# Presentation: 526721

## High Energy Density Physics

and the role of RHIC II

**and the role of RHIC II**

- Barbara Jacak
- Stony Brook
- April 29, 2005

## What is high energy density physics?

**Map of**
**The HED**
**Universe**

**‘****high energy density’: **
****** ****> 10****11 ****J/m****3**
**P > 1 Mbar**
**I > 3 X 10****15****W/cm****2**** **
**Fields > 500 Tesla  **

## 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 Lab**
**Vice chair: Tom Katsouleas, USC**
**NP members: Jacak, Zajc, Hallman (at workshop)**

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

## 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](http://quark.phy.bnl.gov/~bass/workshop.htm)_
**   ****for program, slides**

**Thanks for support from RBRC & NSF!**

## Plasma coupling parameter

**Estimate ******** = <PE>/<KE> **
**	****using QCD coupling strength, g**
**<PE>=g****2****/d  d ~1/(4****1/3****T)****   **
**<KE> ~ 3T**
**g****2 ****~ 4-6 (value runs with T)**
****** ****~ g****2**** (4****1/3****T)**** ****/ 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 plasma**
**As in warm, dense plasma at lower (but still high) T**
**But feels strong interaction rather than electromagnetic**

## 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?**

***novel plasma of ***
*** ******strong interaction***

## 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**

## Plasma Diagnostics

**Many of the interesting systems are short-lived!**
**nanoseconds for laser-heated plasmas**
**both communities study space-time evolution through time integrated****	**** observables (radiation or probes)**
**plasma folks can also measure time dependence**
**both 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 info**
**Diagnostics of collective motions**
**Multiparticle emission variables**
**Single particles in multiparticle field, acoustic waves**

## 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**

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

**1)**** Shock generating laser**

**3)**** Probe laser**

**2)**** x-ray generating laser**

- R. Lee, S. Libby, LLNL

**Notes:**
This is the start of the H2 deal. Note the primary diagnostic is the thing on the left.

## Shock and interface trajectories are measured by x-ray radiography

**Slope of shock front yields U****s**** **
**Slope of pusher interface gives U****p**

**streak camera record**

- R. Lee, S. Libby, LLNL

**P-P****0****=********0****U****s****U****p**

**Notes:**
I show the data and the crucial equation from the conservation laws.

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

**Pressure (Mbar)**

**Density (********/********o****)**

- Data caused, and still causes, great controversy

- R. Lee, S. Libby, LLNL

**Notes:**
I use this representation of the data because it is alos used at the end to show the level of disagreement amongst all the players. Note I include the cold curve and the DAC data to show that is easy.   I include gas gun points to clearly show the limitation of the cuns. I show the high explosives to show that limits of HE.  

## Problems common to both fields

**Thermalization**
**How 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 processes**
**Hydrodynamics**
**Correlations among particles in strongly coupled plasma**
**Affect density structure of plasma**
**Should give rise to correlations also in the final state**
**Quasi-bound states, EOS**

## dense EM plasmas

**usually partially ionized**
**atomic 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. transport**
***does this sound familiar?***
**tools:**
**transport calculations using detailed atomic physics info.**
**	****with some extrapolation to high T, ******
**hydrodynamics (ignoring non-equilibrium effects)**
**molecular dynamics**

## Intermediate Scattering Function

**Consider the intermediate scattering function:**

- Move to a microscopic description:

*Collective behavior is revealed directly in terms of the Fourier transform of the intermediate scattering function: the** “dynamic structure factor”*

- 

- S(k,)

- M. Murillo, LANL

## Structural Quantities

- radial distribution function

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

- M. Murillo, LANL

- weakly polarizable
- neutralizing bkgd.

- homogeneous, inert
- neutralizing backgd.

## Plasma instability in QGP → anisotropy

**small deBroglie wavelength q,g point sources for g fields**
**gluon fields obey Maxwell’s equations**
**add initial anisotropy and you’d expect Weibel instability**
**moving charged particles induce B fields**
**B field traps soft particles moving in A direction**
**trapped particle’s current reinforces trapping B field**
**can 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 lifetime**
**but gluon-gluon interactions may cause instability to saturate ****→**** drives system to isotropy & thermalization**

- G. Moore

## how to profit from the commonality?

**survey the “other” approaches, diagnostics, theoretical tools for ideas to borrow**
**transport approaches, fluctuation-dissipation, molecular dynamics, field theory**
**are there plasma diagnostics that have unexploited parallels?**
**transmission, opacity measures**
**	****nuclear ******** plasma**
**v2 type of analysis for collective expansion **
**	****nuclear ****→**** plasma**
**radiation interference? reflectivity?**
**	****plasma ****→ nuclear**
**a workshop allowing time for real collaborative work**

## High momentum or heavy quark probes
High E(production)/short wavelength probes
Screening properties via (c-anticharm) bound states
Do the heavy quarks thermalize? Lose energy?
higher luminosity sufficient statistics of rare, or high pT quarks
lattice QCD calculation under relevant conditions
Initial quark gluon plasma temperature
Radiated photons, e+e-
detector upgrades for background rejection
lattice, hydro simulations (with relevant , coupling)
Characterize this new kind of plasma
Radiation rate, conductivity, collision frequency, equation of state
need rare probes, including tagged jets
detector & luminosity improvements; simulations
Consistent theoretical picture of 
quark gluon plasma, heavy ion collision to connect with data
need large scale computational resources for numerical simulation

**High E(production)/short wavelength probes**
**Screening properties via (c-anticharm) bound states**
**Do the heavy quarks thermalize? Lose energy?**
***higher luminosity************ sufficient statistics of rare, or high pT quarks***
***lattice QCD calculation under relevant conditions***
**Initial quark gluon plasma temperature**
**Radiated photons, e+e-**
***detector upgrades for background rejection***
***lattice, hydro simulations (with relevant ************, coupling)***
**Characterize this new kind of plasma**
**Radiation rate, conductivity, collision frequency, equation of state**
***need rare probes, including tagged jets***
***detector & luminosity improvements; simulations***
**Consistent theoretical picture of **
**quark gluon plasma, heavy ion collision to connect with data**
***need large scale computational resources for numerical simulation***

**Scientific objectives for RHIC II:**

## backup

## high energy density → plasma

**4****th**** state of matter (after solid, liquid and gas)**
**a plasma is:**
**ionized gas which is macroscopically neutral**
**exhibits collective effects**
**interactions among charges of multiple particles**
**spreads charge out into characteristic (Debye) length, ********D**
**multiple particles inside this length**
**plasma size > ********D**
**	**
**“****normal” plasmas are electromagnetic**
**quark-gluon plasma interacts via strong interaction**
**color forces rather than EM**
**exchanged particles: g instead of ******

## Why high energy density?

**Matter under extreme conditions!**
**Fundamental physics important for astrophysics**
**Fusion ignition, non-linear radiative hydrodynamics, stockpile stewardship **
**Understanding the (many-body) strong interaction**
**In particular: warm dense matter**
**neither cold, condensed matter nor a plasma**
**strongly coupled (i.e. KE not > PE among neighbors)**
**difficult to study analytically or numerically**
**Properties of interest**
**equation of state (i.e. relationship of P to E)**
**radiative and dynamic properties **
**strength of materials**

## Current knowledge on properties

**Extract from models, constrain by data**

| Energy 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 time0 (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?***

## 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**
** **

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

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

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

**A**

**A**

****

**o**

****

**o**

****

**L**

**x**

**U****p**** **= pusher velocity

**U****s**= shock velocity

**Pusher**

**Sample**

**P**

- •  4 unknowns (, P, Us, Up) and 2 equations
-     need 2 quantities for ***absolute*** measurement

**Notes:**
Okay this is the meat of the talk as written. It is here we should mention pointedly that the reason Hugoniot measurement are so popular is that they are the ideal for strong shocks and thus we can do without hydrodynamics. You measure 2 variables and voila! An EOS point.  Trouble is that there is much work done to ensure that the shock is strong and planar and steady and the matter is really responding the correct way. ABSOLUTE is really important here.

## Goal: implement in situ probe of HED matter

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

**Notes:**
The use of the term x-ray scattering can cover either wide angle scattering (what the plasma physicists call Thomson scattering) where we look at the S(k,w) for one fixed k and spectrally disperse the signal.  Or, we look in at SAXS, small angle x-ray scattering where we integrate over all w but look at the position dependent signal (would see Bragg peaks, diffuse scattering, and  small analge structural info). Since the x-ray source must be short , 1 ps or so, (or time-resolved) this would provide a “static” image of the long time >1 ns dynamic shock experiments.

## 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**

**non-neutral plasma**

**dusty plasma**

- Courtesy: J. J. Bollinger

- Courtesy: Lin I