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X Ray Diagnostics

X Ray Diagnostics. LCLS FAC Meeting Oct. 27, 2005. FEE Layout. Slit. Diagnostics Package. Be Mirrors 2 & 3. Solid Attenuator. Collimator 1. Fast close valve. Gas Attenuator. Ion Chamber. SiC Mirror 1. Ion Chamber. Diagnostics Package. SiC Mirror 2. Damage Considerations.

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X Ray Diagnostics

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  1. X Ray Diagnostics LCLS FAC Meeting Oct. 27, 2005

  2. FEE Layout Slit Diagnostics Package Be Mirrors 2 & 3 Solid Attenuator Collimator 1 Fast close valve Gas Attenuator Ion Chamber SiC Mirror 1 Ion Chamber Diagnostics Package SiC Mirror 2

  3. Damage Considerations Dose along the beam line for different materials at Gaussian peak (under normal illumination) Shown is the maximum dose (over Ephoton=827 to 8267eV) SiC melt Si melt Dose (eV/atom) (maximum over 827-8267eV) B4C melt Be melt z (m from end of undulator)

  4. Dose obtained at TTF

  5. TTF VUV Beamline

  6. Damage experiment chamber TOF ion spectrometer Sample holder Visible spectrometer Microscope

  7. SiC thin film, 1 shot, 8 x melt

  8. SiC thin film, 10000 shots, ~ 1 x melt Emission spectra shows plasma was formed

  9. SiC thin film, 10000 shots, 10% melt No spectra can be distinguished above background

  10. Si/C mirror reflects for one shot First shot Second shot

  11. Desired FEL Measurements

  12. Desired Spontaneous Measurements

  13. FEE Cartoon Start of Experimental Hutches 5 mm diameter collimators Windowless Ion Chamber DiagnosticPackage Spectrometer / Indirect Imager mirror Solid Attenuator High-Energy Slit Total Energy Calorimeter e- WFOV Direct Imager Gas Attenuator FEL Offset mirror system Spectrometer camera Windowless Ion Chamber Muon Shield

  14. Redundant Commissioning Instrumentation

  15. Photoelectrons generated by 0.01% FEL Wide Field of View Direct Imager Single shot measurement of f(x,y), x, y ,u Camera Scintillators

  16. Indirect Imager Single shot measurement of f(x,y), x, y, u Multi shot measurement ofl Angle selects energy and attenuation

  17. B4C/SiC Test Multilayers Fabricated • 40 layer pairs • G = 0.7 • P = 6 nm Data at Cu Ka, 8 keV

  18. Thermal diffusion calculations performed Total Energy Calorimeter Single shot measurement of f(x,y), x, y, u t = 300 ms t = 100 ms Nd0.8Sr0.2MnO3 Cold Si substrate CMR Sensor array 100 pixels t = 0 Xray Beam T Cooling ring T, ms 5 0 Sample CMR at LLNL for etching and R(T) measurements

  19. Sensor Development: Nd0.8Sr0.2MnO3

  20. 10 cm Ion Chamber Single shot, non destructive, measurement of x’, y’, x, y ,u Segmented cathodes for position measurement 1 torr Imaging of optical emission for position measurement

  21. Measuring K with photons On axis: But Effect of changing K

  22. Near-Field calculations of detuned single undulator segments Mean, keV Photons/pulse/20 eV First and Last 2mm x 2mm First 8.2658 Last 8.2362 First 2 x 2 mm Last 1 x 1mm First 8.2658 Last 8.2651 Last has K(1+10-4) First 2 x 2 mm Last 1 x 1mm First 8.2658 Last 8.2645 Photon Energy, keV

  23. Single Shot 8 keV Spectrometer Single shot measurement of l 20 m downstream 1.4991 Å Sputter-sliced SiC / B4C multilayer P = 20 nm N = 1x104 D = 200 mm 1.4994 Å 33 mm thick 200 mm Problems: Don't have 20 m. Signal degradation due to grating thickness (coupled waveguides.) Only possible at high photon energies. Beam

  24. Only one diffracted order Other candidates for Single-Shot Spectrometers Mosaic Graphite crystal Asymmetric cut multilayer

  25. Summary • X-ray characterization for LCLS is challenging • Dose limits materials choice • Large range of signal levels • Some measurements require precision near r = 10-4 • Redundant diagnostics techniques will be used to measure pulse energy • Total energy calorimeter • Direct Imager • Indirect Imager • Ion chamber • Much work needed on single-shot spectral measurements • TTF damage experiment to be analyzed

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