Photon Science at SLAC National Accelerator Laboratory Joachim

Photon Science at SLAC National Accelerator Laboratory Joachim Stöhr LCLS Director

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

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

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

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

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

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

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

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

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

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 e. V) (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

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 (~ 1 ps) at great loss of intensity

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

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

SASE versus self seeded x-ray beam Intense x-ray source with spiky spectrum Monochromator filter creates seed with controlled spectrum seeded SASE FEL amplifier (exponential intensity gain) 8. 3 ke. V 40 p. C

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

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

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

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

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

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

X-FEL Science or The Need for Speed !

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

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 = m a …. p = m v • “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”

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

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

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)

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 1900 • most reliably calculated 2000 future • difficult to measure and calculate

“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? ?

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 1980 s 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

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

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

“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-T phase diagram

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 - 3 D 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 fluence limits 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

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

The end

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

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 flash X-rayultrafast Laser 1/20, 000 fast (fs), intense, shortsecond wavelength shutter speed X-rayslow Detector 1/200 second slow (microseconds) flash duration and intensity determine picture quality x-rays can see “the invisible” nanoscale

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

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

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” Slide 41