The inner radius of the quads is determined by aperture requirements and the vacuum chamber thickness. The outer radius is determined by detector clearance requirements, both in operation and during installation. The mechanical stability and reproducibility (e.g., after opening of the poles) must be adequate. A 1 micron transverse motion of an IR quad typically produces an 80 micron peak-to-peak distortion in the closed orbit of the beam.
There are several other magnet functions required in this region. Adjustable dipole steering magnets are needed to correct the closed orbits and also aid in creating localized orbit distortions, or ``bumps,'' to help reduce experiment background and injection losses. The effect of the CLEO solenoid field on the motion of the electrons must be adequately compensated. This will be done as now by rotating normal IR quadrupoles and by additional skew quads.