  A method is presented for characterizing the emittance dilution and dynamic
aperture for an arbitrary closed lattice that includes guide field magnet
errors, multipole errors and misalignments. This method, developed and tested
at the Cornell Electron Storage Ring Test Accelerator (CesrTA), has been
applied to the damping ring lattice for the International Linear Collider
(ILC). The effectiveness of beam based emittance tuning is limited by beam
position monitor (BPM) measurement errors, number of corrector magnets and
their placement, and correction algorithm. The specifications for damping ring
magnet alignment, multipole errors, number of BPMs, and precision in BPM
measurements are shown to be consistent with the required emittances and
dynamic aperture. The methodology is then used to determine the minimum number
of position monitors that is required to achieve the emittance targets, and how
that minimum depends on the location of the BPMs. Similarly, the maximum
tolerable multipole errors are evaluated. Finally, the robustness of each BPM
configuration with respect to random failures is explored.
