DCO Diagnostics & Common Optics Overview

1. LUSI WBS 1.5Diagnostics & Common Optics Yiping Feng – DCO Lead Scientist Eliazar Ortiz – DCO Lead Engineer DCO Engineering Staff Apr. 20-22, 2009

2. Outline Diagnostics & Common Optics (DCO) Overview Global Physics Requirements Components Descriptions Response to CD-2 Recommendations DCO Scope DCO WBS structure Components Designs Overall Status Progress since CD-2 Status Design & Status Cost and Schedule Performance Milestones Risks and Concerns Summary

3. Overview • DCO will provide to all LUSI instruments • Common diagnostics for measuring FEL properties • Transverse beam profile • Incident beam intensity • Beam positions and pointing • Wavefield measurement at focus • Common Optical components for performing FEL manipulations • Beam size definition and clean-up • Attenuation • Pulse pattern selection and/or repetition rate reduction • Isolation of fundamental from high order harmonics • Focusing • Monochromatization* *Engineering of mono is now managed by the XCS team

4. DCO CD-2 Scope • DCO suites *Engineering of mono is now managed by the XCS team

5. Global Physics Requirements • Physics requirements remained same as CD-2 and were based on characteristics of LCLS FEL • Ultra short pulses ~ 100 fs, and rep. rate of 120 Hz • Pulse energy 2 mJ, peak power ~ 20 GW, ave. power ~ .24 W • Fully coherent in transverse directions ~ expected to be predominantly TEM00* • Exhibiting intrinsic intensity, temporal, spatial, timing fluctuations on per-pulse basis†, i.e., • Higher order Laguerre-Gaussian modes possible but negligible • †FEL amplification process based on SASE from noise

6. Challenges Addressed • Scientific/technical challenges that were addressed • Sustaining the instantaneous LCLS X-ray FEL peak power • Exercising careful material selection • Filters, scattering target, slits materials, focusing lens, beam stop etc. • Based on thermal calculations including melting threshold and onset of thermal fatigue & limited experimental data from FLASH • But no active cooling necessary • Providing coherent beam manipulation • Minimizing wavefront distortion/coherence degradation • Filters, scattering target, slits, focusing lens • Reducing surface roughness and bulk non-uniformities • Minimizing diffraction effects • i.e., utilizing cylindrical blades for slits

7. Challenges Addressed • Scientific/technical challenges that were addressed • Detecting ultra-fast signals • Extracting electrical signals in ~ ns to minimize dark current contribution • i.e., charge-sensitive detection using diodes • Making per-pulse measurement if required • Each pulse is different • Averaging over pulses may NOT be an option, requiring sufficiently high S/N ratio for each pulse • i.e., high-precision intensity measurements at < 0.1% based on single pulses, requiring larger raw signal than synchrotron cases

8. Pop-in Profile Monitor (WBS 1.5.2.1) Requirements Destructive; Retractable Variable FOV and resolution At 50 mm resolution, 12x12 mm2 FOV At 4 mm resolution, 1x1 mm2 FOV Capable of per-pulse op. @ 120 Hz if required Attenuation used if necessary Purposes Aid in alignment of X-ray optics FEL is serial operation, automation enables maximum productivity Characterization of X-ray beam spatial profile FEL spatial mode structure Effects of optics on fully coherent FEL beam Characterization of X-ray beam transverse spatial jitter FEL beam exhibits intrinsic spatial fluctuations Implementation X-ray scintillation 50-75 mm thin YAG:Ce single crystal scintillator Optical imaging Capable ofdiffraction limited resolution if required Normal incidence geometry w/ 45º mirror Motorized zoom lens 120 Hz optical CCD camera 45º mirror YAG:Ce screen

9. Pop-in Intensity Monitor (WBS 1.5.2.2) Requirements Destructive; Retractable Relative accuracy < 1% Working dynamic range 100 Large sensor area 20x20 mm2 Per-pulse op. @ 120 Hz Attenuation used if necessary Purposes Aid in alignment of X-ray optics FEL is serial operation, automation enables maximum productivity Simple point detector for physics measurements In cases where 2D X-ray detector is not suitable Implementation Direct X-ray detection using Si diodes Advantageous in cases of working w/ spontaneous or mono beams Capable of high quantum efficiency (> 90% at 8.3 keV) 100 – 500 mm depletion thickness Using charge sensitive amplification Applicable to pulsed FEL Commercially available Large working area (catch-all) easily available simplifying alignment procedure Si diode

10. Intensity-Position Monitor (WBS 1.5.2.3) Requirements In-situ, retractable if necessary Highly transmissive (> 95%) Relative accuracy < 0.1% Working dynamic range 1000; Position accuracy in xy < 10 mm; Per-pulse op. at 120 Hz; Purposes Allow precise measurement of the intensity for normalization Critical to experiments where signal from underlying physics is very small Characterization of FEL fluctuations Positional jitter ~ 10% of beam size Pointing jitter ~ 10% of beam divergence Slitting beam down creates diffraction which may cause undesirable effects Implementation Based on back scattering from thin-foil Detecting both Compton scattering & Thomson scattering Using Low-z (beryllium) for low attenuation especially at low X-ray energies Using Si diode detectors Array sensors for position measurement Pointing measurement using 2 or more monitors Array Si diodes Be thin foil

11. Wavefront Monitor (WBS 1.5.2.1)[in lieu of wavefront sensor] Purposes Wavefront characterization of focused X-ray beam at focal point Wavefront measurement at focal point is not feasible by conventional methods due to damages Providing supplemental scattering data in low Q w/ high resolution Resolution obtained using X-ray direct detection is limited by detector technology, i.e., pixel sizes and per-pixel dynamic range Implementation X-ray scintillation 50-75 mm thin YAG:Ce single crystal scintillator Optical imaging Capable ofdiffraction limited resolution if required Using computational algorithm for reconstruction of wavefield at focus Iterative, post processing only if no large computer farm Requirements In-situ; Retractable Variable FOV and resolution At 50 mm resolution,12x12 mm2 FOV At 4 mm resolution, 1x1 mm2 FOV Per-pulse op. @ 120 Hz Attenuation used if necessary 45º mirror YAG:Ce screen

12. X-ray Focusing Lenses (WBS 1.5.3.2) Purposes Increase the X-ray fluence at the sample Produce small spot size in cases where slits do not work due to diffraction, i.e., sample too far from slits Implementation Based on refractive lenses concept* Concave shape due to X-ray refractive index 1-d+ib Using Beryllium to minimize attenuation In-line focus Simpler than KB systems no diff. orders as in Fresnel lens Chromatic Con: re-positioning of focal point Pro: Providing harmonic isolation if aperture used Some attenuation at very low X-ray energies ~ 2 keV Requirements Produce variable spot size For XPP instrument 2-10 mm in focus 40-60 mm out-of-focus Minimize wavefront distortion and coherence degradation Withstand FEL full flux Be Lens stack Be lenses *B. Lengeler, et al, J. Synchrotron Rad. (1999). 6, 1153-1167

13. Slits System (WBS 1.5.3.3) Purposes define beam transverse sizes Pink and mono beam Clean up scatterings (halo) around beam perimeter Implementation Based on cylindrical blades concept* Minimize scattering from edges and external total reflections Offset in Z to allow fully closing Using single or double configurations for pink or mono beam applications Single configuration Blade material: Si3N4 to stop low energies Or blade material: Ta/W alloy to stop low fluence low or high energies Double configuration 1st blades: Si3N4, 2nd blades: Ta/W alloy to stop low and high energies High-Z Low-Z Pink beam Mono beam D=3 mm High-Z • Requirements • Repeatability in x&y < 2 mm • 0 – 10 mm gap setting • 10-9 in transmission from 2-8.3keV • 10-8 in transmission at 25 keV • Minimize diffraction/wavefront distortion • Withstand FEL full flux *D. Le Bolloc’h, et al, J. Synchrotron Rad. (2002). 9, 258-265

14. Attenuator/Filters (WBS 1.5.3.4) Purposes Reduce incident X-ray flux Sample damage Detector saturation Diagnostic saturation Alignment of optics and diagnostics Implementation Using Si wafers of various thicknesses Highly polished to minimize wavefront distortion & coherence degradation For a given attenuation, use one wafer whenever possible Commercially available (< 1 nm rms roughness) For energies < 6 keV in NEH-3 and in pink beam Employing a pre-attenuator, i.e., LCLS XTOD gas/solid attenuators • Requirements • 108 attenuation at 8.3 keV • 104 attenuation at 24.9 keV • 3 steps per decade for > 6 keV • Minimize wavefront distortion and coherence degradation • Withstand unfocused flux

15. Pulse Picker (WBS 1.5.3.5) • Purposes • Select a single pulse or any sequence of pulses • Reduce LCLS repetition rate • Important if longer sample recover time is needed • Damage experiments - sample needs to be translated • Implementation • Based on a commercial mechanical teeter-totter* • Steel blade fully stops beam • Capable of ms transient time • Simple to operate • Use TTL pulses • Requires 100 mm Si3N4 to protect the steel blade • Requirements • < 3 ms switching time • < 8 ms in close/open cycle time • Only for < 10 Hz operation • Withstand full LCLS flux *http://www.azsol.ch/

16. Harmonic Rejection Mirrors (WBS 1.5.3.6) A B C • Purposes • Provide isolation of FEL fundamental from high harmonics • LUSI detectors not designed to be energy resolved • Implementation • Low pass filter using X-ray mirrors at grazing incidence • Using highly polished Si single crystal substrates • 3.5 mrad incidence angle • 300 mm long • No pre-figure, no bender • Figure-error specs defined to ensure FEL natural divergence not effected • R ~ 150 km • Roughness specs to minimize wavefront distortion and coherence degradation • rms ~ 0.1 nm • Requirements • Energy range: 6-8.265 keV • 104 contrast ratio between fundamental and the 3rd harmonic • 80% overall throughput for fundamental • Minimize wavefront distortion • Withstand full FEL flux

17. DCO Integration into Instruments • XPP Instrument* Intensity-position Intensity-position Intensity/ profile Intensity/ profile Slits Slits Be-focusing lens Pulse picker /Attenuator Harmonic rejection *There are 15 diagnostics/common optics components in XPP

18. DCO Integration into Instruments • CXI Instrument* Intensity-position Intensity-position Profile/ Intensity Intensity/ profile Intensity-position wavefront Not shown are attenuator, pulse picker situated in X-ray transport Slits Slits Slits Slits *There are 13 diagnostics/common optics components in CXI

19. Acknowledgment • DCO Engineering Staff • Tim Montagne • Profile/wavefront monitor • Intensity monitor • Intensity-position monitor • Harmonic rejection mirror • Marc Campell • Attenuator • X-ray focusing lens • Richard Jackson • Slits system • Pulse picker

20. DCO Scope • Work Breakdown Structure *Engineering of mono is now managed by the XCS team

21. Device/Component Counts • Total device/component counts *Engineering of mono is now managed by the XCS team

22. Progress Since CD-2 • DCO progress *Engineering of mono is now managed by the XCS team

23. DCO Overall Status • An example in XPP FDR Complete Intensity-position Intensity-position FDR Complete Intensity/ profile Intensity/ profile RFP Sent out Slits Slits Be-focusing lens PDR Complete Pulse picker /Attenuator FDR Complete Harmonic rejection PDR in June

24. Common Diagnostics Design • Profile & Intensity Monitor • Profile and intensity monitors collocated in same chamber • Same design for wavefront monitor • w/o intensity monitor • Attenuation needed Diode Electronics (Charge sensitive amplification) Optical CCD Camera Motorized zoom lens Quartz window YAG:Ce screen 45º mirror 100 mm travel linear stage with smart motor Hollow shaft for cable routing LCLS Beam Diode Assy. Brazed chamber 6 DOF Stand

25. Common Diagnostics Design Intensity-Position Monitor 4-channel Diode Electronics (Charge sensitive amplification) Hollow shaft for cable routing Be target changer 100 mm travel linear stages with smart motor Roller Stages Smart Motor for X-axis motion* LCLS Beam Be targets 4-Diode Assy. (inclined in y for uniform response) Brazed chamber 6 DOF Stand *IPM needs calibration in both x & y directions

26. Common Optics Design • Attenuator-Pulse Picker • Combined attenuator and pulse picker • Commercial pulse-picker packaged into same chamber 50 mm travel linear stage with smart motor Hollow shaft for cable routing Lens Optical CCD Camera LCLS Beam Si filters 6” Rotating flanges AZSOL Shutter Motorized actuators for attenuator filters Pulse-picker View port 6 DOF Stand

27. Common Optics Design Double blades configuration (4 sets of blades) • Slits System • UHV compatible • Low-z & high-z blades • Single/Double configurations High-Z Low-Z Pink beam Single blades configuration (2 sets of blades) Blades/ blade mounts High-Z Mono beam Rigid Stand w/o DOF Optical encoder Blade Form Factor

28. Common Optics Design • X-Ray Focusing Lenses Accommodates 3 different lens configurations LCLS Beam Actuator design similar to IPM Quick lens stack removal Chamber similar to monitors 6 DOF Stand Z-axis translation stage (±200mm) XPP only Lens Holder

29. Common Optics Design • Harmonic Rejection Mirrors • Design concept in work • In vacuum motion LCLS Beam Plane Si mirrors Mirror chamber Mirror stand In-vacuum stages to be integrated into design Early concept, design effort just started

30. DCO Design Status • Upcoming reviews

31. Cost 36% 64%

32. Cost & Schedule Performance – WBS 1.5

33. Project Critical Path • DCO has one design effort and multiple procurements to support the Instrument requirements. • The project is monitoring strings of activities with the least float • Items on the critical path are: • XFLS Procurement Preps (14 day float, start May 2010) • HRM Procurement Preps (19 day float, start Oct 2010) • Activities to monitor from falling on the critical path: • Check and Approve Dwgs PP (24 day float, start May 09) • PP procurement preps XPP (24 day float, start June 09)

34. Major Milestones

35. Procurement Schedule

36. Risks • No major risks associated with the design or procurement of the DCO components • Bought components (slits) are “off the shelf” items • Assembly components (CCD cameras, zoom lens, actuators, connectors) are commercially made with known performance • In-house electronics design are based on proven technology and implementations

37. Summary Scope of DCO components for XPP, CXI, and XCS instruments has not changed significantly since CD-02 The design of key diagnostics devices and optical components is mature and based on proven developments at synchrotron sources worldwide by XTOD and LCLS e-beam groups DCO overall cost and schedule performance is kept within margins. Critical Path is defined and monitored Advanced Procurements identified DCO is on track to support accelerated schedule!

38. Backup

39. Response to CD-2 Recommendations/Comments • Recommendations • Large-offset mono development for XCS • Will be reviewed in APR for mono scheduled on Apr. 23 • Alternative mono location to improve angular stability • BCR was processed to move closer to sample • R&D on impact of surface roughness of Be lens on FEL transverse coherence • Roughness requirement relaxed in transmission geometry • Prior experiments demonstrated excellent preservation of beam coherence by commercial Be lens* • Comments • Development of physics specifications for mono, especially choices of crystal and cut • Will be reviewed in APR for mono scheduled on Apr. 23 *B. Lengeler, et al, J. Synchrotron Rad. (1999). 6, 1153-1167