Transcript Playing with Goo - Attempting to Recreate Rochester Colloquium -March 2004

Playing with Goo - Attempting to Recreate
Primordial Matter at a Trillion K
Helen Caines - Yale University
“The test of all knowledge is experiment”
(R.P. Feynman, Feynman Lectures on Physics,
Book 1, Chapter 1, Page 1)
Rochester Colloquium -March 2004
STAR
Evolution of the universe
10-44 sec
Quantum Gravity
10-35 sec
Grand Unification
Unification of all 4
forcescooler
The
Reheating
universe Matter
gets
? !
10-35 sec ? Inflation
2
10-10
sec Electroweak
unification
E-M/Weak = Strong
forces
1027 K
universe exponentially
expands by 1026
1027 K
E-M = weak force
1015 K
?
Need temperatures
2·10-6 sec Protoncreation
of nucleons
around
Antiproton pairs
1.5·1012 K
Stars
convert gravitational
6 sec
Electron-Positron creation of electrons
(200 MeV)
energy to temperature.
pairs
3 min
Nucleosynthesis
106 yrs
109 yrs ?
light elements formed
They
“replay” and
finish
Microwave
recombination nucleosynthesis
at to photons
Background
transparent
6 K in the center of
~15·10
Galaxy formation
bulges and halos of
our sun.normal galaxies form
Helen Caines – March 2004
1032 K
1013 K
6 x 109
K
109 K
3000 K
20 K
2
How and why do we do this research?
To explore the phase diagram of nuclear matter
How:
♦ By colliding nuclei in lab.
♦ By varying energy (√s) and
size (A).
♦ By studying spectra and
particle correlations.
Rajagopal and Wilczek,
hep-ph/-0011333
To probe properties of dense
nuclear matter
How:
♦ By colliding most massive and
highest energy nuclei.
♦ By comparing to more elementary
systems.
♦ Through high p studies.
Helen Caines – March 2004
3
The early predictions
- New Scientist
No… the experiment will not
tear our region of space to
subatomic shreds.
the risk of such a catastrophe
is essentially zero. – B.N.L. –
Oct ‘99
- Washington Post – Sept ‘99
Helen Caines – March 2004
4
Lattice QCD calculations
G. Schierholz
et al.,
• Coincident transitions: deconfinement and chiral symmetry
restoration
2003
• Recently extended to mB> 0, order still unclear (1st,Confinement
2nd, crossover
?)
170
C ≈QCD
Action density in 3 quark system inTfull
H. Ichie et al., hep-lat/0212036
MeV
Helen Caines – March 2004
F. Karsch,
hep-ph/0103314
5
RHIC @ Brookhaven National Lab.
Relativistic
Heavy
Ion
Collider
STAR
h
2 concentric rings of 1740
superconducting magnets
3.8 km circumference
counter-rotating beams of ions from
p to Au
Previous Runs:
♦ Au+Au @ sNN=130 GeV & 200 GeV
♦ p+p @ sNN =200 GeV
♦ d+Au @ sNN =200 GeV
Present Run:
♦ Au-Au sNN=200 GeV
Helen Caines – March 2004
6
What Does a RHIC Collision Look Like?
A Central Au+Au Collision:
Npart  sNN
= 40 TeV
~ 6 mJoule
Our Ears are sensitive to
~10-11 ergs
= 10-18 Joule
= 10-12 mJoule
If a RHIC Collision was
converted solely into noise
that‘s one BIG BANG!
HI Collisions converted into
COPIOUS particle production
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Peripheral Collision
Color  Energy loss in TPC gas
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Central Collision
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The Experimental Setup
Magnet
Time
Projection
Chamber
Coils
Silicon
Vertex
Tracker *
TPC Endcap &
MWPC
FTPCs (1 + 1)
ZCal
ZCal
Vertex
Position
Detectors
Endcap
Calorimeter
Barrel EM
Calorimeter
Central Trigger
Barrel
+ TOF patch
RICH
* yr.1 SVT ladder
Year 2000, year 2001, year-by-year until 2003, installation in 2003
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How a TPC works
♦
♦
♦
Tracking volume is an empty volume of gas surrounded by a field cage
Drift gas: Ar-CH4 (90%-10%)
Pad electronics: 140000 amplifier channels with 512 time samples
Provides 70 M pixel, 3D image
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Needle in the Hay-Stack!
How do you do tracking in this regime?
Solution: Build a high resolution detector
so you can zoom in close and “see”
individual tracks
Clearly identify individual tracks
Good tracking efficiency
Helen Caines – March 2004
Pt (GeV/c)
12
A theoretical view of the collision
3
1
2
♦ Hadronic ratios.
♦Resonance production.
♦ p spectra.
4
♦ Partonic collectivity.
♦ High p measurements.
Tc – Critical temperature for transition to QGP
Tch– Chemical freeze-out (Tch  Tc) : inelastic scattering stops
Tfo – Kinetic freeze-out (Tfo  Tch): elastic scattering stops
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Geometry of heavy-ion collisions
Particle production scales with
increasing centrality
Preliminary sNN = 200 GeV
spectators
peripheral
(grazing shot)
participants
central (head-on) collision
Uncorrected
Number participants (Npart): number of nucleons in overlap region
Number binary collisions (Nbin): number of equivalent inelastic
nucleon-nucleon collisions
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Nbin ≥ Npart
14
Exceed critical energy density
Electromagnetic Calorimeter measures transverse energy in collisions
Bjorken-Formula for Energy Density:
 Bj 
1 1 dE
R 2 2 0 dy
Time it takes to
thermalize system
(0 ~ 1 fm/c)
~6.5 fm
R2
dz   0 dy
~ 5 times above critical (0.5-0.7
~3 GeV/fm3
GeV/fm3) from lattice QCD
~30 times normal nuclear density
~1.5 to 2 times higher than at
Have the Energy Density!!
CERN/SPS (s = 17 GeV)
15
Helen Caines – March 2004
Particle creation and distributions
dNch/dh
19.6 GeV
130 GeV
200 GeV
PHOBOS Preliminary
Central
Peripheral
h
♦ Central:
130 GeV
~4200
Total
multiplicity
per Au+Au:
participant
charged
pairparticles
scales with Npart
♦ Central: 200 GeV Au+Au: ~4800
charged
particles (~20ofinp-p
pp)
Not
just a superposition
♦ Plateau at y ~ 0  boost invariant
To get much further need PID
Helen Caines – March 2004
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STAR Data to Date
V0 decay vertices
Ks   + 
+
-
L  p + -
X+
STAR
Au+Au
40% to 80% Preliminary
X
r0
f0
K0S

K*0
+
L  p + STAR
So far we
measured “only”:
Preliminary
0.2  pT  0.9 GeV/c
0


X+ L 
+  ,  , K
W  L + K *0
W
0
0
0
 K (892), K s, r , f, f
in
 p, d,He3, D++
f Resonances
STAR
invariant
mass spectra
STAR Preliminary
Prelimin

*

0
 L, L(1520), X , X , W, * , *
ary
dE/dx in TPC
 D0, D*, D, e
Electron ID via
 … and all antiparticles, and correlations, and …
STAR
X-  L +  -
+
-
K*
L
p/E in EMC
Prelimin
ary
How to characterize this embarrassment of riches?
K0s
Time
of Flight (ToF)
Preliminary
preliminary
K
preliminary
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A theoretical view of the collision
1
Chemical freeze out (Tch  Tc) : inelastic scattering stops
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Net-baryon number at mid-rapidity
STAR Preliminary
♦B - all from pair production
♦ B - pair production +
transported from ybeam
to y=0
♦B/B ratio =1
♦ - Transparent
collision
♦B/B ratio ~ 0
♦ - Full stopping,
little pair
production
♦ ~2/3 of proton from pair production
♦ First time pair production dominates Same trend and values for d-Au, p-p
and Au-Au
♦ Still some baryons from beam
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Models to evaluate Tch and mB
Statistical Thermal Model
Particle density of each particle:
F. Becattini; P. Braun-Munzinger, J. Stachel, D. Magestro
J.Rafelski PLB(1991)333; J.Sollfrank et al. PRC59(1999)1637
Assume:
♦ Ideal hadron resonance gas
♦ thermally and chemically
equilibrated fireball at hadrochemical freeze-out
Recipe:
♦ GRAND CANONICAL ensemble
to describe partition function 
density of particles of species ri
♦ fixed by constraints: Volume V, ,
strangeness chemical potential mS,
isospin
♦ input: measured particle ratios
♦ output: temperature T and baryochemical potential mB
Qi
: 1 for u and d, -1 for u and d
: 1 for s, -1 for s
gi
: spin-isospin freedom
mi : particle mass
Tch : Chemical freeze-out
temperature
mq : light-quark chemical potential
ms : strangeness chemical potential
gs : strangeness saturation factor
si
Compare
particle ratios to experimental data
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Thermal model fit to data
♦ Particle ratios well described:
Tch = 160  5 MeV
mB = 24  5 MeV
ms = 1.4 1.4 MeV
gs = 0.99 0.07
Created a Large System in Local Chemical Equilibrium
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Phase Diagram from AGS to RHIC
Tch [MeV]
mB [MeV]
AGS s = 2-4 GeV
125
540
SPS s = 17 GeV
165
250
RHIC s = 130-200 GeV
175
30
Again slight variations in the models
early universe
Chemical Temperature Tch [MeV]
250
RHIC
200
quark-gluon plasma
QCD on Lattice
Tc = 173±8 MeV, Nf=2
Tc = 154±8 MeV, Nf=3
Lattice QCD
SPS
150
AGS
deconfinement
chiral restauration
Remember:
Measure hadrons not
partons so can’t measure T>
Tc with this method
100
SIS
hadron
gas
50
atomic nuclei
0
0
200
400
600
800
1000
1200
neutron stars
Baryonic Potential mB [MeV]
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Tch systematics
Hagedorn (1965):
 If the resonance mass spectrum grows exponentially
(and this seems to be the case):
 There is a maximum possible temperature for a system of hadrons.
r(m) (GeV-1)
Blue – Exp. fit
Tc= 158 MeV
Green - 1411 states of 1967
Red – 4627 states of 1996
filled: AA
open: elementary
m
Seems he was correct –
don’t get above Tch ~170 MeV
Helen Caines – March 2004
[Satz: Nucl.Phys.
A715 (2003) 3c]
27
A theoretical view of the collision
1
2
Chemical freeze out (Tch ) ~ 170 MeV
Time between Tch and Tfo
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Thermal model reproduces data
Created a Large System
in Local Chemical Equilibrium
Helen Caines – March 2004
Do resonances
destroy
the hypothesis?
29
Resonances and survival probability

K*

♦ Decays in fireball mean daughter
K
measured
tracks can rescatter destroying part of
signal
K lost

K*
lost
K*

K*
K
K
Chemical
freezeout
time
♦ Initial yield established at chemical
freeze-out
Kinetic
freezeout

♦ Rescattering also causes regeneration
which partially compensates
♦ Two effects compete – Dominance
K
measured depends on decay products and
lifetime
Ratio to “stable” particle reveals information on behaviour and timescale
between chemical and kinetic freeze-out
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Resonance ratios
Life time [fm/c] :
f = 40
L* = 13
K* = 4
Thermal model [1]:
NOT
ENOUGH
Tch = 177
MeV
mB = 29 MeV
UrQMD [2]
[1] P. Braun-Munzinger et.al., PLB 518(2001) 41
D.Magestro, private communication
[2] Marcus Bleicher and Jörg Aichelin
Phys. Lett. B530 (2002) 81-87.
M. Bleicher, private communication
Nch
Resonance
Stable

Tfo
Resonance
Stable
e  Dt /
Tch
Need >4fm between Tch and Tfo
Small centrality dependence:
little difference in lifetime!
Helen Caines – March 2004
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A theoretical view of the collision
3
1
2
Chemical freeze out (Tch ) ~ 170 MeV
Time between Tch and Tfo  4fm
Kinetic freeze-out (Tfo  Tch): elastic scattering stops
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Look in transverse direction so
not confused by longitudinal
expansion
Look at p or m= (p2 + m2 )
distribution
A thermal distribution gives a
linear distribution
dN/dm  e-(m/T)
purely thermal
source
T
heavy
m
Slope = 1/T
explosive
source
T,b
If there is radial flow
dN/dm- Shape depends on mass and
size of flow
light
1/mT dN/dmT
Want to look at how energy
distributed in system.
1/mT dN/dmT
Kinetic freeze-out and radial flow
light
heavy
m
Heavier particles show curvature
Helen Caines – March 2004
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Radial flow and hydro dynamical model
Shape of the m spectrum depends
on particle mass
Two Parameters: Tfo and b
p,K,p
fit
R
dn
m cosh r   pT sinh r 
  r dr mT K1  T
I

 0

mT dmT 0
T
T
r  tanh 1 br
E.Schnedermann et al, PRC48 (1993) 2462
bs
R
br =bs (r/R)n
Tfo ~ 90  10 MeV, < b > = 0.59 ± 0.05c
Helen Caines – March 2004
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Flow of multi-strange baryons
♦ , K, p: Common thermal freezeout at Tfo ~ 90 MeV
<b> ~ 0.60 c
♦ X: Shows different thermal freezeout behavior:
Tfo ~ 160 MeV
<b> ~ 0.45 c
Higher temperature
Lower transverse flow
Probe earlier stage of collision?
But:
Already some radial flow!
Tfo ~ Tch Instantaneous Freeze-out of multi-strange particles?
Early Collective Motion?
Helen Caines – March 2004
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A theoretical view of the collision
3
1
2
4
Chemical freeze out (Tch ) ~ 170 MeV
Time between Tch and Tfo  4fm
Kinetic freeze-out (Tfo) ~ 90 MeV (light particles)
Very Early Times
Helen Caines – March 2004
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Early collective motion?
Look at “Elliptic” Flow
y 2  x 2 
 2
2
y + x 
Almond shape overlap region in
coordinate space
Equal Energy Density lines
P. Kolb,
AGS
J. Sollfrank, U. Heinz
Interactions
Anisotropy in
momentum space
v2: 2nd harmonic Fourier coefficient in dN/df with respect to the reaction plane

d 3N
1 d 2N 

E 3 
1 +  2vn cosn  r 
d p 2 p dp dy  n 1

v2  cos2f
Helen Caines – March 2004
f  atan
py
px
37
Measuring elliptic flow
K.M. O’Hara et al, Science 298, 2179, 2002
6 atoms
♦ Example from ultra cold trapped
measurement
Can’tLisee
the plasma
so
lab-plane
probe
number
of particles
♦ Normal gas is transparent l >>
L and
expands
without as
Reaction collisions – isotropicallyfunction of angle with
respect to reaction plane.
Plane
♦ Magnetic field used to induce strong resonant interactions
- effectively zero mean free path l << L
Adler et al., PRL90:032301 (2003), STAR
♦ Release the trap and let it expand
♦ In strong coupling regime l << L it explodes
hydrodynamically!
Fourier analysis  1+2v2cos(2(lab-plane)) as fn p
Helen Caines – March 2004
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v2 at hydrodynamical levels
♦ Multi-strange particles
show sizeable elliptic flow!
♦ Reach hydro. limit
Hydro: P. Huovinen et al.
Hydrodynamical models describe data well for pT (< 2.5 GeV/c)
v2() > vv22(K)
> vto
> v2(L)at high p
♦ All particles
seem
saturate
2 (p)
 compatible with early equilibration
Helen Caines – March 2004
39
Why high p physics at RHIC?
Early production in parton-parton scatterings with large Q2.
Direct probes of partonic phases of the reaction
New penetrating probe at RHIC




Attenuation or absorption
of jets “jet quenching”.
Suppression of high p
hadrons.
Modification of angular
correlation.
Changes of particle
composition – PID needed
jet schematic
productionview
in quark
matter
of jet
production
hadrons
hadrons
q
leading
leading
particle
particle
q
qq
leading
particle
Helen Caines – March 2004
hadrons
40
Au-Au and p-p: inclusive charged hadrons
nucl-ex/0305015
Helen Caines – March 2004
41
The control experiment – d-Au
♦ Partonic energy loss/final state vs gluon saturation/intial state
No Medium!
Medium?
Nucleus-nucleus
collision
Proton/deuteronnucleus collision
♦ Collisions of small with large nuclei quantify all cold nuclear effects.
♦ Small + Large distinguishes all initial and final state effects.
Helen Caines – March 2004
42
Jets in Heavy Ion Collisions?
e+e  q q
(OPAL@LEP)
p-p jet+jet
(STAR@RHIC)
Au-Au ???
(STAR@RHIC)
Jets in Au-Au hopeless Task?
No, but a bit tricky…
Helen Caines – March 2004
43
Jets and two-particle azimuthal distributions
p+p  dijet
peripheral
Au+Au
collisions
min. bias
p+p collisions
central
Au+Au
collisions
Phys Rev Lett 90, 082302
pedestal trigger
and flow subtracted
♦• Trigger:
Df  0: peripheral
central
Au-Au
similar to p-p
highest pand
p >4
GeV/c
 track,
between trigger
andAu-Au
all
♦• Δf
Df distribution
 : strong suppression
in central
trigger
particles
with
2
GeV/c
<
p
<
p


♦ d-Au backwards correlation is visible
• normalize to number of triggers
Jet suppression is a final state effect.
Helen Caines – March 2004
?
44
Path length related to energy loss
y
x
♦ Energy loss related to position where partons collide
♦ Partons leaving in-plane short path length  small energy loss
♦ Partons leaving out-of -plane larger path length more energy loss
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Initial Anisotropy and energy loss
♦ Au-Au: Away-side suppression larger in the out-of-plane direction
♦ Hypothesis seems verified
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Nuclear modification factor
“Hard” Physics - Scales with Nbin: Number of binary collisions
number of equivalent inelastic nucleon-nucleon collisions
Nuclear
d 2 N AA / dp dh
Modification RAA ( p ) 
2 NN
T
d
 / dp dh
AA
Factor:
N-N cross section
<Nbinary>/inelp+p
Can replace p-p with peripheral Rcp
If no “effects”:
R < 1 in regime of soft physics
R = 1 at high-p where hard
scattering dominates
R > 1 “Cronin” enhancements (as
in pA)
Helen Caines – March 2004
47
Suppression of inclusive hadrons at high p
STAR, nucl-ex/0305015
pQCD + Shadowing + Cronin
energy
loss
pQCD + Shadowing + Cronin + Energy Loss
♦ central Au+Au collisions: factor ~4-5 suppression.
♦ p >5 GeV/c: suppression ~ independent of p.
♦ pQCD describes data only when energy loss included.
Helen Caines – March 2004
48
d-Au control experiment
Enhancement is the well
known “Cronin Effect”
Charged Particle
Au-Au, RAA << 1; d+Au, RdAu > 1
RAA results confirm there are final state effects
Helen Caines – March 2004
49
Partonic Energy Loss in Dense Matter
Bjorken, Baier, Dokshitzer, Mueller, Pegne, Schiff, Gyulassy,
Levai, Vitev, Zhakarov, Wang, Wang, Salgado, Wiedemann,…
Multiple soft interactions:
C R S
DE 
qˆL2
4
kT2
medium
qˆ 
  S r glue
Gluon Bremsstrahlung
Opacity
Expansion :

 2 E jet 
DE   C ACa  dr glue  , r   log  2 
m L
3
S
Deduced initial gluon density at 0 = 0.2 fm/c:
dNglue/dy ≈ 800-1200,
 ≈ 15 GeV/fm3
Recall:
QCD on Lattice
(2-flavor):
Strong
dependence
on rglue
: measure DE
 color charge density
at
4
3
♦ TC ≈ 1738 MeV, C ≈ (62) T , C ≈ 0.70  0.27 GeV/fm
early
hot, dense
phasematter :
Recall:
Cold nuclear
♦ cold ≈ u / 4/3r03
cold ≈ 0.13 GeV/fm3
Helen Caines – March 2004
50
Suppression of identified particles
Two groups (2 < p< 6GeV/c):
- K0s, K, K*  mesons
- L, X
 baryons
Mass or meson/baryon
effect?
Rcp
L
K
Clearly not mass dependence
Higher stats. this run get W and f
Helen Caines – March 2004
L show different
behaviour to K
Suppression of K sets
in at lower p
Come together again
at p ~ 6 GeV?
“standard” fragmentation?
51
Parton coalescence and medium p
♦Mesons
recombining partons:
p1+p2=ph
fragmenting parton:
ph = z p, z<1
♦
♦
♦
♦ When slope exponential:
coalescence wins
♦ When slope power law:
fragmentation wins
♦Baryons
Recombination
p(baryons) > p(mesons) > p(quarks)
(coalescence from thermal quark
distribution ...)
Pushes soft physics for baryons out to
4-5 GeV/c
Reduces effect of jet quenching
recombining partons:
p1+p2+p3=ph
fragmenting parton:
ph = z p, z<1
Do soft and hard partons recombine or just soft+soft ?
Explore correlations with leading baryons and mesons
Helen Caines – March 2004
52
v2 and coalescence model
STAR Preliminary
Hadronization via
quark coalescence:
v2 of a hadron at a
given p is the
partonic v2 at p/n
scaled by the # of
quarks (n).
♦ Works for K0s, L & X
♦ v2s ~ v2u,d ~ 7%
Au+Au sNN=200 GeV
MinBias 0-80%
D. Molnar, S.A. Voloshin Phys. Rev. Lett. 91, 092301 (2003)
V. Greco, C.M. Ko, P. Levai Phys. Rev. C68, 034904 (2003)
R.J. Fries, B. Muller, C. Nonaka, S.A. Bass Phys. Rev. C68, 044902 (2003)
Z. Lin, C.M. Ko Phys. Rev. Lett. 89, 202302 (2002)
Helen Caines – March 2004
53
Sampling the elephant
Different physics for different scales
0
1
2
3
4
Hydro
5
6
7
8
9
10
11
12 GeV/c
ReCo
pQCD
Results at each scale essential for understanding RHIC
♦ All evidence suggest RHIC creates a hot and dense
medium with partonic degrees of freedom.
♦ Only just beginning to understand the rich physics of RHIC.
♦ Lots more to come and much already on TAPE!
Helen Caines – March 2004
54
The STAR Collaboration
♦Argonne National Laboratory
♦Institute of High Energy Physics - Beijing
♦University of Birmingham
♦Brookhaven National Laboratory
♦California Institute of Technology
♦University of California, Berkeley
♦University of California – Davis
♦University of California - Los Angeles
♦Carnegie Mellon University
♦Creighton University
♦Nuclear Physics Inst., Acad. Sciences
♦Lab. High Energy Physics - Dubna
♦Particle Physics Laboratory - Dubna
♦University of Frankfurt
♦ Institute of Physics. Bhubaneswar
♦Indian Inst of Technology. Mumbai
♦Indiana University Cyclotron Facility
♦Institut de Recherches Subatomiques de Strasbourg
♦Kent State University
♦Institute of Modern Physics. Lanzhou
♦Lawrence Berkeley National Laboratory
♦Massachusetts Institute of Technology
♦Max-Planck-Institut fuer Physics
♦Moscow Engineering Physics Institute
City College of New York♦
NIKHEF♦
Ohio State University♦
Panjab University♦
Pennsylvania State University♦
Inst High Energy Physics - Protvino♦
Purdue University♦
University of Rajasthan♦
Rice University♦
Inst. de Fisica Univ. de Sao Paulo♦
USTC♦
Shanghai Institue of Applied Physics♦
SUBATECH♦
Texas A&M University♦
University of Texas - Austin♦
Tsinghua University♦
Valparaiso University♦
Variable Energy Cyclotron Centre. Kolkata♦
Warsaw University of Technology♦
University of Washington♦
Wayne State University♦
Institute of Particle Physics♦
Yale University♦
University of Zagreb♦
♦ Countries:
12
♦ Institutions:
50
♦ Collaborators: ~500
Helen Caines – March 2004
55
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Helen Caines – March 2004
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