Proposed NSLS X13B Microdiffraction Instrument

Source & Optics

James M. Ablett

National Synchrotron Light Source

NSLS 2.8 GeV X-ray Storage Ring

MGU

EPW

X13 Straight-Section

NSLS 'Hard' X-Ray Sources

Photon Energy [keV]

◊MGU

◊ IVUN

NSLS Bending Magnet

X21 / X25 Wigglers

X17 Wiggler

X13 Wiggler

1st Harmonic

2nd Harmonic

3rd Harmonic

Log

[ B

righ

tnes

s (

ph /

sec

/ mm

2 /m

rad2

/ 0.1

% B

W /

300

mA

) ]

X13 Undulator Source

The Mini-Gap Undulator [MGU] – the brightest source of hard x-rays (E ~ 3.7 keV –16 keV) at the NSLS.

MGU parameters:54 pole, 1.25 cm periodAt a gap of 3.3 mm , Magnetic field = 0.92 Tesla and Deflection Parameter, K~1.07Fundamental @ 3.7 keV, 4x1017 ph/sec/mm2/mrad2/0.1%BW/300mA

12 14 161086420

2x1017

6x1017

8x1017

Bri

ghtn

ess

(ph/

sec/

mm

2 /m

rad2 /

0.1%

BW

/300

mA

)

Calculated

Experiment

Photon Energy [keV]

4x1017

2 6 10 14 1814

15

16

17

18

Photon Energy [keV]

Log

[Bri

ghtn

ess

(ph/

sec/

mm

2 /m

rad2 /

0.1%

BW

/300

mA

)]

MGU Spectral Measurements(August 2002 Ablett,Berman)

MGU Brightness – Magnetic Gap=3.3 mm MGU Tuning Curves

Current X13B Beamline Status

monochromatorhutch

27 24 20 15 12

numbers (in meters )indicate distance from center of X13 straight-section, where MGU is located.

Specifications

• The X13B microdiffraction instrument will be modular and compactin design, which will make available a variety of x-ray optics forthe experimentalist.

•Focused X-ray Beams on the micron-length scale and below, together with low and high x-ray divergence will be available with these optics.These will be mounted on a motorized rails and will bereadily accessible.

•Pink Beam (Laue) and Monochromatic modes of operationwill be available.- Energy tunability will be accomplished through a 4 bounce monochromator.

24 272625

Distance from MGU source [meters]

detector circle

four-bounce mono tank

x-ray microfocusing optics

diffractometer

vibration isolation table

X13B Microdiffraction Instrument Layout

vibration isolation table

•Suite of Optics offered Pin Holes

Capillaries

KB Mirrors

Zone Plates

Planar Refractive Lenses (Current R&D)

Key Features:

•Achromatic - Energy independent focusing-pink beam and monochromatic modes

•Accurate Elliptical Figures Achievable (either by bending ormetal deposition ) – Small Spot Sizes

•High Reflectivity at Grazing Incidence Angles

Kirkpatrick-Baez Elliptical Mirrors

Heavy metal

Polished sphericalSilicon substrate

Vertical blade scan current derivative Horizontal blade scan current derivative

blade position [ microns ] blade position [ microns ]

~ 3 microns FWHM

~ 9 microns FWHM

…differentially-deposited elliptical KB optics have been used at X13Bduring the past few years, designed primarily for high-pressure x-ray spectroscopy.

X13B Microprobe

X13B Microprobe

3.7 mm

3.3

mm

1.

2.

3.

1.

3.

2.

Calcium K Fluorescence Mapping of Osteoarthritic Bone

3cm 10 cm

2cm

25 m to MGU source

focal position

incident x-rays

Preliminary KB layout

Expected Parameters1 micro-radian figure error

Spot size – 0.7 x 2 micron2

Divergence – 1mrad (v) x 7 mrad(h)

8 keV, 6x109 ph/secGain 5x104

With Figure Error (1 micro-radian)

Position [mm]In

tens

ity

[arb

. Uni

t]

X13B Microprobe R&D Efforts-Planar Refractive Lenses

(K. Evans-Lutterodt, J.M. Ablett)

Summary

A state-of-the-art hard x-ray microdiffraction instrumentis proposed for NSLS mini-gap undulator beamline X13B.

It will offer a variety of x-ray microfocusing optics –micron scale spatial resolution and below

& high and low divergence.

Big-beam (unfocused ) mode.

Pink Beam and Monochromatic Modes of Operation.

Simultaneous fluorescence and diffraction information.