls 7.61 nm 1.49 nm 0.02 nm 6.08 nm Table 2 suggests the following: " The combination of KM and dispersion knobs can completely eliminate dispersion as a source of emittance growth in the RTML "front end", presumably limited only by the resolution of the BPMs and the wire scanners (which were not modeled in this study) " After dispersion correction the most serious problem is coupling correction, which is not addressed by any of the tuning methods in this simulation " The chromaticity of the matching regions is a serious problem which is not addressed by the linear dispersion or coupling corrections; we should examine the possibility of redesigning the matching regions to correct this problem. 5 Acknowledgements These studies would not have been possible without many excellent ideas and discussions with K. Kubo and J. Smith. The work reported in this note was supported by the US Department of Energy under Contract DE-AC02-76SF00515. References [1] K. Kubo, "Emittance Dilution Due to Misalignment of Quads and Cavities of ILC Main Linac," http://lcdev.kek.jp/kkubo/reports/MainLinac-simulation/lcsimu-20050310.pdf (2005). [2] http://www.slac.stanford.edu/ilc/codes/Lucretia/ (2006).