x -ray c orrelation s pectroscopy instrument

Aymeric Robert

XCS Instrument [email protected]

11/12/20081

SLAC National Accelerator Laboratory

X-ray Correlation Spectroscopy

InstrumentAymeric Robert – XCS Instrument Scientist

LCLS Facilities Advisory Committee MeetingNovember 12, 2008

Team Leaders : Brian StephensonGerhard GrübelKarl Ludwig

Lead Engineer: Eric Bong

Aymeric Robert


11/12/20082


X-ray Photon Correlation Spectroscopy

Speckles : scattering patterns produced by the coherent illumination of the sampleXPCS : observation of the time-fluctuation of speckle patternsCharacterization of the underlying dynamics of the system

Coherent X-rays

Coherent Scattering(Speckles)

XPCS is independent of the scattering geometry (SAXS, Diff., GI-SAXS, Refl.,…)XPCS probes dynamical phenomena

Aymeric Robert


11/12/20083


Photon ShutterPrimary Slits

Diagnostics

Secondary SlitsDiagnostics

Split and Delay

Focusing Lenses

Attenuators

Diagnostics

Photon Shutter

Defining Slits

DiffractometerLarge AngleDetector Stage

MonochromatorTransport TunnelFEH

Hutch 4

Harm. Rej. Mirrors

Pulse Picker


Goal Time-resolved observation of coherent diffraction patterns using LCLS coherent hard x-rays (6-25keV)

Tailor and characterize X-ray beam parametersSpatial profileIntensityRepetition RateSpectral Bandwidth

X-ray Photon Correlation Spectroscopy Requirements

Versatility of the instrumentation (SAXS, WAXS, GI)Coherence preservation of x-ray optics (to the extent possible)

Detector with small pixel size/Large sample-detector distance

Key Performance Parameters6-20 keV energy range

Using the fundamental and third harmonic0.1-0.01% energy resolution

Aymeric Robert


11/12/20084



Diagnostics


Split and Delay

Focusing Lenses

Attenuators

Diagnostics

Photon Shutter

Defining Slits



Hutch 4

Harm. Rej. Mirrors

Pulse Picker


Large Angle Detector Mover& Diffractometer

•Sample/detector distance 7-8m•Decoupled from diffractometer•SAXS, WAXS, GI• 2θ up to 55º, vertical tilt•Height adj.

Aymeric Robert


11/12/20085


Previous FAC Reports

FAC Report Oct 2007The committee recommends that the XCS staff retain flexibility in their designs to facilitate change as opportunities and problems are discovered.

FAC Report Jun 2008“ … the committee endorses the decisions that have been made to date.” “ The large offset monochromator also requires design attention and carries risk. This has been recognized by the project and appropriate efforts are being made to create a solid design”

Aymeric Robert


11/12/20086



Diagnostics


Split and Delay

Focusing Lenses

Attenuators

Diagnostics

Photon Shutter

Defining Slits



Hutch 4

Harm. Rej. Mirrors

Pulse Picker

Secondary SlitsDiagnostics Monochromatization

scheme for XCS

Aymeric Robert


11/12/20087



Diagnostics


Split and Delay

Focusing Lenses

Attenuators

Diagnostics

Photon Shutter

Defining Slits



Hutch 4

Harm. Rej. Mirrors

Pulse Picker


Motivations•XCS Science (i.e Early Science)•XCS Science NEEDS a monochromator•Satisfaction of the XCS User Community

First Coherence WorkshopApplication of Coherent X-rays at the LCLS

10/17/2008

Aymeric Robert


11/12/20088


Transport TunnelFEH

Hutch 4

Original Plan for XCS

X-rayCorrelationSpectroscopy

CoherentX-rayImaging

HighEnergyDensity

XCS

Near Experimental Hall

Far Experimental Hall

X-ray Transport Tunnel(200m long)

Source to Sample distance : ~ 420 m

Aymeric Robert


11/12/20089


Transport TunnelFEH

Hutch 4

Original Plan for XCS Monochromator

Double crystal Large Offset Monochromator•Energy Range : 6-25keV•Offset : 600mm•Design similar to XPP•Location at the entrance of the XRT (200m)•Possibility of changing the crystal•Preserve “future” capability of multiplexing (i.e. thin crystals

Total Budgeted cost: 1.2M$

Delivery date : 2012Associated XRT cost : ~0.8M$

Aymeric Robert


11/12/200810


Transport TunnelFEH

Hutch 4

New Plan for XCS Monochromator

Double crystal Large Offset Monochromator•Energy Range : 6-25keV•Offset : 600mm•Design similar to XPP•Location at the entrance of the XRT (200m)•Possibility of changing the crystal•Preserve “future” capability of multiplexing (i.e. thin crystals

Total Budgeted cost: 1.2M$Delivery date : 2012

Associated XRT cost : ~0.8M$

BUT

~35m

Aymeric Robert


11/12/200811


Transport TunnelFEH

Hutch 4

Plan for XCS MonochromatorRelease LO-DCM distance from XCS

Advantages Disadvantages

Relax design parameters for stability

No change in delivery date (2011)

Identical performances More but moderate interferences with ME2 operation

Save the XRT transport cost (0.8M$)

Still not acceptable by XCS User Community

All XCS optical components located on the same concrete slab ( gain in stability)

How to satisfy the request for early science from the XCS User Community and provide

early science capabilities ?

Aymeric Robert


11/12/200812


Transport TunnelFEH

Hutch 4

Plan for XCS MonochromatorS

• Use part of the saving from the XRT transport cost to purchase a commercially available High Resolution Double Crystal Monochromator ( pseudo channel cut in vertical scattering geometry )* with small “almost” fixed exit allowing the use of multiple standard reflections and covering easily the LCLS hard x-ray range 6-25keV•Ease polishing of each monochromator crystal • This can be purchased early (very early)

* For LCLS hard x-ray beam, there is no heat load issue. The major issue of that type of monochromator is known to be the cooling system which in our case is irrelevant

Aymeric Robert


11/12/200813


Transport TunnelFEH

Hutch 4

Plan for XCS MonochromatorImpact on XCS instrument design :almost NONE

•Operation for some time with just the HR-DCM

•Operation of XCS in CXI line (LCLS main line)

•The table supports for optics/diagnostics are identical to XPP instrument and allow that operation with a 600mm offset•The diffractometer can be placed in either line (CXI/XCS)•The Large Angle detector mover can have its center of rotation on both the CXI and XCS line

Provide earlier science capability for the XCS Instrument

Which other benefits ?

Aymeric Robert


11/12/200814


Monochromator for LCLS Instruments : Phase ICX

ICX

IXC

SXC

SXP

PXP

P

X

Provide the High Resolution Double Crystal Monochromator to the XPP Instrument

•Provide the first early LCLS monochromatic beam

•Test the monochromator

•Provide temporarily monochromatic beam to XPP

•Gives XPP more time to get their own monochromator

•Allow EARLY Coherent Scattering experiments in the XPP experimental hutch with control of the longitudinal coherence length (CXI/XCS)

Aymeric Robert


11/12/200815


Monochromator for LCLS Instruments : Phase IICX

ICX

IXC

SXC

S Provide the High Resolution DCM to hard X-

ray Coherence Instruments XCS or CXI

•Provide the first early LCLS monochromatic beam in FEH

•Test the monochromator close to FEH location (far from source and close to definite monochromator location)

•Provide temporarily monochromatic beam to CXI

•Allows early commissioning of XCS Instrument

•Evaluation of the impact of very hard coherent x-rays on XCS Science Program

•Allow EARLY Static and Dynamic Coherent Scattering Science in the CXI or XCS experimental hutches with control of the longitudinal coherence length

Aymeric Robert


11/12/200816


Monochromator for LCLS Instruments : Phase IIICX

ICX

IXC

SXC

S Return High Resolution DCM to XCS

•Use of HR-DCM as Post Monochromator for experiments requiring very large longitudinal coherence lengths

•Allow to relax the parameters of the LO-DCM to use a single type of crystal (Si (220) for example) as post monochromatization can be achieved with the HR-DCM

•The compensation in terms of lower ΔE/E as compared to Si (111) could be obtained with proper focusing optics (i.e CRL’s)

•If multiplexing : a single and identical crystal in CXI beam (i.e easy to correct if necessary)

Aymeric Robert


11/12/200817


Monochromator for LCLS Instruments

XCS Team Leader Meeting Oct 19, 2008

Move the large-offset and split/delay from about 200m upstream of experiment to about 40m upstream of experiment• We therefore endorse moving the large-offset monochromator to the new location.

Adding post-monochromator to scope

• Such a double-crystal monochromator is commercially available, and could be procured immediately for initial use in providing monochromatic beam to all of the early hard x-ray experiments. This will be extremely important for the scientific program. In particular, this will allow the early commissioning of the XCS experiments with the required monochromatic beam prior to the availability of the large-offset monochromator. All of the other XCS beamline components are compatible with operation in the in-line configuration without the large-offset monochromator.• We therefore endorse the concept of adding to the scope a double-crystal, small-vertical-offset monochromator with either multiple or easily changeable crystals.

The CXI team was involved in the discussion and supports the proposed plan

Aymeric Robert


11/12/200818


Summary The cost of the post monochromator (2) should be significantly less than the cost savings associated with moving the location of the large offset monochromator downstream (1). Thus the net result of these changes will be to improve performance, improve capability, and making monochromatic x-ray beam available earlier to all experiments, while decreasing cost.*

* XCS Team Leader Meeting Summary Oct 2008

•Early Science for XCS, CXI, XPP•No increase of cost ( i.e even slight cost saving)•XCS instrument commissioned early (with HR-DCM)•Satisfies the expectation of the XCS User Community•Serve the Science Mission of the 3 LCLS hard x-ray instruments

Aymeric Robert


11/12/200819


Additional Slides

XCS Science

Aymeric Robert


11/12/200820


Sequential XCS

Time-average Brilliance

10 ms < C < hrs

Large Q’s accessible

tt

t

tt

t

12

34

43

21

Intensity autocorrelation function

Aymeric Robert


11/12/200821


Ultrafast XCS : Split & Delay

Peak Brilliance & Pulse Duration

pulse duration < C< several ns

Large Q’s accessible

Detector

Aymeric Robert


11/12/200822


XCS Science @ LCLS

LCLS ParametersFull Transverse Coherence

High Peak BrillianceShort pulse duration 230fs

Ultra Fast Mode

Dedicated 2D-Detector

8 and 24 keV

High Time–average BrillianceRep. Rate 120 Hz

Sequential Mode

Aymeric Robert


11/12/200823


Crystal /Scattering

Angles (2θ)Coherence

Length ξL [μm]

1.5 Å 0.5 Å 1.5 Å 0.5 Å

Si(111) 1.4x10-4 27.6 9.1 1 0.3

Si(220) 6.1x10-5 45.8 14.9 2.45 0.8

C*(111) 5.9x10-5 42.5 13.9 2.54 0.9

C*(220) 2.3x10-5 -- 22.8 6.5 2.2

Multi-crystal XCS Monochromator

x -ray c orrelation s pectroscopy instrument

Documents