Diagnostics WBS 1 5 Yiping Feng Motivations System

Diagnostics (WBS 1. 5) Yiping Feng Motivations System Specifications System Description Technical Challenges WBS Schedule and Costs Summary LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 1 Yiping Feng yfeng@slac. stanford. edu

Motivations X-ray Free-Electron Laser (FEL) is fundamentally different from storage-ring based synchrotron sources Linac-based, single-pass, 120 Hz at LCLS Feedback is limited by low repetition rate Each macro electron bunch is different in timing, length, density, energy (velocity), orbit, etc. X-ray amplification process based on self-seeding SASE* Lasing starts from a random electron density distribution Each X-ray pulse consists of a random time sequence of spikes of varying degrees of saturation è X-ray FEL exhibits inherent Intensity, spatial, temporal, and spectral fluctuations on pulse by pulse basis *Self Amplification of Spontaneous Emission LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 2 Yiping Feng yfeng@slac. stanford. edu

Goals X-ray diagnostics are required to measure these fluctuations since they can’t be eliminated Integral parts of Instruments Timing & intensity measurements for XPP experiments Wave-front characterization for CXI experiments Measurements made on pulse-by-pulse basis Requiring real-time processing by controls and data system Commonalities in needs & specs Standardized and used for all applicable instruments Modularized for greater flexibility of deployment and placement è Critical diagnostics must be performed and data made available on pulse-by-pulse basis LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 3 Yiping Feng yfeng@slac. stanford. edu

Expected Fluctuations of LCLS FEL pulses Parameter Pulse intensity fluctuation Value ~ 30 % Origin* Varying # of FEL producing SASE spikes; 100% intensity fluctuation/perspike; etc. Position & pointing jitter (x, y, ~ 25 % of beam diameter a, b) ~ 25 % of beam divergence Varying trajectory per pulse; Saturation at different locations of b-tron curvature Source point jitter (z) ~5 m SASE process reaching saturation at different z-points in undulator X-ray pulse timing (arrival time) jitter ~ 1 ps FWHM Timing jitter btw injection laser and RF; Varying e-energy per-pulse X-ray pulse width variation ~ 15 % Varying e-energy leading to varying path (compression) in bunch compressors Center wavelength variation ~ 0. 2 % (comparable to FEL bandwidth) Varying e-energy leading to varying FEL fundamental wavelength and higher order *Discussed in Breakout Summary Session LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 4 Yiping Feng yfeng@slac. stanford. edu

X-ray Diagnostics Suite Fluctuation Type Pulse intensity fluctuation Position & pointing jitter Diagnostic Device a) Pop-In Intensity Monitor b) In-Situ BPM/Intensity Monitor c) Pop-In Position/Profile Monitor In-Situ BPM/Intensity Monitor - Pointing determination from multiple BMP’s Source point jitter Focal point jitter w/ focusing optics d) Wave-front Sensor - Back-propagating from radius of curvature measurement X-ray pulse timing jitter e) Electro-Optic Sampling (EOS) Device X-ray pulse width variation EOS Device Center wavelength variation LCLS e-energy calibration LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 5 - Relative timing btw e-bunch & ref. probe laser - Establishes upper limit - X-ray wavelength cross-calibration is needed Yiping Feng yfeng@slac. stanford. edu

System Specifications Purposes Specifications* Coarse beam alignment/monitoring; Destructive; Retractable; Dynamic range 104; Per-pulse operation at 120 Hz; Relative accuracy < 10 -2 Coarse beam alignment/monitoring Destructive; Retractable; At 50 mm resolution - 25 x 25 mm 2 field of view; At 10 mm resolution - 5 x 5 mm 2 field of view (high-resolution) Per-pulse normalization of experimental signals; High-resolution beam position monitoring Transmissive (< 5% loss); Dynamic range 106; Per-pulse operation at 120 Hz; Relative accuracy < 10 -3 In-situ Electro-optic sampling (EOS) device Measure relative timing between electron bunch (thus copropagating x-ray pulse) and a probe optical laser pulse Non-intrusive to e-beam; Non-destructive; Per-pulse operation at 120 Hz; 20 fs resolution; In-situ Wave-front sensor Characterization of wave-front; Locating focal point of focused beam Destructive; Per-pulse operation at 120 Hz; 0. 15 nm < l < 0. 3 nm Pop-in intensity monitor (moderate-resolution) Pop-in position/profile monitor In-situ Intensity Monitor/BPM Technically more challenging Diagnostic Item * Must have high damage threshold LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 6 Yiping Feng yfeng@slac. stanford. edu

Quantities of Diagnostics Di Pop-in Intensity Monitor Pop-in Position Monitor In-situ Intensity Monitor EOS Device XPP 3 4 2 1 CXI 6 6 2 XCS 16 16 2 ag St at no st ic io n s Wave-front Sensor 1 Standardized and Modularized LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 7 Yiping Feng yfeng@slac. stanford. edu

XPP Placement of Diagnostics XCS CXI (EO in LTU) LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 8 Yiping Feng yfeng@slac. stanford. edu

Detailed Placement in XPP LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 9 Yiping Feng yfeng@slac. stanford. edu

Pop-In Intensity Monitor (WBS 1. 5. 3) stages Coarse alignment of X-ray optics monochromators, mirrors, lens, etc. strategically placed in close proximity to optic Detection technique Pulse operation not photon counting Sensor type Si Diode (used successfully at SPPS) CVD Diamond FEL Si Diode LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 10 Destructive; Retractable; Moderate dynamic range 104; Relative accuracy < 10 -2; Per-pulse operation at 120 Hz; Yiping Feng yfeng@slac. stanford. edu

Pop-In Position/Profile Monitor (WBS 1. 5. 2) Coarse alignment of X-ray optics (beam stages CCD Camera finder) Optical imaging of fluorescence from a scintillating screen Positions in x, y 2 D intensity profile Mirror Attenuation of beam may be required to avoid saturation Two modes of operation: low and high resolutions FEL YAG Screen LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 11 Destructive; Retractable; At 50 mm resolution 25 x 25 mm 2 field of view; At 10 mm resolution 5 x 5 mm 2 field of view; Yiping Feng yfeng@slac. stanford. edu

Ultrafast Measurement of Atomic Displacement N=12463 x a a a f n(t), x(t) Precise normalization of incident intensity to 0. 1% Critical to XPP experiments where small change in diffraction intensity need to be resolved, i. e. Bi coherent phonon decay after photo-excitation LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 12 Yiping Feng yfeng@slac. stanford. edu

In-Situ Intensity/Position Monitor (WBS 1. 5. 4) Quadsensor Precise normalization of incident intensity to 0. 1% Critical to XPP experiments where small change in diffraction intensity need to be resolved, i. e. Bi coherent phonon decay after photo-excitation Detection technique Compton back scattering from Be thin foil (up to 108 photons w/ 1012 in incident beam) FEL Precise beam position calibration w/ use of array of sensors to < 5 mm Be thin foil Transmissive (> 98% w/ 100 mm Be 8 ke. V); High dynamic range 106; Relative accuracy < 10 -3 Position resolution < 5 mm; Per-pulse operation at 120 Hz; LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 13 @ Commercial fluorescence monitor using similar design provides equal resolution but not viable due to damage considerations CVD diamond design more complex in fabrication Yiping Feng yfeng@slac. stanford. edu

In-Situ Intensity/Position Monitor Si Diode Used at SPPS 2 mm Single photon 10^4 range 400 mm thick Pulse Detection Circuitry LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 14 Yiping Feng yfeng@slac. stanford. edu

Ultrafast Measurement of Atomic Displacement N=12463 x a a a f n(t), x(t) Relative timing btw e-bunch & EOS-probe laser pulse è Inferring timing btw X-ray pulse & experimental probe laser LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 15 Yiping Feng yfeng@slac. stanford. edu

Electro-Optic Sampling Device (WBS 1. 5. 6) EOS crystal Relative timing btw e-bunch & EOS-probe laser pulse è Inferring timing btw X-ray pulse & experimental probe laser Based on (linear) Pockels effect birefringence in strong E-field exerted by relativistic e-bunch in proximity 1 -D Spatial encoding of timing for detection using CCD Single shot measurement EOS technique proven at SPPS 20 fs timing determination 200 fs resolution for e-bunch length Challenges Probe-laser footprint Non-intrusive to e-beam; Non-destructive; Per-pulse operation at 120 Hz; LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 16 Long distance btw EOS location (LTU) & experiments (NEH) 120 Hz operation requires real-time processing of EOS data Yiping Feng yfeng@slac. stanford. edu

Laser/FEL Timing @ SPPS Master Clock Electron Gun Accelerating Elements RF Distribution Network Experimental Pump Laser Sources of short-term jitter E-beam phase to RF phase jitter Electron beam energy jitter + dispersive electron optics End station laser phase to RF Phase locking jitter Timing jitter reduces the visibility of experimental effects Short-term timing resolution ~ 1 ps Long-term jitter Length of RF cable thermal variation LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 17 Yiping Feng yfeng@slac. stanford. edu

Electro-Optic Sampling EO Crystal LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 18 Yiping Feng yfeng@slac. stanford. edu

time Spatial Encoding Arrival time and duration of bunch is encoded on profile of laser beam LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 19 integrated intensity time; space polarizing beamsplitter integrated intensity Yiping Feng yfeng@slac. stanford. edu

Non-sequential Sampling 100 consecutive shots LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 20 Single shot, Lorentzian fit Yiping Feng yfeng@slac. stanford. edu

Non-sequential Sampling LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 21 Yiping Feng yfeng@slac. stanford. edu

Enhanced Laser/FEL Timing @ LCLS Hub Stabilized Fiber Optic LLRF Distribution Network (< 10 fs) Developed by LBNL fiber link LTU Sector 20 Gun Laser NEH Electro-optic Sampling Laser Pump-probe Laser Electro-optic Sampling Enhanced Temporal Resolution (~ 100 fs) Limited by our ability to phase lock the lasers to the RF backbone Limited by Intra-bunch SASE jitter LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 22 Yiping Feng yfeng@slac. stanford. edu

Length-Stabilized Fiber Network LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 23 Yiping Feng yfeng@slac. stanford. edu

Hartmann Wave-front Sensor (WBS 1. 5. 5) Characterization of wave-front of focused X-ray FEL is a challenge Critical to CXI experiments if atomic resolution is ultimately to be achieved Common scanning or direct imaging techniques made at focus not viable due to FEL high peak power Hartmann Wave-front Sensor technique is viable Measurement made far from focus Focal point determination calculated from radius of curvature measurement Wave-front distortion obtained by back-propagation of diffracted wavefront determined at mask plane Commercial Hartmann wave-front for long wavelength Successful in optical applications (adaptive optics, etc. ) For X-ray applications, X-EUV sensor for energy up to 4 ke. V Needs modification for higher energies and 120 Hz operation LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 24 Yiping Feng yfeng@slac. stanford. edu

Hartmann Wave-front Sensor (con’t) ent Diverg nt ro wavef Algorithm Image obtained from Imagine Optics, Ltd Challenges Working at 8 ke. V Tighter technical specs at shorter wavelength Mask must allow ray-optics approximation New 8 ke. V version being developed & tested now Mask materials must be compatible with FEL application 120 Hz operation will require customization Imaging sensor readout rate not sufficient Use pixelated detector capable of 120 Hz operation Integrate with Controls/Data systems LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 25 Yiping Feng yfeng@slac. stanford. edu

Hartmann Wavefront Sensor Focusing Optic Hartmann Plate Focal Plane FEL Beam W w 0 f 2 D Detector D L Variable Description Value f Focal length 0. 4 m 4 m 40 m D Focus to Hartmann plate distance 5 m 15 m L Hartmann plate to detector distance 100 mm N Number of hole in Hartmann plate 75 x 75 D Hole spacing 130 mm w 0 Focal spot size 0. 1 mm 10 mm W Beam size at Hartmann plate 5 mm 1. 5 mm 0. 15 mm* LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 26 *Requires a defocusing optic Yiping Feng yfeng@slac. stanford. edu

Diffractive Wavefront Reconstruction Attenuator Focal Plane Focusing Optic FEL Beam W w 0 f 2 D Detector L The oversampled diffraction pattern of the focus is measured. The focal spot is iteratively reconstructed by propagating the wave from the optic to the focus and then to the detector plane. The constraints are applied at the optic and detector planes. LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 27 Yiping Feng yfeng@slac. stanford. edu

Diffractive Imaging Nature Physics Vol 2. p 101 LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 28 Yiping Feng yfeng@slac. stanford. edu

1. 5 WBS 1. 5 Diagnostics 1. 5. 1 Physics Support Eng. Integration 1. 5. 2 Pop-in Position Monitor 1. 5. 3 Pop-in Intensity Monitor 1. 5. 4 In-situ Intensity Monitor 1. 5. 5 In-situ Wave-front Sensor 1. 5. 6 In-situ EOS Device 1. 5. 2. 1 Engineering & 1 st article const. 1. 5. 3. 1 Engineering & 1 st article const. 1. 5. 4. 1 Engineering & 1 st article const. 1. 5. 5. 1 Engineering 1. 5. 6. 1 Engineering 1. 5. 2. 2 XPP 1. 5. 3. 2 XPP 1. 5. 4. 2 XPP 1. 5. 5. 2 CXI 1. 5. 6. 2 XPP 1. 5. 2. 3 CXI 1. 5. 3. 3 CXI 1. 5. 4. 3 CXI 1. 5. 2. 4 XCS 1. 5. 3. 4 XCS 1. 5. 4. 4 XCS LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 29 Yiping Feng yfeng@slac. stanford. edu

Diagnostics Schedule in Primavera 3. 1 LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 30 Yiping Feng yfeng@slac. stanford. edu

Diagnostics Milestones CD-1 Conceptual Design Complete CD-2 a CD-3 a Phase I Final Design Complete EOS monitor complete Pop-in position/profiler 1 st article In-situ intensity/position 1 st article Pop-in intensity 1 st article Phase I Installation Complete CD-4 a LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 31 Aug 01, 07 Oct 24, 07 Dec 03, 07 Jul 21, 08 Oct 24, 07 Oct 20, 08 Nov 25, 08 Jan 21, 09 Apr 15, 09 Aug 21, 09 Feb 08, 10 Yiping Feng yfeng@slac. stanford. edu

Diagnostics Cost Estimate LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 32 Yiping Feng yfeng@slac. stanford. edu

WBS 1. 5 - Diagnostics Cost estimate at level 3 by fiscal year – LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 33 Yiping Feng yfeng@slac. stanford. edu

1. 5 Level 3 Costs (M$) LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 34 Yiping Feng yfeng@slac. stanford. edu

Summary Concepts of all diagnostic devices are well developed Frequent design discussions amongst LUSI and LCLS scientists EOS device was successfully deployed at SPPS 1 st articles will help LCLS commissioning/operation and early sciences on LUSI instruments LUSI EOS will aid LCLS e-beam diagnostics LUSI BPM could aid LCLS e-beam fast feedback system Ready to proceed with baseline cost and schedule development LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 35 Yiping Feng yfeng@slac. stanford. edu

LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 36 Yiping Feng yfeng@slac. stanford. edu

FEL Source Propagation A diffraction limited Gaussian source is assumed LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 37 Yiping Feng yfeng@slac. stanford. edu

CVD Diamond BPM LUSI DOE Review July 23, 2007 Diagnostics (WBS 1. 5) 38 Yiping Feng yfeng@slac. stanford. edu