The X-ray Pump-Probe Instrument

1
The X-ray Pump-Probe Instrument
Instrument Scientist David Fritz Second
Scientist Marc Messerschmidt Lead Engineer J.
Brian Langton Designer Jim Defever Designer Jim
Delor
2
Outline

• Brief Instrument Overview
• Sample Goniometer System
• Detector Mover System
• Optics Table Design
• Conclusion

3
XPP Experimental Techniques

• Time-Resolved X-ray Diffraction (TRXD)
• Time-Resolve Diffuse Scattering (TRDS)
• Time-Resolved Protein Crystallography (TRPX)
• X-ray Emission Spectroscopy (XES)
• Small Angle X-ray Scattering (SAXS)
• Optical Probing of X-ray Transients
• The instrument budget is not sufficient to
  provide capability to all techniques

4
XPP Instrumentation Categories

• X-ray Beam
• Preparation (spatial profile, intensity,
  spectrum, repetition rate)
• Delivery to sample
• Characterization (spatial profile, intensity,
  arrival time)
• Optical Beam
• Creation
• Preparation (spatial profile, intensity,
  spectrum, repetition rate, temporal profile)
• Delivery to sample
• Characterization (spatial profile, intensity,
  spectrum, temporal profile)
• Sample Environment
• Orientation Positioning
• X-ray Detection

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Instrument Block Diagram
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XPP Instrument Location
Near Experimental Hall
X-ray Transport Tunnel
AMO (LCLS)
XPP Endstation
XCS
CXI
Far Experimental Hall
7
Instrument Layout Plan View
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Detector Mover Design Goals

• Flexibility to accommodate a wide variety of
  sample environments
• Capable of orienting small samples ( 50 µm) over
  a wide range of reciprocal space
• Sphere of confusion lt 30µm
• Open access to allow close proximity laser optics
• No interference with direct beamline while in
  monochromatic mode

9
Sample Goniometer Tilt Platform

• 400 mm x 400 mm top surface
• 5angular range of arc segments
• Large load capacity (gtgt 50 kg)
• 200 mm working distance

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Sample Goniometer Tilt Platform (2)
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Sample Goniometer Kappa Configuration
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Detector Mover Design Goals

• Operate in both interaction points
• 10 cm 100 cm sample to detector distance in
  forward-scattering upper hemisphere quadrant
• 10 cm 50 cm sample to detector distance in
  back-scattering upper hemisphere quadrant
• Repeatable position the XPP detector pixels to a
  fraction of the pixel size
• Definitively know the position of all detector
  pixels to a fraction of the pixel size

13
Detector Mover Coordinate System
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Detector Mover Coverage Requirements
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Detector Mover Concept

• 6-axis Industrial Robot
• Load capacity (gt 20 kg)
• 50 µm repeatability
• Floor or ceiling mountable
• No counterweights
• Remotely variable sample to detector distance
• Remote control of detector clocking angle

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Detector Mover Path Forward

• Engineering and manufacturing will be broken up
  into 3 work packages
• Statement of work 1
• Verify that a industrial robot has the capability
  of meeting motion requirements
• Statement of work 2
• Create a concept for integrating robot into the
  XPP instrument
• Statement of work 3
• Manufacturer, install, test and integrate system

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Detector Mover SOW 1
Test 1

• Test 1 Spherical motion and pointing
• System is capable of moving the detector about a
  spherical surface of a user defined radii while
  pointing the detector at the interaction region
• Test 2 Repeatability
• Measure repeatability and hysterisis of system
• Test 3 Detector Clocking Angle
• Measure how well the clocking angle can be
  controlled
• Test 4 Stability
• Measure long term ( hours) motion drift for
  various fixed positions

Test 2
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Detector Mover SOW 2

• Concept for integrating system into XPP
• Robot arm mounting
• Reach requirements can be met without intruding
  into mechanical stay clear zones
• Safety system

19
Optics Support Table Design Goals

• Repeatable position optics in two operating
  positions (mono, direct)
• Initial beam based alignment is expected for each
  position but the desire is to have a
  configuration file loaded for each operating mode
  without the need for alignment
• Stably support X-ray optics and diagnostics
• Design logic
• Optical axis will be defined by XPP slits
• X-ray optics and interaction point can drift
  together on the order of 100 µm with minimal
  impact
• However, the diffractometer thermal drift is an
  unknown
• It was determined that it was best to design a
  support table that fixes the position and
  alignment of the optical elements to the highest
  extent reasonably achievable
• This reduces misalignment issues to a one
  dimensional problem
• Design goals in priority order
• Stability of optics with respect to each other
  over short and long term periods
• Absolute position stability
• Slits are the gold standard and need to be the
  most stable of all elements

20
Optics Support Table Case Studies

• Analyzed component displacement due to bowing of
  support structure for a 2 F temp change
• Analyzed global displacement of entire structure
  due to 2 F thermal expansion
• Large granite surface plate with a low profile
  strongback was best option
• Themalization time constant of the granite is
  many days
• However, the drawback is the rigging effort
  must be moved in through the FEH

21
Optics Support Table Design

• Strongback has been split into two sections to
  minimize bowing and to prevent system
  overconstraints
• Strongback is strategically tied down to rails
  near locations of slits

22
Questions for the Committee

• Is the sample goniometer design optimized form
  the scientific goals of the instrument?
• Are the sample mover design requirements
  reasonable?
• Does the sample mover path forward seem
  reasonable?
• Is the design logic of the optics support table
  valid?
• Any other concerns/comments?