Field Quality and Stability of Permanent Magnet Quadrupoles

We plan to increase the peak luminosity of the Cornell Electron Storage Ring by providing tighter vertical focussing at the interaction points. The final focussing devices will be large permanent magnet quadrupoles operating inside the 10-15 kG solenoidal field of the experimental detector. We present the results of tests demonstrating that quadrupoles with the required field quality and resistance to demagnetization can be built from commercially available Rare Earth Cobalt magnets.