1. Elke-Caroline Aschenauer
the electron ion collider
the ultimate Collider to image nucleons and nuclei
What is the EIC:
A high luminosity (1033 – 1034 cm-2s-1) polarized
electron proton / ion collider
with √sep = 20 – 100 GeV upgradable to 140 GeV
Endorsed in the 2015 NSAC Long Range Plan
as the highest priority for new
facility construction following the completion of FRIB
Elke-Caroline Aschenauer
arXiv:
eRHIC: arXiv:
JLEIC: arXiv:

2. 2+1 dimensional Imaging: Quarks & Gluons
Wigner function
W(x,bT,kT)
Momentum
space
Coordinate
space
∫ d2kT
∫d2bT
f(x,kT)
f(x,bT)
Quarks
Gluons
Spin-dependent 3D momentum space
images from semi-inclusive scattering
Spin-dependent 2+1D coordinate space images from exclusive scattering
E.C. Aschenauer

3. Deeply Virtual Compton Scattering at EIC
(Q2) e
gL*
x+ξ
x-ξ
H, H, E, E (x,ξ,t) ~ g p p’ t
DVCS: Golden channel  theoretically clean
wide range of observables
(s, AUT, ALU, AUL, AC)
to disentangle different GPDs
small t
large t
D. Mueller, K. KumerickiS. Fazio, and ECA arXiv:
Fourier
Transform
E.C. Aschenauer

4. What can we learn bT decreasing as a function of x
Model of a quark GPD
bT (fm) x
down valence quark
bT decreasing as a function of x x
eRHIC
Valence (high x) quarks at the center  small bT
Sea (small x) quarks
at the périphérie  high bT ?
GLUONS ???
E.C. Aschenauer

5. Exposing different layers of the nuclear landscape with electron scattering
History:
Electromagnetic
Elastic electron-nucleus scattering  charge distribution of nuclei
Present/Near-future:
Electroweak
Parity-violating elastic electron-nucleus scattering (or hadronic reactions e.g. at FRIB)  neutron skin
Future: at the EIC:
Color dipole
f Production in coherent electron-nucleus scattering  gluon spatial distribution in nuclei
Fourier transform gives unprecedented info on gluon spatial distribution, including impact of gluon saturation
E.C. Aschenauer

6. E.C. Aschenauer

7. DIS Landscape: Lumi vs. √s
Based on:
E.C. Aschenauer

8. What will we learn about 2d+1 structure of the proton
GPD H and E 1d+1
GPD H and E as function of t, x and Q2
arXiv:
A global fit over all pseudo data was done, based on the GPDs-based model:
[K. Kumerički, D Müller, K. Passek-Kumerički 2007]
Known values q(x), g(x) are assumed for Hq, Hg (at x=0, t=0 forward limits Eq, Eg are unknown)
Excellent reconstruction of Hsea, Hsea and good reconstruction of Hg (from dσ/dt)
GPD H and E 2d+1 structure for sea-quarks and gluons
E.C. Aschenauer

9. GPD Hg: J/ψ To improve imaging on gluons add J/ψ observables
cross section
AUT
…..
Fourier
Transform
E.C. Aschenauer

10. eRHIC: Diffractive Events in eA
Diffractive physics will be a major component of the eA program at an EIC
High sensitivity to gluon density: σ~[g(x,Q2)]2 due to color-neutral exchange
Only known process where spatial gluon distributions of nuclei can be extracted
2 Types: Coherent (A stays intact) & Incoherent (A breaks up)
Experimental challenging to identify
Rapidity gap ⇒ hermetic detector
Breakup needs to be detected ⇒ n and γ in Zero Degree Calorimeter, spectator tagging (Roman Pots), IR design!
HERA: σdiff/σtot ~ 15%
E.C. Aschenauer

11. eRHIC: Spatial Gluon Distribution from dσ/dt
: Measurement of charge (proton) distribution in nuclei
Ongoing: Measurement of neutron distribution in nuclei
EIC ⇒ Gluon distribution in nuclei
Diffractive vector meson production:
e + Au → e′ + Au′ + J/ψ, φ, ρ
Method:
Fourier Transform
Diffractive vector meson production:
e + Au → e′ + Au′ + J/ψ, φ, ρ
Momentum transfer t = |pAu-pAu′|2 conjugate to bT
PRC 87 (2013)
spin-dependent gluon distribution
Converges to input F(b) rapidly: |t| < 0.1 almost enough
Recover accurately any input distribution used in model used to generate pseudo-data (here Wood-Saxon)
Systematic measurement requires ∫Ldt >> 1 fb-1/A
dσ/dt: diffractive pattern known from wave optics
φ sensitive to saturation effects, smaller J/ψ shows no effect
J/ψ perfectly suited to extract source distribution
E.C. Aschenauer

12. EIC Project Status
The EIC received in the 2015 Long Range
Planning of the NSAC the following recommendation
“We recommend a high-energy high-luminosity
polarized EIC as the highest priority for new
facility construction following the completion of FRIB”
Next Steps:
A National Research Council (National Academy of Science
(& Engineering & Arts) review of the project is expected to begin soon,
and a report is expected in ~18 months. After the DOE will launch its
Critical Decision (CD) process…
CD0 soon after the NAS review.... (FY2018)
CD1: site selection
with a scenario of 1.6% growth in US nuclear science funding
from now on
 CD3 start of construction estimated in 2022/23
E.C. Aschenauer

13. EIC Timeline LHC 12 GeV Operations RHIC Operations FRIB (2007 LRP)
Activity Name
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
LHC
12 GeV Operations
RHIC Operations
FRIB (2007 LRP)
EIC Physics Case
NSAC LRP
NAS Study
CD0
EIC Design, R&D
CD1 (Side-select)
CD2/CD3
EIC Construction
RUN-I
LS-1
RUN-II
LS-2
RUN-III
LS-3
pp/pA AA/dA pp AA BES-II sPHENIX
CD-1
CD-2/3a
CD-3b
CD-4
pre-project
on-project
CD0 = DOE “Mission Need” statement; CD1 = design choice and site selection (NY/VA)
CD2/CD3 = establish project baseline cost and schedule
E.C. Aschenauer

14. EIC User community
Currently ~630 members from 137 institutions from 27 countries from
6 world regions
US: 47% Europe: 28% Asia: 19%
continuously growing
Please sign up and join us
Very active generic EIC detector R&D program:
37 groups collaborate in tracking, calorimeter, PID consortia and …….
EIC Conference series: POETIC (Physics Opportunities at an ElecTron-Ion Collider)
2016: POETIC combined with CTEQ Workshop
November , 2016 at Temple University, Philadelphia, PA
Next EIC user group meeting:
July 18-22, 2017 in Trieste, Italy
E.C. Aschenauer