david fritz [email protected] lcls fac meeting oct. 30, 2007 1 x-ray pump-probe instrument...

David [email protected]

LCLS FAC MeetingOct. 30, 2007 1

X-ray Pump-Probe Instrument David Fritz

X-ray Pump-Probe Instrument David Fritz

Instrument OverviewInstrument LayoutSystem Description

X-ray Optics &DiagnosticsSample EnvironmentsDetectorsLaser System

FEL/Pump Laser Timing SystemTechnical IssuesSummary

Instrument OverviewInstrument LayoutSystem Description

X-ray Optics &DiagnosticsSample EnvironmentsDetectorsLaser System

FEL/Pump Laser Timing SystemTechnical IssuesSummary



X-ray Pump-Probe ScienceX-ray Pump-Probe Science

Phase TransitionsOrder / Disorder Metal/Insulator Phonon Dynamics

Charge Transfer Reactions

PhotosynthesisPhotovoltaicsVision

Photoactive Proteins

Phase TransitionsOrder / Disorder Metal/Insulator Phonon Dynamics

Charge Transfer Reactions

PhotosynthesisPhotovoltaicsVision

Photoactive Proteins

photo-excitation

Stampfli and Bennemann Phys. Rev. B 49, 7299 (1994)

photo-excitation



Ultrafast Hard X-ray Sources to DateUltrafast Hard X-ray Sources to Date

3rd Generation Synchrotrons (APS)~ 1 x 10 9 photons/second coincident with a 1 kHz Laser100 ps pulse duration

Slicing Source~ 1 x 10 6 photons/second coincident with a 1 kHz Laser100 fs pulse duration

Laser Plasma Source~ 1 x 10 5 photons/second collected at 10 Hz300 fs pulse duration

Sub-Picosecond Pulse Source~ 1 x 10 7 photons/second coincident with a 10 Hz Laser100 fs pulse duration

3rd Generation Synchrotrons (APS)~ 1 x 10 9 photons/second coincident with a 1 kHz Laser100 ps pulse duration

Slicing Source~ 1 x 10 6 photons/second coincident with a 1 kHz Laser100 fs pulse duration

Laser Plasma Source~ 1 x 10 5 photons/second collected at 10 Hz300 fs pulse duration

Sub-Picosecond Pulse Source~ 1 x 10 7 photons/second coincident with a 10 Hz Laser100 fs pulse duration



Ultrafast X-ray Science to DateUltrafast X-ray Science to Date

Limited to slow processes ( > 100 ps)or

X-ray diffraction from single crystals

Limited to slow processes ( > 100 ps)or

X-ray diffraction from single crystals

Large Amplitude Coherent Phonons

-500 0 500 1000 1500 2000

0.2

0.4

0.6

0.8

1.0

t (fs)

norm

aliz

ed d

iffr

acti

on in

tens

ity (220)

(111)

Non-thermal Melting of Semiconductors

20 minute acquisition at SPPSSingle Shot at SPPS



XPP Instrument ScopeXPP Instrument Scope

X-ray Wavelength and Bandwidth

Sample EnvironmentScattering

TechniqueExcitation Laser

Parameters

Fundamental Monochromatic

Fundamental 3rd Harmonic Monochromatic 3rd

Harmonic

Room Press. & Room Temp

Temperature Controlled Cryostat

Liquid Vacuum

Wide Angle Scattering

Small Angle Scattering

Emission

Med. Energy (2 mJ fund.)

Fundamental (800 nm) 2nd Harmonic (400 nm) 3rd Harmonic (266 nm) OPA

High Energy (20 mJ fund.)

Fundamental (800 nm) 2nd Harmonic (400 nm) 3rd Harmonic (266 nm)

Versatility is key to the instrument successVersatility is key to the instrument success

Instrument will operate in the 6-25 keV photon energy range



Instrument SpecificationsInstrument Specifications

Secondary Slits

Wide Angle Stage

Small Angle Stage

Photon Shutter

Focusing Lenses

Photon Shutter

Monochromator

Photon Shutter

Item Purpose Specification

Large Offset Monochromator

Multiplex FEL radiation,Narrow FEL spectrum

600 mm offset,≤ 10-4 spectral bandwidth

Harmonic Rejection Mirrors

Filter 3rd Harmonic Radiation

105 : 1 contrast ratio< 0.5 nm surface roughness

Slits/AperturesBeam definition, Beam halo cleaning

0.1 um stability, 1 um repeatability

Attenuators Control incident x-ray fluxVariable, up to 107 reduction at 1.5 Å

DiagnosticsIntensity Monitor, Position Monitor

0.1% relative intensity measurement,

< 5% incident x-ray attenuation

Be Focusing Lenses

Increase incident x-ray flux

2-10 mm, 40-60 mm spot size at 1.5 Å,

2-10 mm spot size at 0.5 Å

Laser System Photoexcitation of samplesUltrafast pulse duration (<50 fs), Up to 20 mJ pulse energy at 800 nm, 120 Hz

X-ray Diffractometer

Sample orientationKappa diffractometer,

Platform diffractometer

Wide Angle Detector Stage

Move the detector in reciprocal space

Spherical detector motion at a 10-150 cm radius

Small Angle Detector Stage

Collect SAXS patterns2.5, 5, and 10 m Sample-to-detector distance, 0.5 m horizontal detector motion

2D DetectorProvide 2D pixelated detection capability

1024 x1024 pixels, 120 Hz frame/s, dynamic range >103, single-photon sensitivity, pixel size 90x90 mm2

Mirror System

Primary Slits

Diagnostics

Attenuators

Diagnostics

Diffractometer

NE

H H

utch

3

Diagnostics

Diagnostics

Laser Port

FE

E

Diagnostics



XPP Instrument LocationXPP Instrument Location

XCS

AMO(LCLS)

CXI

XPPEndstation



X-ray Pump-Probe Instrument

OffsetMonochromator

Laser System(Fundamental)

X-rayDiffractometer& BNL Detector

WavelengthConversion

Small AngleScattering

X-ray Opticsand Diagnostics



X-ray Optics – Offset MonochromatorX-ray Optics – Offset Monochromator

Double crystal offset monochromatorNarrows x-ray spectrum for resonant scattering experimentsMultiplexes LCLS beam (mono. beam, diagnostic beam)

Double crystal offset monochromatorNarrows x-ray spectrum for resonant scattering experimentsMultiplexes LCLS beam (mono. beam, diagnostic beam)

Parameter Value

Energy Range 6 – 24 keV

Horizontal Offset 600 mm

Scattering Angle 140 - 500

Accuracy 0.02 arcsec

χ Accuracy 4 arcsec

Scattering Angles (2 theta)

1.5 Å 0.5 Å

Silicon 111 27.6° -

Silicon 220 45.8° 14.9°

Diamond 111 42.5° 13.9°

Diamond 220 - 22.8°



X-ray Optics - AttenuatorsX-ray Optics - Attenuators

AttenuatorsVariable, up to 10 7 reduction at 8.3 keVCoherence preservingHigh damage threshold

AttenuatorsVariable, up to 10 7 reduction at 8.3 keVCoherence preservingHigh damage threshold



X-ray Optics – Slit SystemsX-ray Optics – Slit Systems

Slit systemsVariable horizontal and vertical gap from 5 μm – 5 mmCan withstand full LCLS flux – unfocusedMinimize background scatter from blades

Slit systemsVariable horizontal and vertical gap from 5 μm – 5 mmCan withstand full LCLS flux – unfocusedMinimize background scatter from blades

D. Le Bolloc’h et al., J. Synchrotron Rad., 9, 258-265 (2002).



X-ray Optics - Be Focusing LensesX-ray Optics - Be Focusing Lenses

Beryllium CRL> 40% throughput

Positioning resolution and repeatability to 1 µmZ translation to vary spot size

Beryllium CRL> 40% throughput

Positioning resolution and repeatability to 1 µmZ translation to vary spot size

B. Lengeler et al., J. Synchrotron Rad., 6, 1153-1167 (1999).



X-ray Optics – Harmonic Rejection MirrorsX-ray Optics – Harmonic Rejection Mirrors

Harmonic Rejection Mirror System> 80% throughput

10 5 : 1 contrast ratio (10 7 : 1 overall)

Harmonic Rejection Mirror System> 80% throughput

10 5 : 1 contrast ratio (10 7 : 1 overall)

10-4

10-5

10-2

10-6

10-3



Kappa DiffractometerKappa Diffractometer

Kappa X-ray DiffractometerOperate in both direct and monochromatic beamLarge reciprocal space accessGas stream temperature control

Kappa X-ray DiffractometerOperate in both direct and monochromatic beamLarge reciprocal space accessGas stream temperature control

η φ

κ

α = 50º

KinematicMount

XY Table

μ

ν

δ x



Platform DiffractometerPlatform Diffractometer

Platform X-ray DiffractometerOperate in both direct and monochromatic beamAccommodates large sample environments (Cryostats, vacuum chambers, etc…)

Platform X-ray DiffractometerOperate in both direct and monochromatic beamAccommodates large sample environments (Cryostats, vacuum chambers, etc…)

χ

x trans

ω

z trans

y trans

KinematicMount

XY Table

μ

ν

δ



Emission SpectroscopyEmission Spectroscopy

X-ray Emission Spectrometer~ 50 eV dynamic range~ 0.1 eV resolutionLarge collection solid angle

X-ray Emission Spectrometer~ 50 eV dynamic range~ 0.1 eV resolutionLarge collection solid angle

XAMPS

XY Table

μ

ν

δ

sample

PSD

analyzers

vertical cut top view

beam

analyzers

spectrum



Small Angle ScatteringSmall Angle Scattering

SAXS Capability2.5, 5, and 10 m sample-to-detector distance10 µrad angular resolution with XAMPS detector (10 m)Operate in both direct and monochromatic beam

SAXS Capability2.5, 5, and 10 m sample-to-detector distance10 µrad angular resolution with XAMPS detector (10 m)Operate in both direct and monochromatic beam



2D Detectors2D Detectors

2D detector (BNL)1024 x 1024 pixels 90 micron pixel sizeHigh Detector Quantum Efficiency (DQE)10 4 dynamic range at 8 keV120 Hz Readout Rate

2D detector (BNL)1024 x 1024 pixels 90 micron pixel sizeHigh Detector Quantum Efficiency (DQE)10 4 dynamic range at 8 keV120 Hz Readout Rate



Laser SystemLaser System




Ti:Sapphire Oscillator & Power Amplifiers

Compressor, OPA, Harmonic Generation, Delay Stage




Laser DiagnosticsTemporal and spectral characterization

Grenouille – Real time pulse duration, spectrum3rd Order Correlator – Contrast ratio

Energy characterizationPer pulse Joule meter, 120 Hz, 1% accuracy

Spatial characterizationProfile monitor at a “virtual” sample, 5 μm resolution

Laser DiagnosticsTemporal and spectral characterization

Grenouille – Real time pulse duration, spectrum3rd Order Correlator – Contrast ratio

Energy characterizationPer pulse Joule meter, 120 Hz, 1% accuracy

Spatial characterizationProfile monitor at a “virtual” sample, 5 μm resolution



X-ray DiagnosticsX-ray Diagnostics

Transmissive Intensity Monitor> 95 % TransmissionRelative accuracy < 0.1%

Flourescent ScreeensDiodes

Transmissive Intensity Monitor> 95 % TransmissionRelative accuracy < 0.1%

Flourescent ScreeensDiodes



AcceleratingElements

ExperimentalPump Laser

Electron Gun

Master Clock

RF Distribution

Network

Laser/FEL TimingLaser/FEL Timing

Sources of Short Term JitterE-beam phase to RF phase jitter

Electron beam energy jitter + dispersive electron opticsEnd station laser phase to RF Phase

~ 1 ps limit

Sources of Short Term JitterE-beam phase to RF phase jitter

Electron beam energy jitter + dispersive electron opticsEnd station laser phase to RF Phase

~ 1 ps limit



Traditional Pump-probeTraditional Pump-probe

Delay will be achieved by optical delay and/or RF phase shiftResolution limited by LCLS/laser jitter ~ 1 ps limit

Delay will be achieved by optical delay and/or RF phase shiftResolution limited by LCLS/laser jitter ~ 1 ps limit

C. W. Siders



Single Shot Pump-ProbeSingle Shot Pump-Probe

time (fs)di

ffra

cted

in

tens

ity

Limited to X-ray diffractionNeed ‘large’ effectsImaging resolution affects temporal resolution

Limited to X-ray diffractionNeed ‘large’ effectsImaging resolution affects temporal resolution

A. M. Lindenberg et al., Science, 308, 392 (2005).




Electro-optic Sampling

Laser

Pump-probe

Laser

LTU NEH

Gun Laser

Sector 20

Stabilized Fiber Optic RF Distribution (10 fs)

LBNL

Electro-optic SamplingEnhanced Temporal Resolution (~ 100 fs)

Limited by our ability to phase lock the lasers to the RF backboneLimited by Intra-bunch SASE jitter

Electro-optic SamplingEnhanced Temporal Resolution (~ 100 fs)

Limited by our ability to phase lock the lasers to the RF backboneLimited by Intra-bunch SASE jitter



Non-sequential SamplingNon-sequential Sampling

100 consecutive shots

Single shot, Lorentzian fit

Diagnostic required to measure LCLS/laser timingEOS demonstrated at SPPS

Diagnostic required to measure LCLS/laser timingEOS demonstrated at SPPS




Diagnostic Beam for Direct Timing MeasurementPermits destructive x-ray timing measurement in hutchSame excitation laser can be used

Diagnostic Beam for Direct Timing MeasurementPermits destructive x-ray timing measurement in hutchSame excitation laser can be used

600mm

Transmitted Beam85%

8keV

Diagnostic Beam1.3%

Mono. Beam2.5%



Technical IssuesTechnical Issues

1. X-ray/Laser Timing Below 100 fs2. Flexible Diffractometer Design

- Kappa + Platform

3. Thin Monochromator Crystals- Diamond vs. Thin Silicon - (Absorption, Damage vs. Quality)

4. Monochromator Precision Motion- 200 nRad motion & stability

5. Rejecting Fundamental in 3rd Harmonic Operation

1. X-ray/Laser Timing Below 100 fs2. Flexible Diffractometer Design

- Kappa + Platform

3. Thin Monochromator Crystals- Diamond vs. Thin Silicon - (Absorption, Damage vs. Quality)

4. Monochromator Precision Motion- 200 nRad motion & stability

5. Rejecting Fundamental in 3rd Harmonic Operation



SummarySummary

Instrument design emphasizes flexibilityX-ray scattering techniques

WAXSSAXSEmission spectroscopy

X-ray optics can tailor FEL parameters for users Many sample environments are accommodated

VacuumLow temperature (cryostat, cryostream)Samples in solution

Versatile laser system

Instrument design emphasizes flexibilityX-ray scattering techniques

WAXSSAXSEmission spectroscopy

X-ray optics can tailor FEL parameters for users Many sample environments are accommodated

VacuumLow temperature (cryostat, cryostream)Samples in solution

Versatile laser system



Non-sequential SamplingNon-sequential Sampling

D. M. Fritz et al., Science, 315, 633 (2007).A. L. Cavalieri et al., Phys. Rev. Lett., 94, 114801 (2005).

david fritz [email protected] lcls fac meeting oct. 30, 2007 1 x-ray pump-probe instrument...

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