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COOL11 Electron-Ion Collider as a Gluon Microscope Yuhong Zhang Jefferson Lab Alushta, Ukraine, September 12-16, 2011.

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Presentation on theme: "COOL11 Electron-Ion Collider as a Gluon Microscope Yuhong Zhang Jefferson Lab Alushta, Ukraine, September 12-16, 2011."— Presentation transcript:

1 COOL11 Electron-Ion Collider as a Gluon Microscope Yuhong Zhang Jefferson Lab Alushta, Ukraine, September 12-16, 2011

2 COOL11 Outline Introduction Science Accelerator Designs Design Trends for Achieving High Performance Technology Innovations Outlook and Summary

3 COOL11 1. Introduction

4 COOL11 Electron-Ion Collider: The Next Generation HERA, the only electron-proton collider ever built, ended its highly successful physics program in 2007. Four next generation electron-ion colliders have been envisioned worldwide for reaching new frontiers of high energy and nuclear physics. All new proposals are built upon existing or under construction facilities which have already provided one of two colliding beams. Each of the new proposals, driven by the science programs, focuses on a distinct CM energy range from a few GeV to above TeV, accommodates one to three interaction points, and aims for much higher collider performances (luminosity, ion species and polarization) than HERA. Both the science cases and accelerator designs of these proposals are under active development. Collaborations among the high energy and nuclear scientists and accelerator designers are picking up momentum and have already yielded some interesting results.


6 COOL11 A Snapshot of Machine Design Evolution Sources –HERA F. Willeke, talk at DIS 2004, April 17, 2004, Strbske Pleso –LHeC F. Zimmermann, talk at UPHUK-4, Bodrum, Aug. 31, 2010 M. Klein, talk at DIS 2011, Newport News, April 11-15, 2011 A. Bogacz, talk at DIS 2011, Newport News, April 11-15, 2011 (Linac-Ring) M. Fitterer, talk at DIS 2011, Newport News, April 11-15, 2011 (Ring-Ring) –ENC K. Aulenbacher, talk at Spin 2010, Sept. 27, 2010, Twente, and additional slides (private communication) –eRHIC V. Ptitsyn, talk at INT, Seattle, Sept. 13, 2010 V. Litvinenko, talk at EIC Advisory Committee Meeting, Newport News, April 10, 2011 –MEIC Y. Zhang, talk at EIC Advisory Committee Meeting, Newport News, April 10, 2011 Acknowledgement I would like to thank authors for permitting me to use their slides for this talk

7 COOL11 2. Science

8 COOL11 The Nuclear Science of eRHIC/MEIC Overarching Goal: Explore and Understand QCD: Map the spin and spatial structure of quarks and gluons in nucleons Discover the collective effects of gluons in atomic nuclei (role of gluons in nuclei & onset of saturation) Emerging Themes: Understand the emergence of hadronic matter from quarks and gluons & EW The Nuclear Science of ENC Overarching Goal: Explore Hadron Structure Map the spin and spatial structure of valence & sea quarks in nucleons The High-Energy/Nuclear Science of LHeC Overarching Goal: lepton-proton at the TeV Scale Hunt for quark substructure & high-density matter (saturation) High precision QCD and EW studies and possible implications for GUT Science Goals R. Ent

9 COOL11 longitudinal momentum transverse distribution orbital motion quark to hadron conversion Dynamical structure! Gluon saturation? Obtain detailed differential transverse quark and gluon images (derived directly from the t dependence with good t resolution!)  Gluon size from J/Y and f electroproduction  Singlet quark size from deeply virtual compton scattering (DVCS)  Strange and non-strange (sea) quark size from π and K production Determine the spin-flavor decomposition of the light-quark sea Constrain the orbital motions of quarks & anti-quarks of different flavor  The difference between π +, π –, and K + asymmetries reveals the orbits Map both the gluon momentum distributions of nuclei (F 2 & F L measurements) and the transverse spatial distributions of gluons on nuclei (coherent DVCS & J/Y production). At high gluon density, the recombination of gluons should compete with gluon splitting, rendering gluon saturation. Can we see the onset of such saturation? Explore the interaction of color charges with matter & understand the conversion of quarks and gluons to hadrons through fragmentation and breakup. Why a New-Generation EIC? Why not HERA? R. Ent

10 COOL11 3. Accelerator Designs (from high to low CM energy)

11 COOL11 HERA: The 1st EIC Ever Built LeptonProton EnergyGeV27.5920 IntensitiesmA60180x10 11 Magnetic fieldT0.151.5 Acc. voltageMV1302 Luminositycm -2 s -1 (1.5 to 5) x 10 31 e-polarization%50 to 70 A Ring-Ring (polarized) Lepton-Proton collider with 320 GeV CM energy 1981 Proposal 1984 Start Building 1991 Commissioning, first Collisions 1992 Start Operations for H1 and ZEUS,  1st exciting results with low luminosity 1994 Install East Spin Rotators  longitudinal polarized leptons for HERMES 1996 Install 4 th Interaction region for HERA-B 1999 High Luminosity Run with electrons 2000 High efficient Luminosity production:100 /pb/y 2001 Install HERA Luminosity Upgrade, Spin Rotators for H1 and ZEUS 2003 1 st longitudinal polarization in high energy collisions 2007 End of a highly successful program Final luminosity: 1.5 to 5x10 31 cm -2 s -1

12 COOL11 LHeC: Ring-Ring 10 GeV e+/e- injector Electrons/positrons stored in the main ring Need a 10 GeV e+/e- injector, the current design is a recirculating linac Total filling time less than 10 min. Electron/positron is accelerated up to 60 GeV Early History Toward to CDR Power Limit: 100 MW wall plug! Bypass

13 COOL11 LHeC: Ring-Ring High Acceptance (1 deg.)High Luminosity (10 deg.) e-A Collisions Assuming present normal Pb beam in LHC Same beam size as protons Few bunches (592) 7x10 7 fully stripped 208 Pb 82 Assuming e-injector chain can provide the design bunch pattern (596 bunches of 6x10 10 ) Electron SR loss 45 MW Lepton-nucleon Luminosity at 60 GeV lepton energy L eA =1x10 32 cm -2 s -1 Polarization of 25% to 40% can be reasonably aimed for at 60 GeV with harmonic closed orbit spin matching Precision alignment of the magnets to better than 150 μm RMS needed to achieve a high polarization level Option of having Siberian snake Lepton polarization LHeC Polarization vs. Energy

14 COOL11 LHeC: Linac(ERL)-Ring Lots of flavors of 60 GeV Linac recirculating linac with energy recovery Straight linac LHC 10 GeV/pass Linac 1 Linac 2 Arc1, 3, 5 Arc 2, 4 Arc 6 10 GeV/pass IP 0.5 GeV Ring-ring or linac-ring, and which version of linac-ring will be decided at the end of 2011 A. Bogacz High energy, high current beams require GW-class RF systems in conventional linacs ERL alleviates extreme RF power demand  nearly independent of beam current ERL maintains superior beam quality: emittance, energy spread, short bunches (sub-ps) Why ERL?

15 COOL11 LHeC: Linac(ERL)-Ring Electron beamLR ERLLR e- energy at IP[GeV]60140 luminosity [10 32 cm -2 s -1 ]100.44 polarization [%]90 bunch population [10 9 ]2.01.6 e- bunch length [mm]0.3 bunch interval [ns]50 transv. emit.  x,y [mm] 0.050.1 rms IP beam size  x,y [  m] 77 e- IP beta funct.  * x,y [m] 0.120.14 full crossing angle [mrad]00 geometric reduction H hg 0.910.94 repetition rate [Hz]N/A10 beam pulse length [ms]N/A5 ER efficiency94%N/A average current [mA]6.65.4 tot. wall plug power[MW]100 ERL site power Cryo for two 10 GeV SRF Linacs: 28.9 MW RF power to control microphonics:22.2 MW Compensation for SR energy loss:24.1 MW cryo power: 2.1 MW microphonics control: 1.6 MW Injector RF: 6.4 MW Magnets: 3.0 MW grand total:88.3 MW Power Limit: 100 MW wall plug! Proton beamRRLR bunch population [10 11 ]1.7 transv. emit.  x,y [µm] 3.75 spot size  x,y [  m] 30, 167 β* x,y [m]1.8, 0.50.1 bunch spacing [ns]25

16 COOL11 eRHIC: ERL-Ring Brief History 2000 – 1st eRHIC paper (I. Ben Zvi et al.) 2002 – 1st White Paper on eRHIC/EIC 2003 – eRHIC appears in DoE’s “Facilities for the Future Sciences. A Twenty-Year Outlook” 2004 – “eRHIC Zeroth-Order Design Report” with cost estimate for Ring-Ring 2007 – Linac-ring became baseline (~10-fold higher luminosity) 2008 – first staging option of eRHIC 2009 – completed technical design, dynamics studies and cost estimate for MeRHIC with 4 GeV ERL Present - returned to the cost-effective (green) all in tunnel high-luminosity eRHIC design with staging electron energy from 5 GeV to 30 GeV polarized electrons with E e ≤ 30 GeV will collide with either polarized protons with E e ≤ 325 GeV or heavy ions E A ≤ 130 GeV/u eRHIC staging: All energies scale proportionally eSTAR ePHENIX Coherent e-cooler Beam dump Polarized e-gun 3rd detector 0.6 GeV 27.55 GeV 22.65 GeV 17.75 GeV 12.85 GeV 3.05 GeV 7.95 GeV 25.1 GeV 20.2GeV 15.3 GeV 10.4 GeV 30 GeV 5.5 GeV 30 GeV 27.55 GeV

17 COOL11 eRHIC: ERL-Ring ep 2 He 379 Au 19792 U 238 Energy, GeV20325215130 CM energy, GeV 161131102 Number of bunches/distance between bunches 74 ns166 Bunch intensity (nucleons),10 11 0.242355 Bunch charge, nC3.8323119 Beam current, mA50420411250260 Normalized emittance of hadrons, 95%, mm mrad 1.2 Normalized emittance of electrons, rms, mm mrad 233557 Polarization, %8070 none rms bunch length, cm0.24.9888 β*, cm55555 Luminosity per nucleon,x10 34 cm -2 s -1 (hourglass effect is included) 1.461.390.860.92 Reaching high luminosity: high average electron current (50 mA = 3.5 nC * 14 MHz) energy recovery linacs; SRF technology high current polarized electron source cooling of high energy hadrons (Coherent Electron Cooling) β*=5 cm IR with crab-crossing Reaching high luminosity: high average electron current (50 mA = 3.5 nC * 14 MHz) energy recovery linacs; SRF technology high current polarized electron source cooling of high energy hadrons (Coherent Electron Cooling) β*=5 cm IR with crab-crossing Protons Electrons GeV100130250325 50.62 (3.1)1.4 (5)9.715 100.62 (3.1)1.4 (5)9.715 200.62 (3.1)1.49.715 300.120.281.93 Polarized (unpolarized) e (80%) –p (70%) luminosities in 10 33 cm -2 sec -1 units Au ions Electrons GeV5075100130 52.58.311.418 102.58.311.418 200.491.73.98.6 300.10.340.771.7 Limiting factors: - hadron ΔQ sp ≤ 0.035 - hadron ξ ≤ 0.015 - polarized e current ≤ 50 mA - SR power loss ≤ 7 MW Limiting factors: - hadron ΔQ sp ≤ 0.035 - hadron ξ ≤ 0.015 - polarized e current ≤ 50 mA - SR power loss ≤ 7 MW

18 COOL11 eRHIC: Electron ERL Development Compact arc magnets 704 MHz SRF cavity ERL R&D Heavy ions and polarized protons already there at BNL Splitter & combiner Polarized e-injector Electron beams

19 COOL11 MEIC: Ring-Ring Prebooster Ion source Three Figure-8 rings stacked vertically Ion transfer beam line Medium energy IP Electron ring Injector 12 GeV CEBAF SRF linac large booster ion collider ring medium energy IP low energy IP Three compact rings: 3 to 11 GeV electron Up to 20 GeV/c proton Up to 100 GeV/c proton Brief History 2001 1 st paper on JLab EIC (Merminga, et al.) A Linac-Ring proposal based on CEBAF 2002 Circulator ring added to ERL-ring design 2003 ERL based circulator e-cooler 2006 ELIC baseline changed to ring-ring (linac-ring doesn’t help much with CW beam) 2007 ELIC Zero-th Order Design Report 2008 Low energy staging considered 2009 Medium energy EIC (MEIC) became the baseline with a future energy upgrade 2010 JLab User Workshops on EIC 2011 A design document for MEIC Present baseline Ring-ring collider MEIC: 3-11 GeV e on 20-100 GeV p or 8-40 GeV/u ion Upgradable to 20 GeV electron, 250 GeV proton or 100 GeV/u ion New ion complex & two collider rings Up to 3 interaction points Conventional electron cooling

20 COOL11 e-P e-A MEIC: Ring-Ring DetectorFull acceptanceHigh luminosity pepe Beam energyGeV605 5 Collision frequencyMHz750 Beam current & particles per bunchA / 10 10 0.5 / 0.4163 / 2.50.5/ 0.4163 / 2.5 Polarization%> 70~ 80> 70~ 80 RMS bunch lengthcm107.5107.5 Hori. and Vert. emitt., norm.µm0.35 / 0.0754 / 110.35 / 0.0754 / 11 Horizontal and vertical β*cm10 / 2 4 / 0.8 Vert. beam-beam tune shift0.0140.030.0140.03 Laslett tune shift0.06small0.06small Dist. from IP to 1 st FF quadm73.54.53.5 Luminosity per IP, 10 33 cm -2 s -1 5.614.2

21 COOL11 MEIC: A New Ion Complex Length (m) Max. energy (GeV/c) Electron Cooling SRF linac 0.2 (0.08) Pre-booster ~3003 (1.2)DC booster ~130020 (8 to 15) collider ring ~130096 (40)Staged/ERL Generate/accumulate and accelerate ion beams Covering all required varieties of ion species Matching time, spatial and phase space structure of the ion beam with electron beam (bunch length, emittance and repetition rate) * Numbers in parentheses represent energies per nucleon for heavy ions Normal conductingSuperconducting MEBT QWR HWR DSR Ion Sources IH RFQStripper Ion linac Double Spoke Resonator (DSR) Half-Wave Resonator (HWR) Quarter Wave Resonator (QWR) ARC 1 ARC 2 ARC 3 RF Cavities Electron Cooling Solenoids Extraction to large booster Collimation Beam from LINAC Pre-booster ion sources SRF Linac pre-booster (accumulator ring) Large booster medium energy collider ring To future high energy collider ring cooling Scheme

22 COOL11 ENC @ FAIR Use High Energy Storage Ring (HESR) for storing 15 GeV proton beam Add an electron storage ring for 3 GeV 2 A beam Share PANDA detector Head-on collision Baseline: β*=30 cm  2x10 32 cm- 2 s -1 Aggressive: β*=10 cm  6x10 32 cm- 2 s -1 With “traveling focusing”  10 33 cm- 2 s -1 HESR P e-e- polarized electron injector p-Ring e-Ring PANDA 8.2 MV eCool Vision: Electron Nucleon Collider @ FAIR Facility for Antiproton & Ion Research Nuclear structure physics (FAIR@GSI) Physics with antiprotons Nuclear matter physics Plasma physics Atomic physics

23 COOL11 ENC @ FAIR Due to availability of HESR storage ring & PANDA detector (from about year 2018 on), an upgrade to collider operation requires only a fraction of the cost of other projects. Considerable R&D is required to achieve the parameter set; however there seem to be no issues which are beyond the accepted potential of accelerator physics. Physics potential of ENC approaches stage 1 of the EIC concepts at BNL and JLab PANDA

24 COOL11 ENC @ FAIR 130m e-coolerr Antiprotons polarized protons out of SIS-18 Synchrotron 1.65 GeV pulsed. Linac 3.3 GeV Polarized electron source 3.3 GeV- Electron- storage-ring Conventional electron cooling Cooling times at low or ‘high’ energy with un-bunched beams ~1000s  Tricky interplay between space charge/bunching/cooling! Two pass recirculating Linac

25 COOL11 4. Trends for Achieving High Performance

26 COOL11 General Design Trends EIC machine design aims for high performance to meet science needs –US DoE/NSF NSAC Long Range Plan (2007): eRHIC/MEIC 100x higher luminosity than HERA New and forward-looking concepts and technologies have been incorporated into the designs, and shared by multiple proposals LHeC R-RLHeC L-ReRHICMEICENC New beam facilityElectron IonElectron CM energy range, up to (GeV)1296 81@stage 1 161@stage 2 66@stage 1 141@stage 2 13.4 Maximum luminosity (10 33 cm -2 s -1 )1.3114.614.20.2 Ion speciesp & lead p to uraniump to leadp Polarized leptonYes Polarized hadronYes Linac(ERL)-RingYes Reduction of ion (geo.) emittanceHigh energy Cooling Small beta-star of e / p (cm)18 / 5012 / 10510 (x), 2 (y)30 Proton beam-beam tune-shiftVery smallVery small (0.0001)0.015 x 3 IP0.015 x 2 IP0.015 Electron beam-beam disruption (L-R)60.2 to 140 Crab crossingYes (no crab cavity) Yes Advanced IR SchemeDetector-integrated dipole Traveling focus

27 COOL11 In a linac-ring collider, a lepton beam can tolerate much higher non-linear beam-beam perturbations since it is not stored in a ring, thus leading to a higher luminosity than a ring-ring collider of same collision frequency and other beam parameters ERL provides a practical way to accelerate high current lepton beam with a low RF power eRHIC Approach: Linac(ERL)-Ring Ring-ring: Linac-ring: RHIC Electron storage ring RHIC Electron linear accelerator Natural staging strategy ✔ L x 50

28 COOL11 MEIC Approach: High Repetition CW KEK-B e+e- collider already over 2x10 34 /cm 2 /s (a world record) Its luminosity concept Very small β* (~6 mm) Very short bunch length (σ z ~ β*) Very small bunch charge (5.3 nC) High bunch repetition rate CW (509 MHz) KEK BMEIC Repetition rateMHz509750 Particles per bunch10 3.3 / 1.40.42 / 2.5 Beam currentA1.2 / 1.80.5 / 3 Bunch lengthcm0.61 / 0.75 Horizontal & vertical β*cm56/0.5610 / 2 Luminosity per IP, 10 33 cm -2 s -1 205.6 ~ 14 MEIC is designed to replicate same success in electron-ion collider: A high repetition rate electron beam from CEBAF A new ion complex (so can match e-beam) Low Charge Intensity

29 COOL11 5. Technology Innovations

30 COOL11 Coherent Electron Cooling First suggested by Y. Derbenev, 1980, further development, 1991 & 1995 Recent development, V. Litvinenko & Y. Derbenev, PRL 2009 Very promising method for efficient cooling of high energy hadron beam, order of magnitude reduction of cooling time Important application in hadron-hadron & lepton-hadron colliders Potential luminosity increase: RHIC polarized pp ~ 6 fold, eRHIC ~ 5–10 fold, LHC ~ 2 fold ©G.Mahler modulatorAmplifer (via High Gain FEL) kicker undulator Proof-of-Principle experiment in RHIC IR 2 Collaboration between BNL, JLab & Tech-X

31 COOL11 ERL Based Circulator Electron Cooler ion bunch electron bunch circulator ring Cooling section solenoid Fast kicker SRF Linac dump injector Electron bunches circulate 100+ times, leads to a factor of 100+ reduction of current from a photo-injector/ERL Design choice to meet design challenges RF power (up to 50 MW) Cathode lifetime (130 kC/day) Required technology High bunch charge gun (ok) ERL (50 MeV, 15 mA) (ok) Ultra fast kicker energy recovery 10 m Solenoid SRF injector dumper cut cooling time by half, or reduce cooling current by half, or reduce number of circulations by half Cooling section at the center of Figure-8

32 COOL11 eRHIC Gatling Electron Gun Concept JLab 200kV inverted polarized gun recently reached 4 mA Bunches from multiple electron photo- cathode guns merge together to form one high average current beam eRHIC requires 25 guns (each delivers 2 mA current) to meet 50 mA current requirement of present ERL-ring baseline design A recent JLab breakthrough pushed single gun polarized current to 4 mA. This could reduce number of guns down to 12 in the BNL Gatling gun design concept

33 COOL11 MEIC Figure-8 Ring Figure-8 optimum for polarized ion beams –Simple solution to preserve ion polarization by avoiding spin resonances during acceleration –Energy independence of spin tune –A figure-8 ring is the only practical way for accelerating, storing and colliding polarized deuterons (g-2 is small for deuterons) Case 1: Achieving longitudinal polarization of deuterons at one IP Solenoid insert Solenoid Inserti Case 2: Achieving transverse polarization of deuterons at all IP’s Magnetic insert(s) in straight(s) rotating spin by relatively small angle around vertical axis (Prof. A. Kondratenko) Magnetic inserts provide small spin rotation, thus shift the spin tune sufficiently away from 0 Polarization is stable as long as additional spin rotation exceeds perturbations of spin motion Ya. Derbenev 1993

34 COOL11 LHeC High-Gradient SC IR Quadrupoles Non-colliding proton beam colliding proton beam Electron beam Synchrotron radiation High-gradient SC IR quadrupoles based on Nb3Sn for colliding proton beam with common low-field exit hole for electron beam and non-colliding proton beam. S. Russenschuck Inner triplets Exit hole for electrons & non- colliding protons Inner triplets Q1Q2 Q1

35 COOL11 6. Outlook and Summary

36 COOL11 US EIC Collaborations Electron-Ion Collider Collaboration More than 100 physicists from over 20 laboratories & universities worldwide Working to realize an EIC in the US Four working groups (eP physics, eA physics, detector, electron beam polarimetry) Organizes one to two workshops or collaboration meetings each year EIC International Advisory Committee Appointed by directors of BNL and JLab Consists of 14 nuclear & accelerator physicists Three advisory committee meetings (2/2009, 11/2009 and 4/2011) Highlights on Recent EIC Activities Five JLab CEBAF User Workshops on EIC (2010), reports produced Ten-week EIC Science Program at INT (Sept. to Nov. 2010), report produced BNL sponsored generic detector R&D program (in progress) LHeC US participation in accelerator, detector and physics development as well as in steering and oversight.

37 COOL11 US EIC Realization Imagined Activity Name 2010201120122013201420152016201720182019202020212022202320242025 12 Gev Upgrade FRIB EIC Physics Case NSAC LRP EIC CD0 EIC Machine Design/R&D EIC CD1/Downsel EIC CD2/CD3 EIC Construction Note: 12 GeV LRP recommendation in 2002 – CD3 in 2008 (Mont@INT)

38 COOL11 NuPECC Roadmap: New Large-Scale Facilities G. Rosner, NuPECC Chair, Madrid 5/10 (12/2010) Adopted from K. Aulenbacher @ SPIN 2010

39 COOL11 Perspective: Cooling in EIC Proposals Extreme critical to EIC proposals –Required by three proposals, and may also benefit the 4 th one (LHeC) –Identified as ONLY potentially show-stop for eRHIC and MEIC (Could cause luminosity reduction up to a factor of 100 if it does not fully work as expected) R&D Scope: broad and challenging –New concepts proposed Traditional electron cooling with/without ERL Circulator Cooler for MEIC and ENC Coherent electron cooling for eRHIC@BNL Optical Stochastic Cooling for eRHIC by MIT group –New parameter regime (high energy, up to 325 GeV, bunched ion beam) –New working scheme (continuous cooling during collision –Beam dynamics (space charge, coupled beam) and FEL (SASE) Key enable technologies: most state-of-the-art, some way beyond –Cooler: High current source, SRF cavity, ERL, circulator ring, undulator, kicker) –Cooling: FEL Path Forward: high priority, revision/optimization, collaboration –Proof-of-Principle for CEC is planed (BNL-Jlab-TechX collaboration), others considered

40 COOL11 Summary A class of new electron-ion colliders have been proposed worldwide for future high energy and nuclear physics research. Both the science program and the accelerator designs are under active development. All new electron-ion collider accelerator designs aim for high performance, orders of magnitude better than HERA, to meet science needs. In order to deliver the high performance, a class of new technologies have been integrated into the conceptual designs; some are adopted from other facilities; others are very forward looking, resulting in high demands on technology R&D. All machine designs are still in relatively early stages of their evolutions, either some baseline design decisions have not been made yet, or key design parameters are still in dynamic evolution, driven by both science and accelerator technology development. It is very exciting to be part of this development. Please join us!

41 COOL11 Acknowledgement I would like to thank all the following colleagues for helping me to prepare this talk LHeC Max Klein, Frank Zimmermann, Miriam Fitterer, Alex Bogacz, John Jowett eRHIC Steve Vigdor, Thomas Roser, Vadim Ptitsyn ENC Kurt Aulenbacher I would also like to thank Rolf Ent of JLab for preparing the science slides

42 COOL11 Backup

43 COOL11 Towards a “3D” spin-flavor landscape Wigner function W u (x,k,r) t EIC: Transverse spatial distribution derived directly from t dependence: Gluon size from J/Y and f Singlet quark size from g Strange and non-strange (sea) quark size from p and K production Hints from HERA: Area (q + q) > Area (g) (x,r) (x,k) p m x TMD EIC: Transverse momentum distribution derived directly from semi-inclusive measurements, plus large gain in our knowledge of transverse momentum effects as function of x. Exact k T distribution presently essentially unknown – EIC can do this well R. Ent

44 COOL11 Science Summary The last decade+ has seen tremendous progress in our understanding of the partonic sub-structure of nucleons and nuclei, due to: Findings at the US nuclear physics flagship facilities: RHIC and CEBAF The surprises found at HERA (H1, ZEUS, HERMES), and now COMPASS/CERN. The development of a theory framework allowing for a revolution in our understanding of the inside of hadrons … GPDs, TMDs, Lattice QCD … hand in hand with the stellar technological advances in polarized beam and parity-quality electron beam delivery. This has led to new frontiers of nuclear science: - the possibility to truly explore and image the nucleon - the possibility to understand and build upon QCD and study the role of gluons in structure and dynamics - the unique possibility to study the interaction of color-charged objects in vacuum and matter, and their conversion to hadrons - utilizing precision electroweak studies to complement direct searches for physics beyond the Standard Model We have unique opportunities to make a (future textbook) breakthrough in nucleon structure and QCD dynamics. R. Ent

45 COOL11 A High-Luminosity Electron Ion Collider Base EIC Requirements: range in energies from s = few 100 to s = few 1000 & variable fully-polarized (>70%), longitudinal and transverse ion species up to A = 200 or so high luminosity: about 10 34 e-nucleons cm -2 s -1 upgradable to higher energies 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.” R. Ent

46 COOL11 QCD and the Origin of Mass 99% of the proton’s mass/energy is due to the self-generating gluon field –Higgs mechanism has almost no role here. The similarity of mass between the proton and neutron arises from the fact that the gluon dynamics are the same – Quarks contribute almost nothing. R. Ent

47 COOL11 Gluons and QCD QCD is the fundamental theory that describes structure and interactions in nuclear matter Without gluons there are no protons, no neutrons, and no atomic nuclei Gluons dominate the structure of the QCD vacuum Facts:  The essential features of QCD (e.g. asymptotic freedom, chiral symmetry breaking, and color confinement) are all driven by the gluons!  Unique aspect of QCD is the self interaction of the gluons  99% of mass of the visible universe arises from glue  Half of the nucleon momentum is carried by gluons R. Ent

48 COOL11 Gluons in Nuclei NOTHING!!! Large uncertainty in gluon distributions Need range of Q 2 in shadowing region,  x ~ 10 -2 -10 -3  s EIC = 1000+ + Transverse distribution of gluons on nuclei from coherent Deep-Virtual Compton Scattering and coherent J/Y production What do we know about gluons in a nucleus? [Measurements at DESY of diffractive channels (J/ , , ,  ) confirmed the applicability of QCD factorization: t-slopes universal at high Q 2 & flavor relations  :  hold] Gluon radius of a nucleus? Ratio of gluons in lead to deuterium R. Ent

49 COOL11 The Facilities E CM vs. L int -plane for ep [μp]: A.Accardi JLAB12 49/31

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