X-Ray Transport, Diagnostic, & Commissioning Plans. LCLS Diagnostics and Commissioning Workshop

Transcription

1 X-Ray Transport, Diagnostic, & Commissioning Plans LCLS Diagnostics and Commissioning Workshop *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-745-Eng-48 and by Stanford University, Stanford Linear Accelerator Center under contract No. DE-AC3-76SF515. September 22, 24 UCRL-PRES-26663

2 XTOD Layout Outline FEL parameters along Beam line XTOD Diagnostics and Front-End Optics Spontaneous Radiation Model Spontaneous and FEL signals in Direct Imager Diagnostic Spontaneous Reflection in Undulator Vacuum Chamber Conclusions September 22, 24 UCRL-PRES-26663

3 Diagnostics and Front-End Layout

4 1.5 Scope: Front End Enclosure/ Near Experimental Hall 4' Muon shield NEH PPS PPS Front End Enclosure Photon Beam Slit A 83 m Solid Attenuator 112 m Slit B Gas Attenuator Direct Imager Indirect Imager Flipper Mirror Comissioning: Spectrometer, Total Energy Electron Beam Fast close valve 13' Muon shield Electron Dump September 22, 24 UCRL-PRES-26663

5 Diagnostics for Commissioning 83 m from end of undulator 112 m from end of undulator Front End Enclosure Near Hall Hutch 1 Slits Gas Attenuator Solid Slits Attenuator Imaging Systems Calorimeter or spectrometer Muon Shield Muon Shield September 22, 24 UCRL-PRES-26663

6 FEL parameters along Beam line F = A e 2 x 2 + y w 2 2

7 FEL Parameters at KeV Z, m A, γ/nm 2 W, µm Dose Be Dose Si Dose Mo Slit Solid Atten Slit Hutch Flipper mirror Far Hall September 22, 24 UCRL-PRES-26663

8 Dose to melt for various materials Z Melt dose ev/atom Dose in NEH Hutch 1 1 kev 8 kev Beryllium Diamond Aluminum Silicon Copper Molybdenum Tin Tungsten Lead Doses should be compared to dose needed to melt September 22, 24 UCRL-PRES-26663

9 FEL Parameters at 4. KeV Z, m A, γ/nm 2 W, µm Dose Be Dose Si Dose Mo Slit Solid Atten Slit Hutch Flipper mirror Far Hall September 22, 24 UCRL-PRES-26663

10 FEL Parameters at.826 KeV Z, m A, γ/nm 2 W, µm Dose Be Dose Si Dose Mo Slit Solid Atten Slit Hutch Flipper mirror Far Hall September 22, 24 UCRL-PRES-26663

11 Material suitability a strong function of photon energy Fluence to Melt NEH Peak Fluence at entrance Low Z materials such as Be, C, B 4 C and Si will survive at least > 1 shot in the NEH Melts in NEH September 22, 24 UCRL-PRES-26663

12 Diagnostics and Front-End Optics

13 Gas and Solid Attenuators Gas Attenuator stage 2 Gas Attenuator stage 1 Gas Attenuator high pressure vesssel Slit B Autocad Solid Attenuator September 22, 24 UCRL-PRES-26663

14 Solid Be likely to survive at 88 m Xray Dose* Dose* Dose* Dose* Ephoton Li Be B4C C ev ev/atom ev/atom ev/atom ev/atom Be <.1 ev/atom for all photon energies September 22, 24 UCRL-PRES-26663

15 Pressure or thickness for 1-4 attenuation Use Gas Use Solids * 6 m of gas at pressure September 22, 24 UCRL-PRES-26663

16 Gas Attenuator Prototype Design and Analyses Will Validate Concepts 1 DP-Vacuum + Conductance Intermediate Flow Modeled C = C (1.114 P t m avg ( P d Fg + ( P avg avg d F ) g d F ) g Torr Time (s) Chamber Stage 2 Stage 4 September 22, 24 UCRL-PRES-26663

17 NEH Hutch 1 Diagnostic systems Direct Imager Indirect Imager Comissioning Tank September 22, 24 UCRL-PRES-26663

18 Star Cell Imaging Detector Tank Be Isolation valve Direct Imager (Placed directly in beam) Indirect Imager (Sees only a low intensity reflection) varian VA R Turbo pump September 22, 24 UCRL-PRES-26663

19 Imaging detector head prototype CCD Camera Microscope Objective X-ray beam LSO or YAG:Ce crystal prism assembly September 22, 24 UCRL-PRES-26663

20 Direct imager issues Vacuum Operation Low Photon Energy Performance 12 Hz Readout Afterglow in LSO High Energy Spontaneous Background Damage threshold September 22, 24 UCRL-PRES-26663

21 Indirect Imager reflects small amount of FEL into camera, avoiding damage Be Mirror Reflectivity at 8 KeV Be Mirror E-1 Be Mirror Reflectivity 1.E E-2.1 R.1 1.E-3 1.E-4 1.E-5 1.E-6 Be Mirror angle provides "gain" adjustment over several orders of magnitude and discriminates against high energy spontaneous background 1.E-7 1.E-8 Angle (degrees) September 22, 24 UCRL-PRES-26663

22 Minimum mirror reflectivity needed to fill CCD well Objective mag Solid Angle Optical efficiency Scintillator Sensitivity CCD QE 2.5 x 1.88E γ/mev.67 1 kev 4 kev 8 kev Photons / nm Photoelectrons 2. x x x 1 8 Full Well / PE 2.5 x x x 1-3 September 22, 24 UCRL-PRES-26663

23 Indirect imager issues Calibration Mirror roughness Tight camera geometry Compton background Vacuum θ 2θ mechanics Making mirror thin enough for maximum transmission Ceramic multilayers? Use as an Imaging Monochrometer September 22, 24 UCRL-PRES-26663

24 Commissioning strategy Start with Low Power Spontaneous Saturate Direct Imagers, measure linearity with solid attenuators Raise power, Measure linearity of Calorimeter and Indirect imager. Cross calibrate Test Gas Attenuator Raise Power, Look for FEL in Direct Imager Verify linearity with attenuators switch to Indirect Imager if scintilator damages September 22, 24 UCRL-PRES-26663

25 Spontaneous Radiation Model

26 Spontaneous Data Chain UCLA Near-Field Calculator ~2 Gbyte HDF5 HDF5 to Paradox Converter (x,y,e,p) Paradox format, 4 X 1 GByte ReBinner Coarser Energy Bins (159) (x,y,e,p) Paradox format, 35 MByte Blob DB Converter faster to read (E,P[x,y]) Paradox, 5 MBytes y Viewer x E September 22, 24 UCRL-PRES-26663

27 Spontaneous Fluence at NEH Hutch 1 Fluence 6 F x, y = P ( E) E E x, y 4 Y, mm X, mm Te = 4.5 GeV Z = 243 m x = 1. mm y =.3 mm 1.85 mj 4 2 Y, mm Fluence -2 X, mm Te = 14.5 GeV Z = 243 m x =.3 mm y =.1 mm 18.2 mj September 22, 24 UCRL-PRES-26663

28 Energy Slices Near-Field calculation 88 m from End-of-Undulator, Sven Richie, UCLA 2 mm 2 mm Far-Field calculation 4 m from Center-of-Undulator, Roman Tatchyn, SSRL < E < 1 kev 7.6 < E < 9. kev 1 < E < 2 kev 2 < E < 27 kev September 22, 24 UCRL-PRES-26663

29 LCLS beam footprint Expected LCLS beam profile contains FEL and Spontaneous halo 2-3 mj FEL 3 mj High energy core Eγ > 4 kev 2 mj Spontaneous At entrance to NEH, FEL tuned to 8261 ev Fundamental September 22, 24 UCRL-PRES-26663

30 Spontaneous and FEL signals in the Direct Imager Diagnostic

31 Camera Image Calculator Chain Spontaneous DB (E,P[x,y]) Spontaneous + ε x FEL Absorbed in 25 µm LSO Photoelectrons in Camera (2.5 x Zeiss + SITEC CCD) x ε y x E FEL Transmitted by Material September 22, 24 UCRL-PRES-26663

32 14.5 GeV Spontaneous, NEH H1 Y, mm Fluence -2 X, mm 2 All photons 4 6 Number / kev 8,,, 7,,, 6,,, 5,,, 4,,, 3,,, 2,,, 1,,, Photon Energy Spectra 2 4 E, kev 6 8 Y, mm Fluence -2 X, mm Stops in 25 µm LSO Number / kev 8,,, 7,,, 6,,, 5,,, 4,,, 3,,, 2,,, 1,,, Photon Energy Spectra 2 4 E, kev 6 8 September 22, 24 UCRL-PRES-26663

33 14.5 GeV Spontaneous Direct Imager Signal Photons Energy All photons Stops in 25 µm LSO CCD photoelectron levels < 15K e - Full well (16 bit) 327K e - so this is ½ scale on CCD readout (X-Ray resolution 3 x 1 µm) September 22, 24 PhotoElectrons/Pixel 15, 1, 5, -5 UCRL-PRES Photoelectrons/Pixel Horizontal LineOut X, mm

34 14.5 GeV Spontaneous + FEL Photons Energy All photons Stops in 25 µm LSO Y, mm Fluence -1 X, mm PhotoElectrons/Pixel 1,,, 5,, Photoelectrons/Pixel Horizontal LineOut (X-Ray resolution 3 x 1 µm) Need attenuation of 2.4 x 1-4 for CCD full well -4-2 X, mm September 22, 24 UCRL-PRES-26663

35 Use of 16.9 mm B 4 C Attenuator Raw photon spectra of FEL + Spontaneous Spectra of FEL + Spontaneous after B4C Photons/keV Spectra of photons stopping in LSO September 22, 24 UCRL-PRES-26663

36 Direct Imager Image 14.5 GeV 1% FEL + Spontaneous through 16.8 mm B 4 C into 25 mm LSO Y, mm Fluence -2 X, mm PhotoElectrons/Pixel 1, 5, Horizontal LineOut X, mm Good FEL signal at ½ CCD Full Scale but increased background in image (X-Ray resolution 3 x 1 µm) September 22, 24 UCRL-PRES-26663

37 Y, mm How faint can FEL be? 14.5 GeV 1% FEL + Spontaneous directly into 25 mm LSO Fluence -2 X, mm PhotoElectrons/Pixel 3,, 25,, 2,, 15,, 1,, 5,, Horizontal LineOut -4-2 X, mm (X-Ray resolution 3 x 1 µm) Y, mm Fluence.1% FEL + Spontaneous into Horizontal 25 mm LineOut LSO X, mm PhotoElectrons/Pixel 4, 3, 2, 1, X, mm September 22, 24 UCRL-PRES-26663

38 Y, mm Y, mm GeV Spontaneous, NEH H1 All photons -1 Fluence X, mm mj x 1 11 Stops in 25 Fluence µm LSO 1.25 mj , -2 1, , X, mm (X-Ray resolution 1 x 3 µm) PhotoElectrons/Pixel Direct Imager Photoelectrons Photons / kev Direct Imager Horizontal LineOut Photoelectrons X, mm September 22, 24 UCRL-PRES-26663

39 4.5 GeV Spontaneous + ε x FEL Direct Imager Image Direct Imager Photoelectrons 1 % FEL Y, mm Fluence X, mm 1 2 PhotoElectrons/Pixel 5,, 4,, 3,, 2,, 1,, Horizontal LineOut X, mm % FEL Y, mm Fluence X, mm September 22, PhotoElectrons/Pixel (X-Ray resolution 1 x 3 µm) UCRL-PRES , 2, 15, 1, 5, Horizontal LineOut X, mm

40 Commissioning with Direct Imager Direct Imager will see spontaneous on a single shot at GeV Direct Imager will need 1-4 attenuation for on scale operation at full FEL power, which increases background. These calculations show a factor of ~5-1 margin. Without attenuator, Direct Imager will see FEL at.1% power at 4.5 GeV and significantly <.1% at 14.5 GeV September 22, 24 UCRL-PRES-26663

41 Spontaneous Reflection in Undulator Vacuum Chamber

42 Spontaneous Monte Carlo Chain Spontaneous Blob DB (E,P[x,y]) Paradox, 5 Mbytes Inject FEL (E,P[x,y]) Paradox, 5 Mbytes Cumulative DB (x,y,f[e]) Paradox, 5 Mbytes ( E) Photon MC Generator creates random photons according to cumulative distribution (x,y,z,vx,vy,vz,e) of individual photons F x, y = E P P x, y x, y ( E) de ( E) de September 22, 24 UCRL-PRES-26663

43 Spontaneous Monte Carlo Simulation Source spatial distribution 2 1 Photon starting angles generated to give calculated spontaneous spatial distribution y, mm x, mm Photon starting x, y matches electron distribution, a Gaussian with σ = 3 µm 1 2 Events / 2 meter 15, 1, 5, Initial Z 1 z, meter 2 Photon starting z is uniform along undulator (from < z < 13 m) September 22, 24 UCRL-PRES-26663

44 Each photon final x, y has its own cumulative energy distribution Calculated far-field energy spectrum y Source Energy Distribution Events / 1 KeV 9, 8, 7, 6, 5, 4, 3, 2, 1, 5 E, K ev 1 x E September 22, 24 Monte Carlo Energy Distribution UCRL-PRES-26663

45 Simulated spatial distributions agree with far-field calculation Final y, mm Final position All Photons Final x, mm Final y, mm Final Position 1st harmonic Final x, mm Monte Carlo 465 m from beginning of undulator Far-Field Calculation 4 m from center of undulator September 22, 24 UCRL-PRES-26663

46 Simulated spatial distributions agree with far-field calculation higher orders Final y, mm Final position, 2nd harmonic Final y, mm Final Position, 3rd harmonic Final y, mm Final position, E> 4 KeV Final x, mm Final x, mm Final x, mm September 22, 24 UCRL-PRES-26663

47 Spontaneous Emission Angle Below Critical Angle 13 m 243 m 6-2 mm Θ min =.2.8 mrad Θ max = mrad Cu 8261 ev Cu 826 ev 1 1 R.5 R mrad Angle, mrad September 22, 24 UCRL-PRES-26663

48 Vacuum Pipe Simulation 14.5 GeV Without pipe With pipe 2 Final position 2 Final position Final y, mm 5-5 Final y, mm Final x, mm Final x, mm September 22, 24 UCRL-PRES-26663

49 Line outs through center Without pipe With pipe September 22, 24 UCRL-PRES-26663

50 Final y, mm Y, mm Final y, mm Flux Reflection at higher orders UCLA Calculation, without pipe -2 X, mm 2 Final Position 1st harmonic Final x, mm Final Position 1st harmonic Y, mm Final y, mm Monte Carlo, with pipe Final y, mm Monte Carlo, without pipe Final position, 2nd harmonic -4 Flux -2 X, mm Final x, mm Final position, 2nd harmonic Y, mm Final y, mm 6 Final y, mm Final Position, 3rd harmonic -4 Flux -2 X, mm Final x, mm Final Position, 3rd harmonic Final x, mm Final x, mm Final x, mm 4 6 < E < 1 kev 1 < E < 2 kev 2 < E < 3 kev September 22, 24 UCRL-PRES-26663

51 Photon Energies > 4 KeV 2 Final position, E> 4 KeV Final y, mm 1-1 Without pipe Final x, mm Final position, E> 4 KeV Final y, mm 1-1 With pipe Final x, mm September 22, 24 UCRL-PRES-26663

52 Reflection in pipe at 4.5 GeV Final position Final y, mm Final x, mm Final position 5 Final y, mm Final x, mm September 22, 24 UCRL-PRES-26663

53 Tilted pipe at 14.5 GeV Final y, mm F in a l p o s it io n Pipe parallel to beam F in a l x, m m Final y, mm Final position -1 1 Final x, mm Pipe tilted 19 µr, raised.9 mm, and shifted to the right.9 mm September 22, 24 UCRL-PRES-26663

54 Vacuum chamber reflections We will see a lot of reflection of the spontaneous off of the tube. The reflection will increase the spontaneous background in the center by x 3 to 4. Twists and tilts in the vaccum chamber will make it hard(er) to interpret the observed spontaneous radiation pattern September 22, 24 UCRL-PRES-26663

55 Future work and conclusions

56 Near term activities planned Modeling and Simulation - during CR Spontaneous / FEL simulations Calculate Beam sizes at Gas Attenuator, Cameras, etc. with apertures Re-sampling for true response at 14.5 GeV Simulations of Camera response to mix of Spontaneous and FEL with optimum attenuators and scintillator Decide on the apertures! Pipes, Muon shield, Component R&D - after CR Spectrometer, Total Energy, Damage Mechanical & Vacuum - after CR Decide on the apertures! Pipes, Muon shield, Gas Attenuator Calculations and Prototype Beam Line Layout / Standardization / Detailed Specifications September 22, 24 UCRL-PRES-26663

57 Layout geometry is set Summary Beam modeling codes in place Reflection off of undulator vacuum chamber seriously distorts the spontaneous radiation pattern Direct imager model in progress to specify scintillator and attenuator thickness, and CCD gain parameters. Need similar model for Indirect Imager, and Calorimeter. Modeling of other diagnostics will proceed in FY5 September 22, 24 UCRL-PRES-26663