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High Energy Density Physics

and the role of RHIC II

Barbara JacakStony BrookApril 29, 2005

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What is high energy density physics?

Map ofThe HEDUniverse

‘high energy density’: > 1011 J/m3

P > 1 MbarI > 3 X 1015W/cm2 Fields > 500 Tesla

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A “new” interdisciplinary research area

High Energy Density Physics is “area of significant promise”identified on basis of “Physics of the Universe”, etc.first area for agencies to:“develop a science-driven roadmap

that lays out the components of a national program”. National Task Force on HEDP

At request of Interagency Working Group* on the Physics of the Universe chartered under the National Science and Technology Council.

Goal: develop plans and set priorities in scientific areas that cut across agency lines within the federal government

Chair: Ron Davidson, Princeton Plasma Physics LabVice chair: Tom Katsouleas, USCNP members: Jacak, Zajc, Hallman (at workshop)

* NSF, DOE, NASA, NRL, NIST, OSTP

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We saw opportunity for interdisciplinary exchange of ideas, techniques, effort!

RBRC workshop on Dec.16, 17 2004

Strongly Coupled Plasmas:

Electromagnetic, Nuclear and Atomic

organizers: B. Jacak, S. Bass, E. Shuryak, T. Hallman, R. Davidson

An interdisciplinary “experiment”

opportunity to learn from each other

form new collaborations/directions

http://quark.phy.bnl.gov/~bass/workshop.htm

for program, slides

Thanks for support from RBRC & NSF!

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Plasma coupling parameter

Estimate = <PE>/<KE> using QCD coupling strength, g

<PE>=g2/d d ~1/(41/3T)

<KE> ~ 3Tg2 ~ 4-6 (value runs with T) ~ g2 (41/3T) / 3T so plasma parameter NB: such plasmas known to behave as a liquid!

Correlated or bound q,g states, but not color neutral

So the quark gluon plasma is a strongly coupled plasmaAs in warm, dense plasma at lower (but still high) TBut feels strong interaction rather than electromagnetic

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Other strongly coupled plasmas

Inside white dwarfs, giant planets, and neutron stars (n star core may even contain QGP)

In ionized gases subjected to very high pressures, magnetic fields, or particle interactions

Dusty plasmas in interplanetary space & planetary rings Solids blasted by a laser Properties of interest:

How do these plasmas transport energy?How quickly can they equilibrate?What is their viscosity? >10 can even be crystalline! How much are the charges screened? Is there evidence of plasma instabilities at RHIC? Can we detect waves in this new kind of plasma?

nove

l pla

sma

of

str

ong

inte

ract

ion

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gas of strongly interacting Li atoms

M. Gehm, S. Granade, S. Hemmer, K, O’Hara, J. Thomas Science 298 2179 (2002)

excite Feshbach resonance

weakly coupled

strongly coupled

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Plasma Diagnostics

Many of the interesting systems are short-lived!nanoseconds for laser-heated plasmasboth communities study space-time evolution through

time integrated observables (radiation or probes)

plasma folks can also measure time dependenceboth must figure out how to use correlations to extract

Transmission of external probes hard x-rays, electrons, or jets

Final state cluster distributions for early state infoDiagnostics of collective motionsMultiparticle emission variablesSingle particles in multiparticle field, acoustic waves

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From talk of Todd Ditmire (U. Texas)

Diagnostic quantity measured

Transmission of , hard x-rays density, atomic properties

Probe photon interference imaging, expansion velocity

Phase shifts of probe photon release velocity of expanding material

x-ray reflectivity image shock front

spectrum, time structure of hydrodynamic expansion

radiated clusters

Time-resolved absorption density profile with time

Electron radiation plasma oscillations

test hydro predictions

Anisotropy in radiation test calculations of field gradients

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Method using 3 lasers: 1) create shock, 2) x-rays, and 3) probe sample

Sapphire window

Beryllium foil

Metal pusher

Copper

D2

Shock

Radiograph x-rays

X-ray µscope

and streak

camera

Iron foil

1) Shock generating laser

3) Probe laser2) x-ray generating laser

R. Lee, S. Libby, LLNL

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Shock and interface trajectories are measured by x-ray radiography

Slope of shock front yields Us

Slope of pusher interface gives Up

.

Al

D2

time (ns)

shock front

Al pusher

dista

nce (µ

m)

0.0 5.01.0 2.0 3.0 4.0 6.0 7.0 8.0

0

100

200

300

x

L

Lx

=o

=

Us

Us-U

p

streak camera record

R. Lee, S. Libby, LLNL

P-P0=0UsUp

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D2 EOS data shows large differences from standard model: each data point is a shot

3

2

4

4

5

5 6

7

7

0.1

1

10

Sesame 1972LM

Gas Gun

High Explosives

DAC

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cold curve (T=0)T<0

ideal gassingle shockmaximumcompression

Nova

Pre

ssu

re (

Mb

ar)

Density (/o)

Data caused, and still causes, great controversy

R. Lee, S. Libby, LLNL

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Problems common to both fields

ThermalizationHow fast can the systems thermalize?

do they actually thermalize?HOW do they thermalize?

collisions (of what) vs. interaction with (collective) fields Models & their validity range

Kinetic models for collective processesHydrodynamics

Correlations among particles in strongly coupled plasmaAffect density structure of plasmaShould give rise to correlations also in the final stateQuasi-bound states, EOS

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dense EM plasmas

usually partially ionizedatomic levels shifted by plasma screening

of interest: shock hot spot, reflectivity, radiation dynamics underlying physics: EOS, dE/dx, atomic excitations &

interaction cross sections, equilibrium & non-equil. transportdoes this sound familiar?

tools:transport calculations using detailed atomic physics info.

with some extrapolation to high T, hydrodynamics (ignoring non-equilibrium effects)molecular dynamics

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Intermediate Scattering Function

)0,(),(),( 1 kntknNtkF

)0,(),(),( 1 kntknNtkF

Consider the intermediate scattering function:

Move to a microscopic description:

N

ii

N

ii trkitkntrrtrn

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)(exp),())((),(

N

ii

N

ii trkitkntrrtrn

11

)(exp),())((),(

Collective behavior is revealed directly in terms of the Fourier transform of the intermediate scattering function: the

“dynamic structure factor”

titkFdtkS exp),(),(

titkFdtkS exp),(),(

S(k,)

M. Murillo, LANL

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Structural Quantities

rkiergrdnkS

1)(1)( 3 rkiergrdnkS

1)(1)( 3

a

eTa

Ze aY

/2

a

eTa

Ze aY

/2

3/1

2

4

3

na

Ta

ZeOCP

3/1

2

4

3

na

Ta

ZeOCP

radial distribution function

Obtained from:• molecular dynamics• Monte Carlo• integral equations (HNC)

M. Murillo, LANL

weakly polarizableneutralizing bkgd.

homogeneous, inertneutralizing backgd.

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Plasma instability in QGP → anisotropy

small deBroglie wavelength q,g point sources for g fieldsgluon fields obey Maxwell’s equationsadd initial anisotropy and you’d expect Weibel instability

moving charged particles induce B fieldsB field traps soft particles moving in A directiontrapped particle’s current reinforces trapping B fieldcan get exponential growth

(e.g. causes filamentation of beams) could also happen to gluon fields early in Au+Au collision

timescale short compared to QGP lifetimebut gluon-gluon interactions may cause instability to

saturate → drives system to isotropy & thermalization

G. Moore

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how to profit from the commonality?

survey the “other” approaches, diagnostics, theoretical tools for ideas to borrowtransport approaches, fluctuation-dissipation,

molecular dynamics, field theory are there plasma diagnostics that have unexploited

parallels?transmission, opacity measures

nuclear plasmav2 type of analysis for collective expansion

nuclear → plasmaradiation interference? reflectivity?

plasma → nuclear a workshop allowing time for real collaborative work

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High momentum or heavy quark probesHigh E(production)/short wavelength probesScreening properties via (c-anticharm) bound statesDo the heavy quarks thermalize? Lose energy?higher luminosity sufficient statistics of rare, or high pT quarkslattice QCD calculation under relevant conditions

Initial quark gluon plasma temperatureRadiated photons, e+e-detector upgrades for background rejectionlattice, hydro simulations (with relevant , coupling)

Characterize this new kind of plasmaRadiation rate, conductivity, collision frequency, equation of stateneed rare probes, including tagged jetsdetector & luminosity improvements; simulations

Consistent theoretical picture of quark gluon plasma, heavy ion collision to connect with dataneed large scale computational resources for numerical simulation

Scientific objectives for RHIC II:

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backup

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high energy density → plasma

4th state of matter (after solid, liquid and gas) a plasma is:

ionized gas which is macroscopically neutralexhibits collective effects

interactions among charges of multiple particlesspreads charge out into characteristic (Debye) length, D

multiple particles inside this lengthplasma size > D

“normal” plasmas are electromagneticquark-gluon plasma interacts via strong interaction

color forces rather than EMexchanged particles: g instead of

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Why high energy density?

Matter under extreme conditions!Fundamental physics important for astrophysicsFusion ignition, non-linear radiative hydrodynamics,

stockpile stewardship Understanding the (many-body) strong interaction

In particular: warm dense matterneither cold, condensed matter nor a plasmastrongly coupled (i.e. KE not > PE among neighbors)difficult to study analytically or numerically

Properties of interestequation of state (i.e. relationship of P to E)radiative and dynamic properties strength of materials

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Current knowledge on properties

Extract from models, constrain by dataEnergy loss <dE/dz> (GeV/fm) 7-10 0.5 in cold matter

Energy density (GeV/fm3) 14-20 >5.5 from ET data

dN(gluon)/dy ~1000 From energy loss + hydro

T (MeV) 380-400

Experimentally unknown as yet

Equilibration time0 (fm/c) 0.6 From hydro initial condition; cascade agrees

Opacity (L/mean free path) 3.5 Based on energy loss theory

Equation of state? Early degrees of freedom? Deconfinement? Cross section of resonances at high T? Conductivity?

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Taskforce members

Ronald C. Davidson, Chair, Tom Katsouleas, Vice-Chair Jonathan Arons, Matthew Baring, Chris Deeney, Louis DiMauro, Todd Ditmire, Roger Falcone, David Hammer, Wendell Hill,Barbara Jacak, Chan Joshi, Frederick Lamb, Richard Lee,B. Grant Logan, Adrian Mellissinos,David Meyerhofer, Warren Mori, Margaret Murnane, Bruce Remington, Robert Rosner, Dieter Schneider, Isaac Silvera, James Stone, Bernard Wilde, William Zajc Ronald McKnight, Secretary

 

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EOS data for extreme pressures are most easily accessible on the Hugoniot

Hugoniot is locus of -T points arising from an ideal strong shock

Mass Momentum Energy(xA) = o(LA)

P - Po = oUsUp

F - Fo = o(LA)(Up - 0) dQ= dE + PdV

E - Eo = Po

Up

Us

- Up

2

2L

x

o

Us

(Us - Up)

A A

o

o

L x

Up = pusher velocity

Us= shock velocity

Pusher

Sample

P

• 4 unknowns (, P, Us, Up) and 2 equations need 2 quantities for absolute measurement

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Goal: implement in situ probe of HED matter

• Employ x-ray scattering to probe the bulk: measure S(k,)

X-ray scattering

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Two Basic Models: OCP and Yukawa Plasmas

The one-component plasma (OCP) is a single species plasma with an inert, homogeneous, neutralizing background.

The Yukawa (screened-OCP) is a single species plasma with a weakly-polarizable, neutralizing background.

OCP

Yukawa

'

')(2

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rr

Zerd

rr

Zeru

i

N

ij jii

N

ij

ji

ji

i

rr

rr

Zeru

exp)(

2

non-neutral plasma

dusty plasma

Court

esy

: J. J. B

olli

ng

er

Court

esy

: Li

n I

3/1

2

4

3

na

Ta

ZeOCP

3/1

2

4

3

na

Ta

ZeOCP

a

eTa

Ze aY

/2

a

eTa

Ze aY

/2