QCD Fron)ers 2013 Slide 1
JLab 12 GeV Nuclear Program
by
Douglas W. Higinbotham
furthering understanding of nucleons in the nucleus
QCD Fron)ers 2013 Slide 2
Outline • Review of (e,e’) KinemaJcs
• EMC Effect – What is it?
– Recent developments.
• Short Range CorrelaJons (SRC) – What is it? – Recent developments
• SRC and EMC Together!?
• Upcoming Experiments
QCD Fron)ers 2013 Slide 3
Electron ScaTering Regions
xB < 1 xB = 1 xB > 1 xB = Q2/2mω
QCD Fron)ers 2013 Slide 4
What is the EMC Effect? • EMC effect is simply the fact the raCo
of DIS cross secCons is not one – J.J. Aubert et al. PLB 123 (1983) 275. – Simple Parton CounJng Expects One
– MANY ExplanaCons • SLAC E139
– J. Gomez et al., PRD 49 (1994) 4348. – Precise large-‐x data – Nuclei from A=4 to 197
• Conclusions from SLAC data – Q2-‐independent – Universal x-‐dependence (shape) – Magnitude varies with A – Average Nuclear Density Effect
QCD Fron)ers 2013 Slide 5
Jefferson Lab EMC Effect Data J. Seely et al., Phys, Rev. Lett. 103 (2009) 202301.
x
mC/mD Q2=4.06
Q2=4.50Q2=4.83Q2=5.33Q2=6.05
0.9
1
1.1
1.2
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
QCD Fron)ers 2013 Slide 6
New Jefferson Lab EMC Effect Data J. Seely et al., Phys, Rev. Lett. 103 (2009) 202301.
• Plot shows slope of ratio σA/σD at EMC region. • EMC effect correlated with local density not average density.
QCD Fron)ers 2013 Slide 7
If the EMC effect is a local density effect, then it seems reasonable to look for connecJons to other local
density effects.
QCD Fron)ers 2013 Slide 8
Classic (e,e’p) Results
Independent-‐ParJcle Shell-‐Model is based upon the assumpJon that each nucleon moves independently in an average potenJal (mean field) induced by the surrounding nucleons
The (e,e'p) data for knockout of valence and deeply bound orbits in nuclei gives spectroscopic factors that are 60 – 70% of the mean field predicJon.
Target Mass
SPEC
TROSCOPIC STRE
NGTH
L. Lapikas, Nucl. Phys. A553 (1993) 297.
SoluCon: CorrelaCons Between Nucleons
QCD Fron)ers 2013 Slide 9
RealisJc Momentum DistribuJon Benhar et al., Phys. LeT. B 177 (1986) 135.
QCD Fron)ers 2013 Slide 10
Momentum DistribuJons C. Ciofi degli AT and S. Simula, Phys. Rev. C 53 (1996) 1689.
At high ini)al momentums nA(p) = N * nD(p)
QCD Fron)ers 2013 Slide 11
Minimum Missing Momentum Assuming a (e,e’p) reacJon, inclusive (e,e’) can set limits on recoiling system’s momentum.
QCD Fron)ers 2013 Slide 12
Nuclear Scaling Plateaus from CLAS K. Sh. Egiyan et al., Phys. Rev. C 68 (2003) 014313.
Originally done with SLAC data by Frankfurt et al., Phys. Rev. C 48 (1993) 2451.
QCD Fron)ers 2013 Slide 13
New Results From JLab Hall-‐C N. Fomin et al., Phys. Rev. LeT. 108 (2012) 092502.
0
3
6 3He
0
3
6 4He
(mA/
A)/(m
D/2
)
0
3
6
0.8 1 1.2 1.4 1.6 1.8x
9Be
12C
63Cu
1 1.2 1.4 1.6 1.8 2x
197Au
QCD Fron)ers 2013 Slide 14
Coincidence (e,e’pN) Measurement
x > 1 , Q2 = 1.5 [GeV/c]2 and missing momentum of 500 MeV/c
To study nucleon pairs and the fracJon that contribute to momentum tail.
QCD Fron)ers 2013 Slide 15
High pm (e,e’p) events have recoiling neutrons.
Missing Momentum [GeV/c]
0.3 0.4 0.5 0.6
SR
C P
air
Fra
cti
on
(%
)
10
210
C(e,e’p) ] /212
C(e,e’pp) /12
pp/2N from [
C(e,e’p)12
C(e,e’pn) /12
np/2N from
C(p,2p)12
C(p,2pn) /12
np/2N from
C(e,e’pn) ] /212
C(e,e’pp) /12
pp/np from [
R. Subedi et al., Science 320 (2008) 1476.
QCD Fron)ers 2013 Slide 16
Importance of CorrelaJons
• R. Schiavilla et al., Phys. Rev. LeT. 98 (2007) 132501. • M. Sargsian et al., Phys. Rev. C (2005) 044615. • M. Alvioli et al., Phys. Rev. LeT. 100 (2008) 162503.
np
pp
QCD Fron)ers 2013 Slide 17
So How These “Nuclear” Results Relate To The “Deep InelasCc” EMC Effect Results?!
QCD Fron)ers 2013 Slide 18
HolisJc View of the EMC & SRC Data D. Higinbotham et al., arXiv:1003.4497
Q2 = 2.5 [GeV/c]2
EMC Slope
SRC Plateau
• Scaling plateaus are likely due to proton-nucleon local density correlations • So could the EMC slopes (xB<0.7) and SRC plateaus (xB>1.5) correlated?!
QCD Fron)ers 2013 Slide 19
Experimental SRC and EMC CorrelaJon L. Weinstein, E. Piasetzky, D.H., J. Gomez, O.Hen and R. Shneor, Phys. Rev. Lett. 106 (2011) 052301. J. Arrington, A. Daniel, D. Day, N. Fomin, D. Gaskell, P. Solvignon, Phys. Rev. C 86 (2012) 065204
The data show that EMC effect slopes are proportional to the SRC plateaus. An intriguing possibility suggested by this correlation is that the EMC effect and SRCs
are both a consequence of the local QCD effects within the nucleus.
SRC Plateaus (σA/A)/(σd/2)
EMC Slop
es (-‐dR
EMC/dx)
QCD Fron)ers 2013 Slide 20
Quark State of Overlapping Nucleons?
+a b
l =0
l=1
l =0
Deuteron Has Quadripole Moment In All Frames Of Reference!
QCD Fron)ers 2013 Slide 21
Using SRC & EMC to get d/u raJos CTEQ-‐Jefferson Lab (CJ): A. Accardi et al., Phys. Rev. D 84, 014008 (2011). In-‐Medium CorrecJon (IMC): O. Hen et al., Phys. Rev. D 84 (2012) 117501.
Result is between the SU(6) symmetry limit of ½ and the scalar di-‐quark dominance limit of 0.
QCD Fron)ers 2013 Slide 22
Analysis in Progress • E07-‐006: SRC 2nd GeneraJon (e,e’pN) Triple Coincidence Experiment
– Goal to further probe the repulsive part of the nucleon-‐nucleon potenJal with a few body, 4He, target.
• E08-‐014: SRC (e,e’) xB >1 & 2 data on 3He, 4He, 40Ca, & 48Ca – Goal to study Q2, xB > 2 region, and the A/Z dependence of the SRC plateaus.
xB
(σ12
C/1
2)/(σ
3He/3
)
Q2 ~ 2.7 [GeV/c]2 Jefferson Lab 2012
Q2 ~ 2.2 [GeV/c]2
Q2 ~ 1.8 [GeV/c]2
Q2 ~ 1.5 [GeV/c]2
Q2 ~ 1.3 [GeV/c]2
Preliminary
QCD Fron)ers 2013 Slide 23
Upcoming 12GeV Experiments • E12-‐10-‐103 & E12-‐11-‐112 plans 3He & 3H (e,e’) SRC & EMC Measurements
– DIS 3He/3H is a text book u/d experiment
– x>1 to further invesJgate SRC and possible link EMC effect
• E12-‐10-‐008 & E12-‐06-‐105 plans a survey of (e,e’) nuclei from light to heavy. – Exact list being opJmized, but goal is to cover EMC x < 1 and SRC x > 1 for each nucleus
• E12-‐11-‐002 recoil polarizaJon in the 4He(e,e'p)3H, 2H(e,e'p)n, and 1H(e,e'p) reacJons – Classic medium modificaJon experiment pushed to higher precision and higher missing momentum
• E12-‐11-‐107 will use a Large Acceptance Device (LAD) to tag recoiling nuclei – Goal to directly show if the cause of the EMC effect is due to SRC pairings
(σ3H
e / σ
3H)
xB xB
F 2n /F
2p
QCD Fron)ers 2013 Slide 24
Summary • New data points to EMC effect being a local density effect.
• xB>1 nuclear scaling plateaus are likely a local density effect. • Data shows the two effects to be correlated. • Open QuesJons
– What exactly is the high momentum tail?
( i.e. momentum p >> pfermi nA(p) = N * nD(p) but why? )
– Is it hadronic, partonic , or some combinaJon both?
– Can we use this correlaJon to make even more insights?
• Many New EMC (x<1) and SRC (x>1) Experiments Coming with 12GeV Jefferson Lab, including 3H & 3He raCos as an early measurement.
QCD Fron)ers 2013 Slide 25
TriJum Target Cell Development 25cm cell machined from a single piece of Al that can be filled, sealed, and returned.