1 BROOKHAVEN SCIENCE ASSOCIATES A Wiggler Beamline for XAS at NSLS-II Paul Northrup NSLS-II Project and Environmental Sciences Department Brookhaven National

1 BROOKHAVEN SCIENCE ASSOCIATES

A Wiggler Beamline for XAS at NSLS-II

Paul NorthrupNSLS-II Project and Environmental Sciences Department

Brookhaven National LaboratoryJuly 18, 2007 NSLS-II User Workshop


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


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


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


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


Energy-dependent spatial distribution

<5% variationwithin beam spot.


Beamline Layout and Optics

• Be window with protective graphite filter• Additional filters• Collimating mirror

• collimation• heat load• harmonics rejection• Pd-coated glidcop, cooled



• Monochromator (LN2-cooled)• Horizontal focusing• Photon shutter • All inside FOE• Two experimental hutches



• Horizontal focusing options: - Sagittal focusing of 2nd crystal of monochromator - Toroidal mirror



• 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


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


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


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


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.


Downstream (bulk) Hutch: 3 stations1) 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


Downstream (bulk) Hutch: 3 stations1) Classic benchtop XAS station2) 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


Downstream (bulk) Hutch: 3 stations1) Classic benchtop XAS station2) Controlled-atmosphere and

containment station3) 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


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


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

Documents

1 BROOKHAVEN SCIENCE ASSOCIATES A Wiggler Beamline for XAS at NSLS-II Paul Northrup NSLS-II Project and Environmental Sciences Department Brookhaven National