Minutes of the CLIC Meeting - 28 July 2006

The linear optics of the CLIC damping ring to obtain an ultra-low beam emittance is described. The nonlinear optimization of the lattice is also described. An appropriate scheme of chromaticity correction is determined that gives reasonable dynamic aperture and zero chromaticity. The nonlinearities induced by the short period wiggler magnets and their influence on the beam dynamics are studied. In addition, approaches for absorption of synchrotron radiation power produced by the wigglers are discussed. The sensitivity of the CLIC damping ring to various kinds of alignment errors is studied. Without any correction, fairly small vertical misalignments of the quadrupoles and, in particular, the sextupoles, introduce unacceptable distortions of the closed orbit as well as intolerable spurious vertical dispersion and coupling due to the strong focusing optics of the damping ring. A sophisticated beam-based correction scheme has been developed in order to bring the design target emittances and the dynamic aperture back to the ideal value. A number of possible instabilities and their impact on the ring performance are briefly surveyed.

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