Legend: 1 low-energy IP (s ~ 300) 2 medium-energy IPs (s < 3000) ELIC =high-energy (s = 20000?) (E p ~ 250 limited by JLab site) Use CEBAF “as-is” after 12-GeV Upgrade E e = 3 – 11 GeV (upgradeable to 20+ GeV) E p = 20 – 60+ GeV (12 GeV injection energy) (upgradeable to 250 GeV) E cm 2 = s = 4E e E p MEIC/ELIC Design Process at JLab

MEIC Design Choices Achieving high luminosity  Very high bunch repetition frequency (1.5 GHz)  Very small β* to reach very small spot sizes at collision points  Short bunch length (σ z ~ β*) to avoid luminosity loss due to hour-glass effect (unless other mitigation schemes used)  Relatively small bunch charge for making short bunch possible  High bunch repetition restores high average current and luminosity MEIC High repetition rate Small bunch charge Short bunch length Small β* MeRHIC Low repetition rate High bunch charge Long bunch length (but…) Large β* (but…) VS. This luminosity concept has been tested at two B-factories very successfully, reaching luminosity above cm -2 /s -1

Current Ideas for a Collider Energiessluminosity to 11 x Close to Future Up to 11 x 250 (22? x 250) (22000?) Close to Staged  IP12/main ring Up to 4 x x 250? (?)-5000(?) Few x Close to (?) to 20 x Few x to 3 x 15180Few x to 70 x Design Goals for Colliders Under Consideration World-wide Present focus of interest (in the US) are the (M)EIC and Staged MeRHIC versions, with s up to ~3000 and ~5000, resp.

Both laboratories are working together to get advice on the best steps towards a US Electron-Ion Collider. Sam Aronson and Christoph Lehmann/Hugh Montgomery have named an international EIC Advisory Committee: Joachim Bartels Allen Caldwell Albert De Roeck Walter Henning (chair) David Hertzog Xiangdong Ji Robert Klanner Alfred Mueller Katsunobu Oide Naohito Saito Uli Wienands 1 st meeting Feb. 16, 2009 at SURA headquarters, D.C. 2 nd meeting Nov. 2&3, 2009 at Jefferson Lab 3 rd meeting around September???, 2010 At BNL??? Concrete design for requested by this meeting Internal reviewed cost estimate requested by this meeting

Near-Term MEIC Design Parameters ElectronProton Collision energyGeV3 – Ion booster 3–12 GeV, ring accepts 12 GeV injection Max dipole fieldT6Not too aggressive after LHC Max SR powerkW/ m 20Factor two beyond best achieved? Max currentA21~ max B-factory current, HOM in component HERA 0.15 A (?) RHIC 0.3 A RF frequencyGHz1.5 Use combination of gap (crossing angle) and RF shift to accommodate lower ion energies Bunch lengthmm556 mm demonstrated in B-factory, 10 cm in RHIC (?) IP to front face of 1 st quad (l) m+/- 3 to 4+/- 7 Vertical β*cm22Keep β max below ~2 km, with  max = l 2 /  * Crossing anglemrad10050 to 150 desired for detector advantages Luminosity expected to be around 1 x e-nucleons/s/cm 2 around 60x5 GeV 2, and be well above at “s edges”

Plan and Deliverables Accelerator Design “Contract” –Medium energy with scaled down parameters (ELIC version M.1) –“Contract” revision (end of 2010), after user workshops and the next EIC AC meeting “Design Manual” –A 20 to 30 page document, archived in web –Explanation of high level design choices –Main and secondary parameters, schemes –Major components, and interfaces between them Action items –Finish “action items/decision points” in about a week each –Work scope Collecting information/references Performing estimations/calculations if applicable Formulate a solution/recommendation Present in ELIC R&D meeting Write a (minimum) half page on each item for the “design manual” Similar Action Item: Detector/IR document Slide from Yuhong Zhang

MEIC/ELIC Design Process - Status Near-term design concentrates on parameters that are within state-of-the-art (exception: small bunch length & small vertical  * for proton/ion beams) Detector/IR design has concentrated on maximizing acceptance for deep exclusive processes and processes associated with very-forward going particles (detect remnants of struck quark & spectator quarks!) Exact energy/luminosity profile still a work in progress Summer 2010: MEIC design review followed by internal cost review (and finalizing input from user workshops) Many parameters related to the detector/IR design seem to be well matched now (crossing angles, magnet apertures/gradients/peak fields, field requirements), such that we do not end up with large “blind spots”.

Electron-Ion Collider – Roadmap beyond JLab user EIC workshops EIC (eRHIC/ELIC) webpage: Weekly meetings at both BNL and JLab Wiki pages at & EIC Collaboration has biannual meetings since 2006 Last EIC meeting: January 10-12, Stony Brook Next meeting: July 29-31, Catholic University, DC Long INT10-03 Institute for Nuclear Theory, centered around spin, QCD matter, imaging, electroweak Sept. 10 – Nov. 19, 2010 Periodic EIC Advisory Committee meetings (convened by BNL & JLab) After INT10-03 program (2011 – next LRP) need to produce single, community-wide White Paper laying out full EIC science program in broad, compelling strokes and need to adjust EIC designs to be conform accepted energy-luminosity profile of highest nuclear science impact followed by an apples-to-apples bottom-up cost estimate comparison for competing designs, folding in risk factors and folding in input from ongoing Accelerator R&D, EICAC & community

Backup

Quotes from EICAC Report on Accelerator R&D Priorities Highest priority:  Design of JLab EIC  High current (e.g. 50 mA) polarized electron gun  Demonstration of high energy – high current recirculation ERL  Beam-Beam simulations for EIC  Polarized 3He production and acceleration  Coherent electron cooling High priority, but could wait until decision made:  Compact loop magnets  Electron cooling for JLab concepts  Traveling focus scheme (it is not clear what the loss in performance would be if it doesn’t work; it is not a show stopper if it doesn’t)  Development of eRHIC-type SRF cavities Medium Priority:  Crab cavities  ERL technology development at JLAB Slide from Steve Vigdor

EIC – JLab User Meetings Roadmap March 12 + Electron-Nucleon Exclusive Reactions March 14 + Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions April 07, 08, Nuclear Chromo-Dynamic Studies May 17 Electroweak Studies June 04 + MEIC Detector Workshop June 07,08, JLab Users Group Meeting In parallel: MEIC/ELIC design worked out following highest EICAC (Nov meeting) recommendation related to accelerator Energy-Luminosity profile of EIC design will likely be optimized over time to adjust to novel accelerator science ideas & the nuclear science case  For now we assume a base luminosity, say e-ions/cm 2 /s  Fold in what energies are needed for e.g. L/T separations, imaging, range in Q 2 required at fixed x given y cuts, etc.  Study what luminosity is required at what energies to optimize the science output, and fold in implications for the detector/acceptance

EIC Project - Roadmap YearCEBAF UpgradeElectron-Ion Colldier st CEBAF at Higher Energies Workshop 1996 (LRP)CEBAF Upgrade an Initiative ~2000Energy choice settled, “Golden Experiments” 1 st workshops on US Electron-Ion Collider 2002 (LRP)JLab 12-GeV Upgrade 4 th recommendation Electron-Ion Collider an Initiative 2007 (LRP)JLab 12-GeV Upgrade highest recommendation Electron-Ion Collider “half-recommendation” 2010EIC “Golden Experiments”??? 2013? (LRP)JLab 12-GeV & FRIB construction highest recommendation? EIC a formal (numbered) recommendation? 2015JLab 12-GeV Upgrade construction complete EIC Mission Need, formal R&D ongoing? 2025?EIC construction complete?