Photon Science at SLAC National Accelerator Laboratory

1. Photon Science at SLAC National Accelerator Laboratory Joachim Stöhr LCLS Director

2. SLAC was founded in 1962: Over the first 40 years SLAC scientists helped to establish the “Standard Model of Particle Physics”

3. SLAC Professor Richard Taylor Nobel Prize 1990 LINAC completed in 1966 280 Overpass

4. Stanford Board of Trustees Page 4 SLAC Professors Burton Richter (Nobel 1976) and Martin Perl (Nobel 1995) SPEAR completed in 1972 x-ray experiments began in 1974

5. 1999: Particle Physics Gets a Surprise! Studied with particle accelerators 1960-2000 LHC? Nobel Prize in Physics 2011 SLAC particle physics research shifted to address this challenge CAS Dry Run: October 19, 2011 (J. Stöhr) 5

6. Over last six years, SLAC has shifted its focus away from particle physics

7. SLAC National Accelerator Laboratory:A proud history and an exciting future From particles to photons

8. Change in Mission reflected in SLAC Organization Chart SLAC Director Operations Accelerators LCLS SSRL Photon Science Particle & Particle Astrophysics • “Photon Science” • consists of • x-ray user facilities • x-ray research SIMES PULSE SUNCAT ….

9. SLAC operates two world class x-ray user facilities LCLS SSRL storage ring electron beam x-ray beam

10. SLAC played an important role in the last two revolutions in “light” • 1879 - Invention of the light bulb • 1895 - Discovery of X-Rays • 1960 - Invention of the LASER • 1974 - Synchrotron radiation x-rays: SSRL • 2009 - The first x-ray laser: LCLS

11. What is SSRL known for? • Development of X-Ray Absorption Techniques: EXAFS, SEXAFS, NEXAFS • Development of MAD (multiple wavelength anomalous dispersion) phasing • Pioneering Soft X-Ray Science (200 – 3000 eV) (Grasshopper, Jumbo) • Development of Synchrotron-Based Photoemission Techniques • especially core level photoemission, photoelectron diffraction, and ARPES • Development of grazing incidence surface and interface scattering • First Application of Wigglers and Undulators • Pioneered Coronary Angiography (medical imaging) • Pioneered Magnetic Microscopy with X-Rays • Pioneered X-Ray Studies in Molecular Environmental Science

12. X-Rays from Electron Storage Ring X-Ray pulse length determined by electron bunch length Bunch width ~ 100 ps Bunch spacing 2 ns beam line x-ray pulses ~ 100 ps width Can make shorter pulses (~ 1ps) at great loss of intensity

13. Introduction to LCLS What is a x-ray free electron laser, anyway?

14. Optical versus X-Ray Free Electron Laser Optical laser X-ray free electron laser • free relativistic electrons in bunch • - radiation in periodic H-field • amplification through • electron ordering in its own • radiation (SASE) • electron ordering in imposed • radiation (seeding) • tunable photon energy up to 20 keV • very large size • bound electrons in atoms • - transitions between discrete states • amplification through stimulated • emission • fixed photon energy around 1 eV • compact size

15. SASE versus self seeded x-ray beam Monochromator filter creates seed with controlled spectrum FEL amplifier (exponential intensity gain) Intense x-ray source with spiky spectrum 8.3 keV 40 pC seeded SASE

16. X-ray properties: storage ring versus FEL • Assume same energy bandwidth (~ 1eV) • XFEL photons in 10 fs = ring undulator photons in 1 s • XFEL photons are coherent

17. LCLS: the world’s first x-ray free electron laser Injector electron beam 1km linac 14GeV AMO SXR Undulator hall XPP Near-hall: 3 stations XCS x-ray beam CXI Far-hall: 3 stations MEC

18. LCLS X-ray Facilities Near Experimental Hall AMO SXR XPP X-ray Transport Tunnel 200 m XCS CXI MEC Start of operation AMO Oct-09 SXR May-10 XPP October-10 CXI February-11 November-11 XCS Far Experimental Hall MEC April -12

19. LCLS instruments and their focus • AMO:Atomic, Molecular and Optical Science • Multi-Photon processes within atoms and molecules • SXR: Soft X-ray Research • Electronic and magnetic properties of materials and surfaces • XPP: X-Ray Pump Probe • Atomic and electronic dynamics after optical excitation • CXI: Coherent X-Ray Imaging • Single shot imaging of atomic and nanostructures (mostly biology) • XCS: X-Ray Correlation Spectroscopy • Atomic scale equilibrium dynamics in condensed matter systems • MEC: Matter in Extreme Conditions • Properties far, far from equilibrium

20. X-Rays can see the invisible --provide static and dynamic information-- Diffraction EXAFS “Imaging” Photoemission X-ray absorption X-ray emission X-ray magnetic dichroism spin pol. photoemission

21. Understanding the function of today’s devices with SSRL/ALS and tomorrow’s speed limits with LCLS SSRL LCLS ALS work has revealed how most advanced magnetic devices switch today 0 200ps 400ps 600ps 800ps 1 ns 100 nm

22. X-FEL Science or The Need for Speed !

23. The speed of things – the smaller the faster macro molecules molecular groups The technology gap atoms “electrons” & “spins” optical laser pulse

24. What determines the speed of things? rule of thumb…“the smaller the faster”…. • but the devil is in the details… • mechanical “speed” of motion related to concept of inertia or mass • (more massive being “bigger”) • F = ma …. p = mv • “speed” also dependent on the process • conservation laws govern dissipation of energy, linear and angular momentum • e.g. friction, induction, torque • detailed correlation depends on system and process of interest Understanding of motion and speed essential for “function”

25. Characteristic speeds of atoms, electrons and spins • Atoms : speed of sound: 1 nm / 1 ps • Electrons: Fermi velocity: 1 nm / 1 fs • Light: speed of light: 1 nm / 3 as

26. The new science paradigm: Static nanoscale “structure” plus its dynamic “function” Operational Timescales Fundamental Timescales The world of x-rays nanoscale dynamics smaller & faster

27. Important areas in ultrafast science Because of their size, atoms and “bonds” can change fast but how do systems evolve? key areas of interest: equilibrium (“structure”, phase diagram of a system T, P …) close to equilibrium (operation or function of a system, e.g. current flow) far from equilibrium (transient states after excitation, e.g. chemical reaction) far-far from equilibrium (transient states after extreme stimulus, e.g. a plasma)

28. The new paradigm in understanding atomic matter Function and Control Structure and Properties Nanoscale order Dynamic order Transient States Long range order Static disorder Equilibrium States future 2000 1900 • most reliably calculated • difficult to measure and calculate

29. “Equilibrium”: What is the structure of water? Small angle x-ray scattering shows inhomogeneity Disordered soup Ice like clusters Components probably dynamic – form and dissolve - can we take an ultrafast snapshot??

30. A new Paradigm in Macromolecular Crystallography “beating the speed of sound with the speed of light” conventional method Protein crystal Diffraction data Electron density Molecular model of protein suggests its function • In 1980s synchrotron x-rays revolutionized macromolecular crystallography • Protein structure has allowed the developments of drugs • However, synchrotron studies limited to large (> 5 microns) crystals • Data for smaller crystals limited by x-ray beam damage • Studies of nanocrystals at X-FELs leads to a new paradigm

31. “Close to equilibrium” – how does a device function: e.g. how does a spin current turn the magnetization ? magnetic switching today 100nm size in 100ps - the speed of sound how fast can it be done? “bit” in cell Magnetic structure of “bit” Computer chip Electronic circuit Memory cell

32. “Far from equilibrium”:How does a chemical reaction proceed? reaction dynamics & intermediates end reaction products What are the key intermediate reactive species?

33. “Far, far from equilibrium”: Warm and hot dense matter The properties of matter in extreme states - which on earth can only be created transiently on ultrafast time scale- Al r-Tphase diagram

34. What have we learned so far? • Multi-Photon processes within atoms and molecules observed • - Provides new spectroscopic signatures – first non-linear effects • - LCLS can drive atom-based x-ray laser • Concept of “probe-before-destroy” works for atomic structure • Opens the door for atomic imaging of crystalline and disordered systems • Small protein crystals studied to < 2 Å resolution • 3D imaging of cells/viruses with nanoscale resolution appears possible • atomic structure of liquids has begun • Single shot study of electronic structure of solids & surfaces is possible • “probe before destroy” also works, but electronic structure responds faster • fluencelimits apply because of fast (e.g. stimulated) electronic processes • - Surface science studies show proof-of-principle capture of reactive states • - Laser pump/x-ray probe studies have seen time resolved melting of • electronic and spin structure and chemical transformations

35. LCLS in the future soft x-ray hard x-ray LCLS today

36. The end

37. User Input at Workshop • Atoms = electronic cores move slow enough (inertia) that • “probe before atomic motion” concept works • future vision: • Maximum intensity for signal-to-noise – seeding, Terawatt beams • Short pulse length (< 10 fs) to minimize effects of atomic motion • Pursue first killer application: Bio-structures of small crystals • Extend to single macromolecule imaging - requires TW beams < 5keV • Electrons respond faster, take advantage of non-linear phenomena • future vision: • Control photon energy, pulse intensity and shape – seeding • Control polarization to distinguish charge & spin • Explore x-ray/electronic interactions with controlled pulses • Develop x-ray beam manipulation toolbox for non-linear x-ray optics

38. The trick to taking ultrafast pictures -- our cameras are too slow-- • Use a bright flash, faster than existing shutter speed • Capture bright “scattered” light flash with camera • leave shutter open, flash light is stronger than background light X-ray Laser fast (fs), intense, short wavelength ultrafast flash 1/20,000 second X-ray Detector slow (microseconds) slow shutter speed 1/200 second flash duration and intensity determine picture quality x-rays can see “the invisible” nanoscale

39. Future Plans: LCLS-II and LUSI-II hard x-ray soft x-ray • LCLS II: • builds the foundational facilities for enhanced capabilities and capacity • first step to remain at the international forefront • LUSI II: • adds science driven instrumentation to LCLS II baseline • may include source refinements, optics enhancements, end stations

40. 5 things LCLS may become known for • Motion pictures of the formation and dissociation of chemical bonds • viewed at the site of selected atoms • Solving the structure and time-resolved function of non-periodic • macromolecular complexes (e.g. proteins) • Solving the (transient) structure of disordered systems, e.g. water • Characterizing the nature of transient states of matter created by • radiation, pressure, fields, etc. • Revealing the origins of fundamental speed limits of technological • processes

41. LCLS-II science example 1:Studies of carbon related reactions become possible Carbon spectra of molecules Conversion of chemicals Clean fuel • The key challenge: • Understand/control of the transient reactive state • “where the action is”