Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx X Ray Diagnostics Overview FAC X-TOD Breakout October 12, 2006

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Linac-to- Undulator (227m e - beam) Undulator Hall (175m e - and  beam) Near Expt. Hall X-ray Vacuum Transport (250m  beam) Far Expt. Hall e - Beam Dump (40M e - and  beam) (FEE) Front End Enclosure (29m  beam) Linac e - beam LCLS Layout at SLAC

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx 2-3 mJ (0.3 W) FEL 20 mJ (2.4 W) Spontaneous 3 mJ High energy core E  > 400 keV Raw LCLS Beam Contains FEL and Spontaneous Halo At midpoint of FEE, FEL tuned to 8261 eV Fundamental, 0.79 nC 0 < E < 10 keV 7.6 < E < 9.0 keV 10 < E < 20 keV 20 < E < 27 keV 20 mm Spontaneous halo has rich spectral and spatial structure: Pulse duration < 250 fs

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Prioritized List of Desired FEL Measurements (to be measured after finding the FEL) uTotal energy / pulse 1 Photon wavelength   Photon wavelength spread Pulse centroid Beam direction f(x,y)Spatial distribution  u,  1 Temporal variation in beam parameters  Pulse duration

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Prioritized List of Desired Spontaneous Measurements f(x,y, 1 )Spatial distribution around 1 1 1st harmonic Photon wavelength   1st harmonic wavelength spread Beam direction uTotal energy / pulse  u,  1 Temporal variation in beam parameters 1i/ 1j Relative 1 st harmonic wavelength of undulator i and j

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Codes indicate that damage occurs above melt so choose materials whose doses are a fraction of melt Maximum dose along the beam line for different materials (under normal illumination assuming fully saturated FEL a la M. Xie) meters from end of undulator Dose (eV/atom) (maximum over eV) Shown is the maximum dose (over E photon =827 to 8267eV) SiC melted Si melted B 4 C melted Be melted Be - 1/50 melt B 4 C - 1/12 melt SiC - 1/9 melt Si - 5/9 melt FEE e - dump

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Candidate detectors pros and cons ElementTechnologyProblems AttenuatorSignal reduced, background remains the same Differential pumped N 2 gasSpace charge, aperture size Low Z solidsDamage, scattering CCDDeep depletionDamage, Effect of High E spontaneous, dynamic range CZT imagersDental X-rayDamage, Effect of High E spontaneous, dynamic range, resolution Phosphor coated imagersPhase plate coupled to CCDDamage, Effect of High E spontaneous, dynamic range, resolution, phosphor saturation Optical coupled Scintillator screen Camera not in beamDamage, dynamic range, saturation Indirect ImagerMultilayer mirror reflects fraction of beam into camera Damage, Calibration depends on alignment Photodiodes, PC diamondDamage, Effect of High E spontaneous, spatial resolution FlorescenceBe doped with high zDamage, contamination and background, signal level PhotoelectricBe grid with MCPCalibration, geometry, Effect of High E spontaneous ThermalEnergy to heatDamage, sensitivity Ion chamberCount ionssensitivity N 2 PhotoluminescenceCount photonsNon-linear space charge, calibration

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx “Direct Imager” x-ray cameras X-Ray Beam Visible Imager Optical Fiber Scintillator X-ray scintilator with fiber coupled imager X-ray scintilator with lense coupled imager X-Ray Beam Visible Imager Lens Scintillator X-Ray Beam X-ray sensitive CCD or photodiode array

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Short FEL pulse reveals scintillator saturation YAG:Ce Light Output FEL energy

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Candidate detectors pros and cons ElementTechnologyProblems AttenuatorSignal reduced, background remains the same Differential pumped N 2 gasSpace charge, aperture size Low Z solidsDamage, scattering CCDDeep depletionDamage, Effect of High E spontaneous, dynamic range CZT imagersDental X-rayDamage, Effect of High E spontaneous, dynamic range, resolution Phosphor coated imagersPhase plate coupled to CCDDamage, Effect of High E spontaneous, dynamic range, resolution, phosphor saturation Optical coupled Scintillator screen Camera not in beamDamage, dynamic range, scintillator saturation Indirect ImagerMultilayer mirror reflects fraction of beam into camera Damage, Calibration depends on alignment Photodiodes, PC diamondDamage, Effect of High E spontaneous, spatial resolution FlorescenceBe doped with high zDamage, contamination and background, signal level PhotoelectricBe grid with MCPCalibration, geometry, Effect of High E spontaneous ThermalEnergy to heatDamage, sensitivity Ion chamberCount ionssensitivity N 2 PhotoluminescenceCount photonsNon-linear space charge, calibration

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Diagnostics Occupy Upstream End of the Front End Enclosure (FEE) Slit Gas Detector Gas Detector Gas Attenuator Solid Attenuators Direct Imager (Scintillator) Total Energy FEL Offset Mirror System Collimator 1 Spectrometer Package Fixed Mask Beam Direction

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx FEE Schematic Solid Attenuator Gas Attenuator High-Energy Slit Start of Experimental Hutches 5 mm diameter collimators Muon Shield FEL Offset mirror system Total Energy Thermal Detector WFOV NFOV Windowless Gas Detector e-e- Direct Imager K Spectrometer Grating

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Slit and Fixed Mask Define Maximum Beam Spatial Extent Fixed Mask Slit Status: PRD done SCR done PDR done ESD in signature FDR in preparation

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Gas Detector / Attenuator Conceptual Configuration 4.5 meter long, high pressure N 2 section Differential pumping sections separated by 3 mm apertures N 2 Gas inlet 3 mm diameter holes in Be disks allow 880  m (FWHM), 827 eV FEL to pass unobstructed N 2 boil-off (surface) Flow restrictor Green line carries exhaust to surface Solid attenuators Gas detector Status Attenuator: PRD done SCR done Prototype done ESD draft PDR in preparation

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Prototype Gas Attenuator runs well at 0-20 Torr

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Gas detectors share differential pumping with the Gas Attenuator 20 Torr ~1 Torr Gas Attenuator high pressure section ~10 -3 Torr 2 m ~0.1 to 2 Torr N 2 ~10 -3 Torr ~10 -6 Torr Gas detector Optical band pass filter Photo tube Photo diode Optical ND filters ~20 cm inner diameter non-specular reflective surface (e.g. treated Al) LCLS X rays cause N 2 molecules to fluoresce in the near UV Single shot, non destructive, measurement of u

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Gas Detector pressure can be adjusted independently of Gas Attenuator pressure

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Schematic of the gas detector from the ESD Data Acquisition System Photodiode Avalanche Photo Diode Cylindrical Vessel Magnet Coils Bandpass and ND Filters Coating Differential Pumping Section 3 mm apertures along beam path Beam / Gas Interaction Region (~0.1 – 2 Torr N 2 ) Magnet Power Supply and Controller Gas Feed And Pressure Control APD Electronics Photodiode Electronics

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Overview of physical processes H.K. Tseng et al., Phys. Rev. A 17, 1061 (1978) N 2 molecules absorb a fraction of the x-rays by K-shell photoionization, emitting photoelectrons of energy E x-ray − 0.4 keV Ionized nitrogen relaxes by Auger decay, emitting Auger electrons of energy ~ 0.4 keV High-energy electrons deposit their energy into the N 2 gas until they are thermalized or reach the detector walls Excited gas relaxes under the emission of near-UV photons x-rays photo e- Auger e- N 2 gas B  

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx A.N. Brunner Cornell University (1967). Photoluminescence of N 2 N 2 has strongest lines in the near UV (between 300 and 430 nm) Backgrounds in the near-UV are difficult to estimate: Effect of recombination of ions at chamber walls? Effect of electrons hitting the chamber walls? We use existing experimental data to estimate the near UV signal: e.g. measurements made for the Fly’s Eye cosmic ray detector

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx The fluorescence yield per deposited energy depends only weakly on the energy of the exciting electron Fluorescence Yield per deposited energy (a.u.) Electron energy (eV) 1.5 Torr 15 Torr 150 Torr 760 Torr 0.85 MeV 8 keV 400 eV (F. Arqueros et al., submitted) Dependence of the photoluminescence yield on the energy of the incoming electron

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Small magnetic field keeps primary photoelectrons away from walls B = 250 Gauss without magnetic field Electron trajectories and energy deposition in N2 at 8.3 keV

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Expected near-UV signal at FEL saturation 8.3 keV, 2 Torr, 2.3 mJ, 250 Gauss 0.83 keV, 0.1 Torr, 2.3 mJ, 60 Gauss

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Expected near-UV signal for low intensities 8.3 keV, 2 Torr, 1  J, 250 Gauss 0.83 keV, 0.1 Torr, 0.1  J, 60 Gauss 30 cm 2.5” 1 cm recess 30 cm x-rays

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Total Energy (Thermal) Sensor Concept Thermistor (sets operating T op, sensitivity  R/  T) FEL pulse Cu heat sink (sets T bath ) 0.5 mm Si substrate (sets absorption, C and G) Radiation-hard absorber High E halo transmitted Sensor protected from beam Low T operation for high diffusivity (  Speed) and low heat capacity C (  Sensitivity) Thin low-Z high-G substrate for FEL absorption, thermistor deposited on back side. Temperature rise is proportional to FEL energy, heat flow to cold bath through substrate Sensor implementation: Nd 0.66 Sr 0.33 MnO 3 (CMR material) on buffered Si substrate. Cooling in mechanical low-vibration pulse-tube cryocooler

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx FEL induced Temperature pulse quickly diffuses to sensor side, then dissipates t = 0t = 0.1 mst = 0.25 ms Time [ms] Delta Temperature at Chip [K] Tc200 Tc150 Tc100 Peak signals are ~1K per mJ of FEL pulse energy as expected for ~mm 3 of Si at ~150K. 0.5mm Si Sensor FEL

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Sensor temperature maintained by Pulse tube cryocooler Considerations: 1)No liquid cryogens in tunnel 2)Low vibrations to reduce microphonic noise and fluctuations in sensor position frequency [Hz] acceleration [µg/rtHz] 4 1/2” flange Pulse tube Cold head He gas compressor and rotary valve separated Low vibrations (SEM compatible) VeriCold PT: ~5W cooling power at 80K, low vibrations by separating rotary valve. Sensor position should fluctuate less than ~25 µm beam jitter.

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Calibration of Total Energy Sensor will be maintained through in situ Laser system Sources of error (according to specs): Variations in laser output E:±1% rms Absolute accuracy of laser output:Not calibrated Variations in optical components:Negligible (below damage threshold) Absolute accuracy of pulse meters:±5% at 532 nm Reflection at Si:37% at 532 nm (flat surface)  roughen, calibrate Beam focus Attenuator: Filter wheel Minilite pulsed Nd-YAG laser, 532 nm Beam splitter on Gimbal mount Sensor on Si Ophir PE-10 Pulse meters: 3% accuracy Incident beam calibration Reflected beam monitoring to assess radiation damage

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Total Energy Error Budget Summary Calibration errors:<5% (limited by accuracy of pulse meter) Electronic noise error:<0.1% at saturation <10% at low energies (depends on excess 1/f noise) Energy loss error:<2% (limited by electron escape) Jitter error:<3% (if jitter is as low as specified) Total error:< 7% at saturation (2 mJ/ pulse) < 7% at 0.2 mJ < 12% at low energies (10 µJ/pulse) Status Total Energy: PRD done SCR done Prototype in preparation ESD in preparation PDR in preparation

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Total Energy Monitor Prototype Vacuum chamber: Based on 6-way cross Refrigeration: Pulse-tube cryocooler No xy-motion in prototype (yet) XYZ-stage with 5µm steps in z, 3µm in xy Sensor: Nd 0.67 Sr 0.33 MnO 3 on Si chip Surface mount resistor as test heat source, laser soon Multiple sensors for different FEL conditions can be operated in final design. To pulse tube and xy-stage Weak link Heater Cu chip mount Cu-capton-Cu wiring traces Cu clamps Sensor Sensor mount on xy-stage allows ±5 mm field of regard and 40  35 mm 2 stay-clear area.

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Direct Imager Laser Energy Meter Thermal Detector Calibration Laser Beam Direction Thermal Detector and Direct Imager

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Wide Field of View Direct Imager Single shot measurement of f(x,y), x, y,u Camera Scintillators

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Photometrics Cascade:512B The Cascade:512B utilizes a back-illuminated EMCCD with on-chip multiplication gain. This 16-bit microscopy camera’s "e2v CCD97" device features square, 16-µm pixels in a 512 x 512, frame-transfer format. Thermoelectric cooling and state-of-the-art electronics help suppress system noise. Dual amplifiers ensure optimal performance not only for applications that demand the highest available sensitivity (e.g., GFP-based single-molecule fluorescence) but also for those requiring a combination of high quantum efficiency and wide dynamic range (e.g., calcium ratio imaging). The Cascade:512B can be operated at 10 MHz for high-speed image visualization or more slowly for high-precision photometry. Supravideo frame rates are achievable via subregion readout or binning.on-chip multiplication gain

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Objective: Navitar Platinum 50 Power: NA: Run027: Low Energy, All undulator modules, Spontaneous Absorbed in 5 um YAG, Maximum ~ 20,000 photoelectrons/pixel Full Well: 200,000 Camera: Photometrics 512B

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Objective: Navitar Platinum 50 Power: NA: Run030: Low Energy, All undulator modules, FEL Absorbed in 5 um YAG, Maximum ~ 3.7e+8 photoelectrons/pixel Full Well: 200,000 Camera: Photometrics 512B

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Objective: Navitar Platinum 50 Power: NA: Run030: Low Energy, All undulator modules, FEL Absorbed in 5 um YAG, Maximum ~ 3.7e+8 photoelectrons/pixel Full Well: 200,000 Camera: Photometrics 512B Zoomed

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Objective: Linos/Rodenstock Apo-Rodagon-D Power: 0.8 NA: Run025: High Energy, All undulator modules, Spontaneous Absorbed in 50 um YAG, Maximum ~ 10,000 photoelectrons/pixel Full Well: 200,000 Camera: Photometrics 512B

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Camera: Photometrics 512B Objective: Linos/Rodenstock Apo-Rodagon-D Power: 0.8 NA: Run026: High Energy, All undulator modules FEL Absorbed in 50 um YAG, Maximum ~ 5.0e+7 photoelectrons/pixel Full Well: 200,000 Zoomed

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Objective: Navitar Platinum 50 Power: NA: Run036: Low Energy, First undulator module, Spontaneous Absorbed in 1 mm YAG, Maximum ~ 1,800 photoelectrons/pixel Full Well: 200,000 Camera: Photometrics 512B

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Experiments Executed at the FLASH VUVFEL to Verify melt Thresholds FLASH VUV Beamline Samples: Bulk SiC Bulk B 4 C Thin Film SiC Thin Film B 4 C Thin Film a-C Bulk Si Thin Foil Al Diamond YAG The FLASH photon energy of 39 eV is strongly absorbed in C resulting in extreme energy deposition in small volumes yet multipulse effects in mirrors not yet a problem. Linac Undulator Gas Attenuator Gas Detector C Mirror Focusing Mirror Sample 15 single shots at each attenuator setting

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Measured crater depths scale with measured pulse energy Nomarski picture of ~ 30 micron diameter crater in SiC induced by FEL at 8 x melt Crater depths, if any, were measured by Zygo interferometry

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Data shows a consistent damage threshold between 120 and 180 mJ/cm 2 Data shows that the shot-to-shot pulse energy varies ~linearly between 0 and 200% No evidence for surface damage below the melt threshold (~ 90 mJ/cm 2 to reach T melt, ~130 mJ/cm 2 to melt SiC) Statistical analysis shows damage threshold Measured crater depths for 2 low fluence 15 shot series, ordered in increasing depth / pulse 15 shot series shot-to-shot relative pulse energy measurements ordered in increasing energy / pulse

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx S. Hau-Reige and D. Rutyov postulate multipulse thermal fatigue thresholds ~ 1/10 of melt Calculate doses for onset of thermal fatigue (D 3 ), to reach melting T (D 1 ), to melt (D 2 ) Doses below melt but above D 3 will not visibly damage surface in one shot but material may breakdown after an unknown number of repeated shots in the same place. Multipulse exposures with eximer laser was inconclusive for Si but data still under analysis

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Channel-cut Si Monochrometer (K- Spectrometer)

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Diagnostics Summary Instrument Name MethodPurposeCalibration and Physics risks Direct Imager Scintillator in beamSP f(x,y), look for FEL, measure FEL u, f(x,y), x,y Scintillator linearity, Scintillator damage, Must be used with Attenuator, Attenuator linearity and background Total EnergyEnergy to HeatFEL udamage Gas DetectorN 2 PhotolumenescenceFEL uSignal strength, Nonlinearities Soft x-ray Spectrometer Be Reflection grating FEL  FEL u Energy Resolution K SpectrometerChannel-cut Si monochrometer Measure undulator relative K Damage, Signal Strength

Richard M. Bionta X-TOD October 12, 2006 UCRL-PRES-xxxxxxx Conclusions Uncertanties constrain detector technology FEL size, shape, and pulse energy Damage thresholds & mechanisms – melted, melt, fatigue Short pulse effects – saturation High energy spontaneous background Avoid placing active detector electronics in beam Single shot damage thresholds at melt verified at FLASH FEL Three technologies chosen for LCLS YAG Scintillator / camera / attenuator – faint FEL Gas photoluminescence – indestructible Thermal – least unknowns