1. Vasiliy Morozov on behalf of MEIC Study Group JLab Users Group Meeting, June 3, 2015 Status of Medium-energy Electron Ion Collider (MEIC) Design

2. 22 IPAC’15, Richmond, May 5, 2015 2 2 JLab Users Group Meeting, June 3, 2015 2 Outline EIC Science highlights and design strategies for the MEIC at JLAB MEIC baseline design − Overview of collider complex components − Detector integration − Electron cooling − Polarization − Machine performance − R&D overview Summary and Outlook

3. 33 IPAC’15, Richmond, May 5, 2015 3 3 JLab Users Group Meeting, June 3, 2015 3 MEIC Timeline and context MEIC design (10+ years) Physics case and machine requirements defined by White Paper (2011) Preliminary conceptual design report (2012) Design optimization, EICAC reviews, internal reviews NSAC/LRP process starts (2014) NASC/LRP Cost Review (January 2015) Final design optimizations (February-June 2015)  baseline Pre-project R&D planning and execution (2015-2017) Conceptual Design Report planning and execution (2015-2017) GOAL:Ready for CD1 and down-select

4. 44 IPAC’15, Richmond, May 5, 2015 4 4 JLab Users Group Meeting, June 3, 2015 4 Electron Ion Collider NSAC 2007 Long-Range Plan: “An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier. EIC would provide unique capabilities for the study of QCD well beyond those available at existing facilities worldwide and complementary to those planned for the next generation of accelerators in Europe and Asia.” EIC Community White Paper arXiv:1212.1701

5. 55 IPAC’15, Richmond, May 5, 2015 5 5 JLab Users Group Meeting, June 3, 2015 5 EIC Physics Highlights An EIC will study the sea quark and gluon-dominated matter –3D structure of nucleons  How do gluons and quarks bind into 3D hadrons? –Role of orbital motion and gluon dynamics in the proton spin  Why do quarks contribute only ~30%? –Gluons in nuclei (splitting/recombining)  Does the gluon density saturate at small x? Need luminosity, polarization and good acceptance to detect spectator & fragments

6. 66 IPAC’15, Richmond, May 5, 2015 6 6 JLab Users Group Meeting, June 3, 2015 6 Why Jefferson Lab? Large established user community in the field CEBAF, the world highest energy SRF linac, as a full energy injector A Green Field new ion complex and two new collider rings provide opportunity for a modern design for highest performance Design meets experimental needs –Broad CM energy range –Wide range of ion species –Full-acceptance detectors –High luminosity –High polarization Low technical risk –Design largely based on conventional technologies CEBAF MEIC IP CEBAF center

7. 77 IPAC’15, Richmond, May 5, 2015 7 7 JLab Users Group Meeting, June 3, 2015 7 MEIC Design Overview √s from 15 to 65 GeV: 3 -10 GeV electrons, 20 -100 GeV protons Polarized light ions (p, d, 3 He, Li) & unpolarized light to heavy ions (Au, Pb) Up to 2 detectors including a full-acceptance primary detector Luminosity of 10 33 to 10 34 cm -2 s -1 per IP in a broad CM energy range >70% longitudinal e - polarization & transverse/longitudinal ion polarization Possibility of upgrade to higher energies and luminosity possible Warm Electron Collider Ring (3 to 10 GeV) Ion Source Booster Linac Cold Ion Collider Ring (8 to 100 GeV) Superferric magnets PEP-II components

8. 88 IPAC’15, Richmond, May 5, 2015 8 8 JLab Users Group Meeting, June 3, 2015 8 Design Strategy for High Luminosity The MEIC design concept for high luminosity is based on high bunch repetition rate CW colliding beams Beam Design High repetition rate Low bunch charge Short bunch length Small emittance IR Design Small β* Crab crossing Damping Synchrotron radiation Electron cooling “Traditional” hadrons colliders Small number of bunches Small collision frequency f Large bunch charge n 1 and n 2 Long bunch length Large beta-star KEK-B already reached above 2x10 34 /cm 2 /s

9. 99 IPAC’15, Richmond, May 5, 2015 9 9 JLab Users Group Meeting, June 3, 2015 9 Design Strategy for High Polarization The MEIC design concept for high luminosity is based on unique figure-8 shape ring structure –Spin precession in one arc is exactly cancelled in the other –Zero spin tune independent of energy –Spin control and stabilization with small solenoids or other compact spin rotators Efficient preservation of ion polarization during acceleration Energy-independent spin tune Ease of spin manipulation Any desired polarization at IP Spin flip The only practical way to accommodate polarized deuterons Small anomalous magnetic moment Strong reduction of electron depolarization due to the energy independent spin tune Advantages

10. 10 IPAC’15, Richmond, May 5, 2015 10 10 JLab Users Group Meeting, June 3, 2015 10 CEBAF - Full Energy Injector e - collider ring CEBAF fixed target program –5-pass recirculating SRF linac –Exciting science program beyond 2025 –Can be operated concurrently with the MEIC CEBAF will provide for MEIC –Up to 12 GeV electron beam –High repetition rate (up to 1497 MHz) –High polarization (>85%) –Good beam quality

11. 11 IPAC’15, Richmond, May 5, 2015 11 11 JLab Users Group Meeting, June 3, 2015 11 Electron Collider Ring e-e- R=155m RF Spin rotator CCB Arc, 261.7  81.7  Forward e - detection IP:  x,y *=(10,2)cm Tune trombone & Straight FODOs Future 2 nd IP Spin rotator Electron collider ring design –Circumference of 2154.28 m = 2 x 754.84 m arcs + 2 x 322.3 m straights –Reuses PEP-II magnets, vacuum chambers and RF Beam characteristics –3A beam current up to 6.95 GeV –Synchrotron radiation power density 10kW/m –Total power 10 MW

12. 12 IPAC’15, Richmond, May 5, 2015 12 12 JLab Users Group Meeting, June 3, 2015 12 Ion Sources and Linac Optimum lead stripping energy: 13 MeV/u 10 cryostats 4 cryostats 2 Ion Sources QWR HWR IH RFQ MEBT 10 cryos 4 cryos 2 cryos Ion species: p to Pb Ion species for the reference design 208 Pb Kinetic energy (p, Pb) 285 MeV 100 MeV/u Maximum pulse current: Light ions (A/Q 3) 2 mA 0.5 mA Pulse repetition rateup to 10 Hz Pulse length: Light ions (A/Q<3) Heavy ions (A/Q>3) 0.50 ms 0.25 ms Maximum beam pulsed power680 kW Fundamental frequency115 MHz Total length121 m ABPIS for polarized or un-polarized light ions, EBIS and/or ECR for un-polarized heavy ions Linac design based on the ANL linac design. Pulsed linac capably of accelerating multiple charge ion species (H - to Pb 67 +) –Warm Linac sections (115 MHz)  RFQ (3 m)  MEBT (3 m)  IH structure (9 m) –Cold Linac sections  QWR + QWR (24 + 12 m) 115 MHz  Stripper, chicane (10 m) 115 MHz  HWR section (60 m) 230 MHz

13. 13 IPAC’15, Richmond, May 5, 2015 13 13 JLab Users Group Meeting, June 3, 2015 13 Booster Purpose of Booster –Accumulation of ions injected from Linac –Cooling –Acceleration of ions –Extraction and transfer of ions to the collider ring 8 GeV Booster design –Based on super-ferric magnet technology –Circumference of 273 m –Achromatic arcs’ design with partly negative horizontal dispersion to minimize momentum compaction to avoid transition crossing –Figure-8 shape for preserving ion polarization extraction RF cavity Crossing angle: 75 deg. E kin = 285 MeV – 8 GeV injection 272.3060 70 0 7 -7 BETA_X&Y[m] DISP_X&Y[m] BETA_XBETA_YDISP_XDISP_Y Straight Inj. Arc (255 0 ) Straight (RF + extraction) Arc (255 0 )

14. 14 IPAC’15, Richmond, May 5, 2015 14 14 JLab Users Group Meeting, June 3, 2015 14 Ion Collider Ring Layout IP:  x,y *=(10,2)cm disp. supp./ geom. match disp. supp. / geom. match det. elem. norm.+ SRF tune tromb.+ match elec. cool. ions 81.7  disp. supp. / geom. match Future 2 nd IP R=155m Arc, 261.7  Ion collider ring design –match the geometry of PEP-II-component-based electron ring –Use Super-ferric magnets  ~3 T maximum field for maximum proton momentum of 100 GeV/c, 4.5 k operating temperature  Cost effective construction and operation (factor of ~2 cheaper to operate, GSI)

15. 15 IPAC’15, Richmond, May 5, 2015 15 15 JLab Users Group Meeting, June 3, 2015 15 Full-Acceptance Detector 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 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

16. 16 IPAC’15, Richmond, May 5, 2015 16 16 JLab Users Group Meeting, June 3, 2015 16 Far-Forward Detection Performance e p n,  20 Tm dipole 2 Tm dipole solenoid Neutrals detected in a 25 mrad (total) cone down to zero degrees  Space for large (> 1 m diameter) Hcal + Emcal Excellent acceptance for all ion fragments Recoil baryon acceptance:  up to 99.5% of beam energy for all angles  down to at least 2-3 mrad for all momenta  full acceptance for x > 0.005 Resolution limited only by beam  longitudinal  p/p ~ 3  10 -4  angular  ~ 0.2 mrad 15 MeV/c resolution for 50GeV/u tagged deuteron beam

17. 17 IPAC’15, Richmond, May 5, 2015 17 17 JLab Users Group Meeting, June 3, 2015 17 Multi-Step Electron Cooling ion sources ion linac Booster (0.285 to 8 GeV) collider ring (8 to 100 GeV) BB cooler DC cooler RingCoolerFunction Ion energy Electron energy GeV/uMeV Booster ring DC Accumulation of positive ions 0.11 ~ 0.19 (injection) 0.062 ~ 0.1 Emittance reduction21.1 Collider ring Bunched Beam Cooling Maintain emittance during stacking 7.9 (injection) 4.3 Maintain emittanceUp to 100Up to 55 ion bunch electron bunch Cooling section solenoid SRF Linac dump injector energy recovery Cooling of ion beams in the MEIC is critical for delivering high luminosity over a broad CM energy range –Help accumulation of positive ions –Reduce the emittance –Maintain the emittance

18. 18 IPAC’15, Richmond, May 5, 2015 18 18 JLab Users Group Meeting, June 3, 2015 18 Ion Polarization in Booster No special care is needed for ion polarization before the booster –highly polarized ion source + no polarization loss in the linac Polarization in Booster stabilized and preserved by a single weak solenoid –0.7 Tm at 9 GeV/c – d / p = 0.003 / 0.01 Longitudinal polarization in the straight with the solenoid Comparison: Conventional 9 GeV accelerators require B || L of ~30 Tm for protons and ~110 Tm for deuterons beam from Linac Booster to Collider Ring B II L

19. 19 IPAC’15, Richmond, May 5, 2015 19 19 JLab Users Group Meeting, June 3, 2015 19 Ion Polarization in Collider Ring “3D spin rotator” rotates the spin about any chosen direction in 3D and sets the stable polarization orientation –Maximum B  of 3 T and B || of 3.6 T => d / p = 0.00025 / 0.01 Placement of 3D spin rotator in the collider ring Another 3D spin rotator suppresses the zero-integer spin resonance Spin-control solenoids Vertical-field dipoles Radial-field dipoles Lattice quadrupoles 3D Spin Rotator IP ion

20. 20 IPAC’15, Richmond, May 5, 2015 20 20 JLab Users Group Meeting, June 3, 2015 20 Electron Polarization Electron polarization design: –Vertically polarized (>85%) electron beam from CEBAF –Vertical polarization in the arcs and longitudinal at collision points –Spin rotator for the polarization rotation –Compton polarimeter provides non-invasive continuous measurement of polarization –Average electron polarization reaches above 70% IP Spin Rotator e-e- Magnetic field Polarization Energy (GeV)357910 Estimated Pol. Lifetime (hours) 665.22.21.30.8 Polarization Configuration cc Laser + Fabry Perot cavity e - beam Low-Q 2 tagger for low-energy electrons Low-Q 2 tagger for high- energy electrons Electron tracking detector Photon calorimeter IP Compton Polarimeter

21. 21 IPAC’15, Richmond, May 5, 2015 21 21 JLab Users Group Meeting, June 3, 2015 21 e-p Collision Luminosity 10 34 10 33 e: 5 GeV P: 100 GeV e: 10 GeV P: 100 GeV e: 4 GeV P: 30 GeV e: 4 GeV P: 75 GeV e: 4 GeV P: 50 GeV

22. 22 IPAC’15, Richmond, May 5, 2015 22 22 JLab Users Group Meeting, June 3, 2015 22 Overview of R&D Prototypes –Development and testing of 1.2m 3T SF magnets for MEIC ion ring and booster Collaboration with Texas A&M, FY15-16 –Crab cavity development (collaboration with ODU, leveraging R&D for LHC / LARP crab) –952 MHz Cavity development, FY15-17 Design optimization/Modeling –Optimization of conceptual design of MEIC ion linac Collaboration with ANL and/or FRIB, FY 15-17 –Optimization of Integration of detector and interaction region design, detector background, non-linear beam dynamics, PEP-II components Collaboration with SLAC, FY 12-17 –Feasibility study of an experimental demonstration of cooling of ions using a bunched electron beam Collaboration with Institute of Modern Physics, China –Studies and simulations on preservation and manipulation of ion polarization in a figure- 8 storage ring Collaboration with A. Kondratenko, FY 13-15 –Algorithm and code development for electron cooling simulation, FY 15-16

23. 23 IPAC’15, Richmond, May 5, 2015 23 23 JLab Users Group Meeting, June 3, 2015 23 Summary and Outlook MEIC is a ring-ring collider project with mature design –Luminosities from 10 33 up to 10 34 cm -2 s -1 in a broad CM energy range –Beam polarizations over 70% –Low technical risk MEIC design meets the nuclear physics community requirements R&D work continues Cost and performance optimization continues MEIC design upgradable in energy and luminosity

24. 24 IPAC’15, Richmond, May 5, 2015 24 24 JLab Users Group Meeting, June 3, 2015 24 MEIC Collaboration