1. High Energy Density Science and Free-electron Lasers P. Audebert, H. Baldis, J. Benage, M. Bergh, C. Caleman, R. Cauble, P. Celliers, M.H. Chen, H.K. Chung, G. Collins, M. Fajardo, R. Falcone, R. Fäustlin, R. Fedosejevs, E. Förster, J. Gauthier, S. Glenzer, E. Glover, G. Gregori, J. Hajdu, P. Heimann, C.A. Iglesias, S. L. Johnson, L. Juha, F. Y. Khattak, J. Krzywinski, R.W. Lee, A. Lindenbergh, H. Merdji, J. Meyer-ter-Vehn, S. Moon, T. Möller, W.L. Morgan, M. Murillo, B. Nagler, A. Nelson, A. Ng, Y. Ralchenko, R. Redmer, O. Renner, D. Riley, F. Rogers, S. J. Rose, F. Rosmej, W. Rozmus, R. Schuch, H. A. Scott, T. Schenkel, D. Schneider, J. R. Seely, R. Sobierajski, K. Sokolowski- Tinten, T. Stoelker, S. Toleikis, T. Tschentscher, S. Vinko, H. Wabnitz, J. S. Wark., T. Whitcher, K. Widmann, P. Zeitoun… LULI, UC Davis, LANL, Uppsala, LLNL, IST-GoLP, UC Berkeley, Jena, CELIA, LBNL, RAL, Stanford, PSI/SLS, Czech Academy, QU Belfast, Polish Academy, SLAC, MPI, TU Berlin, Kinema, NIST, Stockholm, Rostock, AWE, Marseille, Alberta, Warsaw, Essen, GSI, DESY, Oxford, LIXAM…

2. High Peak Brightness of new x-ray light sources match HEDS needs Current light sources are synchrotron radiation based Low # of photons per bunch Long bunch duration (≥ 50 ps) But, HEDS studies require: Intense x-ray sources - to probe dense matter at finite temperature Ultrashort pulses - to study highly transient behavior and remove hydrodynamic changes Solution is FEL based sources Short bunch duration (~100 fs) High # of photons per bunch Tunable Possibilities for HED studies

3. ExperimentDescription Warm Dense Matter Creation Using the XFEL to uniformly warm solid density samples Equation of State Heat / probe a solid with an XFEL to provide material properties Absorption Spectroscopy Heat a solid with an optical laser or XFEL and use XFEL to probe High Pressure Phenomena Create high pressures using high-energy laser, probe with the XFEL Surface StudiesProbe ablation/damage processes XFEL / Gas Interaction Create exotic, long-lived highly-perturbed electron distribution in dense plasmas XFEL / Solid Interaction Directly creates extreme states of matter Plasma Spectroscopy XFEL pump/probe for atomic state Diagnostic Development Thomson scattering, SAXS, interferometry, radiography, phase-contrast imaging HEDS on FELs have started and will be a part of future facilities WDM HDM HED experiment are ongoing at FLASH at DESY HED experiments have an endstation allotted for the LCLS XFEL at SLAC HED experiments are part of the endstation plan at the EU XFEL at DESY HED proposals approved for the Fermi at Elettra VUV-FE L

4. In the Hot Dense Matter regime, the XFEL will provide critical data Schematic experiment CH Visible laser 0.1 µm 25 µm Al t = 0 laser irradiates Al dot t = 100 ps FEL irradiates plasma CH Al FEL tuned to 1869 eV Observe emission with x-ray streak camera Simulation He-likeH-like 1s 2 1s2l 1s3l 1 2 3

5. Sub-ps FELs create isochoric WDM that expands isentropically Concept is straightforward 10x10x100 µm Al sample 10ev, Z* = 0.3, at 2 Mbar XFEL heats matter rapidly and uniformly to create: Using underdense foams allows fuller sampling Al  -T phase diagram Isochores (constant  ) Isentropes (constant entropy) Isochores Isentropes XFEL 10 µm 100 µm solid sample short pulse probe laser Temperature (eV)   

6. XFEL as a probe provides unique capability X-ray Phase Contrast Imaging one can reach ~5µm resolution ps time scales The XFEL at LCLS will be able to image down to 50 nm at 100 fs In situ optical probing the hot dense matter is not possible yet. LCLS will allow hollow ion pumping to determine ionization state and temperature Probing of high pressure states Bragg, SAXS, and WAXS are important LCLS will provide a versatile x-ray source for measurements with 100 fs resolution and a coherent beam, ideal for polycrystalline samples. X-ray Thompson scattering has been performed using high energy lasers With similar setup LCLS will provide a tunable source with 100 fs resolution

7. Dispersion  n e : Width  damping, T e Detailed balance  T e : Structure factor   internal energy:  2 pl ~  2 p +3k 2  th S(k,  )/S(-k,  ) =e -(h /kTe) U ex = Ze 2 N ∫dk [S(k)-1]/4πk 2 U=3/2NkT+U ex Intensity Forward Scattering -50-100 Energy (eV) E0E0 +100+50 θ=25º Example: H at n e =2x10 24 cm -3 ; T e =30 eV X-ray Thompson Scattering will provide a probe for HED matter Width  T e or T F (n e ) Non-degenerate:  =-hk 2 /2m e ±kv FWHM  k        FWHM    =h 2 /2m (3π 2 n e  3 Degenerate: Ratio of Compton/Rayleigh Scattering  ionization state Intensity θ=130º E0E0 +200 -200 -400 Back Scattering Energy (eV) Experiment Kritcher et al., Science (2008) [coalescing shocks] Gregori et al., PRL 101 (2008) [radiative shocks] Saiz et al, Nature Phys (2008) [strong shocks in solids] Lee et al., PRL (2008) [strong shocks in solids] Glenzer & Redmer, RMP (2008) [review] Experiment by Kritcher et al.: Shaped pulse coalesing shocks Short pulse laser scattering source Measures Te, Z *, n e, and  /  o 4440 4480 4520 Energy (eV) Proof of Principle: LiH LCLS will do this with 100 fs resolution, tunable, high intensity ~10 12 photons, narrow band width

8. Overview of LCLS XFEL at SLAC Beam Transport Hall: 227m above ground facility to transport electron beam Undulator Hall: 170m tunnel housing undulators Near Experimental Hall: 3 experimental hutches, prep areas, and shops X-Ray Transport & Diagnostic Tunnel: 210m tunnel to transport photon beams Far Experimental Hall: 46’ cavern with 3 experimental hutches and prep areas Electron Beam Dump: 40m facility to separate e - and x-ray beams Front End Enclosure: 40m facility for photon beam diagnostics

9. Proposed HEDS endstation layout Long-pulse (~100J, 5ns)Short-pulse (≥100mJ, 30 fs) Lasers used to create various HED conditions e.g., create shocks, WDM, and HDM LCLS XFEL as both a pump and a probe works with short and long pulse lasers 54’

10. Multiplatform collaboration formed to provide a broad HEDS capability Platforms: Advanced Light Source (LBNL/SC) Jupiter Laser Facility (LLNL/NNSA) LCLS (SLAC/SC) Purpose: To allow for the pursuit of integrated applications when diverse capabilities are required Goal: To create an experimental capability where students, young researchers, and Laboratory personnel can join forces to address the scientific foundations of the High Energy Density regime

11. The End