1. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Optics for ELIC  Collider Rings and Interaction Region Design Alex Bogacz Center for Advanced Studies of Accelerators

2. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 ELIC Ring-Ring Collider  Design Choices ‘Figure-8’ Collider Ring Topology Ensures spin preservation and ease of spin manipulation (spin rotators) Removes spin sensitivity to energy for all ion species Arc Optics Features Minimized emittance dilution due to quantum excitations (leptons) Limited synchrotron radiated power (leptons) Small momentum compaction to alleviate bunch lengthening (both species) ‘Aggressive’ Interaction Region (IR) Vertically crossing rings - ‘crab crossing’ Ultra small beta Interaction Point (IP) ‘Dipole second’ IR configuration (D = 0, D’ ≠ 0)

3. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 ELIC Interaction Region Challenges Unprecedented high Luminosity: 7.8×10 34 [cm -2 s -1 ] (peak luminosity per IP) Enabled by short ion bunches (  z = 5 mm), low beta β* = 5 mm), high rep. rate (1.5 GHz) ‘Crab Crossing’ required to alleviate luminosity reduction and to avoid parasitic beam-beam interaction due to high repetition rate Multiple IRs (4) Chromatic compensation with sextupoles necessary

4. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Figure-8 Rings  Vertical ‘Stacking’

5. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Figure-8 Rings  Vertical ‘Stacking’

6. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Figure-8 Rings  Vertical ‘Stacking’

7. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Figure-8 Ring with 80 0 crossing 330 m 150 m 80 deg

8. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility February 22, 2008 Figure-8 Ion Ring (half)  Lattice at 225 GeV 30 full cells 8 empty cells 3 transition cells Arc dipoles $Lb=210 cm $B=80.6 kG Arc quadrupoles $Lb=100 cm $G= 7.6 kG/cm phase adv./cell (  x = 60 0,  y = 60 0 )

9. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility February 22, 2008 Figure-8 Ion Ring (half)  Lattice at 225 GeV 30 full cells 8 empty cells 3 transition cells phase adv./cell (  x = 60 0,  y = 60 0 ) Minimum dispersion lattice (periodic) Dispersion suppression via ‘missing’ dipoles (geometrical) Uniform periodicity of Twiss functions (chromatic cancellations) Dispersion pattern ‘tailored’ to chromaticity compensation with sextupole families One family every third cell ( 3 × 60 0 = 180 0 )

10. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility February 22, 2008 Figure-8 Electron Ring (half)  Lattice at 9 GeV 28 superperiods (3 cells/superperiod) 22 empty cells Arc dipoles $Lb=300 cm $B=2.7 kG Arc quadrupoles $Lb=30 cm $G= 4.3 kG/cm 22 empty cells phase adv./cell (  x = 120 0,  y = 120 0 )

11. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility February 22, 2008 Figure-8 Electron Ring (half)  Lattice at 9 GeV 28 superperiods (3 cells/superperiod) 22 empty cells phase adv./cell (  x = 120 0,  y = 120 0 ) Equilibrium Emittance (120 0 FODO): Minimized emittance dilution due to quantum excitations (emittance disp. inv. H) Limited (manageable) synchrotron radiated power Synchrotron Radiated Power: 14.3MW (total) 10.4kW/m @ 1.85A

12. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility February 22, 2008 Figure-8 Electron Ring (half)  Lattice at 9 GeV 28 superperiods (3 cells/superperiod) 22 empty cells phase adv./cell (  x = 120 0,  y = 120 0 ) Momentum Compaction : Quasi isochronous arc to alleviate bunch lengthening Dispersion pattern ‘tailored’ to chromaticity compensation with sextupole families One family every third quad ( 3/2 × 120 0 = 180 0 )

13. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Figure-8 Rings  Vertical ‘Stacking’ ‘straights’

14. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Figure-8 Straights with two IPs Note: dimension of the drawing not to scale 85 m free space to accommodate e/p injection/ejection, SRF cavity, electron cooling, and electron polarimeter spin rotators spin rotator 35 m collision point vertical bend 85 m i i e e arc dipole 20 m 0.75 m arc bend 85 m spin rotator vertical bend 85 m 35 m 0.75 m 35 m vertical bend 20 m y z straight section (330 m) Vertical crossing angle (22.2 mrad) Minimizing crossing angle reduces crab cavity challenges and required R&D IP 70 m 7.6 m FF Crab cavity Match Chrom FODO Match Chrom Crab cavity FODO

15. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 IP 10cm 1.8m 20.8kG/cm 3m 12KG/cm 0.5m 3.2kG/cm 0.6m 2.55kG/cm 8.4cm 22.2 mrad 1.27 deg 0.2m Vertical intercept 4.5m 3.8m 14.4cm 16.2cm Vertical intercept 22.9cm Vertical intercept 4mm electron ion 5mm IR design with ’interleaved’ FF quads

16. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 10 cm 14cm 3cm 1.8m 20.8kG/cm 4.6cm 8.6cm Electron (9GeV) Proton (225GeV) 2.4cm 10cm 2.4cm 3cm 4.8cm B-Field in coil and force collar following talk by Paul Brindza ‘Lambertson quad’ for the final focus

17. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 ‘Crab Crossing’  Multi-cell SRF cavities KEK B-Factory ‘Crab Cavity’  Squashed cell cavity @ TM110 B field K. Oide Crab Cavity requirement for 22 mrad crossing: Electron: 1.2 MV – (KEK, single cell, 1.4 MV) Ion: 24 MV (multi-cell cavity, R&D raquired)

18. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 E ion = 225 GeV  * = 5/5 mm  N = 1.3/0.06  m rad Final Focus Optics  Beam envelopes 380 cm E electron = 9 GeV  * = 5/5 mm  N = 90/3.6  m rad  max = 4.0/2.4 mm  max = 3.1/32 km Quads L[cm]G[kG/cm] 50 3.2 60 -2.6 80 3.9 220 cm 350 cm 100 cm  max = 5.0/3.8 mm  max = 4.8/54 km Quads L[cm] G[kG/cm] 180 20.8 300 -12.0 200 23.0 200 -22.0 450 cm 100 cm 350 cm 50 cm 450 cm 100 cm 350 cm 50 cm 380 cm220 cm 350 cm 100 cm

19. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 FF doublet IR  Matching to the Ring x,y  x,y * = 5 mm FF doublet FODO matching singlet-doublet E ele = 9 GeV x,y  x,y max = 3.1/32 km 3.8 m

20. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 FF doublet IR  Matching to the Ring x,y  x,y * = 5 mm FF doublet FODO matching singlet-doublet E ele = 9 GeV x,y  x,y max = 3.1/32 km 3.8 m

21. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 FF doublet IR  Matching to the Ring x,y  x,y * = 5 mm FF doublet FODO matching singlet-doublet E ele = 9 GeV x,y  x,y max = 3.1/32 km 3.8 m

22. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 FF doublet IR  Matching to the Ring x,y  x,y * = 5 mm FF doublet FODO matching singlet-doublet E ele = 9 GeV x,y  x,y max = 3.1/32 km 3.8 m

23. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 IR Beta Chromaticity IR Ions IR elactrons  p/p = 0, 0.0001,….., 0.0005 following talk by Hisham Sayed

24. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 following talk by Pavel Chevtsov ‘Spin rotators’  Electron Ring at 9 GeV full ‘bending’ cells empty ‘straight’ cells Solenoid magnet $Lb=300 cm $B=100 kG

25. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 ‘Spin rotators’  Electron Ring at 9 GeV full ‘bending’ cells empty ‘straight’ cells Skew Quads $Lb=90 cm $G=0.18 kG/cm decoupled spin rotator module

26. Operated by JSA for the U.S. Department of Energy Thomas Jefferson National Accelerator Facility EIC Collaboration Meeting, Hampton University, May 19-23, 2008 Conclusions Compelling case for High Luminosity ELIC Based on present assumptions 10 35 [cm -2 s -1 ] luminosity collider is feasible … more studies needed… Optics  Conceptual lattice design of major sub-systems Interleaved Interaction Regions for both species Figure-8 Arc lattices Matching between sections Compact ‘Spin rotator’ Optics Still to come…. Chromatic compensations, higher order effects Complete spin matching Optics (IR-to-IR)