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A Wiggler Beamline for XAS at NSLS-II

A Wiggler Beamline for XAS at NSLS-II. Paul Northrup NSLS-II Project and Environmental Sciences Department Brookhaven National Laboratory July 18, 2007 NSLS-II User Workshop. Mission and Scope. Diverse science applications: Material science and catalysis

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A Wiggler Beamline for XAS at NSLS-II

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  1. A Wiggler Beamline for XAS at NSLS-II Paul Northrup NSLS-II Project and Environmental Sciences Department Brookhaven National Laboratory July 18, 2007 NSLS-II User Workshop

  2. Mission and Scope Diverse science applications: Material science and catalysis Environmental and geological sciences Life sciences and biology Chemistry and physics High productivity Advanced capabilities befitting an advanced source Part of larger picture, including Soft bend and 3-pole wiggler sources “Tender” energy range (1-5 keV) and Quick XAS Beamlines moved from NSLS

  3. Draft Design Synthesis of: user input (so far), and what is technically possible Purpose of Workshop: Gather more user input and comments Refine design and needs Many design decisions are being made NOW Formation of “Beamline Advisory Team” begins here Subject to change for technical/facility reasons

  4. NSLS-II Sources for XAS Type: Useful range: Flux: Brightness: (vs NSLS Bend) Soft Bend: 1-5 keV 2x 100x bright, lower-energy 3-Pole Wiggler: 2-35 keV 2x 25x improvement on NSLS bend Damping Wiggler: 2-65 keV 250x 104x very high power and brightness

  5. DW100 Source Characteristics Heat load: total radiated power = 64.6 KW maximum aperture 1 mrad horiz. x 0.15 mrad vertical (or 30 x 4.5 mm at monochromator) delivers 8KW will require cooling of nearly all samples Source-to-optics distance is ~30m, sample 40-50m Source size: ~100um horiz. x 6um vert. x 7m long 1 mrad off-axis, source appears 7mm wide Energy-dependent spatial distribution of beam

  6. Energy-dependent spatial distribution <5% variation within beam spot.

  7. Beamline Layout and Optics • Be window with protective graphite filter • Additional filters • Collimating mirror • collimation • heat load • harmonics rejection • Pd-coated glidcop, cooled

  8. Beamline Layout and Optics • Monochromator • (LN2-cooled) • Horizontal focusing • Photon shutter • All inside FOE • Two experimental hutches

  9. Beamline Layout and Optics • Horizontal focusing options: • - Sagittal focusing of 2nd • crystal of monochromator • - Toroidal mirror

  10. Beamline Layout and Optics • High energy resolution option: • - Second monochromator • - in series with first • - no cooling needed • - useful for Cr, Mn, As, etc. • - requires mechanism for • perfectly matching tune

  11. Canting • Separate 7m wiggler into two 3m segments • Canting angle is ~2 mrad • Optics must be designed to allow second set of components, and leave room for second beam to pass by only a few cm away

  12. Beam Characteristics at Sample Energy range: 4.7-50+ keV Energy resolution: Standard, e.g. Si(111) or higher-resolution mode Beam size depends on focusing and on energy Stability is a priority: beam position within 5 microns at sample energy calibration/repeatability within 10-5 intensity repeatability through optics

  13. Beam Characteristics at Sample Preliminary flux estimates (for guidance only) Energy range: Beam size: Flux(ph/s/0.1%BW): 4.5-10 keV 4.5x30mm 1x1015 10-20 keV 2.5x30mm 8x1014 20-50+ keV 1.2x30mm 2x1014 High-resolution mode would have 1/10 flux Microbeam mode would have 1/100 flux at 1 micron

  14. Experimental Stations • Two hutches in series, initially served by single beam • Future canting will provide independent beam to each hutch • Access to downstream hutch for experimental setup while upstream hutch is in use, but not the inverse.

  15. Downstream (bulk) Hutch: 3 stations • Classic benchtop XAS station • transmission, fluorescence • cryostat/LN2 stages • fluid, catalysis, and electrochemical cells • capable of grazing incidence geometry • ideal for polarization-dependent measurements • option for high-energy-resolution detector • suitable for wide variety of applications

  16. Downstream (bulk) Hutch: 3 stations • Classic benchtop XAS station • 2) Controlled-atmosphere and containment station • operates either open or as glove box for air-sensitive samples • contained/clean enclosure for radioactive, nano, or hazardous materials • multi-element detector • expected applications in environmental, nano and biological sciences

  17. Downstream (bulk) Hutch: 3 stations • Classic benchtop XAS station • 2) Controlled-atmosphere and containment station • 3) Open floor space for larger roll-in apparatus • data and control channels and utilities available • expected uses include magnets, large-volume high pressure cell, and catalysis instruments

  18. Upstream (microbeam) Hutch • Standard K-B mirror set focusing beam to ~1 micron • enclosure can operate as glove box • multi-element detector • can accommodate diamond-anvil cell for measurements at high pressure • suitable for single-crystal EXAFS • wide variety of applications in material science, geology, and environmental science

  19. Bigger picture… • One of several XAS beamlines at NSLS-II • Neighboring soft bend and 3-pole wiggler beamlines could be developed for complementary lower-energy and Quick XAS facilities • Other microprobe and nanoprobe beamlines optimized for imaging

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