Slide1: XTOD Diagnostics for Commissioning the LCLS* January 19-20, 2003 LCLS Undulator Diagnostics and Commissioning Workshop Richard M. Bionta *This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48 and by Stanford University, Stanford Linear Accelerator Center under contract No. DE-AC03-76SF00515.


WBS 1.5 X-Ray Transport, Optics, & Diagnostics (XTOD) : WBS 1.5 X-Ray Transport, Optics, & Diagnostics (XTOD) Provides unobstructed vacuum path from end of undulator to end of FEH LCLS X-Ray Beam Tunnel NEH - Near Experimental Hall Flux densities in NEH will be the highest available Flux densities in FEH will be similar to synchrotron facilities FEE Front End Enclosure FEH - Far Experimental Hall


X-ray Transport, Optics, and Diagnostics Layout: X-ray Transport, Optics, and Diagnostics Layout Front End Enclosure Diagnostics Slits Attenuators Low Energy Order Sorting Mirror FEL Measurements & Experiments: Compression Spectra Coherence Pulse Length Monochrometer Pulse-Split & Delay Diagnostics Experiments Optics Structual Bio Nano-scale Femtochem FEE NEH FEH Tunnel Experiments: Optics Warm Dense Matter Atomic Physics Each 13 m long hutch has two vacuum tanks for experimental and facility hardware


Slide4: Beam Models


FEL beam power levels: FEL beam power levels Saturated power FEL r parameter Plasma frequency Gain length parameterization Correct definition of h parameters


Spatial-temporal shape: Spatial-temporal shape FEL can be modeled as a Gaussian beam in optics Phase curvature function Gaussian width Gaussian waist Origin is one Rayleigh length in front of undulator exit Amplitude is given in terms of saturated power level


LCLS Fundamental Electric Field and Dose Equations: LCLS Fundamental Electric Field and Dose Equations Gaussian Electric Field: With origin waist Phase Curvature Waist at origin matches electron distribution gives Electric field intensity x duration Matches photon distribution with Peak photon density Dose


FEL parameters at absorber exit, z = 65 meters: FEL parameters at absorber exit, z = 65 meters And at other locations:


Slide9: Ginger provides complex Electric Field envelope at undulator exit Data in the form of radial distributions of complex numbers representing the envelope of the Electric Field at the undulator exit. Samples are separated in time by wavelengths. Time between samples is R, mm Each radial distribution has radial points. Electric Field Envelope Power Density vs time at R = 0 watts/cm2


Tools for manipulating GINGER output: Tools for manipulating GINGER output GINGER output: Tables of electric field values at undulator exit at different times viewer Viewer Transformation to Frequency Domain Propagation to arbitrary z R, mm


FEL spatial FWHM downstream of undulator exit, l = 0.15 nm: FEL spatial FWHM downstream of undulator exit, l = 0.15 nm Transverse beam profile at undulator exit Transverse beam profile 15 m downstream of undulator exit Ginger (points) Gaussian Beam (line)


Total power at undulator exit: Total power at undulator exit Ginger simulations Theoretical FEL saturation level 10 Ginger simulations were run at different electron energies but with fixed electron emittance through 100 meter LCLS undulator. The Ginger runs at the longer wavelengths were not optimized, resulting in significant post-saturation effects. Results at longer wavelengths carry greater uncertanty.


RMS Bandwidth: RMS Bandwidth l= 0.15 nm Time Domain l= 0.15 nm Frequency Domain


FWHM vs. wavelength at 0, 75 and 300 meters: FWHM vs. wavelength at 0, 75 and 300 meters


We can confidently calculate the dose to transmissive optics.: We can confidently calculate the dose to transmissive optics. Low Z materials for transmissive optics can be chosen to survive in the LCLS experimental halls in the simple dose model on the left. The survivability of common high Z reflectors depends on additional assumptions. Transmissive Dose Model Reflective Dose Model


Dose / Power Considerations: Dose / Power Considerations Fluence to Melt Energy Density Reduction of a Reflector Be will melt at normal incidence at E < 3 KeV near undulator exit. Using Be as a grazing incidence reflector may gain x 10 in tolerance.


Roman’s far Field spontaneous: Roman’s far Field spontaneous


Detailed Spontaneous, in progress: Detailed Spontaneous, in progress


E > 400 KeV: E > 400 KeV


FEE Instrumentation: FEE Instrumentation


Front End Enclosure Layout: Front End Enclosure Layout Valve Pump Pump Slow valve Fast valve Fixed Mask Slits Diagnostics Windowless Ion Chamber Gas Attenuator Solid Attenuator Slits Diagnostics PPS 40m WestFace Near Hall 33m WestFace Dump 16.226 m Eastface Last Dump Mag Westface front End Enclosure 10.5 m 0 m End of Undulator


Slide22: Intended to intercept spontaneous beam, not FEL beam -- but will come very close, so peak power is an issue Two concepts being pursued for slit jaws Treat jaw as mirror (high-Z material) Treat jaw as absorber (low-Z material Either concept requires long jaws with precision motion Mechanical design based on SLAC collimator for high-energy electron beam


Front End Diagnostic Tank: Front End Diagnostic Tank Direct Imager Indirect Imager ION Chamber Turbo pump Space for calorimeter Be Isolation valve Solid Filter Wheel Assembly


Prototype LCLS X-Ray imaging camera: Prototype LCLS X-Ray imaging camera CCD Camera Microscope Objective LSO or YAG:Ce crystal prism assembly X-ray beam X-ray beam


Indirect Imager: Indirect Imager Be Mirror Reflectivity at 8 KeV 1 0.1 0.01 0.001 0.0001 Be Mirror Be Mirror angle provides "gain" adjustment over several orders of magnitude


Multilayer allows higher angle and higher transmision but high z layer gets high dose: Multilayer allows higher angle and higher transmision but high z layer gets high dose Be Mirror needs grazing incidence, camera close to beam Single high Z layer tamped by Be may hold together


First check CCD by measuring Response Equation Coefficients: First check CCD by measuring Response Equation Coefficients Digitized gray level of pixel in row r, column c. Electronic gain in units grays/photo electron. Signal in units photo electrons. Pixel Sensitivity non-uniformity correction. Pixel Dark Current in units photo electrons/msec. Pixel fixed-pattern in units grays. Integration time in units msec.


Photon Transfer Curve: Photon Transfer Curve Temporal mean gray level of pixel r,c. Temporal gray level fluctuations of pixel r,c.


Calibration Data for one pixel: Calibration Data for one pixel


Calibration Coefficients for All Pixels: Calibration Coefficients for All Pixels


Photon Monte Carlo Simulations for predicting lens and camera performance: Photon Monte Carlo Simulations for predicting lens and camera performance SPEAR source simulation Visible photons X, microns Y, microns X Ray Photons


Direct Imager Version 1 efficiency: Direct Imager Version 1 efficiency


Camera Sensitivity Measurements at SPEAR 10-2: Camera Sensitivity Measurements at SPEAR 10-2 Sum of gray levels Ion Chamber Photon rate attenuator Imaging camera Ion chamber


Measured and predicted sensitivities in fair agreement: Measured and predicted sensitivities in fair agreement


Camera Resolution Model: Camera Resolution Model


Camera Resolution in qualitative agreement with models: Camera Resolution in qualitative agreement with models 1.5 mm 1.1 mm 1.5 mm


Camera Resolution Quantitative Data Analysis in progress: Camera Resolution Quantitative Data Analysis in progress


Micro Strip Ion Chamber: Micro Strip Ion Chamber Differential pump Differential pump Cathodes Segmented horizontal and vertical anodes Isolation valve with Be window Windowless FEL entry


Slide39: For use when solid absorber risks damage (low-E FEL, front end) Windowless, adjustable attenuation Can provide up to 4 orders of magnitude attenuation


Slide40: B4C attenuators can tolerate FEL beam at E > 4 keV in FEE, and at all energies in experimental hutches Linear/log configurations Can be wedged in 2 dimensions for continuously variable attenuation Translation stages provide precision X and Y motion


Missing: Missing Predicted performance of direct and indirect imager for Spontanous vs. I, and FEL vs. Power Calculations of linearity and signal levels in Ion chamber Integration with FEE + Beam Dump floor plan


Commissioning Diagnostic Tank: Commissioning Diagnostic Tank


Commissioning Diagnostics: Commissioning Diagnostics Measurements Total energy Pulse length Photon energy spectra Spatial coherence Spatial shape and centroid Divergence


Commissioning diagnostic tank: Commissioning diagnostic tank Aperture Stage “Optic” Stage Detector and attenuator Stage Rail alignment Stages Rail


Costing based on SSRL 2-3 set up: Costing based on SSRL 2-3 set up


Total Energy: Total Energy Crossed apertures On positioning stages absorber Temperature sensor Attenuator Scintillator Poor Thermal Conductor Heat Sink


Photon Spectra Measurement: Photon Spectra Measurement Aperture Stage Crystal (8KeV) Grating (0.8 KeV) Stage Detector and attenuator Stage X ray enhanced linear array and stage


Spatial Coherence Measurement: Spatial Coherence Measurement Slits Stage Detector and attenuator Stage Array of double slits


Spatial shape, centroid , and divergence: Spatial shape, centroid , and divergence FEE: A1 A2 A4 FFTB HALL A Diagnostic Tanks FEE 1 & 3: Diagnostic Tank A1-1 Commissioning Diagnostic Tank A4-1 Spatial shape, centroid , and divergence measured by combining data from the imagers in these tanks.


Rad Sensor - a candidate technology for LCLS pulse length measurement and pump probe synchronization: Rad Sensor - a candidate technology for LCLS pulse length measurement and pump probe synchronization Rad sensor is an InGaAs optical wave guide with a band gap near the 1550 nm. 1550 nm optical carrier Reference leg Detector beam splitter 1550 nm optical carrier Fiber Optic Interferometer Rad sensor is inserted into one leg of a fiber-optic interferometer. X-Rays strike the rad sensor disturbing the waveguide’s electronic structure. This causes a phase change in the interferometer. The process is believed to occur with timescales < 100 fs. X-Ray Photons Point of interference X-Ray induced phase change observed as an intensity modulation at point of interference X-Ray measurements of the time structure of the SPEAR beam in January and March 2003 confirmed the devices x-ray sensitivity for LCLS applications. time phase SPEAR Single electron bunch mode Mark Lowry,


NIF Rad-Sensor Experimental Layout at SLAC: NIF Rad-Sensor Experimental Layout at SLAC Ion chamber attenuator Imaging camera Diamond PCD RadSensor slit


Slide52: RadSensor Response to single-bucket fill pattern Fast rise Long fall-time will be improved Complementary outputs => index modulation Xray pulse history (conventional) 781 ns Mark Lowry


Slide53: Significant Improvements in sensitivity are realized near the band edge Systematic spectral measurements of both index and absorption under xray illumination must be made to get a clear understanding of the sensitivity available Absorption width = 0.01 nm Absorption width = 1 nm Adding in x4 for QC enhancement we should detect a single xray photon at least 8x10-4 fringe fractions. If we allow for a cavity with finesse 10-100, this allow the development of a useful instrument Data to date = exciton abs peak width From Gibbs, pg 137 Absorption edge at 1214 nm Mark Lowry


XRTOD Diagnostics Timeline: XRTOD Diagnostics Timeline FY04 – PED year 4 PCMS certification - Jan 2004 Baseline Review - Aug 2003 Complete simulations of camera response to FEL and Spontanous Prototype Windowless Ion Chamber / gas attenuator FY05 – PED year 3 FEE Detailed design FY06 - Start of Construction FEE Build and test NEH Design FY07 FEE Install NEH Build and Test FEH Design FY08 NEH Install FEH Build and Test FY09 - Start of Operation


Startup Procedure: Startup Procedure


FEE Diagnostics Comissioning: FEE Diagnostics Comissioning Start with Low Power Spontaneous Saturate DI, measure linearity with solid attenuators Test Gas Attenuator Raise Power, Look for FEL in DI, switch to Indirect Imager when attenuator burns Move behind Gas Attenuator Move to Comissioning Diagnostic Tank Attenuator Direct Imager Indirect Imager Ion Chamber Attenuator Direct Imager Indirect Imager Ion Chamber Gas Attenuator


Summary: Summary 3 detector designs for flexibility Move back if necessary Bring on the beam!