Towards an Electron Ion Collider
R. D. McKeown
Jefferson Lab
INT Workshop
November 19, 2010
Outline
• Looking back over the last year
• The INT workshop
• Golden Experiments or Topics?
• The Road Ahead
Thanks to Rolf Ent, Christian Weiss,
Z.-E. Meziani, and many others.
2
Beyond the 12 GeV Jlab Upgrade
• 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. An EIC aims to study the sea
quarks, gluons, and scale (Q2) dependence.
mEIC
EIC
12 GeV
3
3
The Wakeup Call(s)
EICAC Report (Nov. 2009):
- develop “unimpeachable” science case
- Jlab concept less mature
“the highest R&D priority for JLab should be the design, even if
that activity is not strictly considered R&D, and resources need
to be made available to do the work”
•
•
Jlab user group, encouraged by Jlab director,
organized workshops to further develop science
case
Encouraged by lab director, Jlab initiates effort
to develop a “credible” and “cost-able” MEIC
design
4
JLAB EIC Workshops
 Study group on Hadronic Physics
• Nucleon spin and quark-gluon correlations: Transverse spin, quark and gluon orbital motion,
semi-inclusive processes
(Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark
Gluons Interactions: workshop at Duke U., March 12-13, 2010)
H. Gao et al.
http://michael.tunl.duke.edu/workshop
• 3D mapping of the glue and sea quarks in the nucleon
(Electron-Nucleon Exclusive Reactions: workshop at Rutgers U., March 14-15, 2010)
R. Gilman et al.
http://www.physics.rutgers.edu/np/2010rueic-home.html
 Study group on Nuclear Physics
• 3D tomography of nuclei, quark/gluon propagation and the gluon/sea quark EMC effect
(EIC Nuclear Chromodynamics: workshop at Argonne National Lab, April 7-9, 2010)
K. Hafidi, et al.
http://www.phy.anl.gov/mep/EIC-NUC2010/
 Study group on Electroweak Physics
• Electroweak structure of the nucleon and tests of the Standard Model
(workshop at the College of W&M , May 17-18, 2010)
K. Kumar, D. Armstrong et al.
 Study group on interaction region and detectors
• EIC Detectors/Instrumentation
(workshop at JLab, June 04-05, 2010)
C. Hyde et al.
5
5
Jlab User Workshops
•
•
•
Excellent development of physics possibilities
4/5 will generate written papers to summarize
the workshops – goal is early 2011.
General emergent theme:
Experimental study of multidimensional
distribution functions that map out the
quark/gluon properties of the nucleon, including:
- (quark) flavor
- spin and orbital angular momentum
- longitudinal momentum
- transverse momentum and position
6
11 + 60 GeV
3+20 GeV
SIDIS SSA at EIC
7
Huang, Qian, et al
Duke workshop
A Personal View
•
There has been much progress on the physics
case in the last year
•
There has been good convergence on the
machine design specifications to include the
broader physics program.
•
Jlab user workshops benefited from 12 GeV
physics development. However, some topics
could use more work to extend the physics case
from the valence region into the sea for EIC.
8
Medium Energy EIC@JLab
Three compact rings:
• 3 to 11 GeV electron
• Up to 12 GeV/c proton (warm)
• Up to 60 GeV/c proton (cold)
9
2010 INT Workshop
Organizers:
Daniel Boer
KVI, University of Groningen
Markus Diehl
DESY
Richard Milner
MIT
Raju Venugopalan
Brookhaven National
Laboratory
Werner Vogelsang
University of Tübingen
week
dates
topics
13–17 Sept
Workshop on "Perturbative
and Non-Perturbative
Aspects of QCD at Collider
Energies"
20–24 Sept
open conceptual issues:
factorization and
universality, spin and flavor
structure, distributions and
correlations
27 Sept –15 Oct
small x, saturation,
diffraction, nuclear effects;
connections to p+A and A+A
physics;
fragmentation/hadronization
in vacuum and in medium
18–29 Oct
parton densities (unpolarized
and polarized),
fragmentation functions,
electroweak physics
8–9
1–12 Nov
longitudinal and transverse
nucleon structure; spin and
orbital effects (GPDs,
TMDs, and all that)
10
15–19 Nov
Workshop on "The Science
Case for an EIC"
1
2
3–5
6–7
10
10
INT Workshop
•
•
•
•
•
Nine weeks of intensive discussions
Excellent organization, communication
- talks online
- weekly summaries
We continue to see the physics case develop.
Many good ideas are emerging.
Written summaries to be prepared
“Golden” experiments?
11
A Personal View
•
•
•
•
Perhaps it is not realistic to agree upon
“Golden Experiments”
As an alternative, “Golden Topics” can be a
useful and unifying theme (ref. FRIB)
It is essential to keep the community united
behind physics topics that motivate the facility
we are proposing
At Jlab we have started to think about “Golden
Topics” as a possible way to both sell the
physics and maintain coherence in the
community
12
The Science of an 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
• Discover the collective effects of gluons in nuclei
• Map the spin and spatial structure of quark and gluons in
nucleons
• Understand the emergence of hadronic matter from quarks and
gluons
• EW Topic?
(Discussion with R. Ent, C. Weiss, and others at Jlab)
13
Golden Topic #1
Discover collective effects of Gluons in Nuclei
•
Explore the nuclear gluon density and coherence in
shadowing through
e + A  e‘ + X and e + A  e' + cc + X
•
Discover novel signatures of dynamics of strong color
fields in nuclei at high energies in
e + A  e‘ + X (or A)
and e + A  e' + hadrons + X
•
Measure gluon/quark radii of nuclei
through coherent scattering g* + A  J/Y + A
14
Golden Topic #2
Map the spin and spatial quark-gluon structure of nucleons
•
•
•
•
Image the 3D spatial distributions of gluons and sea
quarks through exclusive J/Y, g (DVCS) and meson
production
Measure DG, and the polarization of the sea quarks
through SIDIS, g1, and open charm production
Establish the orbital motion of quarks and gluons
through transverse momentum dependent observables
in SIDIS and jet production
Discover QCD-induced quark-gluon correlations in the
nucleon through SIDIS and target fragmentation?
15
Golden Topic #3
Understand the emergence of hadronic matter from
quarks and gluons
•
Explore the interaction of color charges with
matter (energy loss, flavor dependence, color
transparency) through hadronization in nuclei in
e + A  e' + hadrons + X
•
Understand the conversion of quarks and gluons
to hadrons through fragmentation of correlated
quarks and gluons and breakup in e + p  e' +
hadron + hadron + X
16
EIC Realization Imagined
Activity Name
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
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
17
Looking Forward
•
We have made excellent progress in
developing and refining the physics case
for EIC over the last 2 years.
• We need to document the Jlab
workshops and the INT workshop
• Machine designs and accelerator R&D
need to continue
• A community white paper to synthesize
this information is a logical next step (g
Steve V.)
18
A Final Word
•
We are on a good path to put the EIC forward at the next NSAC
Long Range Plan
•
We still need additional work, building on the discussions at the
INT program, to produce a much more compelling physics
justification
•
We need to sharpen the arguments for a more general audience
•
How could we expand the community of interested physicists?
•
We need to continue to work together to advance the physics
case for this exciting new facility
19