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On the Trail of a Dense Plasma at RHIC (a detector builder’s point of view) Jim Thomas Lawrence Berkeley Laboratory Cornell University Journal Club 5/21/2004. The Phase Diagram for Nuclear Matter. One of the goals of RHIC is to understand the QCD in the context of the many body problem - PowerPoint PPT Presentation
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1Jim Thomas - LBL
On the Trail of a Dense Plasma at RHIC(a detector builder’s point of view)
Jim ThomasLawrence Berkeley Laboratory
Cornell University Journal Club5/21/2004
2Jim Thomas - LBL
The Phase Diagram for Nuclear Matter
K. Rajagopol
The goal is to explore nuclear matter under extreme conditions – T > mc2 and > 10 * 0
• One of the goals of RHIC is to understand the QCD in the context of the many body problem
• Another goal is to discover and characterize the Quark Gluon Plasma
• RHIC is a place where fundamental theory and experiment can meet after many years of being apart
3Jim Thomas - LBL
This gap is a manifestation of the approximate SU(2)R x SU(2)L chiral symmetry of QCD with pions as the Nambu-Goldstone bosons
QCD is a Rich Theory with Many Features
Hadron “level” Diagram
Hadron 'level' diagram
0
500
1000
1500
0 10 20 30 40
Degeneracy
Mass (MeV)
Kfo
{W. Zajc
MFFDiL a
aˆ~
4
1We have a theory of the strong
interaction
Low(er) energy nuclear physics uses OPEP or descriptions in terms of a pion gas. These worked because QCD is a theory with a mass gap.
4Jim Thomas - LBL
Lattice QCD predictions
TC ~ 170 MeV, a very stable prediction over time & technologies(F. Karsch, hep-lat/0106019, edited by JT)
Stephan Boltzman limits for a free Quark Gluon gas
En
erg
y D
ensi
ty
Temperature
TC ~ 170 15 MeV
C ~ 0.7 GeV/fm3
0 ~ 0.16 GeV/fm3
Karsch QM2004
5Jim Thomas - LBL
Who is RHIC and What Does He Do?
RHIC
• Two independent rings
• 3.83 km in circumference
• Accelerates everything, from p to Au
s L p-p 500 1032
Au-Au 200 1026
(GeV and cm-2 s-1)
• Polarized protons
• Two Large and two small detectors have been built
h
BRAHMS
PHOBOS
PHENIX
Long Island
Long Island
STARSTAR
6Jim Thomas - LBL
RHIC Physics is Relativistic Nuclear Physics
7Jim Thomas - LBL
The Initial State is Important
• Only a few of the nucleons participate as determined by the impact parameter
• There is multiple scattering in the initial state before the hard collisions take place
– Cronin effect
• The initial state is Lorentz contracted
• Cross-sections become coherent. – The uncertainty principle allows
wee partons to interact with the front and back of the nucleus
– The interaction rate for wee partons saturates ( ρσ = 1 )
• The intial state is even time dilated– A color glass condensate
• proton • neutron • delta • pion string
8Jim Thomas - LBL
How do we ‘see’ RHIC physics?
Barrel EM Calorimeter
FTPCs
Time Projection Chamber
Silicon TrackerSVT & SSD
Endcap Calorimeter
Magnet
Coils
TPC Endcap & MWPC
Central Trigger Barrel & TOF
Beam Beam Counters
4.2 meters
Not Shown: pVPDs, ZDCs, PMD, and FPDs
A TPC lies at the heart of STAR
9Jim Thomas - LBL
TPC Gas Volume & Electrostatic Field Cage
• Gas: P10 ( Ar-CH4 90%-10% ) @ 1 atm
• Voltage : - 28 kV at the central membrane 135 V/cm over 210 cm drift path
420 CM
Self supporting Inner Field Cage: Al on Kapton using Nomex honeycomb; 0.5% rad length
10Jim Thomas - LBL
Pixel Readout of a Pad Plane Sector
A cosmic ray + deltaelectron
3 sigma threshold
11Jim Thomas - LBL
Particle ID using Topology & Combinatorics
Secondary vertex: Ks + p +
+ + K e++e-
Ks + + - K + + K -
p + - + + -
from K+ K- pairs
K+ K- pairs
m inv
m inv
same event dist.mixed event dist.
background subtracted
dn/dm
dn/dm
“kinks”
K +
12Jim Thomas - LBL
Au on Au Event at CM Energy ~ 130 GeV*A
Real-time track reconstruction
Pictures from Level 3 online display. ( < 70 mSec )
Data taken June 25, 2000.
The first 12 events were captured on tape!
13Jim Thomas - LBL
Au on Au Event at CM Energy ~ 130 GeV*A
Two-track separation 2.5 cm
Momentum Resolution < 2%
Space point resolution ~ 500 m
Rapidity coverage –1.8 < < 1.8
A Central Event
Typically 1000 to 2000 tracks per event into the TPC
14Jim Thomas - LBL
Cold nuclear matter:0 ~ 0.16 GeV/fm3
30x0
nucl-ex/0311017
PRL 87 (01) 52301
R2
dydz 0
Boost invariant hydrodynamics: Bjorken Estimate of Initial Energy Density
d
dNp
Rdy
dE
Rch
TT
2
31122
~ 0.2 - 1 fm/ctime to thermalize the
system
~ 6.5 fm
Bjorken Estimate of Initial Energy Density
3/5.4 fmGeV3/7.0 fmGeVC
15Jim Thomas - LBL
0
0 .2
0 .4
0 .6
0 .8
1
1 .2
1 .4
1 .6
-6 -4 -2 0 2 4 6
y
dy
dn
Rapidity vs xf
• xf = pz / pmax
– A natural variable to describe physics at forward scattering angles
• Rapidity is different. It is a measure of velocity but it stretches the region around v = c to avoid the relativistic scrunch
– Rapidity is relativistically invariant and cross-sections are invariant
)/(tanh 1 Epyor z
Rapidity is the natural kinematic variable for HI collisions
( y is approximately the lab angle where y = 0 at 90 degrees )
1tanh yy
z
z
pE
pEy ln
2
1
β
16Jim Thomas - LBL
Identified Particle Spectra at 200 GeV
+, -, K+, K- spectra versus centrality
PRL 92 (2004) 171801 and nucl-ex/0206008
Bose-Einstein fits
mTmAe
/mt exponential fits
K-)1/( / effTmeA
+
17Jim Thomas - LBL
Anti-Proton Spectra at 200 & 130 GeV / N
Au + Au p + X
130 GeV data
p
200 GeV data
22 2/ pAegaussian fits
p andp spectra versus centrality
PRL 92 (2004) 171801 and PRL 87 (2001) 262302
p
18Jim Thomas - LBL
• In the early universe
p / p ratio = 0.999999
• At RHIC, pair-production
increases with s
• Mid-rapidity region is not yet
baryon-free!
• Pair production is larger than
baryon transport
• 80% of protons from pair
production
• 20% from initial baryon
number transported over 5
units of rapidity
Anti-Baryon/Baryon Ratios versus sNN
In HI collisions at RHIC, more baryons are pair produced than are brought in by the
initial state
4Tr
pair
Y
Y
8.0
Transpair
pair
p
pbar
YY
Y
Y
Y
19Jim Thomas - LBL
Anti-Particle to Particle Ratios
Excellent agreement between experiments at y = 0, s = 130
STAR results on thep/p ratio p/p = 0.11 ± 0.01 @ 20 GeV p/p = 0.71 ± 0.05 @ 130 GeV p/p = 0.80 ± 0.05 @ 200 GeV
p/p ratios
K+/K- ratios
20Jim Thomas - LBL
Chemical Freeze-out – from a thermal model
Thermal model fits
Compare to QCD on Lattice:
Tc = 154 ± 8 MeV (Nf=3)
Tc = 173 ± 8 MeV (Nf=2)(ref. Karsch QM01)
MeV 629(RHIC)μ
MeV 7177(RHIC)T
B
ch
MeV 270(SPS)μ
MeV 170160(SPS)T
B
ch
• The model assumes a thermally and chemically equilibrated fireball at hadro-chemical freeze-out
• Works great, but there is not word of QCD in the analysis. Done entirely in a color neutral Hadronic basis!
input: measured particle ratios output: temperature T and baryo-chemical potential B
21Jim Thomas - LBL
• Final-state analysis suggests RHIC reaches the phase boundary
• Hadron spectra cannot probe higher temperatures
• Hadron resonance ideal gas (M. Kaneta and N. Xu,
nucl-ex/0104021 & QM02)
– TCH = 175 ± 10 MeV
– B = 40 ± 10 MeV
• <E>/N ~ 1 GeV(J. Cleymans and K. Redlich, PRL 81, p. 5284, 1998 )
Lattice results
Neutron STAR
Putting RHIC on the Phase Diagram
We know where we are on the phase diagram but now
we want to know what other features are on the diagram
22Jim Thomas - LBL
Chemical and Kinetic Freeze-out
• Chemical freeze-out (first)– End of inelastic interactions
– Number of each particle species is frozen
• Useful data– Particle ratios
• Kinetic freeze-out (later)– End of elastic interactions
– Particle momenta are frozen
• Useful data– Transverse momentum distributions
– and Effective temperatures
space
tim
e
inelasticinteractions
Chemicalfreeze-out
elasticinteractions
Kineticfreeze-out
blue beam yellow beam
23Jim Thomas - LBL
Transverse Flow
The transverse radial expansion of the source (flow) adds kinetic energy to the particle distribution. So the classical expression for ETot
suggests a linear relationship
-
K -
p
Au+Au at 200 GeV
STAR Preliminary
2KFOObs massTT
Slopes decrease with mass. <pT> and the effective temperature increase with mass.
T ≈ 575 MeV
T ≈ 310 MeV
T ≈ 215 MeV
24Jim Thomas - LBL
Kinetic Freezeout from Transverse Flow
<ßr> (RHIC) = 0.55 ± 0.1 cTKFO (RHIC) = 100 ± 10 MeV
Explosive Transverse Expansion at RHIC High Pressure
Tth
[GeV
]<
r>
[c]
STA
RPH
EN
IX
Thermal freeze-out determinations are done with the blast-wave model to find <pT>
STAR Preliminary
25Jim Thomas - LBL
Anisotropic (Elliptic) Transverse Flow
• The overlap region in peripheral collisions is not symmetric in coordinate space
– Almond shaped overlap region• Easier for particles to emerge in the
direction of x-z plane• Larger area shines to the side
– Spatial anisotropy Momentum anisotropy• Interactions among constituents
generates a pressure gradient which transforms the initial spatial anisotropy into the observed momentum anisotropy
• Perform a Fourier decomposition of the momentum space particle distributions in the x-y plane
– v2 is the 2nd harmonic Fourier coefficient of the distribution of particles with respect to the reaction plane
2cos2 vx
y
p
patan
Peripheral Collisions
Anisotropic Flow
x
yz
px
py
...)2cos(2)cos(21 21 vv
26Jim Thomas - LBL
v2 vs. Centrality
• v2 is large– 6% in peripheral
collisions
– Smaller for central collisions
• Hydro calculations are in reasonable agreement with the data
– In contrast to lower collision energies where hydro over-predicts anisotropic flow
• Anisotropic flow is developed by rescattering
– Data suggests early time history
– Quenched at later times
Anisotropic transverse flow is large at RHIC
PRL 86, (2001) 402
more central
Hydro predictions
27Jim Thomas - LBL
v2 vs. pT and Particle Mass
• The mass dependence is reproduced by hydrodynamic models
– Hydro assumes local thermal equilibrium
– At early times
– Followed by hydrodynamic expansion
D. Teaney et al., QM2001 Proc.P. Huovinen et al., nucl-th/0104020
Hydro does a surprisingly good job!
PRL 86, 402 (2001) & nucl-ex/0107003
28Jim Thomas - LBL
V2 at high Pt shows meson / baryon differences
Asym. pQCD Jet Quenching
Bulk PQCD Hydro
qn Coalescence
29Jim Thomas - LBL
The Recombination Model ( Fries et al. PRL 90 (2003) 202303 )
The flow pattern in v2(pT) for hadrons
is predicted to be simple if flow is developed at the quark level
pT → pT /n
v2 → v2 / n ,
n = (2, 3) for (meson, baryon)
30Jim Thomas - LBL
What does this mean?
• Hadrons are created by the recombination of quarks and this appears be the dominant mechanism for hadron formation at intermediate PT
• Baryons and Mesons are produced with equal abundance at intermediate PT
• The collective flow pattern of the hadrons appears to reflect the collective flow of the constituent quarks.
Partonic Collectivity
31Jim Thomas - LBL
Lets look at some collision systems in detail …
Final stateInitial state
Au + Au
d + Au
p + p
32Jim Thomas - LBL
Partonic energy loss via leading hadrons
Energy loss softening of fragmentation suppression of leading hadron yield
ddpdT
ddpNdpR
TNN
AA
TAA
TAA /
/)(
2
2
Binary collision scaling p+p reference
33Jim Thomas - LBL
Au+Au and p+p: inclusive charged hadrons
p+p reference spectrum measured at RHIC
PRL 89, 202301 nucl-ex/0305015, PRL in press
34Jim Thomas - LBL
Suppresion of inclusive hadron yield
• central Au+Au collisions: factor ~4-5 suppression • pT>5 GeV/c: suppression ~ independent of pT
nucl-ex/0305015
Au+Au relative to p+p Au+Au central/peripheral
RAA RCP
35Jim Thomas - LBL
PHENIX observes a similar effect (0s)
nucl-ex/0304022
Factor ~5 suppression for central Au+Au collisions
lower energy Pb+Pb
lower energy
36Jim Thomas - LBL
The Suppression occurs in Au-Au but not d-Au
37Jim Thomas - LBL
Jet Physics … it is easier to find one in e+e-
Jet event in eecollision STAR Au+Au collision
38Jim Thomas - LBL
Identifying jets on a statistical basis in Au-Au
STAR DataAu+Au @ 200 GeV/c
0-5% most central4 < pT(trig) < 6 GeV/c
2 < pT(assoc.) < pT(trig)
• Identify jets on a statistical basis in Au-Au
• Given a trigger particle with pT > pT (trigger), associate particles with pT > pT (associated)
),(11
),(2 NEfficiencyN
CTRIGGER
• You can see the jets in p-p data at RHIC
39Jim Thomas - LBL
Angular Distribution: Peripheral Au+Au data vs. pp+flow
C2(Au Au) C2(p p) A *(1 2v22 cos(2))
Ansatz: A high pT triggered Au+Au event is a superposition of a high pT triggered p+p event plus anisotropic transverse flow
v2 from reaction plane analysis
“A” is fit in non-jet region (0.75<||<2.24)
40Jim Thomas - LBL
Angular Distribution: Central Au+Au data vs. pp+flow
C2(Au Au) C2(p p) A *(1 2v22 cos(2))
41Jim Thomas - LBL
correlations vs the reaction plane
pTtrigger=4-6 GeV/c, 2<pT
associated<pTtrigger, ||<1
y
x
in-plane
Out-of-plane
Effect of path length on suppression is experimentally accessible
-/4
/43/4
-3/4
Back-to-back suppression out-of-plane stronger than in-plane
42Jim Thomas - LBL
What does it mean?
• The backward going jet is missing in central Au-Au collisions when compared to p-p data + flow
• The backward going jet is not suppressed in d-Au collisions
• These data suggest opaque nuclear matter and surface emission of jets
Surface emission
Suppression of back-to-back correlations in central Au+Au collisions
43Jim Thomas - LBL
Exp: Conclusions About Nuclear Matter at RHIC
• Its hot– Chemical freeze out at 175 MeV
– Thermal freeze out at 100 MeV
– The universal freeze out temperatures are surprisingly flat as a function of s
• Its fast– Transverse expansion with an average velocity greater than 0.55 c
– Large amounts of anisotropic flow (v2) suggest hydrodynamic expansion and high pressure at early times in the collision history
• Its opaque– Saturation of v2 at high pT
– Suppression of high pT particle yields relative to p-p
– Suppression of the away side jet
• And its not inconsistent with thermal equilibrium– Excellent fits to particle ratio data with equilibrium thermal models
– Excellent fits to flow data with hydrodynamic models that assume equilibrated systems
44Jim Thomas - LBL
‘They say …’
• ‘Some theorists say’ we have discovered the Quark Gluon Plasma at RHIC
– Evidence for PQCD via vn bulk collective flow of 104 , K,p,– Evidence for pQCD jet quenching in Au+Au at RHIC
– Evidence jet un-quenching in D+Au = Null Control
• The experimental community is somewhat more cautious because, in part, its not clear what the words mean
– Web definition for plasma: A low-density gas in which the individual atoms are charged, even though the total number of positive and negative charges is equal, maintaining an overall electrical neutrality.
– In the collision of two heavy ions, we have found a high density plasma containing quarks and gluons.
So whats the problem with the experimentalists?
45Jim Thomas - LBL
Are the theories a unique explanation for the data?
46Jim Thomas - LBL
Au+Au Datasets
This year: extremely successful run, all goals met Greater than order of magnitude increase in dataset
Au Events
0
20
40
60
80
100
120
2000 2001 2002 2004
Year
Mil
lio
n E
ven
ts d+Au
AuAu 62 GeV
AuAu 130 GeV
AuAu 200 GeV
47Jim Thomas - LBL
Rcp ratios
At At =0 the =0 the central events central events have the ratio have the ratio systematically systematically above that of above that of semi-central semi-central events. We see events. We see a reversal of a reversal of behavior as we behavior as we study events at study events at =3.2=3.2
Rcp
1/<Ncoll central> NABcentral(pT,
1/<Ncoll periph> NAB
periph(pT,)
48Jim Thomas - LBL
RdAu ratios
CroninCronin like like enhancement enhancement at at =0.=0.
Clear Clear suppression suppression as as changes changes up to 3.2up to 3.2
Same ratio Same ratio made with made with dn/ddn/d follows the follows the low plow pTT R RdAudAu
RdA d2Nd+Au/dpTd
<Ncoll> d2Nppinel/dpTd
where < < Ncoll> = 7.2> = 7.2±0.3
49Jim Thomas - LBL
Current State of Affairs
• A theory is something nobody believes, except the person who made it.
• An experiment is something everybody believes, except the person who made it.
– attributed to Albert Einstein
50Jim Thomas - LBL
Recombination TestedThe complicated observed flow pattern in v2(pT)
d2n/dpTd ~ 1 + 2 v2(pT) cos (2 )
is predicted to be simple at the quark level under pT → pT / n , v2 → v2 / n , n = 2,3 for meson,baryon
if the flow pattern is established at the quark level
Compilation courtesy of H. Huang
51Jim Thomas - LBL
At low pt: mass ordering
hydrodynamics
At larger pt: Baryons – mesons
quark coalescence
We need v2 of and 0
Quark Coalescence
S.A. Voloshin, Nucl. Phys. A715, 379 (2003).
Z. Lin et al., Phys. Rev. Lett., 89, 202302 (2002).
R. Fries et al., nucl-th/0306027.
D. Molnar and S.A. Voloshin, PRL 91, 092301(2003).
52Jim Thomas - LBL
Multi-Strange Baryons v2
Multi-strange baryons flow !
Partonic Collectivity !Partonic Collectivity !
53Jim Thomas - LBL
Outer and Inner Sectors of the Pad Plane
60 cm
190 cmOuter sector
6.2 × 19.5 mm pads3940 pads
Inner sector2.85 × 11.5 mm pads
1750 pads
• 24 sectors (12 on a side)
• Large pads good dE/dx resolution in the Outer sector
• Small pads for good two track resolution in the inner sector
54Jim Thomas - LBL
Sector Operation for 20:1 signal to noise
Sector gas gain anodevoltage
inner 3000 1150outer 1100 1380
TPC Sector Detail
• Gating Grid
• Ground Plane of Wires
• Anodes– No field shaping wires
• Simple and reliable
– Individually terminated anode wires limit cross-talk
– Low gain
• Pad Plane
55Jim Thomas - LBL
Sector Readout of Pad Planes
Readout arranged like the face of a clock - 5,690 pixels per sector
56Jim Thomas - LBL
Particle Identification by dE/dx
dE/dx PID range:
~ 0.7 GeV/c for K/
~ 1.0 GeV/c for K/p
Anti - 3He
57Jim Thomas - LBL
Summary of Performance Achieved to date
• Features of the STAR TPC– 4 meters in diameter, 210 cm drift
– No field wires in the anode planes
– Pad readout, Low gain on anodes
– Low drift field
– Very compact FEE electronics
– Analog Delay with SCA then onboard ADC
– Data delivered via optic fiber
– Uniform E and B fields
– ‘ExB’ and most Electrostatic distortions correctable to 50 – 100 m level
• Position resolution– 500 m in the real world with calibration
errors
– Space point resolution ~ 100 m for select laser events, 250 - 350 m for select tracks
– Function of dip angle and crossing angle
• Good particle separation using dE/dx– 6.5% dE/dx resolution @ 100 cm – -proton separation : > 1 GeV/c
• 2-Track resolution– 2.5 cm for HBT pairs – 1.5 cm for laser tracks– limited by 3 pad response function
and desire for fast algorithms
• Momentum resolution– 2% minimum at 0.25 Tesla (half field)– for pT > 1.5 GeV in 0.25 T field
• dk/k = 0.016 pT + 0.012 (central)• dk/k = 0.011 pT + 0.013 (peripheral)• 2.9% 3.3% peripheral/central
@ 1.5 GeV
STAR performance is excellent and meets essentially all design
specifications!
58Jim Thomas - LBL
Something Funny Happens at T > mc2
An exponentially increasing density of hadronic states suggests– A “limiting temperature” TH
– A phase transition(?) in hadronic matter
This was noticed before quarks were identified as the constituents of matter– ( Hagedorn, Nuovo Cimento Supp., 3 (147) 1965 )
Fit this form with TH = 163 MeVDensity of States .vs. Energy
HTmaemdm
dnm /~)(
dmem
dmem
TTm
a
Tm
H
)11
(
/
~
)(
Which requires T < TH
Thermal equilibrium suggests
59Jim Thomas - LBL
Meson – baryon Effect ?
Exp. data consistent with quark
recombination/coalescence scenario
S.A. Voloshin, Nucl. Phys. A715, 379 (2003).Z. Lin et al., Phys. Rev. Lett., 89, 202302 (2002).R. Fries et al., nucl-th/0306027.D. Molnar and S.A. Voloshin, PRL 91, 092301(2003).
Further tests: , 0, K*, …
v2: Scaling
60Jim Thomas - LBL
single point
fluctuation excesstp
statisticalreference
data
2D scale inversion
pt fluctuation inversion
minijet dissipation & velocity/temperature structure:• elongation on
• necking on
200 GeV Au-Au data
fluctuation scale dependence two-particle correlations
STAR preliminary
soft partons asextended objects
peripheral
central
<pT> Fluctuations → Correlations
61Jim Thomas - LBL
Baryon Enhancement
Simple fragmentation picture fails for pT less than ~6 GeV/c
p+pbar/h enhancement in Au + Au not fully explained by Cronin effect
Strong baryon/meson modification in Au + Au also in /K0s ratio
S.S. Adler et al., nucl-ex/0305036.
62Jim Thomas - LBL
RCP of Strange Hadrons
Two groups (2<pt<6GeV/c):
- K0s, K, K*, mesons
- , , baryons
dependence on number of
valence quarks
limited to pt<6GeV/c ?
hadron production from
quark recombination/
coalescence ?
63Jim Thomas - LBL
Jet Quenching
Au + Au, RAA << 1; d+Au, RdAu > 1
p+p, away side jet exists Au + Au, away-side correlation suppressed d+Au, away-side correlation exists
jet quenching ?J. Adams et al., Phys. Rev. Lett. 91, 072304 (2003).
64Jim Thomas - LBL
Hadron suppression @62 GeV
• Significant suppression @62, 130, 200 GeV
• Smooth evolution of suppression with energy
65Jim Thomas - LBL
Triggered Correlation Studies
blue band: <pt> in away-side
correlation, decreases with centrality
solid line: <pt> of bulk, increases with
centrality transverse radial flow
Au+Au: Away-side
suppression is larger in the out-
of-plane direction compared to
in-plane
jet quenching ?
STAR PreliminarySTAR Preliminary
pTrigger = 4 -6GeV/c
66Jim Thomas - LBL
0
0.2
0.4
0.6
0.8
1
-3 -2 -1 0 1 2 3
y
antiprotonto proton
ratio
BRAHMS
STAR
PHOBOS
PHENIX
Points reflected about y = 0
s = 130 Results
Pbar/ P | Y=0.0 = 0.64
Pbar/ P | Y=0.7 = 0.66
Pbar/ P | Y=2.0 = 0.41
BRAHMS PRL 87 No. 11 (2001).
Evidence for the development of a (nearly) baryon-free central region
Anti-Proton to Proton Yields vs. Y
67Jim Thomas - LBL
Part I: full jet reconstruction in p+p, d+Au
ET
ET
Including EMCal information
A first look…
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