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SuperKEKB Lattice and Dynamic Aperture H. Koiso Apr. 20, 2005 Super B Factory Workshop in Hawaii

SuperKEKB Lattice and Dynamic Aperture H. Koiso Apr. 20, 2005 Super B Factory Workshop in Hawaii. Lattice Parameters. No major change in arcs. Only the interaction region in Tsukuba straight section (~200m) will be fully reconstructed. 2.5π cell structure.

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SuperKEKB Lattice and Dynamic Aperture H. Koiso Apr. 20, 2005 Super B Factory Workshop in Hawaii

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  1. SuperKEKB Lattice and Dynamic ApertureH. KoisoApr. 20, 2005 Super B Factory Workshop in Hawaii

  2. Lattice Parameters • No major change in arcs. • Only the interaction region in Tsukuba straight section (~200m) will be fully reconstructed.

  3. 2.5π cell structure x and α are independently adjustable. x10 ~ 36 nm , α -4~ 4×10-4 Noninterleaved sextupoles (52HER/54LER pairs)

  4. Geometrical Conditions • Both rings are geometrically adjusted in the accuracy of 1> mm. • The position of IP is same as that of KEKB. • Crossing angle at IP is satisfied the requirements. e+/e-:before charge switch)

  5. Unit Cellx =24 nm LER (left), HER(right) Both rings reserve sufficient tuning range of x and α.

  6. RF RF IP wiggler RF LER ring The horizontal emittance is adjusted as xarc ~xwig

  7. RF IP RF (ARES) (Super) HER ring

  8. IR Lattice • x-y coupling components and H/V dispersions are all corrected to zero at IP, and are localized on each side of IP with 6(LER)/6(HER) skew quadrupoles and H/V dipoles. • SuperBelle solenoid field is compensated on each side of IP. • Field distributions of solenoids, QCS are given by 2-cm slices with constant strengths. • Conditions for Crab cavities are not satisfied. • Crab cavities can be placed in Nikko straight section if the test at KEKB is successful.

  9. Solenoid Field QC2RP (QC1RE) QCSR IP QCSL (QC1LE) QC2LP QCS field gradient (T/m) (top) Solenoid field (T) (bottom)

  10. QCS Multipole Fields QC2RP (QC1RE) QCSR IP QCSL (QC1LE) QC2LP QCS field gradient (T/m) (top) K5(12-pole), K9(20-pole), K13(28-pole)

  11. (crab) SL SL IP SL SL (crab) LER IR(bx*/by* = 20/0.3 cm) bx/by LER IR with local chromaticity correction. beam→

  12. Coupling Components (LER IR) bx/by

  13. HER IR (bx*/by* = 20/0.3 cm) bx/by (crab) IP (crab)

  14. injection beam LER dynamic aperturebare latticeBXBY=20/.3 cm (4cm-thick slices) Required: H/V 7.5/1.2 ×10-6m

  15. HER dynamic aperturebare latticeBXBY=20/.3 cm (4cm-thick slices) injection beam Required: H/V 4.5/0.52 ×10-6m

  16. Dynamic Aperture with Beam-Beam Effect by Y.Onishi Stored beam Jy/Jx = 2 % Stored beam Jy/Jx = 2 % * no machine error nx/ny = 45.510/43.545 nx/ny = 45.510/43.570 LER HER • Case xy = 0.14, dynamic aperture shrinks in large momentum deviation for LER. • Transverse aperture decreases in HER due to beam-beam effect. • Touschek lifetime with beam-beam(xy= 0.14): 50 min in LER / 180 min in HER No beam-beam No beam-beam xy = 0.14 xy = 0.07 xy = 0.14 xy = 0.07

  17. LER dynamic aperturebare latticeBXBY=20/.3 cm (2 cm-thick slices) injection beam Required: H/V 7.5/1.2 ×10-6m

  18. LER dynamic aperturelattice with QCS multipoles BXBY=20/.3 cm (2 cm-thick slices) injection beam Required: H/V 7.5/1.2 ×10-6m

  19. HER Sextupole Magnet • Strengths of 9 SD pairs K2 ~ -14. (the present limit is -12) • New sextupole magnets are needed to improved the dynamic apertures. • Local chromaticity correction in HER may be needed.

  20. Optics measurement and correction dispersion beta function Interactive procedure of measurement + analysis + correction • Knobs: • Local bumps at sextupoles • Fudge factors for quads/skews Works very well ! XY-coupling

  21. Chromaticity Measurement There are differences from the model in off-momentum optics.

  22. Summary • LER dynamic aperture satisfies the requirements for transverse acceptances at injection. • Modeling method of QCS and solenoid fields (for example, the thickness of slices) affects the dynamic aperture. • Effect of the edge of quadrupole field? Need to check. • QCS multipoles do not change the dynamic aperture significantly. • HER aperture still needs improvement. • Local chromaticity correction may be necessary. • Dynamic apertures are decreased by the beam-beam effect. • Dynamic apertures of both rings will be improved by further optimization of sextupole strengths. • should be estimated at a working point ~(.503 ,530) . • Correction methods for off-momentum optics should be developed.

  23. Synchro-betatron Resonance HER(KEKB) by K. Oide, et.al.

  24. LER dynamic aperturebare latticeBXBY=20/.3 cm injection beam Required: H/V 7.5/1.2 ×10-6m

  25. Bumps at sextupoles scan • Horizontal/Vertical bumps at sextupoles are used for optics correction. • 8 vertical bumps at SD sextupoles in each side of IP. • Vertical dispersion and its angle, x-y coupling components are independently adjustable. R1,R2,R3,R4,EY, and EPY • Sextupole movers will be used instead of vertical bumps.

  26. Merit of Local Chromaticity Correction LER dynamic aperture with a crab cavity (KEKB) by A. Morita

  27. Solenoid Field QC2RP (QC1RE) QCSR IP QCSL (QC1LE) QC2LP QCS field gradient (T/m) (top) Solenoid field (T) (bottom)

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