Motivation for Top-Up: A beamline perspective David Paterson Top-Up Workshop

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Transcript of Motivation for Top-Up: A beamline perspective David Paterson Top-Up Workshop

  • Slide 1
  • Motivation for Top-Up: A beamline perspective David Paterson Top-Up Workshop
  • Slide 2
  • 4 good reasons for topup 1.stability 2.resolution 3.speed 4.flexibility Cobolt Calcium ZincIron I 0 incident fluxPotassium
  • Slide 3
  • Energy range 4.0 to 25 keV E/E =10 -4 Si(111) and Si(311) KB mirror Microprobe 1 m spatial resolution FZP Nanoprobe 60 nm spatial resolution laser interferometry Measurements X-ray fluorescence mapping (XRF), X-ray absorption spectra (XAS, XANES, EXAFS) Elements accessible Aluminium & heavier by XRF Calcium & heavier by XAS fluorescence Information Elemental mapping, chemical state mapping, ppm sensitivity X-ray fluorescence microscopy beamline Pt spectrum located in a tumour cell Hambley et al, U Sydney
  • Slide 4
  • 1. Stability Beamline optics constant heat load on critical optics can ensure maximum stability Micro and nano-focus optics depend on stable illumination especially angular
  • Slide 5
  • Conceptual design D. Paterson, et al., AIP Conf. Proc. 879, 864 (2007). B. Lai, et al., AIP Conf. Proc. 879, 1313 (2007). I. McNulty, et al., Rev. Sci. Instrum. 67, 9 CD-ROM (1996).
  • Slide 6
  • Beamline optics: horizontal diffracting DCM B. Lai, et al., AIP Conf. Proc. 879, 1313 (2007).
  • Slide 7
  • DCM stability for XANES spectroscopy Monochromator reproducibility Tandem scanning of undulator and horizontal DCM 1 st derivative peak centroid ~ 0.05 eV Data courtesy of Andrew Berry, Imperial College
  • Slide 8
  • X-ray Fluorescence Microprobe OSA scan stage sample zone plate APD or segmented detector fluorescence detector Fresnel Zone Plate (FZP) lenses: ~60-200 nm focus Kirkpatrick-Baez (KB) mirrors: 1-10 m focus (achromatic) Vortex: Single element silicon-drift detector Maia: planar silicon 384 detector array (CSIRO-BNL) Stage: Xradia precision XYZ ~10 nm resolution (FZP mode) with laser- interferometry encoders and feedback Transmission detector: APD or BNL segmented detector SXRF elemental imaging Phase contrast imaging X-ray beam 4-25 keV undulator source, monochromatic, Si (111) E/E ~ 1-2 10 -4
  • Slide 9
  • KB mirror microprobe with Maia-96 prototype Beam Prototype Maia 96 detector enclosure Be entrance window KB mirror pair Sample stage (XY) Microscope Sample holder
  • Slide 10
  • Rat brain sections 1 micron pixels, 50 hours Cobolt Calcium ZincIron I 0 incident fluxPotassium
  • Slide 11
  • Cerebral malaria in rat brain ZincCoboltIron CalciumPotassium Decay in beam current requires accurate normalisation to quantify concentrations
  • Slide 12
  • 2. Resolution Beam stability Microprobe optics require beam stability especially angular stability from source Improve emmitance Low beta function see 4. Flexibility
  • Slide 13
  • Resolution test of nanoprobe with 100 nm r zone plate Cr test pattern 100 nm Period Scan over 16 hours duration 2 m
  • Slide 14
  • Fluorescence detector: geometry for fluorescence detection Traditional geometry Detector perpendicular to incident beam sample @ 75-45 Minimises elastic scatter detection Limits solid angle, lateral sample size and scan range Annular geometry Maximises solid angle, sample @ 90 No constraint on lateral sample size and scan range Horizontal sample scan detector Solid angle detector TransmissionDPCdetector P. Siddons, et al., AIP Conf. Proc., 705 (953) (2004). C. Ryan, et al., Nucl. Instr. Meth. B, 260, 1 (2007).
  • Slide 15
  • Maia detector Cooling/ vacuum connections Optimum sample position 1 mm from front face 10 mm from detector wafer Peltier cooled to -35 C Electrical/ optical data connections Beryllium window Mounting points Incident beam
  • Slide 16
  • Imaging with Maia-96 prototype Sr = Red Fe = Green Rb = Blue
  • Slide 17
  • Imaging gold Rb = Red Au = Green Fe = Blue 8000 X 8000 pixels, 1.25 m, 1.6 msec dwell
  • Slide 18
  • X-ray fluorescence map of ilmenite concentrate 80003600 1.25 m pixels collected in 6 hours (0.75 msec/pixel) Blue = titanium Elemental map: Red = thorium, Green = niobium, Blue = titanium. Display range: Th ~ 800 ppm Nb ~ 1500 ppm
  • Slide 19
  • Mouse brain section 8 Megapixel image in 10 hours 10 keV incident Iron=Red Manganese=Green Zinc=Blue 1 mm Wednesday morning Damian Myers X-ray Fluorescence Microscopy of brain slices.... abs#097 Biological samples tissue sections
  • Slide 20
  • Importance of high definition images Potentially unlimited field of view of scanning microscopy Statistical threshold accumulation strategy Explore heterogeneity Enables 3D studies . As Fe Br Image area is 8.0 x 7.2 mm 2, 6400 x 5760 pixels, each 1.25 m (cropped from 12 x 10 mm 2, 9600 x 8000 pixels), 0.6 msec/pixel dwell
  • Slide 21
  • Br Au Fe 9600 x 8000 binned to 4800 x 4000 Gold particles
  • Slide 22
  • Ultrafast x-ray fluorescence enables High definition 2D maps Statistical accumulation strategy But a 2D 64 megapixel image can be divided into 3D scan 400 X 400 X 400 projections Fluorescence tomography Or 1000 X 1000 X 64 energy steps micro-XANES imaging. Martin de Jonge Fast fluorescence tomography of Cyclotella at 200 nm resolution abs#294
  • Slide 23
  • Fluorescence tomography Martin de Jonge, et al., abs#294
  • Slide 24
  • 3. Speed Scanning microscopy is coherent flux hungry No loss of time during fills Higher average current No settling time required after fills
  • Slide 25
  • Fluorescence tomography
  • Slide 26
  • 4. Flexibility To try unusual operation modes with potentially poor lifetime Low emittance e.g. low beta function Timing modes Special beam size
  • Slide 27
  • Undulator tuning curves Tuning Curves for in vacuum 22mm, 90 period, 6 mm minimum gap undulator with 0.83 T max field. Harmonics to 15 are shown. (achieved 0.97 T!) Brightness 5 keV on 3 rd harmonic 8.7x10 18 ph/s/0.1%BW/mrad 2 /mm 2 25 keV on 9 th harmonic 4.6 x10 15 ph/s/0.1%BW/mrad 2 /mm 2. Curves assume zero phase errors but include allowance of 0.1% for energy spread Phase errors on undulator specified at 90% of theoretical flux at peak 7 th harmonic, > 85% of theoretical flux in the peak at the 9 th harmonic.
  • Slide 28
  • Horizontal diffraction geometry Polarization losses? Pi polarization Acceptance of optics 5.0 keV 50% -> 80% 10 keV 91% -> 99%