MEIC Shifting Magnet Tim Michalski August 6, 2015

Maximum change in magnet spacing Arc Chicane Using current 22.8 m FODO cell design (8 m 3 T dipoles with 3.4 m separation) One chicane per arc (also helps with synchronization of the 2nd IP), one extra FODO cell per arc Takes up cells, which could otherwise be used for chromaticity compensation x = 52 cm x = -69 cm Total bending angle and z length are fixed # of FODO cells # of magnet moved Path length change Radial movement range Maximum change in magnet spacing 3 4 dipoles, 5 quads 10 cm +52 / -69 cm 20 mm 4 6 dipoles, 7 quads +36 / -39 cm 14 mm 5 8 dipoles, 9 quads +28 / -29 cm 11 mm 2

Concept Layout of Superferric Arc Half Cell Magnets

Magnet Interconnect From LHC (Superferric Magnets Will Be Similar)

Considerations for Repositioning Superferric Magnets Moving radially inward and outward is feasible Use slides and measurement scheme to make repeatable Rotation of magnets will be required as well Considerations for interfaces between magnets and to outside world Beamline Vacuum – bellows between adjacent beam pipe vacuum chambers Insulating Vacuum – bellows between adjacent Arc Half-Cells (?) Power – “service loop” for conductors Cryogens – may require flex hoses between adjacent Arc Half-Cells and assessment of U-Tubes

Considerations for Repositioning PEP-II Magnets Moving radially inward and outward is feasible Use slides and measurement scheme to make repeatable Rotation of magnets will be required as well – if doing a short string Considerations for interfaces between magnets and to outside world – no major issues Vacuum – assess capacity to expand/contract RF shielded bellows between rafts Potential to use different bellows for different energies Current design architecture has the Electron Collider Ring suspended above the Ion Collider Ring

Considerations for Repositioning PEP-II Magnets Length of Bellows is .125m or 4.92” Location of Bellows With a single bellows in a Arc Half-Cell, Raft and Dipole must be moved as a pair. Without Corrector With Corrector

SuperKEK B and PEP-II HER Shielded Bellows PEP-II HER Bellows

Potential Positioning Systems