Some Like it REALLY Hot! Studying Matter Under Extreme Conditions Mark D. Baker Chemistry Department Brookhaven National Laboratory

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Some Like it REALLY Hot!Studying Matter Under
Extreme Conditions Mark D. BakerChemistry
DepartmentBrookhaven National Laboratory
What is the universe made of?What holds it
together?
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What is the universe made of?
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What holds it together?The Fundamental Forces
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Lets smash some atoms!
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neutron
u
d
u
d
proton
u
d
u
d
u
d
u
d
u
u
u
u
u
u
pion (p)
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If you cant smash it, heat it!
Pressure
Plasma
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Temperature
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Sideways slide - How much heat?
Placeholder
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Heat is also a window back in time
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Hot and Dense Laboratory MatterTry 1 Diamond
Anvil
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Hot and Dense Laboratory MatterTry 2 X-pinch
plasma
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Hot and Dense Laboratory MatterTry 3 Free
Electron Laser
XFEL, Tellerhoop, Germany
l 0.1 nm planned (6 nm achieved)
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Hot and Dense Laboratory MatterTry 4 Heavy
Ion Collisions
Collide Gold nuclei at 99.99 of the speed of
light
2x1012 K, 5x1021 atm
But Will these fast violent collisions
teach us anything?
10-23 seconds, 10-38 liters
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RHIC...
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The PHOBOS Collaboration
Birger Back, Alan Wuosmaa Mark
Baker, Donald Barton, Alan Carroll, Nigel George,
Stephen Gushue, George Heintzelman, Burt Holzman,
Robert Pak, Louis Remsberg, Peter Steinberg,
Andrei Sukhanov Andrzej Budzanowski,
Roman Holynski, Jerzy Michalowski, Andrzej
Olszewski, Pawel Sawicki , Marek Stodulski, Adam
Trzupek, Barbara Wosiek, Krzysztof Wozniak
Wit Busza (Spokesperson), Patrick Decowski,
Kristjan Gulbrandsen, Conor Henderson, Jay Kane ,
Judith Katzy, Piotr Kulinich, Johannes
Muelmenstaedt, Heinz Pernegger, Corey Reed,
Christof Roland, Gunther Roland, Leslie
Rosenberg, Pradeep Sarin, Stephen Steadman,
George Stephans, Gerrit van Nieuwenhuizen, Carla
Vale, Robin Verdier, Bernard Wadsworth, Bolek
Wyslouch Chia Ming Kuo, Willis Lin, Jaw-Luen
Tang Joshua Hamblen , Erik Johnson, Nazim
Khan, Steven Manly,Inkyu Park, Wojtek Skulski,
Ray Teng, Frank Wolfs Russell Betts,
Edmundo Garcia, Clive Halliwell, David Hofman,
Richard Hollis, Aneta Iordanova, Wojtek Kucewicz,
Don McLeod, Rachid Nouicer, Michael Reuter, Joe
Sagerer Richard Bindel, Alice Mignerey
ARGONNE NATIONAL LABORATORY BROOKHAVEN NATIONAL
LABORATORY INSTITUTE OF NUCLEAR PHYSICS,
KRAKOW MASSACHUSETTS INSTITUTE OF
TECHNOLOGY NATIONAL CENTRAL UNIVERSITY,
TAIWAN UNIVERSITY OF ROCHESTER UNIVERSITY OF
ILLINOIS AT CHICAGO UNIVERSITY OF MARYLAND
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PHOBOS Apparatus
135,000 Silicon Pad channels
12 meters of Beryllium beampipe
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PHOBOS Silicon Detector
Octagon Detector
Vertex Detector
Octagon Detector 2.7 x 8.8 mm2 Vertex Detector
0.4 x 12 mm2
Ring Counter
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RHIC Computing Facility
PHOBOS writes 1 Gigabyte of data / minute!
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The plan of attack

• Collide gold nuclei at high energy
• Collider, detectors, computers
• Understand the collision dynamics
• Collective motion, equilibrium
• Temperature, density
• Learn about the strong interaction
• Quantum ChromoDynamics
• Confinement

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How many produced particles?
simulation
Measured of charged particles in ahead-on
collision 4100210 _at_ 130 GeV 5055250 _at_ 200
GeV
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Multiplicity at mid-rapidity
PRL 88 (2002) 022302
Models NPA 698, (2002) 78c,299c
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Energy Dependence

• Data favors models with minimal entropy production

PRL 88 (2002) 022302
Hard
Soft
90 C.L. band
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Implications

• The initial state is dominated by soft physics
• Limited entropy production in late stages.

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Colliding Nuclei
Parton Cascade
Hadron Gas Freeze-out
HardCollisions
QGP? / Fragmentation
Gentle Freeze-out
Geometry/Saturation
QCD
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Many ways to slice pz
Rapidity Generalized velocity
Feynman x scaled pz
Pseudorapidity y easier to measure
Away from mid-rapidity
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Latest PHOBOS results
Typical Systematic Errors
200 GeV
130 GeV
dN/dh
dN/dh
dN/dh
Peripheral
h
h
h
dN/dh
dN/dh
dN/dh
Central
h
h
h
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Naïve expectation (boost-invariance)
Increasing E
y
y
Fragmentation Region
dN/dy
0
yy-ybeam
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Results Limiting Fragmentation
PHOBOS results in target frame
PHOBOS 200 0-6 PHOBOS 130 0-6 EMU-13 17
0-9.4 (different frame)
Limit curve extent grows with energy
Systematic errors not shown
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Can we see the Limit Curves?
UA5, Z.Phys.C33, 1 (1986)
AuAu
p p inel.
Systematic errors not included
Line p to guide the eye
1.45 x line p
Systematic errors not shown
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Elliptic Flow A collective effect
dN/d(f -YR ) N0 (1 2V1cos (f-YR) 2V2cos
(2(f-YR)) ... )
midrapidity h lt 1.0
V2
Hydrodynamic model
Hydrodynamic Flow
Preliminary
No collective motion
Normalized Multiplicity
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Elliptic Flow
Particle asymmetry
midrapidity h lt 1.0
V2
Hydrodynamic model
Preliminary
Normalized Multiplicity
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Flow also non-boost-invariant
v2 quantifies elliptical anisotropy
Azimuthal shape changes as strong function of h
Averaged over centrality
PHOBOS Preliminary
Consistent with large e suggested by
saturation (and required by some hydro models)
Errors are statistical only (systematic errors
0.007)
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Plan of attack - where are we?

• Collide gold nuclei at high energy
• Collider, detectors, computers
• Understand the collision dynamics
• Collective motion, equilibrium
• Temperature, density
• Learn about the strong interaction
• Quantum ChromoDynamics
• Confinement

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We see the conditions at freezeout (a lower limit
to the maximum Temperature)
Freezeout
Hottest period
Expansion cooling
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RHIC shows rapid expansion a high temperature
Effective Temperature (GeV)
STAR Preliminary
CERN NA49
1.7 1012 oK
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Another thermometer
In an equilibrium system, two parameters are
sufficient to predict the chemical mix (
pions) / ( protons) ( kaons) / ( pions) (
anti-protons)/( protons) et cetera.
Temperature (T) and net amount of matter (mB)
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Particle Ratios tell us about final state
Braun-Munzinger et. al., Phys. Lett. B 518 (2001)
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Statistical models consistent with particle ratio
data simple filling of phase space?
Suggest thermalization at T Tc, nonzero net
baryon density (SPS value mB 270 MeV)
T 176 MeV mB 46 MeV
65 65 GeV beam energy
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Temperature at Freezeout

• Temperature in MeV units
• Chemical T (170 20) MeV
• Kinetic T (150 40) MeV
• Temperature in oK (1eV 11,600 K)
• Chemical T (2.0 0.2) 1012 oK
• Kinetic T (1.7 0.3) 1012 oK
• We did reach 2 trillion K!

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Particle ratios at 100100 GeV!
Fully reversible magnetic field
Positive Charge
p
K
p
Truncated ltdE/dxgt MIP
Preliminary
Negative Charge
p
K-
p-
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Excitation function of mB
Nucl. Phy. A697 902-912 (2002)
Extrapolation of fit
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Energy Density Estimate (Bj)
PRL 87 (2001) 052301
formation time 0.2 - 1 fm
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If you just believe the lattice...

Karsch et al.
CERN SPS (?s 17 GeV) ei 3-10
GeV/fm3 Ti 220-290 MeV BNL RHIC (?s
200 GeV) ei 5-25 GeV/fm3 Ti
250-350 MeV


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Putting it all together
LEP!

• Universal curve!
• RHIC
• bulk matter
• high energy density
• einitial 5-25 GeV/fm3
• (lattice ? Ti gt250 MeV)
• freezeout near TC
• early collective expansion
• vt 0.65 c

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Summary so far

• Weve learned a lot about the system
• The system is behaving collectively.
• We have reached 2-4 trillion degrees K.
• The system is expanding rapidly.
• AA may illuminate QCD directly
• Low Nch soft initial state effects dominate
• Thermal partons?
• The source is not boost invariant
• dN/dh limit curve from QCD and GAu(x)

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PHOBOS Future I (analysis)
Quantum Mechanical Source imaging (HBT)
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Plan of attack - where do we go?

• Collide gold nuclei at high energy
• Collider, detectors, computers
• Understand the collision dynamics
• Collective motion, equilibrium
• Temperature, density
• Learn about the strong interaction
• Quantum ChromoDynamics
• Confinement

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What happens before freeze-out?

• Energetic particles come from quark or gluon
  jets.
• They interact with the dense medium, but cant
  thermalize.
• Jet energy loss (quenching) is predicted.
• Jet quenching measures the density early in the
  collision.

pion
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Failure to scale! (jet quenching?)
Details need to be understood before conclusions
can be drawn.
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PHOBOS Future II
Compare high Pt behavior of pp, dA, AA (as well
as soft behavior)
I. Faster!! Upgrade DAQ from 40 Hz to 500-700
Hz Upgrade triggering II. Better particle
ID Move TOF wall ...
Sukhanov
R.Pak
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PHOBOS future III (analysis)
Lower pT at pp midrapidity ISR data is inelastic
Universality?
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Brookhaven Future (!) eRHIC

• Directly probe dense strongly interacting
  matter.
• Nonabelian QCD effects in the low x nuclear
  structure function...

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Conclusion

• Weve accomplished a lot already
• Detector, physics, papers.
• RHIC should illuminate QCD directly
• dN/dh limit curve from QCD and GAu(x)
• Universality of fragmentation
• Jet quenching or new scaling law
• Something we havent thought of yet...
• Physics on the distant horizon
• eRHIC - probing QCD in a different way.