Roy Holt

JLab Users Group Meeting

15-18 June 2008

Introduction to the Electron Ion Collider

The “big picture” (for Ron)

Our ancestors lived in caves for about 7600 generations. The nucleus was discovered less than three generations ago. We are the first generation to study QCD and the Standard

Model.

Our species is about 8000 generations old.

We are just beginning to understand the nature of visible matter.

What is the Electron Ion Collider?

Lab JLab BNL CERN

EIC ELIC eRHIC LHeC

Electron energy (GeV) 9 10 140

Proton energy (GeV) 150 250 7000

Luminosity (x1033 cm-2s-1) 50 1 1

The EIC has different meanings for different labs.

9-GeV electrons on 150-GeV protons -> Ee = 1440 GeV for fixed target

140-GeV electrons on 7-TeV protons -> Ee = 2080 TeV for fixed target

~ 1015 eV highest energy cosmic rays ~ 1020 eV

EIC Kinematics and Luminosity

D. Hasch

The EIC has:

• a c.m. energy greater than COMPASS or FNAL E665.

• a luminosity of 100 to 5000 x HERMES.

• polarized electron/positron and light ion beams (not LHeC).

• nuclear targets.

1 10 100 CM energy (GeV)

101

102

Lu

min

osit

y(*

103

0/

cm

2/s

) 103

104

105

109

106

108

107

107

JLab

JLab@12 GeV

HERMES

COMPASSHERA-collider

ELIC

eRHIC LHeC

EIC White Papers 2007 – an astounding year

The Electron Ion Collider (EIC) White Paper

The GPD/DVCS White Paper Position Paper: e+A Physics at an

Electron Ion Collider The eRHIC machine: Accelerator

Position Paper ELIC Zero’th Order Design Report

Available at:• NSAC LRP2007 home page• Rutgers Town Meeting page• http://www.bnl.gov/eic

The EIC Working Group

17C. Aidala, 28E. Aschenauer, 10J. Annand, 1J. Arrington, 26R. Averbeck, 3M. Baker, 26K. Boyle, 28W. Brooks, 28A. Bruell, 19A. Caldwell, 28J.P. Chen, 2R. Choudhury, 10E. Christy, 8B. Cole, 4D. De Florian, 3R. Debbe, 26,24-1A. Deshpande*, 18K. Dow, 26A. Drees, 3J. Dunlop, 2D. Dutta, 7F. Ellinghaus, 28R. Ent, 18R. Fatemi, 18W. Franklin, 28D. Gaskell, 16G. Garvey, 12,24-1M. Grosse-Perdekamp, 1K. Hafidi, 18D. Hasell, 26T. Hemmick, 1R. Holt, 8E. Hughes, 22C. Hyde-Wright, 5G. Igo, 14K. Imai, 10D. Ireland, 26B. Jacak, 15P. Jacobs, 28M. Jones, 10R. Kaiser, 17D. Kawall, 11C. Keppel, 7E. Kinney, 18M. Kohl, 9H. Kowalski, 17K. Kumar, 2V. Kumar, 21G. Kyle, 13J. Lajoie, 16M. Leitch, 27A. Levy, 27J. Lichtenstadt, 10K. Livingstone, 20W. Lorenzon, 145. Matis, 12N. Makins, 6G. Mallot, 18M. Miller, 18R. Milner*, 2A. Mohanty, 3D. Morrison, 26Y. Ning, 15G. Odyniec, 13C. Ogilvie, 2L. Pant, 26V. Pantuyev, 21S. Pate, 26P. Paul, 12J.-C. Peng, 18R. Redwine, 1P. Reimer, 15H.-G. Ritter, 10G. Rosner, 25A. Sandacz, 7J. Seele,

12R. Seidl, 10B. Seitz, 2P. Shukla, 15E. Sichtermann, 18F. Simon, 3P. Sorensen, 3P. Steinberg, 24M. Stratmann, 22M. Strikman, 18B. Surrow, 18E. Tsentalovich, 11V. Tvaskis, 3T. Ullrich, 3R. Venugopalan, 3W. Vogelsang, 28C. Weiss, 15H. Wieman,15N. Xu,3Z. Xu, 8W. Zajc.

1Argonne National Laboratory, Argonne, IL; 2Bhabha Atomic Research Centre, Mumbai, India; 3Brookhaven National Laboratory, Upton, NY; 4University of Buenos Aires, Argentina; 5University of California, Los Angeles, CA; 6CERN, Geneva, Switzerland; 7University of Colorado, Boulder,CO; 8Columbia University, New York, NY; 9DESY, Hamburg, Germany; 10University of Glasgow, Scotland, United Kingdom; 11Hampton University, Hampton, VA; 12University of Illinois, Urbana-Champaign, IL; 13Iowa State University, Ames, IA; 14University of Kyoto, Japan; 15Lawrence Berkeley National Laboratory, Berkeley, CA; 16Los Alamos National Laboratory, Los Alamos, NM; 17University of Massachusetts, Amherst, MA; 18MIT, Cambridge, MA; 19Max Planck Institüt für Physik, Munich, Germany; 20University of Michigan Ann Arbor, MI; 21New Mexico State University, Las Cruces, NM; 22Old Dominion University, Norfolk, VA; 23Penn State University, PA; 24RIKEN, Wako, Japan; 24-1RIKEN-BNL Research Center, BNL, Upton, NY; 25Soltan Institute for Nuclear Studies, Warsaw, Poland; 26SUNY, Stony Brook, NY; 27Tel Aviv University, Israel; 28Thomas Jefferson National Accelerator Facility, Newport News, VA

-95 Scientists, 28 Institutions, 9 countriesSteering Committee•Abhay Deshpande, Stony Brook, RBRC (Co-

Chair/Contact person) •Rolf Ent, Jlab •Charles Hyde, ODU/UBP, France •Peter Jacobs, LBL

•Richard Milner, MIT (Co-Chair/Contact person) •Thomas Ulrich, BNL •Raju Venugopalan, BNL •Antje Bruell, Jlab •Werner Vogelsang, BNL

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.”

Introduction

Profound issues in nuclear physics– Structure of visible matter– Role of gluons in hadronic matter– Fundamental symmetries

New facilities on the horizon International activities Concluding statement

The EIC will explore the most compelling issues in nuclear science and technology.

Explore the structure of visible matter

What is the internal landscape of the hadron? – Benchmark: Spatial, spin, flavor and gluonic

structure What is the nature of the nuclear force that binds

protons and neutrons into nuclei?– Frontier: QCD properties of nuclear force– Mysteries: QCD effects in nuclei

“If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generation, what statement would contain the most information in the fewest words? I believe it is the atomic hypothesis, that all things are made of atoms -- little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. In that one sentence, there is an enormous amount of information about the world, if just a little imagination and thinking are applied.” - R. Feynman

Explore the structure of the nucleonExplore the structure of the nucleon

• Parton distribution functions• Longitudinal and transverse spin

distribution functions• Generalized parton distributions• Transverse momentum distributions

ep Physics Working GroupAntje Bruell, JLAB Ernst Sichterman, LBL Werner Vogelsang, BNL Christian Weiss, JLAB

S. Kuhn, Z.-E. Meziani, J. Conrad, F. Myhrer, A. Bacchetta,

J. Qiu, S. Niccolai, C. Roberts, F. Benmokhtar, B. Sawatzky

Explore the structure of the nucleon (continued)

Strange quark distribution - HERMES

What about charm quark distribution?Spectator forward tagging: minimize deuteron structure

Forward tagging also necessary for :DVCS, diffraction, forward N structure fns, …

Neutron structure function – JLab

C. Keppel et al S. Kuhn

Generalized Parton Distributions

Q2

t ),,( txH Bjx~Bjxx

Bjx~

x x

form factors )(),,( 1 tFtxHdxe q

q q PDFs

)()0,0,(, xqxH gq )()0,0,(

~ , xqxH gq …

D. Hasch

S. NiccolaiDVCS is the “golden mode”.

GPD’s provide a 2D spatial image as a function of x

C. Weiss

eg, choose J meson:sensitive to gluons

Consider “Dirac” GPD: H(x,t)

Explore the structure of the nucleon (continued)Transverse Spin and Momentum Distributions

Harut Avakian – “Welcome to the exciting world of 3D parton distributions.”– Transversity, Sivers, Boer Mulders, …

Alessandro Bacchetta “EIC, a precision machine for TMD’s” “Proof of principle” - Ralf Seidl - measure transversity, Collins fragmentation

function, determine tensor charge

HERMES +COMPASS + Belle

Prokudin - DIS 2008

J. Qiu - Sivers effect for gluon, detect D-meson

QCD and the Origin of Mass

Most of the proton’s mass arises from QCD dynamics

–Higgs mechanism has a small role.–Current quarks contribute

negligible mass.–Gluons have a huge role.

Comparison of lattice “data” with Dyson-Schwinger calculations

C. Roberts’ talk

Explore gluon-dominated matterExplore gluon-dominated matter

EIC: most precise measure of gluon densities

What is the role of gluons and gluon self-interactions in nucleons and nuclei? NSAC-2007

– Gluon dominance in the proton

Gluon distribution G(x,Q2)

• Scaling violation in F2: F2/lnQ2

• FL ~ s G(x,Q2)

• inelastic vector meson production (e.g. J/)

• diffractive vector meson production ~ [G(x,Q2)]2

• …

Recent progress – direct FL measurements from HERA

),(2

),(2

14 2

22

2

2

4

2

2

2

QxFy

QxFy

yxQdxdQ

dL

eXep

EIC – an FL factory

Explore the low energy precision frontier

What are the unseen forces present at the dawn of the Universe but have disappeared from view as the universe evolved? precision electroweak experiments: sin2W , …

Questions for the Universe, Quantum Universe, HEPAP, 2004; NSAC Long Range Plan, 2007

“The task of the physicist is to see through the appearances down to the underlying, very simple, symmetric reality.”

- S. Weinberg

The LHC is driving global interest in low energy tests of the Standard Model.

Relatively high x -> charge symmetry violation?

Preliminary - EIC

T. LeCompte, R. Young

What new facilities are essential to this quest?

eRHIC

“We recommend the allocation of resources to develop accelerator and detector technology necessary to lay the foundation for a polarized Electron-Ion Collider.” NSAC LRP 2007

ELIC

•Energy recovery

•Crab cavities

•Ion cooling

•SRF cavity improvement

•Detector Working Group•Elke Aschenauer, JLAB •Edward Kinney, Colorado •Bernd Surrow, MIT

•Electron Beam Polarimetry •Wolfgang Lorenzon, Michigan

See Yuhong Zhang’s talk

World Community in 2015 and Beyond

Three new major facilities investigating nuclear physics at hadronic level (QCD): FAIR, J-PARC and 12-GeV JLab

Two new facilities that explore nuclei at the partonic level: RHIC with upgrades and the LHC

Two new proposed facilities that can carry our field to the next level: EIC, Proton Driver or Project X (FNAL)

Petascale computing facilities will be “standard”, Exascale will be on the way.

Outstanding opportunities for the future

The International Picture

NuPECC activities– EIC study group approved at the meeting in

Bucharest on 10/27/2007 with G. Rosner, chair– Charge is to produce a report outlining:

• The science possibilities• The interest among European groups• Possible links with proposals outside Europe

Glasgow meeting in Fall 2008.

The International Picture (continued)

OECD (Organization for Economic Co-operation and Development) Global Science Forum

– Nuclear Physics Working Group- report on ‘optimal evolution of Nuclear Physics at an international level during the next 10-15 years’

Membership – 14 countries Two projects may be ‘Global’ due to size (report: May 2008)

– EURISOL

– EIC

The International Picture (continued)

First ECFA-CERN Workshop on the LHeC - Divonne, France 1-3 Sept 2008

Based on advice from the CERN Council, ECFA (European Committee for Future Accelerators) and CERN have expressed interest in receiving a Conceptual Design Report for an electron/positron proton/ion collider using LHC hadron beams.

40-140 GeV leptons with protons between 1000 and 7000 GeV

Deliver CDR by 2010

Columbus’ vision

Look! Purple mountains! Spacious skies! Fruited plains! …Is someone writing this down? - adapted from G. Larson

Yes! white papers, NSAC LRP 2007, but we

need an even more compelling case by next NP LRP (2012-13)

Concluding Statement

EIC research can penetrate some of the most profound mysteries and questions of 21st century physics.

Technology is improving at an astounding rate:

– Accelerator design, cavity improvement, energy recovery, … There are many new opportunities worldwide. The next 10 years

will be even more exciting than the last 10 years. A most compelling case must be put forward for the EIC on the

timescale of 2012, the next LRP. It will be extraordinarily interesting to see what the 8001st

generation brings.

“Twenty years from now you will be more disappointed by the things you didn’t do than the ones that you did do.” - Mark Twain