Transcript CXI Experiment

Coherent Single Particle Imaging
(WBS 1.3)
J. B. Hastings*
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
Science Team
Specifications and instrument concept developed
with the science team.
The team
Janos Hajdu, Photon Science-SLAC, Upsala University
(leader)
Henry Chapman, LLNL
John Miao, UCLA
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
A 3D dataset can be assembled from diffraction patterns in
unknown orientations
Diffraction from a single molecule:
Noisy
diffraction
pattern
FEL pulse
Unknown
orientation
Combine 105 to 107 measurements into 3D dataset:
Classify
Average
The highest achievable resolution is limited by the ability to
group patterns of similar orientation
Gösta Huldt, Abraham Szöke, Janos Hajdu (J.Struct
Biol, 2003 02-ERD-047)
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
Combine
Reconstruct
Miao, Hodgson, Sayre, PNAS
98 (2001)
J. B. Hastings
[email protected]
The diffraction imaging interaction chamber and detector arrangement
Particle injection
Pixel
detector
Intelligent
beam-stop
Hartman
Wavefront
Mask
XFEL beam
(focussed, possibly
Compressed)
PotentialParticle
orientation beam
To mass
spectrometer
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
Optical and xray
diagnostics
Readout and
reconstruction
J. B. Hastings
[email protected]
Wavefront
sensor
1 micron
KB system
0.1 micron
KB system
Coherent X-ray Imaging Instrument
Sample
chamber
Coherent X-ray Imaging Instrument
Detector
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
Detector geometry
‘Hole’ in detector to pass
Incident beam
Tiled detector, permits variable ‘hole’ size:
•Ideally the hole is ~ x2 bigger than incident beam at most
•Dead area at edges of detector tiles limits minimum ‘hole’ size
•Alternate approach: larger ‘hole’ and a single tile for forward direction
Simulations required
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.2 X-ray Optics
X-ray optics (1.3.2)
Focusing
K-B systems for 1 and 0.1 micron foci
Be lens for 10 micron focus
Slits, attenuators, ‘pulse picker’
Pulse compression optic
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.2 X-ray Optics - focusing
Two approaches: separate optical components for 10,
1, 0.1 micron focii or a single 0.1 micorn optic and
work out of focus for ‘variable’ spot size
Separate optics:
Ideally wavefront is ‘flat’
Complicated motion for sample chamber-detector system
Single optic:
Simple ‘translation of sample varies focus’
Wavefront curavture when ‘out of focus, is this harmful?
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.2 X-ray Optics - focusing
Focusing
optics
Be Lens
FEL source
Offset mirror
pair
Sample handler
KB Mirrors
1 µm
0.1 µm
Monochromator/ pulsecompressor
f1 µm
f0.1 µm
zd
Pixel
detector
Beamstop
Sample chamber &
diagnostics
zs ≈ 400 m
Image
reconstruction
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
Kirkpatrick Baez (KB) focusing mirrors
1.3.2.2 Mirror system (1
µm and 0.1 µm KB)
KB mirrors have produced
50 nm focuses of
SR(Yamauchi et al., SRI
2006).
Can use bent plane
mirrors – plane mirrors
most accurate polishing.
Achromatic focusing.
Use B4C as coating
Damage resistant
Good reflectivity
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
KB Pair for 1 μm focus
Grazing angle 0.2 Deg
B4C coating
Horz. Mirror 20 cm
Vert. Mirror 10 cm
Focal spot size (FWHM in microns)
Horz: 0.6
Vert: 0.9
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
KB Pair for 0.1 μm focus
Grazing angle 0.2 Deg
B4C coating
Horz. Mirror 20 cm
Vert. Mirror 10 cm
Focal spot size (FWHM in microns)
Horz: 0.097
Vert: 0.083
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.2 X-ray Optics - focusing
Focusing
optics
Be Lens
FEL source
Offset mirror
pair
Sample handler
KB Mirrors
1 µm
0.1 µm
Monochromator/ pulsecompressor
fBe lens
zd
Pixel
detector
Beamstop
Sample chamber &
diagnostics
zs ≈ 400 m
Image
reconstruction
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.2 X-ray Optics - focusing
1.3.2.2 – Beryllium lens focusing optic
~ 10µm FWHM focal spot size
Positioning resolution and repeatability to 1 µm
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
Be lens calculation for 10 micron focus
Focal spot size including diffraction and
roughness
FWHM in microns:
Horiz: 12.0
Vert: 10.1
http://www.institut2b.physik.rwth-aachen.de/xray/applets/crlcalc.html
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.2 X-ray Optics – pulse picker
1.3.2.1.2 – Pulse picker
Permit LCLS operation at 120 hz
Single pulses. Useful for samples supported on substrates
Reduced rate ex. 10 hz operation
High damage threshold
Use rotating discs, concept already in use at ESRF
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.2 X-ray Optics - compressor
476 µm
λ
(nm)
d
(nm)
θ
φ
b
Sin β
H*
(mm)
Δλw/λ
(%)
0.15
2.0
2.1º
-90º
+1
0.03
2600
0.5%
Henry Chapman LLNL
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.3 Sample environment - Vacuum requirements
Assumptions:
‘unshielded’ beam path of 10 cm for 1 µm2 beam
bio-molecule ~ 500kDa ~ 5 x 104 atoms
Background scatter 1%
500 atoms in path
Atoms in background gas same z as in the molecule
p ≤ 1 x10-7 torr
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.3 Sample environment – detector position
Sample environment (1.3.3)
Sample chamber (vacuum better than 10-7 torr)
Detector positioning 50-4000 mm from sample
Sample diagnostics - ion and electron ToF
Cryo-EM stage
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
The number and solid angle of the detector elements are dependent on particle size
and resolution
N x
f
x
fmax
D = N x / s
Real space samples: x
Smallest period sampled: 2x = d or fmax = 1/d
Oversampling (per dimension): s
Array size: N = D s / x = 2 D s / d
  /(D s)
E.g. D = 57 nm, d = 0.3 nm, s = 2  N = 760
 = 0.15 nm
pix= 1.3 mrad
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
f  2 f max /N
1/(Ds)
 pix   f

Henry Chapman LLNL
J. B. Hastings
[email protected]
Detector size fixes resolution
E.g., d = 0.3 nm, s = 2 , = 0.15 nm, N = 760  D ≈57 nm
110 m pixels
2 = 30º
zd = 83.6 mm,
760 pixels
D = 57 nm
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
zd
zd =1450 mm,
760 pixels
D = 1000 nm, d=5.2 nm
J. B. Hastings
[email protected]
1.3.3 Sample environment
Sample environment (1.3.3)
Sample chamber (vacuum better than 10-7 torr)
Detector positioning 50-4000 mm from sample
Sample diagnostics - ion and electron ToF
Cryo-EM stage
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.3 Sample environment - Sample diagnostics
3 x1012 photons in 100 nm
spot
(a) 2 fs pulse
(b) 10 fs pulse
(c) 50 fs pulse
Provide diagnostics to
understand the ‘explosion’
Electron and Ion ToF
detectors
able to resolve single atom
fragments (1 AMU)
1/1000 in electron energy
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
System Specifications
Item
Purpose
Specification
Focusing
optics
Produce required flux.
Focal spot sizes of 10,1, 0.1 micron
Sample
chamber
Vacuum sample env.,
reduced background
Vacuum below 10 -7 torr
Detector
Measurement of diffraction
pattern
2-D, 760 x 760 pixels,
110110 µm pixel size,
with central hole (shared LCLS det.)
Sample
diagnostic
Ion TOF analysis of sample
fragments
Resolution of one mass unit up to 100
AMU
Sample
diagnostic
Electron TOF analysis of
sample fragments
Resolution of 10 -3
Optical
Compressor
Reduce pulse length
20 fs pulse length
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.3 Sample environment – cryo-EM stage
Sample environment (1.3.3)
Sample chamber (vacuum better than 10-7 torr)
Detector positioning 50-4000 mm from sample
Sample diagnostics - ion and electron ToF
Cryo-EM stage
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
1.3.3 Sample environment - Cryo-EM stage
Cryo-EM Goniometer
All motion drives
outside vacuum
In use on SR sources for
STXM
Provides full angularspatial degrees of
freedom to collect 3D
data
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
Summary
Instrument concept advancing well
Near term issues: detector hole, single versus multiple
optics
Sample chamber: design should accommodate
Raster system (samples on substrate)
Particle injector
Cryo-EM stage
Data acquisition-storage-analysis are challenging
Diagnostics-wavefront in particular are challenging
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]
LCLS FAC April 17, 2007
Coherent X-Ray Imaging
J. B. Hastings
[email protected]