1. Ion Collider Ring Design V.S. Morozov for MEIC study group MEIC Collaboration Meeting, JLab October 5-7, 2015

2. 22 December 18 2014 Page 2 2 MEIC Collaboration Meeting, JLab, October 5-7, 20152 Provide the necessary beam parameters ̶ 20(8)-100 GeV protons, 12-40 GeV/u ions ̶ Focusing at the IP that supports luminosities above 10 33 cm -2 s -1 ̶ Sufficient beam and luminosity lifetime Capability of operating multiple detectors ̶ One full-acceptance detector incorporated  Small angle detection ̶ Space for a second detector reserved Polarization preservation and control using figure-8 geometry ̶ Light ion (p, d, 3 He, and possibly Li) polarization above 70% ̶ Transverse and longitudinal polarization orientations adjustable at the IP ̶ Sufficient polarization lifetime Match the electron collider ring geometry ̶ Same tunnel Incorporate provisions for non-linear dynamics correction ̶ Sextupole families ̶ Chromatic correction scheme Ion Collider Design Requirements

3. 33 December 18 2014 Page 3 3 MEIC Collaboration Meeting, JLab, October 5-7, 20153 Figure-8 ring with a circumference of 2153.9 m Two 261.7  arcs connected by two straights crossing at 81.7  Ion Collider Ring R = 155.5 m Arc, 261.7  IP disp. supp./ geom. match #3 disp. supp./ geom. match #1 disp. supp./ geom. match #2 disp. supp./ geom. match #3 det. elem. disp. supp. norm.+ SRF tune tromb.+ match beam exp./ match elec. cool. ions 81.7  future 2 nd IP Polarimeter

4. 44 December 18 2014 Page 4 4 MEIC Collaboration Meeting, JLab, October 5-7, 20154 Ion Collider Ring Parameters Circumferencem2153.89 Straights’ crossing angledeg81.7 Horizontal / vertical beta functions at IP  * x,y cm10 / 2 Maximum horizontal / vertical beta functions  x,y max m~2500 Maximum horizontal dispersion D x m3.28 Horizontal / vertical betatron tunes  x,y 24(.38) / 24(.28) Horizontal / vertical natural chromaticities  x,y -101 / -112 Momentum compaction factor  6.45  10 -3 Transition energy  tr 12.46 Normalized horizontal / vertical emittance  x,y µm rad0.35 / 0.07 Horizontal / vertical rms beam size at IP  * x,y µm~20 / ~4 Maximum horizontal / vertical rms beam size  x,y mm2.8 / 1.3 All design goals achieved Resulting collider ring parameters Proton energy rangeGeV20(8)-100 Polarization%> 70 Detector spacem-4.6 / +7 Luminositycm -2 s -1 > 10 33

5. 55 December 18 2014 Page 5 5 MEIC Collaboration Meeting, JLab, October 5-7, 20155 Basic building block of the arcs ̶ Length of 22.8 m = 1.5  electron FODO cell lengths (26 cells per arc) ̶ Betatron phase advance of 90  in each plane Dipoles ̶ Magnetic/physical length of 8/8.28 m (implemented as two 4 m long pieces) ̶ Bending angle of 73.3 mrad (4.2  ), bending radius of 109.1 m, sagitta of 18.3 mm ̶ Field of 3.06 T at 100 GeV/c ̶ x aperture =  (4 cm+sagitta/2) =  5 cm, y aperture =  3 cm (10  + 1 cm orbit allowance) Quadrupoles ̶ Magnetic/physical length of 0.8/0.9 m ̶ Field gradients of 52.7/-52.9 T/m at 100 GeV/c ̶ Field of 2.1/-2.1 T at 40 mm radius Sextupole/corrector package next to each quadrupole ̶ Magnetic/physical length of 0.5/0.6 m ̶ 3 T at 40 mm focusing sextupole adds 34.8/-7.1 units of x/y chromaticity ̶ 3 T at 40 mm defocusing sextupole adds -3.7/18.1 units of x/y chromaticity BPM next to each quadrupole ̶ Physical length of 0.15 m Arc FODO Cell

6. 66 December 18 2014 Page 6 6 MEIC Collaboration Meeting, JLab, October 5-7, 20156 MEIC Super-Ferric Dipole 2 x 4 long dipole NbTi cable 3 T Correction sextupole Common cryostat talks by P. McIntyre and A.D. Kovalenko

7. 77 December 18 2014 Page 7 7 MEIC Collaboration Meeting, JLab, October 5-7, 20157 Provide dispersion suppression and geometric match to the electron ring Arc end upstream of IP ̶ Shaped to provide 50 mrad crossing angle at the IP Arc end downstream of IP ̶ Shaped to provide 1.5 m separation from the electron beam Arc Ends ions IP 20 m 5 m ions 10 m 2 m

8. 88 December 18 2014 Page 8 8 MEIC Collaboration Meeting, JLab, October 5-7, 20158 Detector Integration Fully-integrated detector and interaction region design that meets: –Detector requirements: full acceptance and high resolution –Beam dynamics requirements: consistent with non-linear dynamics requirements –Geometric constraints: matched collider ring footprints far forward hadron detection low-Q 2 electron detection large-aperture electron quads small-diameter electron quads central detector with endcaps ion quads 50 mrad beam (crab) crossing angle n,  e p p small angle hadron detection ~60 mrad bend (from GEANT4) 2 Tm dipole Endcap Ion quadrupoles Electron quadrupoles 1 m IPFP Roman pots Thin exit windows Fixed trackers Trackers and “donut” calorimeter RICH + TORCH? dual-solenoid in common cryostat 4 m coil barrel DIRC + TOF EM calorimeter Tracking EM calorimeter e/π threshold Cherenkov talks at the Detector & Interaction Region Sessions concept by P. Nadel-Turonski, R. Ent, and C. Hyde

9. 99 December 18 2014 Page 9 9 MEIC Collaboration Meeting, JLab, October 5-7, 20159 IR design features ̶ Modular design ̶ Based on triplet Final Focusing Blocks (FFB) ̶ Asymmetric design to satisfy detector requirements and reduce chromaticity ̶ Spectrometer dipoles before and after downstream FFB, second focus downstream of IP ̶ No dispersion at IP, achromatic optics downstream of IP Ion IR Optics IP ions match/ beam expansion FFB detector elements geom. match/ disp. suppression match/ beam compression

10. 10 December 18 2014 Page 10 10 MEIC Collaboration Meeting, JLab, October 5-7, 201510 Space reserved for two 30 m long cooling solenoids in one straight ̶ Solenoids of opposite fields for coupling compensation and polarization dynamics Electron Cooling Section ions cooling solenoidmatch cooling solenoid match

11. 11 December 18 2014 Page 11 11 MEIC Collaboration Meeting, JLab, October 5-7, 201511 Bunched Beam Electron Cooler Baseline cooling requirements –Emittance 0.5 to 1 mm-mrad -> reduce IBS effect –Magnetized beam, up to 55 MeV energy, 200 mA current –Linac for acceleration –Must utilize energy-recovery-linac (beam power is 11 MW) Solution : cooling by a bunched electron beam ion bunch electron bunch Cooling section solenoid SRF Linac dump injector energy recovery Electron energyMeV up to 55 Current and bunch chargeA / nC0.2 / 0.42 Bunch repetitionMHz476 Cooling section lengthm60 RMS Bunch lengthcm3 Electron energy spread10 -4 3 Cooling section solenoid fieldT2 Beam radius in solenoid/cathodemm~1 / 3 Solenoid field at cathodeKG2 talks at the Beam Cooling Sessions

12. 12 December 18 2014 Page 12 12 MEIC Collaboration Meeting, JLab, October 5-7, 201512 Two FODO cells with matching sections for betatron tune control ̶ One of the matching sections shared with electron cooling section Tune Trombone ions match 2  FODO match

13. 13 December 18 2014 Page 13 13 MEIC Collaboration Meeting, JLab, October 5-7, 201513 Filled with FODO Matching geometry of arc ends RF placed between FODO quadrupoles Second Straight without IR ions match FODO match RF talk by R. Rimmer

14. 14 December 18 2014 Page 14 14 MEIC Collaboration Meeting, JLab, October 5-7, 201514 Optics of a complete ring with all sections incorporated and matched Complete Ion Collider Ring Lattice ions Arc 1 Straight 2 IP Arc 2 Straight 1 Arc 1

15. 15 December 18 2014 Page 15 15 MEIC Collaboration Meeting, JLab, October 5-7, 201515 Nonlinear Dynamics: Ion Ring Explored multiple compensation schemes  –I sextupoles pairs in the arcs –Compensate chromatic smear at the IP –Compensate residual linear chromaticity with additional sextupoles (- 8   p/p, + 13   p/p ) At  p/p = 0.3% (- 40  x, + 40  x ) (- 40  y, + 40  y ) IP work and talks by Y. Nosochkov and M.-H. Wang of SLAC and G. Wei of JLab with a lot of help from D. Trbojevic, W. Guo, and Y. Jing of BNL

16. 16 December 18 2014 Page 16 16 MEIC Collaboration Meeting, JLab, October 5-7, 201516 Ion Polarization Figure-8 design –Zero spin tune independent of energy: spin precession in one arc is cancelled in the other –Spin control and stabilization with small solenoids or other compact spin rotators Spin tracking in progress –figure-8 with an error 2 T  2 m control solenoids can stabilize proton and deuteron spins up to 100 GeV no stabilization stabilization by 1  solenoid talk by A.M. Kondratenko

17. 17 December 18 2014 Page 17 17 MEIC Collaboration Meeting, JLab, October 5-7, 201517 Crab Crossing Restores effective head-on collisions with 50 mrad crossing angle –Luminosity preserved Deflective crabbing technology (demonstrated at KEK-B) –Transverse electric field of SRF cavities Local crabbing scheme –One set of cavities upstream of IP next to FFB –Another set of cavities  (n+1/2)  downstream of IP IP e-e- ions crab cavities talks by A. Castilla and J. Delayen

18. 18 December 18 2014 Page 18 18 MEIC Collaboration Meeting, JLab, October 5-7, 201518 Design of the baseline ion collider ring completed All design requirements met Beam parameters: 20(8)-100 GeV protons, luminosity > 10 33 cm -2 s -1 One full-acceptance detector integrated, room for a second detector reserved High polarization (>70%) adjustable to any orientation using figure 8 geometry Electron ring geometry matched Non-linear correction scheme developed and provisions for it incorporated into lattice Ongoing and future work –Design optimization –Non-linear dynamics correction –Error sensitivity studies –Integration of remaining components Detector solenoid and compensation Crab cavities Vertical doglegs Current Status & Outlook

19. 19 December 18 2014 Page 19 19 MEIC Collaboration Meeting, JLab, October 5-7, 201519 Backup

20. 20 December 18 2014 Page 20 20 MEIC Collaboration Meeting, JLab, October 5-7, 201520 50 mrad crossing angle ̶ Improved detection, no parasitic collisions, fast beam separation Forward hadron detection in three stages ̶ Endcap ̶ Small dipole covering angles up to a few degrees ̶ Far forward, up to one degree, for particles passing through accelerator quads Low-Q 2 tagger ̶ Small-angle electron detection Full-Acceptance Detector R. Ent, C.E. Hyde, P. Nadel-Turonski

21. 21 December 18 2014 Page 21 21 MEIC Collaboration Meeting, JLab, October 5-7, 201521 Detector Region Layout e-e- ions IP forward ion detection forward e - detection FFQs

22. 22 December 18 2014 Page 22 22 MEIC Collaboration Meeting, JLab, October 5-7, 201522 One straight contains an IR The other straight filled with FODO Layouts of Two Straights

23. 23 December 18 2014 Page 23 23 MEIC Collaboration Meeting, JLab, October 5-7, 201523 Dipoles: 133 ̶ 127 super-ferric, B < 3.06 T ̶ 2 special-design for IR + 4 cos(  ) super-conducting, B < 4.7 T Quadrupoles: 205 ̶ 155 with integrated field < 48 T ̶ 44 with integrated field < 72 T ̶ 6 special-design final-focusing quadrupoles Sextupoles: 125 ̶ Maximum pole-tip field ~1.5 T Correctors: 197 ̶ Each combines x/y kicker, skew quad and higher-order multipoles BPMs: 197 RF: 20 m of normal and 20 m of SC (talk by R. Rimmer) Special elements (talk by L. Harwood) ̶ Injection kicker ̶ Abort system ̶ Electron cooler solenoids ̶ Spin control elements: short solenoids and dipoles ̶ Polarimeter ̶ Crab cavities ̶ Collimators ̶ Detector solenoid compensating elements Basic Element Count