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”

280 Overpass

SLAC Professor Richard Taylor

Nobel Prize 1990LINAC completed in 1966

Stanford Board of TrusteesPage 4

SLAC Professors Burton Richter (Nobel 1976)and Martin Perl (Nobel 1995)

SPEAR completed in 1972x-ray experiments began in 1974

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

Particle & Particle Astrophysics

LCLS

SSRL

Change in Mission reflected in

SLAC Organization Chart

SLAC Director

Accelerators

Operations

Photon Science

“Photon Science” consists of• x-ray user facilities• x-ray research

SIMESPULSESUNCAT….

electron beam

x-ray beam

SSRL storage ring

SLAC operates two world class x-ray user facilities

LCLS

SLAC played an important role in the last tworevolutions 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

• 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

What is SSRL known for?

Bunch spacing 2 ns

Bunch width ~ 100 ps

beam line

x-ray pulses~ 100 ps width

X-Ray pulse length determined by electron bunch length

Can make shorter pulses (~ 1ps) at great loss of intensity

X-Rays from Electron Storage Ring

What is ax-ray free electron laser, anyway?

Introduction to LCLS

Optical laser X-ray free electron laser

• bound electrons in atoms - transitions between discrete states

• amplification through stimulated emission

• fixed photon energy around 1 eV

• compact size

• 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

Optical versus X-Ray Free Electron Laser

SASE versus self seeded x-ray beam

Intense x-ray source with spiky spectrum

Monochromator filter creates seed with controlled spectrum

FEL amplifier (exponential intensity gain)

seeded

SASE

8.3 keV40 pC

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

LCLS: the world’s first x-ray free electron laser

electron beam

x-ray beam

Injector Injector

1km linac 14GeV1km linac 14GeV

AMOSXR

XPP

XCS

CXI

MEC

Near-hall: 3 stationsNear-hall: 3 stations

Far-hall: 3 stationsFar-hall: 3 stations

Undulator hallUndulator hall

Far Experimental Hall

Near Experimental Hall

AMOSXR XPP

XCSCXIMEC

X-ray Transport Tunnel

200 m

Start of operation

Oct-09AMO

November-11XCS

February-11CXI

October-10XPP

May-10SXR

MEC April -12

LCLS X-ray Facilities

• 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

LCLS instruments and their focus

DiffractionEXAFS

PhotoemissionX-ray absorptionX-ray emission

X-ray magnetic dichroismspin pol. photoemission

“Imaging”

X-Rays can see the invisible X-Rays can see the invisible --provide static and dynamic information----provide static and dynamic information--

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

200ps 400ps 600ps 800ps

100 nm

0 1 ns

X-FEL Science

or

The Need for Speed !

The speed of things – the smaller the faster

atoms

“electrons” & “spins”

macromolecules

molecular groups

optical laser pulse

The technology gap

• 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

rule of thumb…“the smaller the faster”….

What determines the speed of things?

Understanding of motion and speed essential for “function”

• Atoms : speed of sound: 1 nm / 1 ps

• Electrons: Fermi velocity: 1 nm / 1 fs • Light: speed of light: 1 nm / 3 as

Characteristic speeds of atoms, electrons and spins

The new science paradigm: The new science paradigm: Static nanoscale “structure” plus its dynamic “function” Static nanoscale “structure” plus its dynamic “function”

The world of x-rays nanoscale dynamics smaller & faster

Fundamental Timescales

Operational Timescales

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)

Long range orderStatic disorderEquilibrium States

Nanoscale order Dynamic order Transient States

1900 2000 future

Structure and Properties Function and Control

The new paradigm in understanding atomic matterThe new paradigm in understanding atomic matter

• most reliably calculated

• 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??

Diffraction data Electron density Molecular model of proteinsuggests its function

Protein crystal

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

A new Paradigm in Macromolecular Crystallography “beating the speed of sound with the speed of light”

Studies of nanocrystals at X-FELs leads to a new paradigm

conventional method

magnetic switching today100nm size in 100ps - the speed of sound how fast can it be done?

Electronic circuit Memory cell Magnetic structure of “bit”Computer chip

100 nm

““Close to equilibrium” – how does a device function:Close to equilibrium” – how does a device function:e.g. how does a spin current turn the magnetization ? e.g. how does a spin current turn the magnetization ?

“bit” in cell

What are the key intermediate reactive species?

end reaction products reaction dynamics & intermediates

“Far from equilibrium”:How does a chemical reaction proceed?

“Far, far from equilibrium”:Warm and hot dense matter

Al -T phase diagram

The properties of matter in extreme states - which on earth can only be created transiently on ultrafast time scale-

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 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

What have we learned so far?

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: 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

The trick to taking ultrafast picturesThe trick to taking ultrafast pictures-- our cameras are too slow---- 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

ultrafast flash1/20,000 second

slow shutter speed 1/200 second

flash duration and intensity determine picture quality x-rays can see “the invisible” nanoscale

X-ray Detector slow (microseconds)

X-ray Laser fast (fs), intense, short wavelength

Future Plans: LCLS-II and LUSI-II

hard x-raysoft 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

5 things LCLS may become known for5 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

The key challenge:• Understand/control of the transient reactive state • “where the action is”

Conversion of chemicalsClean fuel

Carbon spectra of molecules

LCLS-II science example 1:Studies of carbon related reactions become possible

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