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X-ray Correlation Spectroscopy Aymeric Robert

X-ray Correlation Spectroscopy Aymeric Robert. Instrument Overview Instrument Layout System Description Offset monochromator Split and Delay Slits system Focusing optics Detector Stages 2D detector Technical Issues Summary. XCS Science.

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X-ray Correlation Spectroscopy Aymeric Robert

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  1. X-ray Correlation SpectroscopyAymeric Robert • Instrument Overview • Instrument Layout • System Description • Offset monochromator • Split and Delay • Slits system • Focusing optics • Detector Stages • 2D detector • Technical Issues • Summary

  2. XCS Science • Characterizing the time fluctuations of speckle patterns • (scattering patterns produced by the coherent illumination of the sample) • Characterizing the underlying dynamics of the system

  3. Current XPCS Capabilities XPCS is a “photon hungry “ technique ! • Limited by : • coherent flux • degree of coherence • detector performances • beam damages

  4. High Time–average Brilliance Rep. Rate 120 Hz Sequential Mode XCS Instrument Capabilities LCLS Parameters Transverse Coherence 8 and 24 keV Dedicated 2D-Detector

  5. Sequential XCS 120Hz Rep Rate High time-average Brilliance

  6. D t Intensity autocorrelation function D t D t D t D t 4 D t 3 2 1 1 2 3 4 Sequential XCS • Time-average Brilliance • 10 ms < tC < hrs • Large Q’s accessible

  7. Ultra Fast Mode High Time–average Brilliance Rep. Rate 120 Hz High PeaK Brilliance Pulse duration : 230fs Current max delay 3ns Sequential Mode XCS Instrument Capabilities LCLS Parameters Transverse Coherence 8 and 24 keV Dedicated 2D-Detector

  8. Ultrafast XCS : Split & Delay High Peak Brilliance Short pulse duration 230fs

  9. Ultrafast XCS • Peak Brilliance & Pulse Duration • pulse duration < tC< several ns • Large Q’s accessible

  10. XCS Science • Ultra dilute systems ( gazes , aerosol, fogs, fumes) • Ionic liquids and Transport theories • Nano-systems (nanoscale = sub ns dynamics) • Biological samples dynamics (in their native state) • Dynamics of hard materials ( overdamped modes… ) • Hard condensed matter phase transitions • Using properties of X-rays : • Anomalous scattering • Polarization effects (magnetization dynamics,…)

  11. XCS Instrument Scope Instrument will operate in the 6-25 keV photon energy range • Coherence Preserving for high contrast speckle observation

  12. XCS Instrument Concept Photon Shutter Primary Slits Diagnostics Monochromator Secondary Slits Diagnostic Transport Tunnel Split and Delay Focusing Lenses Attenuators Photon Shutter Local Optics Diagnostics Slits Diagnostics CXI Station FEH Hutch 4 Diffractometer Wide Angle Detector Stage Small Angle Detector Stage

  13. Monochromator Located in Hutch 4 XCS Instrument Location

  14. SAXS Detector Stage Monochromator and Split & Delay upstream WAXS Detector Stage Diffractometer

  15. XCS CXI LCLS pulse Large-offset Monochromator • Large-offset (600mm) non monolithic channel-cut multi-crystals monochromator

  16. J. Schneider G. Grübel W. Roseker Split and Delay • Provided by DESY/SLAC MoU • Prototype existing • 1st Commissioning May 2007 (ESRF, Troika beamline) • pulse duration < delay < 3 ns • based on Si(511) • E=8.389 keV

  17. X-ray Optics – Slit Systems D. Le Bolloc’h et al., J. Synchrotron Rad., 9, 258-265 (2002). • Slit systems • Variable horizontal and vertical gap from 5 μm – 5 mm • Can withstand full LCLS flux – unfocused • Minimize background scatter from blades

  18. X-ray Optics - Be Focusing Lenses B. Lengeler et al., J. Synchrotron Rad., 6, 1153-1167 (1999). • Beryllium CRL • > 40% throughput • Positioning resolution and repeatability to 1 µm • Z translation to vary spot size

  19. X-ray Optics - Attenuators • Attenuators • Variable, up to 10 7 reduction at 8.3 keV • Coherence preserving • High damage threshold

  20. Local Optics • Double-mirror harmonic rejection system • (when performing on 1st harmonic) Similar to XPP • Bending mirror for Grazing incidence experiments • (using the second mirror of the harmonic rejection system) • Local focusing optics • Others : quarter-wave plate, post monochromator, … Two different optical configurations are expected Change beam height Keep the optical axis DZ LOCAL OPTICS

  21. 4-circle Diffractometer Restriction to the horizontal scattering plane Massive granite base-plate for stability and vibration purpose • Standard 4-circle: • θ-rotation • local 2θ-arm • tilts (χ,φ) • translation (X,Y,Z) • sample environment • SAXS chamber • Goniometer head • Low-T cryostat • High-T furnace • Others…

  22. Proposal for Detector Stages

  23. Detector Stages CXI-Transfer Line 600mm 2θ 10m 20m 7-8m • Sample detector Distances • 3.5-4m • 7.5-8m • 10 to 20m Wide Angle Detector Stage “Pseudo 2θ-arm” 2θ up to 55º

  24. 2D Detector • Pixel array detector • 1024 x 1024 pixels • 35 mm x 35 mm pixel size • High (DQE) • 10 2 dynamic range • Noise << 1 photon • 120 Hz Readout Rate

  25. Vacuum System • Vacuum system • Hardware-flanges, pumps, bellows,… • supports • 200 meter long

  26. Technical Issues 1. Thin Monochromator Crystals - Diamond vs. Thin Silicon - (Absorption, Damage vs. Quality) 2. Monochromator Precision Motion • 200 nRad motion & stability 3. WAXS Detector Stage - Airpad motion vs linear translation stage

  27. Summary • X-ray scattering techniques • WAXS • SAXS • Grazing Incidence Techniques • X-ray optics can tailor FEL parameters for users • Many sample environments are accommodated • Vacuum • Low temperature (cryostat, cryostream) • Samples in solution

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