sébastien boutet [email protected] lcls fac meeting oct 30, 2007 coherent x-ray imaging1...
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Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 1
Coherent X-ray Imaging InstrumentSébastien Boutet
Coherent X-ray Imaging InstrumentSébastien Boutet
Coherent Imaging ExperimentsInstrument OverviewInstrument LayoutSystem Description
X-ray opticsSample environmentsDetectorDiagnostics
Technical ChoicesSummary
Coherent Imaging ExperimentsInstrument OverviewInstrument LayoutSystem Description
X-ray opticsSample environmentsDetectorDiagnostics
Technical ChoicesSummary
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 2
Molecular Structure Determination by Protein CrystallographyMolecular Structure Determination by Protein Crystallography
Molecular structure is crucial for medical applications.Inability to produce large high quality crystals is the main bottleneck.Radiation damage is overcome by spreading it over 1010 or more copies of the same molecule.
Molecular structure is crucial for medical applications.Inability to produce large high quality crystals is the main bottleneck.Radiation damage is overcome by spreading it over 1010 or more copies of the same molecule.
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 3
Coherent Diffractive Imaging of BiomoleculesCoherent Diffractive Imaging of Biomolecules
Combine 105-107 measurements into 3D dataset
Noisy diffraction pattern
XFEL pulse
Particle injection
One pulse, one measurement
Gösta Huldt, Abraham Szöke, Janos Hajdu (J.Struct Biol, 2003 02-ERD-047)
Wavefront sensor or second detector
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 4
Particle injection
LCLS beam
(focused, possibly optically compressed)
Optical and x-ray
diagnostics
Pixel detector
Intelligent beam-stop (wavefront
sensor)
To Time Of Flight (TOF) mass
spectrometer
Conceptual Design of CXI InstrumentConceptual Design of CXI Instrument
Readout and reconstruction
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 5
CXI Science at LCLSCXI Science at LCLS
Unique Characteristics of LCLSShort pulses (100 fs)
Instantaneous snapshots with no thermal fluctuations.Limited radiation damage during the exposure.
Organic samples
Time-resolved imaging experimentsTime evolution after laser excitation
High brightness (1012 photons all at once)Perform experiment in a single shot
Flash imaging of radiation sensitive samples
Large Spatial coherence (~400 µm transversely for unfocused beam in the Far Experimental Hall)
Coherent Imaging of larger samplesLCLS has fundamental limitations in the longitudinal coherenceObject size limited to 1000 x resolution unless a monochromator is used
Unique Characteristics of LCLSShort pulses (100 fs)
Instantaneous snapshots with no thermal fluctuations.Limited radiation damage during the exposure.
Organic samples
Time-resolved imaging experimentsTime evolution after laser excitation
High brightness (1012 photons all at once)Perform experiment in a single shot
Flash imaging of radiation sensitive samples
Large Spatial coherence (~400 µm transversely for unfocused beam in the Far Experimental Hall)
Coherent Imaging of larger samplesLCLS has fundamental limitations in the longitudinal coherenceObject size limited to 1000 x resolution unless a monochromator is used
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 6
CXI Instrument LocationCXI Instrument Location
XCS
AMO(LCLS)
CXIEndstation
XPP
Near Experimental Hall
Far Experimental Hall
X-ray Transport Tunnel
Source to Sample distance : ~ 440 m
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 7
System SpecificationsSystem Specifications
Item Purpose Specification
Focusing optics
Produce required flux. Focal spot sizes of 10,1, 0.1 micron
Slits/Apertures Beam halo cleaning0.1 m stability1 m repeatability
X-ray pulsecompressor
Reduce pulse length < 20 fs pulse length
Attenuators Control incident x-ray flux Up to 107 reduction at 1.5Å
Slits/Apertures Beam halo cleaning0.1 m stability1 m repeatability
Sample chamber
Vacuum sample env., reduced background
Vacuum below 10 -7 torr
Particleinjector
Deliver single particles inthe gas phase
Particle size range : 10 – 1000 nmParticle beam focus < 150 microns
DetectorMeasurement of diffraction pattern
2-D, 760 x 760 pixels, 120 Hz readout110110 µm pixel size, with central hole
Samplediagnostics
Analysis of samplefragments after Coulombexplosion
Ion TOF : resolution of one mass unit up to 100 AMU
Wavefront Sensor
Measure the wavefront on every shot
Resolution: 10% of the beam waist
X-ray DiagnosticsIntensity monitorBeam position/profile monitor
0.1% relative intensity measurement< 5% incident x-ray attenuation
Photon Shutter
Guard Slits
Focusing Lenses
Attenuators
Pulse Picker
Diagnostics
Sample EnvironmentParticle InjectorIon TOF-MS
KB Mirrors
FE
H H
utch
5
Wavefront Sensor
Detector Stage
Compressor
Beam Dump
Guard Slits
Guard Slits
KB Mirrors
Aperture
Aperture
X-ray T
ransp
ort T
un
nel
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 8
1 micron focusKB system
0.1 micron focusKB system
Sample Chamber with raster stage
Detector
Wavefrontsensor
10 micron focus Be lens (X-ray Transport Tunnel)
Particle injectorIon Time of Flight
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 9
X-ray OpticsX-ray Optics
Slit systemsVariable horizontal and vertical gap from 5 μm – 5 mmCan withstand full LCLS flux – unfocusedMinimal background scatterUsed as cleanup slits only
Slit systemsVariable horizontal and vertical gap from 5 μm – 5 mmCan withstand full LCLS flux – unfocusedMinimal background scatterUsed as cleanup slits only
D. Le Bolloc’h et al., J. Synchrotron Rad., 9, 258-265 (2002).
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 10
X-ray OpticsX-ray Optics
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
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 11
X-ray OpticsX-ray Optics
Pulse pickerPermit LCLS operation at 120 hzMillisecond shutter.
Allows any pattern of pulses to be selected.
Single pulses for samples supported on substratesHigh damage threshold
Pulse pickerPermit LCLS operation at 120 hzMillisecond shutter.
Allows any pattern of pulses to be selected.
Single pulses for samples supported on substratesHigh damage threshold
http://www.azsol.ch/
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 12
X-ray OpticsX-ray Optics
Beryllium Compound Refractive Lenses
Produce 10 m focusFor large particles
> 40% throughput
Positioning resolution and repeatability to 1 µm
Beryllium Compound Refractive Lenses
Produce 10 m focusFor large particles
> 40% throughput
Positioning resolution and repeatability to 1 µm
B. Lengeler et al., J. Synchrotron Rad., 6, 1153-1167 (1999).
-40 m
0 m
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 13
Kirkpatrick-Baez MirrorsKirkpatrick-Baez Mirrors
KB Mirror system (1 µm and 0.1 µm KB)
KB mirrors have demonstrated <50 nm focus with SRAchromatic focusing.Use B4C as coating
Damage resistantClose to 100% reflectivity
KB Mirror system (1 µm and 0.1 µm KB)
KB mirrors have demonstrated <50 nm focus with SRAchromatic focusing.Use B4C as coating
Damage resistantClose to 100% reflectivity
0 m
-0.4 m
-4 m
H. Mimura et al, Japanese Journal of Applied Physics 44, L539-L542 (2005)
-40 m
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 14
Sample environmentSample environment
Sample chamber Vacuum better than 10-7 torrSample raster stageAperture raster stagesOptical diagnosticsSample diagnostics (Time-of-Flight Mass Spectrometers)
Sample chamber Vacuum better than 10-7 torrSample raster stageAperture raster stagesOptical diagnosticsSample diagnostics (Time-of-Flight Mass Spectrometers)
FEL
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 15
Sample Environment - Fixed TargetsSample Environment - Fixed Targets
Detector
SampleAperture
Particle Injector
FEL
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 16
Sample Environment - Injected ParticlesSample Environment - Injected Particles
Aperture
The entire assembly is translated upstream to let the particle beam passThe last aperture is close to the particle beam to minimize background
The entire assembly is translated upstream to let the particle beam passThe last aperture is close to the particle beam to minimize background
Particle Beam
Particle Injector
FEL
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 17
Apodized Edge AperturesApodized Edge Apertures
If 1 part in 106 of the LCLS beam gets scattered off the slits onto the detector, there is on average 1 photon per pixel and the background is too high!Soft edge apertures, such as etched Silicon minimize scattering.Use extra apertures to remove the scatter from the upstream apertures.
If 1 part in 106 of the LCLS beam gets scattered off the slits onto the detector, there is on average 1 photon per pixel and the background is too high!Soft edge apertures, such as etched Silicon minimize scattering.Use extra apertures to remove the scatter from the upstream apertures.
LCLS Beam
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 18
Particle InjectorParticle Injector
Aerodynamic lens: stack of concentric orifices with decreasing openings. Can be used to introduce particles from atmosphere pressure into vacuum Near 100% transmission achievableCreates a tightly focused particle beam. Final focus can be as small as ~10 m diameterParticle size range : 10 – 1500 nm
Aerodynamic lens: stack of concentric orifices with decreasing openings. Can be used to introduce particles from atmosphere pressure into vacuum Near 100% transmission achievableCreates a tightly focused particle beam. Final focus can be as small as ~10 m diameterParticle size range : 10 – 1500 nm
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 19
A
B
C D
E F
G
A. Aerodynamic lensB. Particle beam steering C. Charge detectorD. Particle beam skimming apertureE. Particle beam alignment aperturesF. Time-of-flight mass spectrometerG. Faraday cup
Atmospheric pressure droplets evaporate
1-10 Torr ~1 Torr ~0.05 Torr<1x10-7 Torr
Particles in
Aerodynamically Focused Particle BeamAerodynamically Focused Particle Beam
Aerodynamic lens
FEL out of page
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 20
Sample DiagnosticsSample Diagnostics
Ion TOF3 x1012 photons in 100 nm spot
(a) 2 fs pulse(b) 10 fs pulse(c) 50 fs pulse
Provide diagnostics to understand the ‘explosion’
Ion ToF detectorsable to resolve single atom fragments (1 AMU)
Ion TOF3 x1012 photons in 100 nm spot
(a) 2 fs pulse(b) 10 fs pulse(c) 50 fs pulse
Provide diagnostics to understand the ‘explosion’
Ion ToF detectorsable to resolve single atom fragments (1 AMU)
Particle Injector TOF-MS
Aperture
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 21
DetectorDetector
Tiled detector, permits variable ‘hole’ size<1 photon readout noise110x110 m2 pixels760x760 pixels103 dynamic range120 Hz readoutSample-detector distance : 50-3000mm
Tiled detector, permits variable ‘hole’ size<1 photon readout noise110x110 m2 pixels760x760 pixels103 dynamic range120 Hz readoutSample-detector distance : 50-3000mm
‘Hole’ in detector to passIncident beam
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 22
2D Pixel Array Detector2D Pixel Array Detector
High resistivity Silicon (500 µm) for direct x-ray conversion.Reverse biased for full depletion.Bump-bonding connection to CMOS ASIC.ASIC limit on size, 21 mm2
Collaboration with
the Gruner Group
at
Cornell University
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 23
Hartmann Wavefront SensorHartmann Wavefront Sensor
Focal PlaneFocusing Optic
2D Detector
FEL Beam
Hartmann Plate
Variable Description Value Value Value
f Focal length 0.4 m 4 m 40 m
D Focus to Hartmann plate distance 5 m 15 m 15 m
w0 Focal spot size 0.1 m 1 m 10 m
W Beam size at Hartmann plate 5 mm 1.5 mm 0.15 mm*
f D L
Ww0
* Requires a defocusing optic
Detector
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 24
Diffractive Wavefront ReconstructionDiffractive Wavefront Reconstruction
The oversampled diffraction pattern of the focus is measured.The focal spot is iteratively reconstructed using phase retrieval methods by propagating the wave from the optic to the focus and then to the detector plane.
The constraints are applied at the optic and detector planes.
The oversampled diffraction pattern of the focus is measured.The focal spot is iteratively reconstructed using phase retrieval methods by propagating the wave from the optic to the focus and then to the detector plane.
The constraints are applied at the optic and detector planes.
Focal PlaneFocusing Optic
2D Detector
FEL Beam
f L
Ww0
Attenuator
Detector
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 25
X-ray DiagnosticsX-ray Diagnostics
Pop-in diodes to check alignment of different opticsPop-in fluorescent screens for beam position monitoringNon destructive Be foil backscattering can monitor intensity during measurement.
95% transmission0.1% accuracy
Pop-in diodes to check alignment of different opticsPop-in fluorescent screens for beam position monitoringNon destructive Be foil backscattering can monitor intensity during measurement.
95% transmission0.1% accuracy
Pop-in diode
Thin Be backscattering beam monitor
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 26
Key Technical ChoicesKey Technical Choices
Nanoparticle InjectorShotgun versus pulsed triggered approach
Focusing OpticsKB mirrors versus Be lenses or zone plates
Pulse PickerFlipping blade versus rotating disks
Wavefront SensorHartmann plate versus diffractive imaging
Apertures versus slits
Nanoparticle InjectorShotgun versus pulsed triggered approach
Focusing OpticsKB mirrors versus Be lenses or zone plates
Pulse PickerFlipping blade versus rotating disks
Wavefront SensorHartmann plate versus diffractive imaging
Apertures versus slits
Sébastien [email protected]
LCLS FAC Meeting Oct 30, 2007Coherent X-ray Imaging 27
SummarySummary
Instrument designed for imaging of submicron particles at near atomic resolution.Sample environments
Fixed targetsInjected samples
X-ray optics can tailor FEL parameters for users 3 focal spot size : 0.1, 1 and 10 micronsVariable attenuationSingle pulse selection with pulse picker
Instrument designed for imaging of submicron particles at near atomic resolution.Sample environments
Fixed targetsInjected samples
X-ray optics can tailor FEL parameters for users 3 focal spot size : 0.1, 1 and 10 micronsVariable attenuationSingle pulse selection with pulse picker