Realization of an ElectronIon Collider – BNL View
Steve Vigdor
Workshop on Perturbative and Non-Perturbative
Aspects of QCD at Collider Energies
INT Sept. 13, 2010
“An EIC with polarized beams
has been embraced by the
U.S. nuclear science community as embodying the
vision for reaching the
next QCD frontier.”
How can we
realize this
vision?
Much of 2007 LRP is Well Under Way:
12 GeV upgrade under way –
should be complete by 2014-15.
FRIB had successful CD-1
review July 2010. Construction
anticipated for ~2013-19.
Much of 2007 LRP is Well Under Way:
DUSEL Preliminary Design
Report anticipated to NSF by
end of CY2010, presentation to
Science Board during 2011.
Technology breakthrough
(bunched-beam stochastic
cooling)  RHIC luminosity
upgrade well under way,
expected complete in 2013.
Detector upgrades complete by
2015.
Next (2013?) LRP Will Benefit from New LongRange Major Construction Project
1st un-numbered 2007 recommendation:
Accelerator R&D, started
with BNL, Jlab resources,
now has ONP funding.
Need detector R&D funds
as well.
However, there are no entitlements ! EIC will
be an expensive facility. Major new construction
~2020 in parallel with operations of 3 major
facilities (CEBAF, RHIC, FRIB) seems
unrealistic. Something will have to give !
What is Needed for NP Community
Endorsement of EIC?
 Compelling science vision, backed by plausible feasibility
simulations for “golden experiments”  this workshop and
subsequent White Paper (necessary, but not sufficient!)
 Clear understanding of critical machine performance
requirements
 Proofs of principle of beyond state-of-the-art accelerator &
detector technology needed to achieve required performance
 Credible cost plan for 1st stage that addresses clear subset
of science goals at ≲ $500M (OS guidance) for machine +
detectors
 Timeline and plan that fits with likely ONP funding realities
for coming decade (i.e., construction following FRIB, with
large contribution from ongoing operations…)
What is Needed for NP Community
Endorsement of EIC?
 A clear path forward for both BNL and JLab
 A sufficiently strong and focused user community, not
bifurcated along BNL /JLab fault lines
EIC  Important Extension of RHIC Science
“Condensed matter physics with a force of a different color”
 Jody Wright
What are the unique quantum many-body manifestations of a non-Abelian
gauge theory? Are there lessons for other fundamental (e.g., EW) theories,
that are harder to subject to laboratory investigation?
1)
Does asymptotic freedom  dense (in color charge) ideal gas QGP?
Find “near-perfect” strongly correlated liquid behavior instead !
2)
Does rich vacuum structure  sphalerons near QGP transition &
local symmetry violation? Observed behavior consistent with local
(chiral magnetic) P- and CPV; ~ B-violation @ EW phase transition?
3)
Do gluon self-interactions  universal saturated gluonic matter in
hadrons and nuclei? Hints at RHIC, need EIC for definitive answer.
EIC Science: Gluon-Dominated Cold Matter in e+A
Search for supersymmetry @
LHC, ILC (?): seeking to unify
matter and forces
Electron-Ion Collider: reveal
that Nature blurs the distinction
Deep inelastic scattering @ HERA 
Gluons dominate the
soft constituents of
hadrons! But density
must saturate…
EIC probes weak coupling regime of very
high gluon density, where gauge boson
occupancy >> 1. All ordinary matter has
at its heart an intense, semi-classical
force field -- can we demonstrate its
universal behavior? Track the transition
from dilute parton gas to CGC? “See”
confinement reflected in soft-gluon
spatial distributions inside nuclei?
EIC e + N  Important
Extension of Nucleon Structure
Studies at HERA, RHIC, JLab,…
 DIS,  -gluon fusion  G(x > few  104)
 Bjorken sum rule test to ≲  2%
 SIDIS for low-x sea-quark polarization and
transverse spin studies
More luminosity-hungry:
 Polarized DVCS, exclusive reactions +
LQCD  GPD’s  map low-x transverse
position-dep. PDF’s; Jq from Ji sum rule; Jg?
 High-Q2 e+p,d parity viol’n  weak
coupling running below Z-pole; e LFV?
Proton
tomography
via exclusive x < 0.1
reactions
x ~ 0.3
x ~ 0.8
BNL Planning Assumptions
 Strongest science case made for the eventual full EIC:
 e+A for low-x gluon densities, probing conjectured
universal saturation surface ( need HI beams, s > 100 GeV,
far forward coverage in both e and A directions)
 e+N DIS & SIDIS for nucleon spin structure in gluondominated regime, TMD’s, etc. ( need polarized beams)
 deep exclusive e+p for GPD’s, (2+1)-D imaging of proton
wave fcn. ( need L ~ 1034, high-precision detectors)
 EW e+N program likely to still be relevant in mid-2020’s
 parton interactions & hadronization in cold matter
 But need to
identify clear science
deliverables for
lower-s 1st facility
stage…
BNL Planning Assumptions
 Work on plan to allow straightforward upgrade path from
1st stage, but to incorporate starts on as much of the science
program as possible in 1st stage (needed to keep strong user
community engaged  recent design advances)
 Fully utilize RHIC A, p beams and infrastructure
 Utilize RHIC detector infrastructure, halls, subsystems as
possible to control costs
 Utilize BNL LDRD funds plus RHIC R&D funds to jumpstart accelerator and detector R&D where possible
 Work with JLab as possible to arrange collaborative
approach to LRP
eRHIC Design Under Active Consideration
 more IP’s
 reusing infrastructure + det.
components for
STAR, PHENIX?
 reduced cost
 easier upgrade path
 minimal
environmental
impact concerns
 IR design to
reach 1034 luminosity
eRHIC detector
2 SRF linac
1 -> 5 GeV per pass
4 (6) passes
eRHIC-I  eRHIC: energy
of electron beam is
increased from 5 GeV to
30 GeV by building up the
linacs
RHIC: 325 GeV p
or 130 GeV/u Au with
DX magnets removed
eSTAR
© V. Litvinenko
20 GeV
e-beam
15 GeV
e-beam
Common vacuum
chamber
Vis-à-vis earlier
MeRHIC design,
this allows for:
Vertically
separated
recirculating
passes.
# of passes will
be chosen
to optimize
eRHIC cost
10 GeV
e-beam
5 GeV
e-beam
5 mm
5 mm
5 mm
5 mm
Gap 5 mm total
0.3 T for 30 GeV
30 GeV e+ ring
1.27 m beam high
30 GeV ERL
HE ERL
passes
LE ERL
passes
6 passes
30
25
20
15
10
5
GeV
© V. Litvinenko
Modified eRHIC
Design 
Improved
Luminosity
 Achieve *=5 cm
with 200 T/m LARP
SC quads
 No e bend near
detector, 10 mrad
hadron beam
crossing angle
 Can eventually cover s
from 80-160 GeV with
above L, 30-200 GeV with
> 2  1033 cm2s1
 e+A luminosities per
nucleon very similar
 1st stage e energy will
depend on cost
Pursuing Aggressive R&D on Critical Technologies
Developing high-current electron ERL (20 MeV) with RHIC R&D funds;
704 MHz SRF cavities for ERL with HEP funding via BNL-SBU CASE.
Developing proof-of-principle
of Gatling Gun approach to
multi-cathode high-current
(eventually ~50 mA) polarized
e gun with BNL LDRD funds.
Also laser system for
polarized gun with LDRD
funds.
Pursuing Aggressive R&D on Critical Technologies
 Aiming for ~2014 proof-of-principle demo of Coherent e Cooling
for hadron beams @ RHIC, aided by BNL LDRD and
Program Devel. Funds + pending ONP proposal
(joint with Jlab and Tech-X)
Gap 5 mm total
0.3 T for 30 GeV
 Prototyping small-gap dipole and
quadrupole magnets and vacuum
chambers for compact recirculation arcs
on electron beam, with BNL LDRD funds.
 Also exploring relevance of CeC for
improving RHIC p+p luminosities and
ERL-driven options for X-ray FEL (LDRD).
All in addition to ongoing work on lattice, IR and detector design, plus
beam & spin dynamics and beam-beam simulations.
Anticipated FY11 Milestones
Oct. 2010: STAR, PHENIX submit decadal plans, including
assessment of detector adaptation to e+p and e+A collisions
Oct. 2010: Begin LDRD funding for BNL/Columbia/IPHC
collab’n on CMOS Active Pixel Sensor R&D for EIC vertexing
Q2 FY11: Launch competitive (not site-specific!) EIC
detector R&D program, with independent review committee,
using either RHIC R&D or ONP funds (under discussion…)
Q2 FY11: Workshop on strategy for RHIC future – decadal
planning for A+A, p+p, d+A, e+p, e+A, detector upgrades, …
Q2 FY11: External review of eRHIC design
Q4 FY11: External review of eRHIC cost estimation, as
function of s reach
Q4 FY11: Community-wide EIC science White Paper, to
make compelling case to rest of NP community and DOE
Anticipated FY12 Milestones
Q2 FY12: JLab, BNL, EIC Collaboration, EICAC, DOE define
facility design down-select criteria and review mechanism.
N.B. If both labs are not willing to participate in a downselection prior to LRP, then we must at least go into LRP
with clear mechanism for making a subsequent selection.
Q4 FY12: Update EIC Science White Paper with realizable
EIC design(s), including cost range, performance goals,
science deliverables and upgrade paths, in preparation for
(assumed) Spring 2013 LRP resolution meeting.
Quotes from Nov. 2009 EICAC Report on Science
and Community Convergence
• The [Fall 2010] INT Program should be used to articulate the theoretical
motivation, but also to compare those goals with reality by examining the
sensitivities of simulated experiments. An outcome should be the science /
machine matrix discussed earlier. At the conclusion of the INT program, we
can anticipate some follow-up event(s) in 2011 where the joint community
agrees on the theme of a final White Paper.
• The EIC Community appears to be made of two sub-groups, roughly
associated with the BNL or JLab concepts for the machine…it is our opinion
that there remains time for vigorous debate about scientific options and
priorities; however, for full consideration at the next LRP, one coherent,
joint-QCD-community request should be made.
• To progress further, some assurance from lab managements would be
useful, stating that, which ever facility scheme will be chosen in the end of
the evaluation process, both laboratories are committed to making it a
success together.
Backup Slides
The √s vs. luminosity landscape
Diffraction
Minimum luminosities
to “get in the game” -from Elke Aschenauer
EIC should  HERA +
exclusive DIS (PS & VM)
electro-weak
  2 orders of magnitude
in luminosity
 polarized p, 3He beams
exclusive DIS (DVCS)
 heavy-ion beams
semi-inclusive DIS
HERA
inclusive DIS
4x100 10x100 20x100
4x250
20x250
30x325
21
eRHIC IRs, β*=5cm, l*=4.5 m
Star detector
Plan to use newly commissioned
LARP Ni3Sn SC quads with 200
T/m gradient
0.45 m
©Dejan Trbojevic
30 GeV ebeam
90.m
The first Nb3Sn Long Quadrupole (LQS01) designed and fabricated by
the US LHC Accelerator Research Program (LARP) reached its target
gradient of 200 T/m during the first test. LQS01 is a 90 mm aperture,
4 meter long quadrupole with Nb3Sn coils made of RRP 54/61 strand
L=1.4x1034cm-2s-1,
200 T/m gradient
Accelerator R&D working with detector R&D
Polarized Gun Laser System (LDRD)
parameter
unit
wavelength
nm
repetition rate
pulse energy at
photocathode
kHz
uJ
spec
comment
780
704
14.07 MHz /
20 cathodes
2.8
assuming
QE=0.2%
assuming
QE=0.2%
average laser power
at cathode
W
2
average laser power
W
4
pulse width
nsec
1.2
jitter
psec
50
amplitude stability
1.00E-04
contrast
1.00E-06
Gaussian
FWHM
• 10 W Erbium doped fiber amplifier
system at 1560 nm, frequency doubled
in periodically-poled material
• CW diode laser + electro-optic
modulation for pulse source
• control of pulse shape, low jitter
• Two companies proposing designs
• high peak power in the amplifier is
the technical challenge
• problem has been solved in
similar commercial systems
• cost $100-$200 K
Progress on eRHIC design: Coherent
Electron Cooling
General EIC R&D item: Over the past three years, we
developed an impressive arsenal of analytical- and
numerical-tools to predict the performance of a CeC. Joint
proposal with Jlab and Tech-X submitted to carry out a
Proof of Principle demonstration of coherent electron
cooling.
Get Good Advice
EIC Advisory Committee (to JLab and BNL)
Joachim Bartels (Universitait Hamburg, DESY)
Allen Caldwell (Max-Planck Institute for Physics, Munich)
Albert De Roeck (CERN)
Walter Henning (ANL, Chair)
David Hertzog (University of Illinois)
Xiangdong Ji (University of Maryland)
Robert Klanner (DESY)
Al Mueller (University of Columbia)
Katsunobu Oide (KEK)
Naohito Saito (JPARC)
Uli Wienands (SLAC)
1st meeting 2/16/09. 2nd meeting 11/02/09.
Quotes from EICAC Report on Facility Design & Strategy
• The EICAC is impressed with the…work…on accelerator designs since the last
meeting… the two laboratories are at very different levels of design maturity.
• It is the growing view of several members of EICAC that as soon as possible a
“down select” should be made…there is much R&D that needs to be
done…addressing all the challenges of both [designs] is expensive and perhaps
unwarranted. The highest priority on the facility side is to develop the JLAB
design to a stage similar to where the BNL design is at present.
• In terms of strategy…the EICAC feels that the proponents might consider
aiming for the EIC facility from the beginning, with a medium-range
performance scope and future upgrade opportunities.
• It may…be wise to consider the possibility of more than one interaction region
to satisfy these different [science and detector] requirements. This would also
provide a natural way for different physics communities to group themselves.
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
Quotes from EICAC Report on Detector Development
• The EICAC feels that there is no need at this point to carry out detailed
GEANT simulations, but rather to study responses based on parameterizations.
The trade-off between the resolutions and acceptances of the detectors on the
one hand, and luminosity, polarization and beam energies on the other hand for
the physics can be understood with these kinds of studies.
• In a prioritized way, R&D suggested for the near term should begin to address
the following areas:
-Low-mass vertex-tracker/tracker, and integration of a TRD detector in the
tracker
-particle identification at mid-rapidity for particles with momenta up to 4 GeV,
e.g., using DIRC technology
-low cost photon detection, e.g., SiPMs
-ion polarimeters
• The EICAC considers it important that the detector R&D efforts are conducted
jointly for MeRHIC and MEIC. Contacts with other communities like LHeC are
also strongly encouraged.
Quotes from EICAC Report on Path to “Down Select”
• [At Fall 2010 INT Workshop]: i) For each of the two directions, it would be
very useful to prepare a concrete list of the requested measurements (including
the scientific motivation, kinematic region, required accuracy etc.); and/or ii)
each of the two groups should investigate to what extent their scientific goals
could be reached by the other machine (i.e. 'proton imaging' etc by the BNL
design, 'saturation' etc by the JLab version).
• …it would be useful to define a few sets of parameters (energy, luminosity,
polarization) based on the expectations from each machine for simulation
studies. Available space at the IR should also be defined. These can then be
put together with detector designs to understand the physics capabilities for the
signature (and other) measurements. These results should then be put together
with expected cost, time scale for the accelerator development, and
possibilities for future upgrades to higher energies and luminosity in
determining which accelerator option is to be backed by the community.