Beam transport magnets for CEBAF

With respect to the optical system, the challenging parameters of the Continuous Electron Beam Accelerator Facility (CEBAF), a five-pass recirculating electron linac, are the design goals for the emittance and energy spread of its beam. The design goals are an emittance of 2×10^-9 m-rad at E<1 GeV and an energy spread of ΔE/E (4σ) of 10^-4. The magnetic elements specified by the optics design are not, in general, extraordinary. There are, however, many magnets: 1047 corrector dipoles (l=0.15 m, 0.3 m; B₀⩽0.8 kG), 390 major dipoles (l=1, 2, and 3 m; 2⩽B₀⩽6 kG), 707 quadrupoles (l=0.15, 0.30, 0.6 m; B₀⩽4 kG), 96 sextupoles (l=0.3 m; B₀⩽0.2 kG), 26 septa (l=1, 2 m; 0.3⩽B₀⩽6 kG), and one Lambertson septum (l=1 m; B₀≃4 kG), for a total of 2267 individual magnets. Furthermore, the fact that the quadrupoles, sextupoles, and correctors are to be individually powered to provide flexibility in tuning the optics lattice leads to restrictions on their design parameters. To ensure that the required magnetic parameters are achieved, all magnets will be magnetically mapped before installation. Therefore, systems to accurately and rapidly measure the multipoles and major dipoles are required. Present planning and the results of tests performed on the system to date are outlined