Motivation for Top-Up: A beamline perspective

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

2. I0 incident flux Potassium Calcium Iron Cobolt Zinc 4 good reasons for topup • stability • resolution • speed • flexibility

3. Pt spectrum located in a tumour cell Hambley et al, U Sydney X-ray fluorescence microscopy beamline • Energy range4.0 to 25 keV ΔE/E =10-4 Si(111) and Si(311) • KB mirror Microprobe • 1 µm spatial resolution • FZP Nanoprobe 60 nm spatial resolution –laser interferometry • MeasurementsX-ray fluorescence mapping (XRF), X-ray absorption spectra (XAS, µXANES, µEXAFS) • Elements accessibleAluminium & heavier by XRFCalcium & heavier by XAS fluorescence • InformationElemental mapping, chemical state mapping, ppmsensitivity

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

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).

6. Beamline optics: horizontal diffracting DCM B. Lai, et al., AIP Conf. Proc. 879, 1313 (2007).

7. DCM stability for XANES spectroscopy • Monochromator reproducibility • Tandem scanning of undulator and horizontal DCM • 1st derivative peak centroid • ~ 0.05 eV • Data courtesy of • Andrew Berry, Imperial College

8. APD or segmented detector OSA sample zone plate fluorescence detector scan stage X-ray Fluorescence Microprobe Fresnel Zone Plate (FZP) lenses: ~60-200 nm focus Kirkpatrick-Baez (KB) mirrors: 1-10 µm focus (achromatic) Transmission detector: APD or BNL segmented detector X-ray beam 4-25 keV undulator source, monochromatic, Si (111) DE/E ~ 1-2 10-4 Phase contrast imaging SXRF elemental imaging 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

9. Beam KB mirror microprobe with Maia-96 prototype Prototype Maia 96 detector enclosure Be entrance window KB mirror pair Microscope Sample holder Sample stage (XY)

10. I0 incident flux Potassium Calcium Iron Cobolt Zinc Rat brain sections 1 micron pixels, 50 hours

11. Cerebral malaria in rat brain Potassium Calcium Decay in beam current requires accurate normalisation to quantify concentrations Iron Cobolt Zinc

12. 2. Resolution • Beam stability • Microprobe optics require beam stability especially angular stability from source • Improve emmitance • Low beta function see 4. Flexibility

13. Resolution test of nanoprobe with 100 nm Δr zone plate Cr test pattern 100 nm Period Scan over 16 hours duration 2 µm

14. Transmission DPC detector detector detector Fluorescence detector: geometry for fluorescence detection P. Siddons, et al., AIP Conf. Proc., 705 (953) (2004). C. Ryan, et al., Nucl. Instr. Meth. B, 260, 1 (2007). • 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 Solid angle

15. Incident beam Maia detector Mounting points Electrical/ optical data connections • Optimum sample position • 1 mm from front face • 10 mm from detector wafer • Peltier cooled to -35 ºC Cooling/ vacuum connections Beryllium window

16. Sr = Red Fe = Green Rb = Blue Imaging with Maia-96 prototype Sr = Red Fe = Green Rb = Blue

17. Imaging gold Rb = Red Au = Green Fe = Blue 8000 X 8000 pixels, 1.25 µm, 1.6 msec dwell

18. Display range: Th ~ 800 ppm Nb ~ 1500 ppm X-ray fluorescence map of ilmenite concentrate • 8000×3600 1.25 µm pixels collected in 6 hours (0.75 msec/pixel) • Elemental map: Red = thorium, Green = niobium, Blue = titanium.

19. Biological samples – tissue sections Mouse brain section 8 Megapixel image in 10 hours 10 keV incident Iron=Red Manganese=Green Zinc=Blue Wednesday morning Damian Myers “X-ray Fluorescence Microscopy of brain slices....” abs#097 1 mm 1 mm

20. Importance of high definition images • Potentially unlimited field of view of scanning microscopy • Statistical threshold accumulation strategy • Explore heterogeneity • Enables 3D studies • ……. AsFeBr Image area is 8.0 x 7.2 mm2, 6400 x 5760 pixels, each 1.25 µm (cropped from 12 x 10 mm2, 9600 x 8000 pixels), 0.6 msec/pixel dwell

21. Gold particles BrAuFe 9600 x 8000 binned to 4800 x 4000

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

23. Fluorescence tomography Martin de Jonge, et al., abs#294

24. 3. Speed • Scanning microscopy is coherent flux hungry • No loss of time during fills • Higher average current • No settling time required after fills

25. Fluorescence tomography

26. 4. Flexibility • To try unusual operation modes with potentially poor lifetime • Low emittance e.g. low beta function • Timing modes • Special beam size

27. 1 3 9 5 22 mm undulator 90 periods 6 mm gap 0.83T max field 7 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 3rd harmonic • 8.7x1018 ph/s/0.1%BW/mrad2/mm2 • 25 keV on 9th harmonic • 4.6 x1015 ph/s/0.1%BW/mrad2/mm2. • Curves assume zero phase errors but include allowance of 0.1% for energy spread • Phase errors on undulator specified at <2.5 degrees Specified > 90% of theoretical flux at peak 7th harmonic, > 85% of theoretical flux in the peak at the 9th harmonic.

28. Horizontal diffraction geometry Polarization losses? Pi polarization Acceptance of optics 5.0 keV 50% -> 80% 10 keV 91% -> 99%