Possibility of Recuperating PEP-II HER Magnets for MEIC Electron Ring (II) Fanglei Lin, Andrew Hutton, Vasiliy S. Morozov, Yuhong Zhang MEIC R&D Meeting, JLab, August 14, 2014 F. Lin

MEIC FODO & TME-like Cell MEIC FODO cell MEIC TME-like cell Phase advance: 1.5(H), 0.5(V) Every 2 cells generate 3 and  phase advance in horizontal and vertical plane, respectively Maximum sextupole pole-tip field at 4.5cm aperture radius is ~ 0.5 T for compensation of cell’s chromaticities (PEP or PEP-II sextupoles can be reused in MEIC ) Phase advance: 135(H & V) Every 4 cells generate 3 phase advance in both horizontal and vertical planes Maximum sextupole pole-tip field at 4.5cm aperture radius is ~ 0.2 T for compensation of cell’s chromaticities

PEP-II HER vs. MEIC Arc Cell Parameters Unit PEP-II HER MEIC FODO cell (135 phase advance) MEIC TME-like cell (1.5/0.5 pha. adv.) MEIC TME-like cell (1.5/0.5 pha. adv.) Energy GeV 9 12 5 Dipole length m 5.4 Bending angle deg 1.875 4.108 4.85 4.45 Bending radius 165.0 75.3 (57.9) 75.3 63.7 69.5 Magnetic field T 0.1819 0.5314 0.2214 0.6280 0.2617 0.5757 0.2399 Quad length 0.7185 0.37 0.7/0.6/0.6 Field gradient T/m 5.48 29.5 28/29/29 12/12/12 Aperture radius cm ~5 4.5 Cell length 15.2 13.78 17.36 Number of cell 16*6 52 44 48 Arc length 243.2*6 716.56 (673.92) 716.56 763.84 833.28 Arc 43 90 160 C 83 173 308 Nor. emittance um 845 2746 (438) 199 (31.7) 312 (438) 22.6 (31.7) 240 (438) 17.4 (31.7) Sagitta R 2.2 4.8 5.7 5.2 * The current values are given in parenthesis

Some Practical Considerations Orbit curvature changes inside the dipoles  limit maximum sagitta R PEP-II FODO cell MEIC FODO cell MEIC TME-like cell optimal curvature   4

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MEIC’s e-Ring Current Equilibrium Emittance Normalized Equilibrium Horizontal Emittance εxN (μm) Energy (GeV) 3 5 6 7 8 9 10 11 12 Arc FODO (120 phase advance) 6.8 31.7 54.7 86.9 129.8 184.8 253.5 337.4 438.2 Arc (FODO + spin rotators) 11.8 54.5 94.2 149.6 223.2 317.8 435.9 580.4 753.4 Whole ring (Arc + IR) 15.4 71.3 123.2 195.7 292.1 415.8 570.4 759.2 985.7 Beam energy Gev 3 5 6 7 8 9 10 11 12 Beam current A 2.0 1.1 0.65 0.4 0.26 0.18 0.13 Total SR power MW 0.49 3.82 5.28 5.38 5.43 5.35 5.37 5.49 Linear SR power density kW/m 1.02 7.87 10.88 11.08 11.10 11.01 11.06 11.31 Energy loss per turn MeV 0.17 1.27 2.64 4.89 13.37 29.84 Energy spread 10-3 0.34 0.56 0.68 0.79 1.01 1.24 Longitudinal damping time ms 83.6 18.1 10.4 6.6 3.1 1.7

PEP-II HER vs. MEIC Arc Cell Parameters Unit PEP-II HER MEIC FODO cell MEIC TME-like cell Energy GeV 9 12 5 Dipole length m 5.4 Bending angle deg 1.875 4.272 5.34 Bending radius 165.0 72.4 (57.9) 72.4 57.9 (57.9) 57.9 Magnetic field T 0.1819 0.5527 0.4145 0.2303 0.6908 0.2878 Quad length 0.45 0.35 0.5/0.6/0.6 Field gradient T/m 9.79 29 22 27/28/26 11/12/11 Aperture radius cm 3.6 (?) 4.5 FODO length 15.2 13.74 17.16 Number of FODO 16*6 50 40 Arc length 243.2*6 687 (673.92) 687 686.4 Normalized emittance um 845 3478 (438) 1446 (184.8) 252 (31.7) 951 (438) 69 (31.7) SR power density kW/m 7.23 (11.31) 7.04 (11.01) 5.03 (7.87) 11.31 7.87 Total SR power MW 4.39 (5.49) 4.28 (5.35) 3.05 (3.82) 5.49 3.82 * The current values are given in parenthesis

Some Practical Considerations Orbit curvature changes inside the dipoles  limit maximum sagitta R PEP-II FODO cell MEIC FODO cell MEIC TME-like cell optimal curvature   8