There is a proposal to build a new 9 GeV electron synchrotron as a dedicated injector for the storage rings DORIS and PETRA. This machine will be housed in the old DESY-tunnel side-by-side with the original DESY-synchrotron. It is characterized by a separated function lattice, a 12.5 Hz repetition frequency, and all-metal vacuum chamber and a high shunt impedance rf-system. After commissioning of this new machine in 1984, the old DESY-synchrotron could be converted into a dedicated proton-accelerator as part of the injection chain for HERA.

Lattice and magnet parameters DESIGN, CONSTRUCTION AND PERFORMANCE OF THE DESY II MAGNETS Dipoles, quadrupoles and sextupoles have been de signed and constructed for the new separated function synchrotron, DESY II. The special constraints for the magnets were: 12.5 Hz repetition frequency and a 50 MeV to 10 GeV energy operation range. Special care was taken in selecting the steel, chosing the thickness of lamina tions and designing the endfield shape. To ensure easy access to the vacuum chamber, and because there are nine inlet and outlet beam pipes to be installed, a c-type pole shape design for the dipole was chosen. The quadrupoles and sextupoles have the same cross section as the PETRA magnets, but they are different in length, lamination thickness, coils and endfield shape. Back-leg windings are applied on the dipoles to enable horizontal orbit displacements to be made. The major part of the vertical orbit correction will be made using four coils mounted on the return yokes of the sextupoles so as to create superimposed horizontal magnetic fields.

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It is essential that the storage-ring beam injection time be minimized at an e + e -collider factory in order to maximize the integrated luminosity output of the facility. We describe a program of improvements to the CESR injector chain and injection process which have resulted in a reduction in the CESR fill time of ∼40%. This has in turn allowed shorter high-energy-physics run lengths so that a higher average luminosity is maintained. Shorter fill times have resulted from increased linac beam intensity, stability and reliability, improved synchrotron transmission, faster machine condition switching time, improved CESR injection efficiency and a change to the CESR filling cycle in which both the positron and electron beam currents are topped up at the end of a run.

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