Recent Progress toward a High-Luminosity EIC at JLab

1. Recent Progress toward a High-Luminosity EIC at JLab 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. In support of this new direction: We recommend the allocation of resources to develop accelerator and detector technology necessary to lay the foundation for a polarized Electron Ion Collider. The EIC would explore the new QCD frontier of strong color fields in nuclei and precisely image the gluons in the proton.”

2. 2007: The ELectronIon Collider at JLab Concept • NSAC LRP: EIC = a 3-10 GeV on 25-250 GeV ep/eA collider •  fully-polarized, longitudinal and transverse • JLab implementation: luminosity ~7x 1034 cm-2 s-1 • JLab implementation: 4 Interaction Regions (IRs) ElectronCooling Snake IR •  large asymmetry between electron/ion energies •  reduced luminosity (factor of 10) at low Ecm • new ion complex with Ep ~ 250 GeV is expensive IR Snake ELIC New Ion Complex: 30-250 GeV Protons 15 -125 GeV/n Ions CEBAF: 3-11 GeV Electrons

3. Recent Progress toward a High-Luminosity EIC at JLab Brought to you by the MEIC/ELIC Study Group Nuclear Physics (exp) Tanja Horn Charles Hyde Franz Klein Pawel Nadel-Turonski (thy) Vadim Guzey Christian Weiss CASA Alex Bogacz Slava Derbenev Geoff Krafft Yuhong Zhang (+ help from many others) With input from Larry Cardman Andrew Hutton Hugh Montgomery Tony Thomas

4. EIC@JLab High-Level Science Overview • Hadrons in QCD are relativistic many-body systems, with a fluctuating number of elementary quark/gluon constituents and a very rich structure of the wave function. • With 12 GeV we study mostly the valence quark component, which can be described with methods of nuclear physics (fixed number of particles). • With an (M)EIC we enter the region where the many-body nature of hadrons, coupling to vacuum excitations, etc., become manifest and the theoretical methods are those of quantum field theory.

5. The Science of an (M)EIC Nuclear Science Goals: How do we understand the visible matter in our universe in terms of the fundamental quarks and gluons of QCD? Overarching EIC Goal: Explore and Understand QCD • Four Major Science Questions (paraphrased from NSAC LRP07): • What is the three-dimensional spatial landscape of nucleons? • What is the internal spin landscape of nucleons? • What is the role of gluons in nuclei? • 4)What governs the transition of quarks and gluons into pions and nucleons? Or, Elevator-Talk EIC science goals: Map the spin and 3D quark-gluon structure of protons (show the nucleon structure picture of the day…) Discover the role of gluons in atomic nuclei (without gluons there are no protons, no neutrons, no atomic nuclei) Understand the creation of the quark-gluon matter around us (how does E = Mc2 work to create quarks/anti-quarks and hadrons?)

6. (M)EIC@JLab: Basic Considerations • Optimize for nucleon/nuclear structure in QCD • - access to sea quarks/gluons (x > 0.01 or so) • - deep exclusive scattering at Q2 > 10 • - any QCD machine needs range in Q2 •  s = 1000 or so to reach decade in Q2 •  high luminosity, >1034 and approaching 1035, essential •  lower, more symmetric energies for resolution & PID • Not driven by gluon saturation (small-x physics) … • … avoid fundamental conflict of “classical” EIC • “Sweet spot” for • - electron energies from 3 to 5 GeV (minimize synchrotron) • proton energies ranging from 30 to 60 GeV • but larger range of s accessible (Ee = 11 GeV, Ep = 12 GeV) • Decrease R&D needs, while maintaining high luminosities • Potential future upgrade to high-energy collider, • but no compromising of nucleon structure capabilities

7. A High-Luminosity EIC at JLab - Concept Legend: MEIC = EIC@JLab 1 low-energy IR (s ~ 200) 3 medium-energy IRs (s < 2600) ELIC = high-energy EIC@JLab (s = 11000) (limited by JLab site) MEIC Coverage Use CEBAF “as-is” after 12-GeV Upgrade

8. A High-Luminosity Electron-Ion Collider for Nuclear Physics at JLab – main parameters • MEIC is ring-ring collider with • electron energies ranging from 3 to 11 GeV • proton energies ranging from 12 to 60 GeV • Luminosity L ~ few x 1034, approaching 1035 cm-2 s-1 • MEIC requires less R&D, parameters within reach (?) • MEIC estimated cost ~ Half of ELIC • Most components reusable at higher energies • Physics: Nucleon/nuclear structure in QCD • (Gluon and sea quark imaging of the nucleon, nucleon spin, • nuclei in QCD, QCD vacuum and hadron structure) • Natural extension of 12 GeV • Consistent with NSAC Long-Range Plan

9. 2009: A High-Luminosity Medium-Energy Collider (MEIC) for Nuclear Physics at Jlab • fully-polarized, longitudinal and transverse • energy range more optimized for JLab-type NP •  luminosity ~ few x 1034 cm-2 s-1 over range of Ecm •  more symmetric energies •  reduced cost, ~ half of ELIC •  less R&D needs MEIC New Ion Complex: 30-60 GeV Protons 15 -30 GeV/n Ions CEBAF: 3-11 GeV Electrons

10. WM City of NN State City of NN MEIC Footprint (~600m) SURA ELIC Footprint (~1800m) CEBAF MEIC/ELIC Figure-8 Collider Ring Footprint Medium Energy IP Low Energy IP Snake Insertion 60° • MEIC luminosity is limited by • Synchrotron radiation power of e-beam •  requires large ring (arc) length • Space charge effect of p-beam •  requires small ring length • Multiple IRs require long straight • sections. Recent thinking: start with • 18 meter detector space for all IRs • to make life easier (?) • Straight sections also hold other required components (electron cooling, injection & ejections, etc.)

11. EIC@JLab – Interaction Region Assumptions Can one use pluses of green field (M)EIC/ELIC in IR design? - Four Interaction Regions available - novel design ideas promise high luminosity - more symmetric beam energies  “central” angles - figure-8 design optimized for spin (no impact on IR design) Main IR assumptions (make life simple…): - concentrate on one IR as main-purpose detector - separate diffractive/low-Q2 “Caldwell-type” detector from main-purpose detector (if needed) - define relatively long (18 meter) fixed detector space (albeit with loss in luminosity) - use flexibility in RF frequency to advantage (high RF for main detector physics?, low for eA diffraction?, etc.)

12. (M)EIC@JLab Interaction Region Concept Medium Energy IP Snake Insertion 60° Low Energy IP IR1: General Purpose detector (but not diffractive/low-Q2?) IR3: Diffractive/Low-Q2 detector p e IR4: Low Energy detector IR2: Polarimetry etc. Low Energy: 12 on 3-5 [sqrt(s) only factor of three higher than 12-GeV program] Medium Energy: 30-60 on 3-5 (11) IR Regions: +/- 9 meter

13. Why an Electron-Ion Collider? • Longitudinal and Transverse Spin Physics! • 70+% polarization of beam and target without dilution • transverse polarization also 70%! • Detection of fragments far easier in collider environment! • fixed-target experiments boosted to forward hemisphere • no fixed-target material to stop target fragments • access to neutron structure w. deuteron beams (@ pm = 0!) • Easier road to do physics at high CM energies! • Ecm2 = s = 4E1E2 for colliders, vs. s = 2ME for fixed-target •  4 GeV electrons on 12 GeV protons ~ 100 GeV fixed-target • Easier to produce many J/Y’s, high-pT pairs, etc. • Easier to establish good beam quality in collider mode Longitudinal polarization FOM

14. What Ecm and Luminosity are needed for Deep Exclusive Processes? • New Roads: • r and f Production give access to gluon GPD’s at small x (<0.2) • Deeply Virtual Meson • Production @ Q2 > 10 GeV2 •  disentangles flavor and spin! Well suited processes for the EIC  transverse spatial distribution of gluons in the nucleon Can we do such measurements at fixed x in the valence quark region? This IS important if we really want a full picture of orbital motion… fixed x: s ~ s/Q2 (Mott) x 1/Q4 (hard gluon exchange)2

15. Science reach as function of ECM and integrated luminosity 50 fb-1 1 year ~ 20 weeks @ 50% eff. @ 1 x 1034 = 6 x 1040 ~ 60 fb-1 ECM (GeV) 120 xmin ~ 10-4 100 gluon saturation DISnucleon structure exclusive, electroweak processes quarks, gluons in nuclei 80 need multiple conditions: Longitudinal, Transverse, 1H, 2H, 3He, heavy A, low, high Ecm 60 MEIC 40 xmin ~ 10-3 sin2θW 20 xmin ~ 10-2 0 1 10 100 ∫L dt (fb-1)

16. (M)EIC@JLab: Where we are (or, were for 8 m detector space) Polarized ep Facilities Plot assumptions: (M)EIC Luminosities optimized at 5 GeV on 12 GeV and 5 GeV on 60 GeV. Detector/DAQ/electronics limits the luminosity to 1035. Scale to higher electron beam energies (up to 11 GeV) at fixed synchrotron limit. Luminosity for staged eRHIC at 2 on 250 is similar as for 4 GeV on 250 GeV. JLab/12 HERMES Draft ENC/GSI COMPASS Luminosity (1033 s-1 cm-2) (M)EIC Staged eRHIC Note: chose more conservative 18 m detector space estimated L = few x 1034, work in progress s (GeV2) • Design provides excellent luminosity for 200 < s < 1200 (x = 0.0008 @ Q2 = 1) • (x = 0.01 @ Q2 = 12) • Good luminosity (1033 or more) down to s = 100 and up to s = 2640 • (can access gluons down to x = 0.001 or so)

17. Recent Progress toward a High-Luminosity EIC at JLab - High-Level Summary What science goals are accessed/appropriate? • Gluon and sea quark (transverse) imaging of the nucleon • Nucleon Spin (DG vs. ln(Q2), transverse momentum) • Nuclei in QCD (gluons in nuclei, quark/gluon energy loss) • QCD Vacuum and Hadron Structure and Creation • Energies and figure-8 ring shape and size chosen to optimize • polarization and luminosity • Try to minimize headaches due to synchrotron and large leaps in • state-of-the-art through R&D • 4 Interaction Regions, with function and size optimized to “decouple” • detector from accelerator – can optimize later to increase luminosity

18. General Info MEIC/ELIC web pages are now accessible to all: http://www.jlab.org/meic General EIC web page: http://web.mit.edu/eicc/ Bi-weekly meetings on EIC accelerator/IR design in ARC 728 (in collaboration with CASA/Accelerator), and bi-weekly meetings on EIC science/detector in CC F326/7 All meetings can be accessed by all, also remotely. (1st meeting is call-in, 2nd meeting is EVO video conferencing) If interested, please subscribe to meic@jlab.org Friday, 9:30 – 11:00 am

19. Backup Slides

20. s = 2650 sufficient to transcend into region of large rise of gluon density MEIC@JLab coverage

21. Science Matrix – alternate version 1036 x ~ Q2/ys 1035 EW Luminosity (s-1 cm-2) 1034 DES SIDIS 1033 DIS DIFF Saturation 1032 10 100 1000 10000 100000 s (GeV2)

22. CTEQ Example at Scale Q2 = 10 GeV2 “dip” in u,d pdf’s at x ~ 0.01 (@ Q2 =10 GeV2)  s ~ 1000 appropriate

23. The Venerable (Nuclear) EMC Effect F2A/F2D “EMC Effect” 10-4 10-3 10-2 10-1 1 x x < (5 times 10-3) for saturation in shadowing to start? Need about decade in Q2 to verify LT vs. HT of effects  want to push down to x ~ 0.0005 (@ Q2 = 1) w. MEIC. Space-Time Structure of Photon Ecm = 10 – 45 (s = 100 – 2000) is in the right ballpark for nucleon/nuclear structure studies

24. Reaching Saturation: EIC Options G ~ A1/3 x s0.3 (A = 208)

25. e-cooling (RHIC II) PHENIX Main ERL (2 GeV per pass) STAR Four e-beam passes Four Electron-Ion Collider Facilities Considered eRHIC ELIC ElectronCooling Snake IR IR Snake MANUEL LHeC Add electron beam (COSY ring) to GSI/HESR

26. Four Electron-Ion Collider Facilities Considered EICx2: L > 1x1033 cm-2s-1 Ecm = 20-100+ GeV LHeC: L = 1.1x1033 cm-2s-1 Ecm = 1.4 TeV • Variable energy range • Polarized and heavy ion beams • High luminosity in energy region • of interest for nuclear science • Add 70-100 GeV electron ring to • interact with LHC ion beam • Use LHC-B interaction region • High luminosity mainly due to • large g’s (= E/m) of beams • Nuclear science goals: • Explore the new QCD frontier: • strong color fields in nuclei • Precisely image the sea-quarks • and gluons to determine • the spin, flavor and spatial • structure of the nucleon. • High-Energy physics goals: • Parton dynamics at the TeV scale • - physics beyond the • Standard Model • - physics of high parton • densities (low x) • Add 3 GeV electron accelerator to interact with FAIR ion beam MANUEL@FAIR: L > 1x1033 cm-2s-1? Ecm = 13 GeV • Nuclear science goal: • Precisely image the sea-quark and gluon structure of the nucleon.

27. ELIC/MEIC in JLab Site

28. Recent Progress with a High-Luminosity EIC at JLab • 2007 LRP: EIC = a 3-10 GeV on 25-250 GeV ep/eA collider • fully-polarized, longitudinal and transverse •  luminosity ~ 1033-1034 cm-2 s-1 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.”